.D AND DESCRIPTIVE
LOGUE
LIBRARY OF 1
IVERSITYofCALE
LICK OBSERVAT
NEGRETTI & ZAMBRA'S
/; ENCYCLOPEDIC
ILLUSTRATED AND DESCRIPTIVE
REFERENCE
CATALOGUE -
OF
OPTICAL, MATHEMATICAL, PHYSICAL, PHOTOGRAPHIC,
AND
STANDARD
METEOROLOGICAL INSTRUMENTS,
MANUFACTURED AND SOLD BY THEM.
NEGRETTI AND ZAMBRA,
©ptidans ani jJrientifit Jfnsirununt Utabrs to
HER MAJESTY THE QUEEN;
H.R.H. THE PRINCE OF WALES;
THE ROYAL OBSERVATORY, GREENWICH; THE ADMIRALTY; BOARD OF TRADE ;
THE ROYAL BRITISH METEOROLOGICAL SOCIETY; THE OBSERVATORIES, KEW, TORONTO, WASHINGTON, VICTORIA; AND CAPE OF GOOD HOPE.
HOLBORN VIADUCT, E.G.,
45, COBNHILL, E.G., and 122, REGENT STREET, W., PHOTOGRAPHERS TO THE CRYSTAL PALACE, SYDENHAM.
LONDON.
PRICE FIVE SHILLINGS AND SIXPENCE. Revised and Corrected Edition.
Oi vvv^
MAYMAN BROTHERS AND LILLY,
PRINTERS,
HATTON HOUSE, FARRINGDON ROAD. LONDON. E.G.
NEGRETTI & ZAMBRA, photographers to tbe Crystal palace Company
OPTICIANS,
AND
METEOROLOGICAL INSTRUMENT MAKERS,
CERAMIC COURT, CRYSTAL PALACE, SYDENHAM, S,E,
NEGRETTI & ZAMBRA' S PHOTOGRAPHIC ROOMS
Are open daily, and Portraits taken in all the most approved Styles, from Carte de Visite to Life Size.
MINIATURES, CARTE DE VISITE, AND OTHER PORTRAITS ENLARGED,
PORTRAITS FROM LIFE. OR ENLARGEMENTS COLOURED IN THE HIGHEST AND MOST FINISHED STYLE EITHER IN OIL OR WATER COLOURS.
All kinds of Photographic Work undertaken, and executed with ability and despatch.
Price Lixts Posted Free.
XEGRETTI & ZAMBRA have, in connection with their Photographic Rooms in the Ceramic Court, Crystal Palace, a department for the sale of Optical, Meteorological, Philosophical, and Photographic Instruments; and respectfully invite inspection of their extensive stock, conveniently arranged for examination, every facility for so doing- being- afforded by the Assistants in attendance.
NEGHETTI & CAMERA, Opticians anfc meteorological instrument
TO
HER MAJESTY THE QUEEN,
AND H. R. H. THE PRINCE OF WALES
A SPECIAL PRIZE MEDAL was awarded at the International Exhibition
of 1 862 to Negretti and Zambra ; and the
AUSTRIAN GOLD MEDAL was also presented to the Firm for the EXCELLENCE oj their PHOTOGRAPHS UPON GLASS, 6V.
740482
HONORARY AWARDS TO NEGRETTI AND ZAMBRA.
1881.
1882.
1883.
1883.
1884.
1851. The only Prixe Medal for Meteorological Instruments was awarded to Negretti and Zambra.
1855. " Honourable Mention."— Paris Exhibition.
The £ew Committee exhibited among their Apparatus one of -A7". <$[ Z*s. Patent Maximum Thermometers ; the Jury awarded an Honour able Mention for this Instrument. Negretti and Zambra not having exhibited at all.
The "Austrian Gold Medal." — For Stereoscopic Photographic Views on Glass. ^
1862. Two Prize Medals. — J. Meteorological Instruments. — The terms of the Award being as follows : — " For many important inventions and improvements, together with accuracy and excellence in objects exhibited."
II. Photographic Transparencies, "for beauty and excellence of, and adaptation of Photography to 'Book Illustrations"
1875. A Prize Medal. — Santiago, Chili, awarded for their exhibited collection of Optical and Physical Instruments.
1876. Three Prize Medals.— Philadelphia, "/or Meteorological Instruments ; " "for Thermometers" and "for Microscopes J*'
1878. A Gold Medal, Paris. The only Gold Medal awarded for Meteorological Instruments in the British Section.
Fisheries Exhibition, Norwich. A Silver Medal and Diploma for Deep Sea Recording Thermometers and Sextants.
Fisheries Exhibition, Edinburgh. A Silver Medal for Deep Sea Recording Thermometers, &c.
Buitenzorg, Batavia, Java Exhibition. A Gold Medal for general excellence of Optical Instruments exhibited.
International Fisheries Exhibition, London. A Gold Medal for Meteorological Instruments. A Silver Medal for Deep Sea Recording Thermometers. A Bronze Medal for Current Meter. A Gold Medal for Standard Barometers.
International Health Exhibition, London. A Gold Medal for Hourly Recording and other Registering Thermometers.
NEGRETTI AND ZAMBRA'S INVENTIONS AND IMPROVEMENTS.
1. — Enamelling the centre or back of Thermometer Tubes. By this invention, Negretti and Zambra have been enabled to make Thermometers at least twenty times more sensitive than heretofore. The delicate Clinical Thermometers now so extensively used could never have been efficiently constructed without the aid of the enamelled tube. See Sensitive Thermometers, pages 32 and 160.
2. — Negretti and Zambra's Patent Self-Registering Maximum Thermometer. Pp. 36 to 45. For a Report on the value of this Thermometer by the Kew Committee see pages 37 and 38.
3. — The Application of Porcelain and Enamelled White Glass Scales to Barometers and Thermometers, the divisions being permanently etclied or painted thereon ; a plan now universally adopted by all makers.
4. — Negretti and Zambra's Patent Mercurial Minimum Thermometers (two patents). See pages 47 to 50.
5. — Negretti and Zambra's Patent Self -Registering Maximum Thermometer, specially arranged for obtaining underground temperatures, Mines, Springs, &c., Marine service, Solar Observations, &c., &c. Seepages 42, 44, 145, 171, and 172.
6. — FitzRoy's Marine Gun Barometer, constructed for use in Her Majesty's Navy, by Negretti and Zambra, the only one adopted and in use in Her Majesty's vessels. See pages 11 and 12.
7. — FitzRoy's Storm or Life-Boat Service Barometer. See page 143.
8. — Pocket and Watch- sized Aneroid Barometer. The first Pocket Aneroid ever produced was manufactured by Negretti and Zambra for the late Admiral FitzRoy. See pages 24 to 27.
9. — The Double Bulb Deep Sea Thermometer, first constructed and supplied to Her Majesty's Navy by Negretti and Zambra in 1 862. For full particulars and the history of this important invention see pages 63, 64, 65, and 173.
10. — Improved Standard Mercurial Deep-Sea Thermometer, the only Instrument capable of giving correct temperatures of the bottom or any intermediate depth of the sea. See pages 66 and 67.
11-— Negretti and Zambra's Patent Strengthened Glass Hydrometer. Seepage 194. 12.— A Portable form of the Open Range Glycerine Barometer. See page 18.
13. — Self Recording Aneroid Barometers with various Improvements.
See pages 27 and 28.
14.— Improved Self-Recording Barographs, Thermographs, Hygrometers.
Seepages 30, 53 to 56, 130.
15-— Negretti and Zambra's Patent Apparatus for recording Hourly Temperatures.
Seepages 55 and 78.
16.— Recording Anemometers, Electrical. Various arrangements constructed by Negretti and Zambra.
CONTENTS.
PAGE
Preface v. to vii
Standard Meteorological Instruments and Meteorological Publications . . 1 to 133 Barometers, Aneroids, Thermometers, and Hygrometers . . . 134 to 151, 152 to 175
Hydrometers and Saccharometers 176 to 195
Steam, Vacuum, Hydraulic, and Gas Pressure Gauges, and Counting Machines 198 to 210
Surveying Instruments, Land Chains, Measures, &c 283 to 307
Nautical Instruments, Sextants, Quadrants, Ships' Lamps, Logs, Mariners'
Compasses, &c., and Sun Dials 308 to 327
Mathematical Drawing Instruments, Scales and Rules 330 to 349
Globes and Orreries 328 to 329
Spectacles, Pocket and Hand Magnifiers 213 to 224
Various Optical Instruments 225 to 228
Opera, Race, and Field Glasses *234 to 240
Microscopes and Apparatus 256 to 275
Telescopes 241 to 255
Polarising Apparatus 277 to 280
Stereoscopes and Slides . . . 229 to 233
Magic Lanterns and Dissolving View Apparatus 350 to 374
Spectrum Apparatus, and the Radiometer 276, 281, 282
Chemical Apparatus, of Glass, Porcelain, and Earthenware .... 375 to 394
Apparatus for Organic Analysis 394, 395
Chemical and Philosophical Apparatus and Instruments, of Metal, &c. . . 396 to 410
Chemical Cabinets and Portable Laboratories 410,411
Frictional Electrical Apparatus 412 to 427
Voltaic or Galvanic Apparatus 428 to 436
Electro-Metallurgical Apparatus 440 to 442
Magnetic and Electro-Magnetic Apparatus 443 to 449
Electric Bells and Alarms 459 to 467
Electric Light Apparatus 437 to 439
Thevmo-Electric Apparatus 450'
Induction Coils and Apparatus 451 to 455
Medical Galvanic and Magnetic Apparatus 455 to 459
Pneumatic Apparatus 468 to 476
Hydrostatics and Hydraulics 477 to 480
Photometers 497
Acoustic Instruments, &c 494
Mechanics and Dynamics 491 to 495
Models of Steam Engines, &c., Apparatus for Illustrating the Phenomena of Heat 481 to 490
Portable Steam Engines ) .... 211
Gun Metal Fittings, for Steam Engines and Boilers, &c. ' .... 210
Bourdon's Steam Gauges 205 to 210
Telegraph Instruments and Apparatus 449, 461, 466
Surgical and Medical Instruments, &c. 498 to 503
Soda Water Machinery and Diving Apparatus, and Ice Machines . . . 504 to 508
Hydraulic Machinery 509
Gas Motors 510, 511
Photographic Apparatus 517 to 553
Appendix 554
General Reference Index 567
Mineralogical and Geological Collections . 503
PKEFACE.
IN again submitting to our numerous friends and patrons a greatly enlarged and revised edition of our Encyclopaedic Catalogue, we do so with some decree of pride, — firstly, that all previous editions have been such as to command the extensive patronage bestowed upon them ; and, secondly, from the award made known at the " Great International Exhibition at Paris," that the superiority and excellence of our instruments, which gained for us the only Prize Medal in 1851, is still maintained, and manifested by the fact that at Paris in 1873 we had awarded to us the ONLY GOLD MEDAL given for our class of instruments in the British Section.
This is further confirmed by the award of THREE GOLD MEDJLL>, SILVER, and BRONZE MEDALS at the International Exhibitions, London, 1883-1884, and other awards specified on page iii.
In this edition, as in all that have preceded it, our endeavour has been to make the the work, not merely a list of prices, but in reality a guide for those who are purchasing Scientific Instruments and Apparatus generally. All instruments are well described, some more fully than others, depending upon the importance of the apparatus or article under consideration.
Our Meteorological Instruments we particularly recommend to those who are about to commence making observations in the science of Meteorologv as being the most recently improved and reliable that can possibly be produced. In confirmation of this we have only to state that for nearly forty years our firm have had the honour of supplying Standard Instruments to all the most important Meteorological Observatories, Scientific Institutions, and Govern- ments of the World ; most of the Geographical and Deep Sea Exploring Expeditions of the last thirty years have been supplied with our Instruments.
To enumerate our various inventions and improvements here would be, with few exceptions, to repeat all that has been said in previous editions ; as it would be tedious, we specify these Inventions and Improvements on pao-e iv., and indicate the section or page in the Catalogue where they will be found fully described. Our doing so must not be taken as an act of egotism ; but for the special purpose of placing on record that we are the Inventors and Improvers of such instruments, as many of our inventions have been appropriated by manufacturers, and sold without the slightest acknowledgment of their origin.
Our extensive business knowledge and experience in each of the various sections of our Trade enables us to obtain full and correct information respecting any new Instruments or Inventions : hence we are in a position to supply to our Correspondents any Specialities made and sold by other firms at their advertised or Catalogue prices.
Viii PREFACE.
At page v. will be found a Table of Contents, referring to the pages where any particular section or class of apparatus will be found, and at page 567 an extensive general Index, giving the marginal number or page for each Instrument: these, combined with upwards of Thirteen Hundred "Wood Engravings (a large proportion of them new), will assist the reader in searching for any particular item.
When Orders are transmitted in Foreign Languages, N". & Z. advise their friends to send verbatim copies of such orders in the original language, as it often occurs that where the order has been translated and copied by persons unacquainted with the nature or use of the articles written for, serious errors arise in the carrying out their correspondents' commands.
Correspondents may, if preferable to them, write in French, Italian, Spanish, or German.
A liberal commission allowed to Merchants, Shippers, or Agents on large transactions. Merchants favouring us with copies of their clients' orders will have special quotations furnished to them if desired.
Full and explicit instructions should accompany orders as to the Address, mode of Conveyance, Shipment, Insurance, Consular Forms, and Declarations, etc., etc. Foreign or Country orders must be accompanied by an adequate Remittance or Order for Payment, or Satisfactory Reference in London.
Every possible care being taken in packing Apparatus and Instruments to insure safety in carriage, ibe cannot be responsible for any damage that may occur in transit after the goods leave our establishment.
The probable expense of Packing Cases, Tin or Zinc-lined, may be taken at say from 5 to 10 per cent, on the value of articles of ordinary dimensions and weight. Yery bulky or extremely heavy goods can. hardly be estimated for ; but 1ST. & Z. will undertake that all packages, &c., shall be supplied at the lowest possible net charge.
All communications from abroad should be directed to the Chier Establishment, Negretti & Zambra, Holborn Viaduct, E.G., London. Letters for their Branches to be specially addressed 45, Cornhill, E.G. ; 122, Regent Street, W. ; or, Negretti & Zambra's Photographic Department, Crystal Palace, Sydenham, S.E.
The compilation and revision of this New Edition of our Catalogue has again been entrusted by us to Mr. R. WILLATS, the Manager of our retail department at Holborn Viaduct ; and we hope that both as a Price List and a Book of Reference it will be found much superior to its predecessors.
NEGEETTI & ZAMBEA.
ERRATA.
PAGE.
7 Last line 0'45 should read 0'6. 20 Fig. 21. Price should read £27 !<»-. 27 Last line, 18s., should read 15s. 32 No. 39. For T\jth of degree read ^ths. 58 Last line, 20s., should read 7s.
(This instrument has been considerably improved since catalogue was printed.
Full particulars forwarded on application.) 65 The line "1 Cubic Foot of Sea Water" should read "Fresh Water" (see
page 558).
67 Price of Magnaghi Pattern Deep Sea Thermometer, £5 10s. 75 No. 98. 63s. should read 50s.
94 No. 133 is no longer made, having been superseded by No. 132. 102 No. 144. 4-inch Anemometer, 63s. should read 60s. 114 No. 158 is no longer made. 124 No. 1 Set of Instruments, instead of £330 to £450, read £170 to £250.
131 Dip Circle No. 136. £35 should read £40.
132 Prices of Charts for figures 21 and 29. 25s. should read 21s. For fig. 28 read 15s.
For Anemometers and Tide Gauges read 35s.
133 Negretti and Zambra's Treatise and Ksemtz's Meteorology are both out of
print.
143 No. 171. FitzRoy Barometer, £6 10s., should read £6 6s. 14§ Fig. 182 should read 183.
Fig. 183 should read 182. 149 No. 199 can also be supplied at £5 5s. 157 No. 267 14-inch, 10s., should read 8s. 6d. 159 No. 299. 400° should read 140?.
No. 300. 600° should read 212°.
No. 301 should read to 600°.
162 The Thermometers, Nos. 313, 314, and 315, are not to be recommended, and
are superseded by Nos. 316 and 317.
163 No. 316 are also supplied on Boxwood Scales at 5s. 6d. and 7s. 6d. Porcelain Scale in Japanned Metal Case, 10s. 6d. should read 7s. 6d. No. 317. 12s. 6d, should read 10s. 6d.
No. 321. 10s. 6d. should read 7s. 6d.
No. 322. 12s. 6d. should read 10s. 6d.
168 No. 366. 16s. 6d. should read 15s.
169 No. 386. 130° should read 110°. 177 No. 423. 27s. 6d. should read 21s. 186 No. 485. 16s. 6s. should read 12s. 6d.
No. 486. 10s. 6d. should read 7s. 6d. 188 No. 510 is no longer made.
No. 514. Fig. 466 should read 514.
No. 515. Fig. 467 should read 515.
No. 517. Fig. 469 should read 517. 196 No. 559. " Vacuum Gauge " should read " Pressure Gauge."
Fig. 459 should read 559. 199 Fig. 578 should read 587. 201 Fig. A should read C.
Fig. C should read A.
Small Machine Counter " with 4 figures at 63s." should read " with 6 figures and reciprocating."
ERRATA.
PAGE.
223 Fig. 697 should read 679.
226 Fig 40 should read 740.
250 No. 859, referred to as fig. 859, should read fig. 861.
251 No 861 should read 859.
252 No. 864. For 190 diameters read 100.
253 No. 866. £8 8s, should read £S.
254 No. 868. £8 8s. should read £8. No. 871. £14 should read £14 10s.
£200 should read £190. £300 should read £280. „ £400 should read £390.
268 No. 925. ith Object Glass £4 10s., should read £6 10s.
ith ditto £5 should read £7 10s. 272 No. 995 6s. should read 5s. 275 No. 1042. £8 8s. should read £7 7s. No. 1044. 10s. 6d. should read 6s. 6d. No. 1045. 12s. 6d. should read 8s. 6d. 280 No. 1075 are also supplied at 5s. and 7s, 6 d. 285 No. 1115. 20 seconds should read 30.
291 No. 1155. £18 18s. should read £19 10s.
292 No. 1165. 36s. should read 35s.
297 No. 1186. £3 3s. should read £3 10s.
307 30-inch Pentagraph, £10 10s., should read £9 10s.
308 No. 1293. 5-inch should read 6-inch. 317 No. 1345. £3 3s. should read £2 2s. 325 No. 1404. 5s. should read 3s.
No. 1407. Is. should read Is. 9d. No. 1418. Is. should read Is. 6d. 356 No. 1761. £12 12s. should read £10 10s.
397 No. 2167.* 16s. should read 10s. 6d.
398 No. 2181 is no longer made.
412 No. 2380. 9-inch at 63s. should read 10-inch
432 Fig. 1888 should read 2564.
434 No. 2554. No. 1 size, 5s. 6d. should read 4s. 6d.
No. 2 size, 4s., should read 3s. 6d. „ No. 3 size, 3s. 6d., should read 3s.
No. 2604 has now been superseded by machines of improved construction.
447 Fig. 2079 should read 2709.
448 No. 2709 is no longer made. 458 No. 2784. 32s. should read 30s.
477 No. 2912. Fig 2612 should read 2912.
479 Fig. 9240 should read 2940.
481 Fig. 2995 should read 2955.
483 No. 2951. Fig. 2251 should read 2951.
No. 2954. No. 2144 should read fig. 3044.
490 No. 3009. Figs. 2109 and 2109* should read figs. 3009 and 3009*,
493 Fig. 2694 should read 3042.
517 No. 3159. For £ plate at £3 3s. read \ plate.
545 No. 3282. £5 15s. should read £6 5s.
NEGRETTI AND ZAMBRA'S
DESCRIPTIVE CATALOGUE.
STANDARD METEOROLOGICAL INSTRUMENTS.
THE practical usefulness of Meteorological Instruments as weather indicators, and their increasing employment for Scientific and Sanitary investigation, render a knowledge of their construction and principles desirable to all. Impressed with the idea that we shall be supplying a want, in giving simple descriptions of those now in use, we have endeavoured to condense such information regarding the instruments used in Meteorology in the present section of our Catalogue.
Every Meteorological Instrument of any practical value being described, with plain instructions for using them, purchasers will be enabled to select such as seem to them most suited to their requirements.
For convenience of reference and comparison we arrange and describe the different instruments used for Meteorological observation under the following headings, viz. : Instruments to show, 1st, the pressure of the atmosphere; 2nd, the temperature of the air ; 3rd, the absorption and radiation of the sun's heat by the earth's surface ; 4th, the humidity of the air ; 5th, the amount and duration of rainfall ; 6th, the direction, the horizontal pressure, and the velocity of winds ; 7th, the electric condition of the atmosphere, the prevalence and activity of ozone, magnetic, and tidal phenomena, &c., &c.
B
INSTRUMENTS FOR ASCERTAINING THE ATMOSPHERIC PRESSURE,
BAEOMETEES.
1. Principle of the Barometer.— The first instrument which gave the exact measure of the pressure of the atmosphere was invented by Torricelli, a Florentine pupil of Galileo, in 1643. It is constructed as follows : A glass tube, C D (fig. 1), about 34 inches long, and from two to four-tenths of an inch in diameter of bore, having one end dosed, is filled with mercury. In a cup, B, a quantity of mercury is also poured. Then, placing a finger securely over the open end, C, invert the tube vertically over the cup, and remove the finger when the end of the tube dips into the mercury. The mercury in the tube then partly falls out, bat a column, A B, about 30 inches in height, remains supported. This column is a weight of mercury, the pressure of which upon the surface of that in the cup is pre- cisely equivalent to the corresponding pres- sure of the atmosphere. As the atmospheric pressure varies, the length of this mercurial column also changes. It is by no means constant in its height ; in fact, it is very seldom stationary, but is constantly rising or falling in the tube. It is, there- fore, an instrument by which the fluctuations taking place in the pressure of the atmosphere, arising from changes in its weight and elasticity, can be shown and measured. It has obtained the name Barometer, or measurer of heaviness, — a word certainly not happily expressive of the utility of the invention. If the bore of the barometer tube be uniform throughout its length, and have its sectional area equal to a square inch, it is evident that the length of the column, which is supported by the pressure of the air, expresses the number of cubic inches of mercury which compose it. The weight of this mercury, therefore, represents the statical pressure of the atmosphere upon a square inch of surface.
In England the annual mean height of the barometric column, reduced to the sea-level, and to the temperature of 32° Fahrenheit, is about 29'95 inches. A cubic inch of mercury at this temperature has been ascertained to weigh 0-43967 Ibs. avoirdupois. Hence 29'95 xO'48967^14'67 Ibs., is the mean
NEGEETTI AND ZAMBKA, HOLBOEN VIADUCT, E.G. 3
value of the pressure of the atmosphere on each square inch of surface, near the sea-level, about the latitude of 50 degrees. Nearer the equator this mean pressure is somewhat greater ; nearer the poles, somewhat less. For common practical calculations it is assumed to be 15 Ibs. on the square inch. When it became apparent that the movements of the barometric column furnished indi- cations of the probable coming "changes in the weather, an attempt was made to deduce from recorded observations the barometric height corresponding to the most notable characteristics of weather. It was found that for fine dry weather the mercury in the barometer at the sea-level generally stood above 30 inches ; changeable weather happened when it ranged from 30 to 29 inches, and when rainy or stormy weather occurred it was even lower. Thus, it became the practice to place upon barometer scales words (Fair, Change, Rain, &c.), indicatory of the weather likely to accompany, or follow, the movements of the mercury ; and the instruments bearing them obtained the name " Weather Glasses."
COMPARISON
OF THE
ENGLISH AND METRICAL SCALES OF BAROMETERS
AT ALL
TEMPERATURES COMMON TO BOTH.
Inches. 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17
BY F. F. TUCKETT, ESQ.
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812-5312 |
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787-1396 |
15 |
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761-7480 |
14 |
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736-3564 |
13 |
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710-9648 |
12 |
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685-5732 |
11 |
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660-1816 |
10 |
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634-7900 |
9 |
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609-3984 |
8 |
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584-0068 |
7 |
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558-6152 |
6 |
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533-2236 |
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507-8320 |
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457-0488 |
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Millimetres. 406-2656 380-8740 355-4824 330-0908 304-6992 279-3076 253-9160 228-5244 203-1328 177-7412 152-3496 126-9580 101-5664 76-1748 50-7832 253916
B 2
NEGEETTI AND ZAMBEA, HOLBOKN TIADUCT, E.G.,
s
II
FIG, 2.
INSTRUMENTS FOR ASCERTAINING THE ATMOSPHERIC PRESSURE.
STANDAKD BAEOMETEES.
2. Negretti & Zambra's Standard Barometers are
constructed on Fortin's principle,* which has been proved to be the most reliable and convenient arrangement yefc introduced. The level of the mercury in the cistern being adjusted previous to each observation to a fixed zero point of ivory, loss of mercury from leakage or oxidation is of little or no importance, and does not affect the accuracy of the readings of the instrument. The tubes are of varying internal diameter, according to the price of each barometer. These tubes are filled with pure mercury, very carefully boiled in the tube to perfectly expel all air or moisture.
The barometer tube is mounted in a brass tubular frame, extending throughout its whole length ; the upper portion of it has two longitudinal openings 5 on one side of the front opening is the barometrical scale of English inches, divided to show, by means of a vernier, -^oth of an inch ; on the opposite side is some, times divided a scale of French millimetres, reading also by a vernier to y^th of a millimetre. The reservoir or cistern of the barometer is of glass, closed at bottom by means of a leather bag, acted upon by a thumb-screw passing through the bottom of an arrangement of brass- work, by which it is protected. A delicate thermometer with the scale divided on its stem, so arranged as to give as accurately as possible the temperatures of the column of mercury, is attached to the brass tube. A mahogany board, with brass bracket and ring, with three adjusting screws for suspending and adjusting the barometer, is supplied with each instrument.
* This form of barometer, now universally adopted by all makers, was originally introduced by Negretti and Zambra.
45, CORNHILL, E.G., AND 122, "REGENT STREET, W., LONDON.
Fortin's barometer cistern shown in section by fig. 3, is formed of a glass cylinder, which allows of the level of the mercury within being seen. The bottom of the cylinder is made of flexible leather, like a bag, so as to allow of being pushed up or lowered by means of a screw, D B, worked from beneath. This screw moves through the bottom of a brass cylinder, C C, which is fixed outside, and protects the glass cylinder containing the mercury. At the top of the interior of the cistern is fixed a small piece of ivory, .A, the point of which exactly coincides with the zero of the scale. This
screw and moveable cistern-bottom FIG. 3.
serve also to render the barometer portable, by con-
fining the mercury in the tube, and preventing its
descending into the cistern.
Fig. 4 exhibits the external construction of the cistern portion of a standard barometer. S S are metal screws that secure the glass cylinder or cistern G Gr partly filled with mercury, M, through this the tube T passes down into the flexible leather bag, with which the instrument is adjusted or made portable by the screw, D B, as previously described. At P is shown the white ivory zero point to which the level of the mercury in the glass cistern is always corrected previous to reading off the height of the mercurial column. This ivory point is seen at A in the section FIG. 4. fio- 3, and at P in fig. 4.
Directions for fixing Hie Barometer. — In selecting a position for a barometer care should be taken to place it so that the sun cannot shine upon it, and that it is not affected by direct heat from a fire. The cistern should be from two to three feet above the ground, which will give a height for observing convenient to most persons. Having determined upon the position in which to place the instrument, fix the mahogany board as nearly vertical as possible ; and ascer- tain if the barometer is perfectly free from air, in the following manner : — lower the adjusting screw at the bottom of the cistern several turns, so that the mercury in the tube, when held upright, may fall two or three inches from the top ; then slightly incline the instrument from the vertical position, and if the mercury in striking the top elicit a sharp tap, the instrument is perfect. If the tap be dull, or not heard at all, there is air above the mercury ; this must be driven into the cistern by partially rescrewing and then inverting the instrument, and gently tapping it with the hand. The barometer being in perfect condition,
6 NBGRETTI AND ZAMBEA, HOLBOEN VIADUCT, B.C.,
suspend it on the brass bracket, its cistern passing through the ring at bottom, and allow it to find its vertical position ; after which firmly clamp it by means of the three clamping screws.
Directions for taking an Observation. — Having taken the temperature by the attached thermometer, the mercury in the cistern must be raised or lowered by means of the thumb-screw (s), fig. 2, until the ivory point (E), and its reflected image in the mer- cury (D), are just in contact ; the vernier is then moved by means of the milled head, until its lower edge just excludes the light from the middle and uppermost point of the mercurial column as seen in fig. 5 ; the reading is then taken by means of the scale on the limb and the vernier. In observing, the eye should be placed in a right line with the fore and back edges of the lower termination or edge of the vernier. A small white reflector placed behind the barometer will assist in throwing the light through the brass frame and the glass tube ; and the observer's vision may be further assisted by the use of a magnifying lens. The great object in standard barometers, is to obtain exact readings, which can only be done by having the eye, the front of the zero edge of the vernier, the top of the mercurial column, and the back of the vernier, in the same horizontal plane.
To remove the Instrument. — If it should be necessary to remove the barometer, first, by means of the adjusting screw (s), fig. 2, drive the mercury to the top of the tube, turning the screw gently when the mercury approaches the top, and stop turning directly any resistance is experienced ; next remove the instrument from the bracket, slowly invert it, and in carrying keep the cistern end uppermost.
3. The Barometer Vernier. — The Vernier, an invaluable contrivance for measuring small spaces, was invented by Peter Vernier, about the year 1630. The barometer scale is divided into inches and tenths. The vernier enables us to accurately sub-divide the tenths into hundredths, and, even to thousandths of an inch. It consists of a short scale made to pass along the graduated fixed scale by a sliding or rack-and-pinion adjustment.
The scales of standard barometers are usually divided into half-tenths, or •05, of an inch, as represented, in fig 6, by AB. The vernier, C D, is made equal in length to twenty-four of these divisions, and divided into twenty-five equal parts ; consequently one space on the scale is larger than one on the vernier, by the twenty-fifth part of *05, which is '002 inch, so that such a vernier shows
FIG 5.
45, CORNHILL, E.G., AND 122, REGENT STREET, W., LONDON.
r/H
c
h
a
0
differences of "002 inch. The vernier of the figure reading upwards, the lower edge, D, will denote the top of the mercurial column ; and is the zero of the vernier scale. In fig. 6, the zero being in line exactly with 29 inches and five- tenths of the fixed scale, the barometer reading would be 29*500 inches. It will be seen that the vernier line, a, falls short of ^
a division of the scale by, as we have ex- plained, -002 inch ; 6, by '004 ; c, by '006 ; d, by "008 ; and the next line by one hun- dredth. If, then, the vernier be moved so as to make a coincide with z, on the scale, it will have moved through '002 inch ; and if 1 on the vernier be moved into line with y on the scale, the space measured will be1 010. Thus, the figures 1, 2, 3, 4, 5 on the vernier measure hundredths, and the intermediate lines even thousandths of an inch. In fig 6*, the zero of the vernier is between 29'65 and 2970 on the scale. Passing the eye up the vernier and scale, the second line above 3 is perceived to lie evenly with a line of the scale. This gives '03 and '004 to add to 29*65, so that the actual reading is 29'684 inches.
For the ordinary purposes of the
30
B
FIG
6.
barometer as a " weather glass," such minute measurement is not required. In household and marine barometers, the scale is only divided to tenths, and the vernier constructed to measure hundredths of an inch. This is done by making the vernier either 9
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FIG 6*.
or ll-10ths of an inch long, and dividing it into ten equal parts. The lines above the zero line are then numbered from 1 to 10 ; sometimes the alternate divisions only are numbered, the intermediate numbers being very readily inferred. Hence, if the first line of the vernier agrees with 1 on the scale, the next must be out one-tenth of a tenth, or '01 of an inch from agreement with next scale line ; the following vernier line must be "02 out, and so on. Conse- quently, when the vernier is set to the mercurial column, the difference shown by the vernier from the tenth on the scale is the hundredths to be added to the inches and tenths of the scale.
Price, Standard Barometer (fig 2) £880
Ditto, with English and Millimetre Scales 990 10 10 0 Ditto, with Tube 0'45-inch internal diameter . 12 12 0
NEGEETTI AND ZAMBEA, HOLBORN VIADUCT, E.G.
m
FIG. 9.
FIG. 7. FIG. 8.
4. Large Standard Barometers with attached Thermometer suited for Observatories and Public Institutions. The tubes are T6oths internal diameter, and the bulbs of the thermometers are of the same dimensions.
Price, Fig. 7. £21 0 0
5. Observatory Standard Barometers with extra large tube and cistern, arranged for observations being taken by the Cathetometer for extreme precision, as used at the Greenwich and Kew Observatories.
Price, Barometer, Fig. 8, , £25 0 0 £30 0 0 Cathetometer, Fig. 9 ... £35 0 0
45, CORNHILL, E.G., AND 122, BEGENT STREET, W., LONDON.
FIG. 10.
FIG. 11.
6. Cathetometer,^ (fig. 10.) Improved arrangement, suited for Observing Stations of the First Class. Price £50 to £80 ; varying with the fineness and accuracy of the divisions and the number of adjustments attached to the instrument.
10 NEGEETTI AND ZAMBEA, HOLBOEN VIADUCT, E.G.,
7. Observatory Standard Barometer, fig. 11, of the highest class suitably mounted, for being read off with the Cathetometer, with a tube of exceedingly large internal diameter, the cistern also being of very large area — especially arranged for taking observations with the most extreme precision. Our woodcut shows the Barometer to be without any scale, the readings being obtained by observing the level of the mercury in the tubes and the upper point of the cistern index, (or zero screw) through the telescope of the Cathetometer. Price, as fig. 11, £50 0 0 to 70 0 0
8. The Cathetometer, shown in fig. 9, is used for ascertaining with the utmost accuracy the space or distance between any two points. A brass rod or cylinder is firmly supported on a heavy base having three arms, each arm furnished with adjusting screws for setting the upright rod truly vertical. This rod is accurately divided throughout its length, and so arranged that it will revolve horizontally.
Exactly at right angles to this scale and attached to it is a framework carrying a small Achromatic Telescope furnished with fine wire or spider lines in the eye-piece. This telescope is mounted with levels, having coarse and fine adjustments with clamps, &c., much' in the same manner as a Theodolite Telescope. The distance between the points to be ascertained is observed through the telescope, which can be moved with its adjustments vertically up or down upon the divided scale — and its indications read off by means of verniers, which sub-divide the scale to the five-hundredth or one-thousandth part of an inch.
The Cathetometer scale may be divided either in English inches or Centimetres and Millimetres as desired.
Price of Cathetometer, as fig. 9, £35 0 0
9. Glass Cases for Standard Barometers of polished ebonized wood with plate glass sides and door with secure fastenings for the exclusion of dust and preserving the instrument from injury. .Price £5 5 0 to £10 10 0
10. Testing Chamber with double-action Air Pump for testing Standard Barometers, as used at the Kew Observatory. £70 0 0
11. Negretti and Zambra's Mountain Barometer (fig. 12), on Fortin's principle, is more portable, and less liable to derangement than ordinary mountain barometers. The arrangement of the flexible leather cistern is so simple that should the mercury become oxidized, it can be quickly removed, cleaned, and returned to the cistern without fear of affecting the correctness of the indications. The vernier reads to '002 of an inch, and the whole
45, CORNHILL, E.G., AND 122, EEGENT STEEET, W., LONDON.
11
FIG.
FIG. 14.
instrument is arranged in the most compact and convenient form for safety in travelling, and obtaining very accurate altitude
measurements.
Price, Including Brass Tripod Stand (as fig. 12) and Travelling Case for the Barometer, with English or Millimetre Scale £10 10 0
12. Standard Mountain Barometer of simpler form and smaller tube. Price £8 8 0
13. Standard Syphon Barometer (Gay Lussac's), divided on the glass tube, suited for Laboratory use (fig. 13), mounted on mahogany board, with thermometer and two verniers. Price £550
14. Standard Syphon Tube Mountain Barometer (Gay Lussac's), with attached thermometer, and improvement in the tube for excluding air. This is shown in fig. 14, and known as Gay Lussao's Air Trap : its use being to arrest any air that may pass up between the glass and the mercury. The bubbles of air are stopped and collected at the shoulder of the trap at K, and cannot possibly get up into the tube. This barometer is light and convenient for travelling. The graduations are upon the brass tube with verniers at each extremity reading from the centre. By adding the two readings together the correct height of column is obtained to -g^th °f an inch.
Price of Barometer, in leather travelling case, with Brass
Tripod Stand (fig. 15) £880
This Syphon Barometer does not require correction for either capillarity or capacity, as each surface of the mercury is equally depressed by capillary attraction, and the quantity of mercury which falls from the long limb of the tube occupies the same length in the short one. The barometric height must, however, be cor- rected for temperature, as in the cistern barometer.
15. Board of Trade Standard or Kew Marine Barometer, bronzed brass frame, with iron cistern, and mounted on mahogany board, as in fig. 16. The graduations on the scale are so arranged that the exact reading can be obtained at once, without any previous adjustment of the level of the mercury in the cistern, as in the Fortin barometer. Price £550
16. Meteorological Offi.ee Station Barometer, Bronzed metal frame, with iron cistern and glass scales mounted on mahogany board. Exact readings can be taken without any previous adjust- ment of the mercury, fig. 17. Price, £770
17. Board of Trade Marine Barometer, similar to No. 16, but mounted on arm, with gymbal ring, instead of a mahogany board. Price, Packed in travelling case .£440
12 NEGEETTI AND ZAMBRA, HOLBORN VIADUCT, E.G.,
18. FitzRoy's Marine Gun Barometer, constructed by Messrs. Negretti & Zambra under the immediate superintendence, and named by permission of, the Admiral for the special use of Her Majesty's navy, mounted with vulcanised India-rubber packing to prevent concussion and breakage caused by gun-firing.
Packed in case £5 10 0
Extra tube for ditto 1150
See also Section Marine Barometers.
Trials of the FitzRoy Marine Barometer under Fire of Guns.— Some of the first baro- meters made by Messrs. Negretti and Zanibra on Admiral FitzRoy's principle were severely tried under the heaviest naval gun firing, on board H. M.S. Excellent', and under all the circumstances they withstood the concussion. The purpose of the trials was " to ascertain whether the vulcanised India-rubber packing round the glass tube of a new marine "barometer did check the vibration caused by firing, and whether guns might be fired close to these instruments without causing injury to them." In the first and second series of experiments, a marine barometer on Admiral FitzRoy's plan was tried against a marine barometer on the Kew principle, both instruments being new, ani treated in all respects similarly. They were " hung over the gun, under the gun, and by the side of the gun, — the latter both inside and outside a bulkhead ; in fact, in all ways that they would be tried in action with the bulkheads cleared away." The result was that the Kew barometer was broken and rendered useless, while the new pattern barometer was not injured in the least. In a third series of experiments, Mr. Negretti being present, five of the new pattern barometers were subjected to the concussion produced by firing a 63-pounder gun with shot, and IGlbs. charge of powder. They were suspended from a beam immediately under the gun, then from a beam immediately over the gun, and finally they were suspended by the arm to the bulkhead, at the distance of only 3ft. 6in from the axis of the gun ; and the result was, according to the official report, "that all these barometers, however suspended, would stand, without the slightest injury, the most severe concussion that they would ever be likely to experience in any sea-going man-of-war." These trials were conducted under the superintendence of Captain Hewlett, C.B., and the guns were fired in the course of his usual instructions. His reports to Admiral FitzRoy, giving all the particulars of the trials* are published in the " Ninth number of Meteorological Papers," issued by the Board of Trade.*
* With reference to these barometers, we have received the subjoined testimonial, with permission to use as we please.
" Meteorologic Office, June 12th, 1863. " MESSRS. NEGRETTI AND ZAMBRA,
" The barometers which you have lately supplied to Her Majesty's ships through this Office are much approved, being good for general service, afloat or on land.
"(Signed) R. FITZROY."
Admiral FitzRoy writes : —
" This marine barometer, for Her Majesty's service, is adapted to general purposes.
" It differs from barometers hitherto made in points of details, rather than principle : — 1. The glass tube is packed with vulcanised India-rubber, which checks vibration from con- cussion, but does not hold it rigidly, or prevent expansion. 2. It does not oscillate (or pump), though extremely sensitive. 3. The scale is porcelain, very legible, and not liable to change. 4. There is no iron anywhere (to rust*). 5. Every part can be unscrewed, examined, or cleaned, by any careful person.
" These barometers are graduated to hundredths, and they will be found accurate to that degree, namely, the second decimal of an inch."
19. Negretti & Zambra's Short Tube Barometer, specially constructed by N". & Z. for Balloon experiments, Altitude Measurements, or for use at elevated mountain stations. price £770
45, COENHILL, E.G., AND 122, REGENT STREET, W., LONDON.
13
FIG. 15.
FIG. 16.
FIG. 12.
20. Negretti and Zambra's Students' Standard Barometer. In laying off and dividing the scale of this instrument, allowances have been made to compensate for the ordinary rise and fall of the mercury, making it sufficiently accurate for observers who do not wish to incur the expense of Fortin's arrangement for adjusting to a Zero Point. Fig. 16. Price £550
14
NEGRETTI AND ZAMBRA, HOLBORN VIADUCT, E.C.
21. Magnifying the Barometer Eange. — The limit within which the barometric column oscillates, does not exceed four inches for extreme raDge, while the ordinary range is confined to about two inches ; and it has often been felt that the utility of the instrument would be much enhanced if by any means the scale indications could be increased in length. This object has been sought to be obtained by bend- ing the upper part of the tube from the vertical, so that the inches on the scale could be increased in length. Such an instrument was invented by Sir S. Moreland, in 1772, and named by him " the Diagonal Barometer." Another variation of Barometer, invented by M. Cassini, and improved by M. J. Benoulli, about the same date, was constructed with the upper part of the tube expanded into a large Bulb, and the lower part of the tube giving the scale is very much contracted in the bore, and bent at a right angle. From this the instru- ment was termed the Horizontal Rectangular Barometer. The upper part of the Barometer tube has also been forme d into a Spiral, with the scale placed along it, which is thus greatly enlarged.
Another form of Extended Range Barometer was in- vented and made by M. Amontons in 1695, and named by him the Pendent Barometer. It is a Mercurial Barometer, the upper half of the tube (the indicating portion) being of smaller internal diameter than the lower half. By this arrangement, an extended range of scale is obtained. The lower end of this tube is open, and the mercury supported in it at varying distances by the upward pressure of the atmosphere, very similar in action to that of Howson's Barometer.
Like the previously described instruments, this Barometer can only be regarded as a scientific curiosity, and is very subject to become out of adjustment in transit. This is unfortunate, as these Barometers are curiously sensitive, or perhaps we should more properly say, the movements of the mercury are rendered more visible.
These methods of enlargement Barometer indications are not so convenient as Dr. Hook's elegant arrangement em- ployed in the ordinary Dial or Wheel Barometer. Therefore they are now very little used, and are of very little practical utility.
FIG. 18.
45, COENHILL, E.G., AND 122, EEGENT STEEET, W., LONDON.
15
FIG. 18*.
22. Negretti and Zambra's Howson's Patent Long Range Barometer.
" The object of this instrument is to add to the sensitive- ness of the ordinary mercurial column, by giving it an increased range, a desideratum which it appears to accomplish with simplicity and efficiency.
" The principle of construction -will be understood on refer- ence to the diagram, fig. 18, which represents a section of the working parts of the barometer divested of its case.
" A is the barometer tube, which is of large dimensions, and of greater length than usual in proportion to the additional length of range which it is intended to apply to it. The cistern, B, is of a tubular shape, so as to contain a fixed depth of mercury, also determinable by the range. To the bottom of this cistern is attached, concentrically, a light glass stem or long hollow tube, S, hermetically sealed, springing to a height of about 28 inches above the fixed level of the mercury in the cistern.
" When all the parts are in situ, as in the diagram, fig 18*, the tube A being freely suspended, and the whole filled with the requisite quantity of mercury, the immediate result of the arrange- ment is that the cistern hangs in suspension without any fixed support. The stem C, it will be observed, passes up the tube A, and terminates a little below the upper level of the mercury M : its upper end is therefore exposed to no more downward pressure than that caused by the weight of the mercury above it, and consequently there is an excess of upward pressure from the atmosphere exteriorly which tends to raise the cistern.
" If we suppose, for instance, the area of the stem to be half a square inch, and its top to be covered with 1 inch in depth of mercury (the space above being of course a vacuum), there will be a pressure tending to push the cistern downwards of only J Ib. or thereabouts, while the atmosphere will be pressing upwards on an equal area with a force of 7 Ibs. or more. Thus it will be seen that when the excess of upward pressure is exactly balanced by the weight of the cistern with its stem, and contained mercury up to the level &, an equilibrium will be established which will keep the cistern stationary. If from any cause the cistern should become lighter, it will ascend : if it should become heavier, it will descend, and the extent to which it will move in either case will be limited by the immer-
16 NEGEETTC AND ZAMBEA, HOLEOBN VIADUCT, B.C.,
sion or emersion of the tube A, or rather of the glass which bounds it. This is precisely the action which takes place under the influence of the fluctuations of atmospheric pressure. For, let the internal area of the tube A be supposed to be 1 square inch, and let a barometric rise take place equal to 1 inch by the ordinary standard, it is evident that a cubic inch of mercury will under these conditions leave the cistern, pass into the tube, and accumulate above the top of the stem : consequently the cistern, being relieved of a portion of its weight, will be pushed upwards until the cubic inch is replaced by the immersion of the glass of the tube A. As soon as this point has been reached it will become stationary ; but in the meantime, in the act of rising, it will have pushed up the entire column before it ; so that the total rise of the top of the column will be compounded of two motions, viz., of the ordinary barometric rise, and the rise of the cistern. The converse of this takes place on the occurrence of a diminution of atmospheric pressure. When the column moves, the cistern follows it, and when the cistern moves, it drags the entire column with it.
" The instrument has been in use for many years, and its movements have been found to follow with accuracy those of the best standard Barometers. Its sensitiveness and activity during storms is conspicuous. There is also another advantage which this construction confers, viz., that the cistern is self-adjusting with regard to its level. Readings may be taken to three places of decimals without a vernier, and without any adjustment for variation of level in the cistern. At the same time, the error due to temperature is of an almost in- appreciable amount." * Price, in Ornamental carved Oak Case as fig. 18*. £14 14 0
23. McNield's Long Range Barometer. — A barometer designed on a directly opposite principle to the one just described. The tube is made to float on the mercury in the cistern. It is filled with mercury, inverted in the usual manner, then allowed to float, being held vertically by glass points or guides. By this contrivance, the ordinary range of the barometer is greatly increased. As the mercury falls in the tube with a decrease of pressure, the surface of the mer- cury in the cistern rises, and the floating tube rises also, which causes an additional descent in the column, as shown by graduations on the tube. With an increase of pressure, mercury will leave the cistern and rise in the tube, while the tube itself will fall, and so cause an additional ascent of mercury.
Price, £12 12 0
Both Howson's and McNield's Barometers are constructed by Negretti and Zambra with scales of from five to eight times that of the ordinary standard. Their sensitiveness is consequently increased in an equal proportion, and they have the additional advantage of not being affected by differences of level in the cistern.
* Extract from the Proceedings of the .British Meteorological Society, Nov. 20th, 1861. Vol. i. p. 81.
NEGRETTI AND ZAMBRA, HOLBOEN VIADUCT, E.G. 16 A
Negretti and Zambra's Self -compensating Standard Barometer
consists of the usual form of standard instrument, but attached to the vernier is a double rack moved by one pinion, so that when adjusting the vernier in one position, the second rack moves in the opposite direction, carrying along with it a plunger (the exact size of the internal diameter of the tube) dipping in the cistern, so that whatever displacement has taken place in the cistern, owing to the rise or fall of the mercury, it is exactly compensated by the plunger being more or less immersed in the mercury, consequently no capacity correction is required. Price, £18 18 0
Standard Barometer, with Electrical Adjustment. — This barometer consists of an upright glass tube dipping into a glass cistern of mercury, so contrived, that an up-and-down movement, by means of a screw, can be imparted to it. Through the top of the tube a piece of platinum wire is passed and her. metically sealed. The cistern also has a metallic connection, so that by means of copper wires (in the back of the frame) a galvanic circuit is established ; another connection also exists by means of a metallic point dipping into the cistern. The circuit, however, can be cut off from this by means of a switch placed about midway up the frame. On one side of the tube is placed a scale of inches ; with a small circular vernier, divided into 100 parts, connected with the dipping point, and working at right angles with this scale.
Eor taking an observation, a galvanic battery is connected by two binding screws at the bottom of the frame. The switch is turned upwards, thereby disconnecting the dipping point ; the cistern is then screwed up, so that the mercury in the tube is brought into contact with the platinum wire at the top ; the instant this is effected a magnetic needle arranged as a galvanometer on the barometer board will be deflected. The switch is now turned down ; by so doing the connection with the upper platinum wire is cut off, and established between the dipping point carrying the circular vernier and the bottom of the cistern ; the point is now screwed by means of the milled head until the needle is again deflected, and the line on the vernier cutting the division on the scale is the exact reading of the barometer. Price, £18 18 0
The two Barometers above-mentioned were exhibited 1y Negretti and Zambra at the Meeting of the Royal Meteorological Society, March, 1886.
45, CORNHILL, E.G., AND 122, BEQENT STREET, W., LONDON. 17
24. The Water Barometer first constructed by Professor Daniell of King's College for the Royal Society in 1830 was fitted up under his superintendence at their rooms in Somerset House. It consisted of a glass tube 40 feet in length and about one inch in diameter. This barometer was in action at Somerset House for some two years, and a series of observations made with it showed " that the Water Barometer preceded by one hour the indications of a mercurial instrument having a column of mercury of f inch diameter."
On the removal of the Royal Society from Somerset House this Water Barometer was taken down by Messrs. Negretti and Zambra, refilled, and mounted by them at the Crystal Palace, Sydenham, where for a short time it excited considerable interest, but owing to various causes the indications were found to be incorrect scientifically. Eventually the instrument was destroyed by fire during the winter of 1866. At the suggestion of Dr. D. Price another Water Barometer was erected by Mr. Jordan for the Crystal Palace Company ; but although the Water Barometer is of great interest as a weather glass, its indications were again found to be of but little scientific value, owing to the effect of varying temperature on the aqueous vapour above the column of water. This difficulty led to the substitution by Mr. Jordan of glycerine for water, and the construction of the now well-known Jordan Glycerine Barometer, one of which is erected at the Times office and one also at the Kew Observatory by a grant from the Royal Society. Mr*. Whipple, the director at Kew, states the records obtained by it are fairly satisfactory.
The tube of the Glycerine Barometer is composed chiefly of ordinary com- position gas tubing of f inch internal diameter : to this is very carefully joined and cemented about four feet of glass tube one inch internal diameter. The upper end of this tube is formed into a funnel-shaped cup, having a conical shaped stopper of India-rubber arranged for conveniently filling and adjusting the instrument. The glass portion of the tube is the indicating part of the barometer. Suitable divided scales are placed at the sides of the glass portion of the tube, one showing inches and tenths of absolute measure, and on the opposite side another scale of equivalent values of a column of mercury at a temperature of 60° Fahrenheit.
R. H. Scott, Esq., of the Royal Meteorological Society, writes that during the continuance of a violent gale and storm, " a fall of more than 16 inches of glycerine has been noted." "The movements of the glycerine column are 10' 76 times greater than those of the mercurial column at the standard tem- perature, 333*57 inches of glycerine being equivalent to 31 inches of the mercurial barometer." We are chiefly indebted for these details of the Glycerine Barometer to Mr. Jordan's Pamphlet,* to which we refer our readers for further- particulars as to the construction and use of the instrument.
* The Glycerine Barometer with Plate and Table of Corrections for Temperature, by James B. Jordan^ Mining Record Office Museum of Practical Geology. Price, One Shilling.
C
18
KEGRETTI AND ZAMJ'.KA, HOLBORN VIADUCT, E.G.,
It will be seen that owing to the great length of the tube, viz., 27 feet, Jordan's Barometer can only be fitted up in very few buildings. To gain the advantage of so extended a range of scale in a convenient sized instrument, Messrs. Negretti and Zambra have constructed their
NEW LONG RANGE MERCURIAL AND GLYCERINE BAROMETER,
.28
B
-31
24*. The Long Range or Open Scale Barometer is shown in section in fig. 19. It consists of a glass tube of the syphon form ; one side of the syphon, A, or closed end, being about 33| inches long, and the other only a few inches in length. To this short end is joined a length of glass tubing, B, of a much smaller (internal) diameter ; both tubes are of equal length, the smaller one being open at the top. The large ||_£2|| tube, A, is filled with Mercury, and the small tube, B, partly filled with Glycerine, a fluid many times lighter in specific gravity than Mercury ; the rising and falling of the mer- curial column in the large tube having a lighter fluid to balance, and that dispersed over a larger space by reason of the difference in the diameter of the two tubes, a longer range is obtained, due loth to the unequal capacity of the tivo tubes and the difference in the specific gravity of Mercury and Glycerine.
The range of these barometers is from six to ten inches to the inch of the ordinary Mercurial Barometer, yi^ of an inch can easily be observed without the use of a vernier. It is a most interesting instrument, as from the extremely extended scale the slightest variation is plainly visible. The actual size and form is about that of an ordinary Barometer, as seen in fig. 20 ; extreme length about 40 inches.
FAIR
FIG. 20.
FIG. 19.
Price, as fig. 20 ... Do., with Portable Stop Cock
£5 5 5 10
45, CORNHILL, B.C., AND 122, KEGENT STREET, W., LONDON.
19
SELF-REGISTERING BAROMETERS.
For many years a good and accurate self-recording barometer was much desired. This want is now satisfactorily supplied, not by one, but by several descriptions of apparatus. The first was the design of Admiral Sir A. Milne, who himself constructed, in 1857, we believe, the original instrument, which he used with much success.
25. Negretti and Zamtora's improved Self- Registering Mercurial Barometer or Baro- graph.— In this instrument the various parts of the mechanism have been so modified and arranged that the record on the papers is obtained with the greatest precision and delicacy. The engraving (fig. 21) will give the general details. It should, however, be mentioned, that it is not a picture of the outward appearance of the instrument. The position of the barometer should be behind the clock ; it is represented on one side merely for the purpose of clearly illustrating the arrangement. The instrument has a large syphon barometer tube, in which the mercurial column is represented. On the mercury at A, floats a glass weight, attached to a silk cord, the other end of which is connected to the top of the arched head on the short arm of a lever-beam. The long arm of this beam is twice the length of the short arm, for the following reason. As the mercury falls in the long limb, it rises through an equal space in the short limb of .the tube, and vice versa. But the barometric column is the difference of height of the mercury in the two limbs ; hence the rise or fall of the float through half-an-inch will correspond to a decrease FIG. 21. or an increase of the barometric column of one
inch. In order, then, to record truly the movements of the mercurial column, and not those of the float, the arm of the beam connected with the float is only half the radius of the other arm. From the top of the large arched head a piece of watch-chain descends, and is attached to the marker, B, which properly counterpoises the float, A, and is capable of easy movement along a groove in a brass bar, so as to indicate the barometric height on an ivory scale, C, fixed on the same vertical framing. On the opposite side of the marker, J?, is a metallic point, which faces the registration sheet and is nearly in
20
NEGEETTI AND ZAMBEA, HOLBOBN VIADUCT, E.G.,
contact with it. The framing, which carries the scale and marker, is an arrangement of brass bars, delicately adjusted and controlled by springs, so as to permit of a quick horizontal motion being communicated to it by the action of the hammer, E, of the clock, whereby the point of the marker is caused to impress a dot upon the paper. The same clock gives rotation to the cylinder, D, upon which is mounted the registering paper. The clock must be re- wound when a fresh paper is attached to the cylinder, which may be daily, weekly, or monthly, according to construction ; and the series of dots impressed upon the paper shows the height of the barometric column every hour by day and night. The space traversed by the marker is precisely equal to the range of the barometric column.
Price, in an Ornamental Oak Case, fig. 21 £18 18 0 and 22 0 0
26. King's Self - Registering Barometer. Mr. Alfred King, Engineer of the Liverpool Gas-Light Company, designed, in 1854, a barometer to register, by a continuous pencil- tracing, the varia- tions in the weight of the atmosphere ; and a highly-satisfactory instrument, on his principle, and constructed under his immediate superintendence, was erected at the Liverpool Observatory.
Fig. 22 is a front elevation of this Barometer. A, the barometer tube, is three inches internal diameter, and it floats freely (not being fixed as usual) in the fixed cistern, B, guided by friction- wheels, W. The top end of the tube is fastened to a chain, which passes over a grooved wheel, turning on friction rollers. The other end of the chain supports the frame, D, which carries the tracing pencil. The frame is suitably weighted and guided, and faces the cylinder, C, around which the tracing paper is wrapped, and which rotates, once in twenty-four hours by a clock movement. For one inch change in the mercurial column the pencil is moved through five inches, so that the horizontal lines on the
FIG. 22.
45, CORNHILL, E.G., AND 122, REGENT STREET, W., LONDON. 2T
tracing, which are half an inch apart, represent one-tenth of an inch change in the barometer. The vertical lines are hour lines, and being nearly three- quarters of an inch apart, it will be seen that the smallest appreciable change in the barometer, and the time of its occurrence, are recorded. The barometer in this instrument is similar to Mr. McNeild's " Long-Range Barometer," described page 16. Constructed to order £280 to £300
THE ANEROID BAROMETER.
27. The Aneroid Barometer. The extremely ingenious instrument called the Aneroid, is no less remarkable for the scientific principles of its con- struction and action, than for the nicety of its mechanism. As its name implies, it is constructed " without fluid." It was invented by M. Vidi, of Paris. In the general form in which it is made it consists of a brass cylindrical case about five inches in diameter and two inches deep, faced with a dial graduated and marked similarly to the dial-plate of a " wheel-barometer," upon which the index or pointer shows the atmospheric pressure in inches and decimals in accordance with the mercurial barometer. Within the case, is placed a flat metal box made of German Silver, generally not more than half an inch deep and about two inches or a little more in diameter, from which nearly all the air is exhausted. The top and bottom of this box is corrugated in con- centric circles, so as to yield inwardly to external pressure, and return when it is removed. The pressure of the atmosphere continually changes, and with this varying pressure, the top and bottom of the box approach to and recede from each other by a small quantity ; but the bottom being fixed to the base, nearly all this motion takes place on the top. The top of the box is elastic, and rises and falls according as the compressing force lessens or increases. To the eye these expansions and contractions are not perceptible, so small is the motion. But they are rendered very evident by a delicate mechanical arrangement, communicating with a system of levers ; and, by the intervention of a piece of watch-chain and a fine spring passing round the arbour, turning the index to the right or left, according as the external pressure increases or decreases. Thus, when by increase of pressure the vacuum box is compressed, the mechanism transfers the movement to the index, and it moves to the right ; when the vacuum box expands under diminished pressure, the motion is reversed, and the index moves to the left. As the index traverses the dial, it shows upon the scale the pressure corresponding with a good mercurial barometer.
The Aneroid being placed under the receiver of an air pump the scale is laid off to correspond with a Mercurial Barometer Gauge, and afterwards compared and corrected by a Standard instrument.
22 NEGRETTI AND ZAMBRA, HOLBORN VIADUCT, E.G.,
The engraving ("fig. 23) represents the latest improved mechanism of an aneroid. The outer casing and face of the instrument are removed, but the index hand is left attached to the arbour. A is the corrugated vacuum box
which has been exhausted of air through the tube J, and hermetically sealed by soldering. B is a powerful curved spring, resting in gudgeons fixed on the base-plate, and attached to a socket be- hind, Fj in the top of the vacuum box. A lever, (7, joined to the stoub edge of the spring, is connected, by the bent lever at I), with the chain, .E7, the other end of which is coiled round, and fastened FIG 23. to the arbour, F. As the box, A, is com-
pressed by the weight of the atmosphere increasing, the spring, J9, is tightened, the lever, (7, depressed, and the chain, E, uncoiled from F, which is thereby turned so that the hand, H, moves to the right. In the meanwhile the spiraj spring, G, coiled round F, and fixed at one extremity to the frame- work, and by the other to F, is compressed. When, therefore, the pressure decreases, A and B relax, by virtue of their elasticity ; E slackens, G unwinds, turning F, which carries the index hand, H, to the left. Near / is shown an iron pillar, cast as part of the stock of the spring, B. A screw works in this pillar through the bottom of the plate, by means of which the spring, J?, may be so adjusted to the box, A, as to set the index, H, to read on the scale in accordance with the indications of a Mercurial Barometer. In the higher class of aneroid baro- meters, the lever, C, is formed of a compound bar of brass and steel, so skilfully arranged as to perfectly compensate for the effects of extreme variations of temperature.
The greatest perfection in Aneroids is now attained by having as perfect and dry a Vacuum as possible. Compensation being obtained by the compound metal bar previously mentioned.
A Thermometer is sometimes attached to the Aneroid, as it is convenient for indicating the present temperature of the air, but for accuracy and safety from breakage, N. and Z. recommend the use of a separate Thermometer.
Admiral FitzRoy, in his Barometer Manual, writes : " The Aneroid is quick in showing the variation of atmospheric pressure ; and to the navigator who knows the difficulty, at times, of using barometers, this instrument is a great boon, for it can be placed anywhere, quite out of harm's way, and is not affected by the ship's motion, although faithfully giving indication of increased or diminished pressure of air. In ascending or descending elevations, the hand or the Aneroid may be seen to move (like the hand of a watch), showing the
45, CORNHILL, E.C., AND 122, REGENT STREET, W., LONDON.
23
height above the level of the sea, or the difference of level between places of comparison."
Aneroid barometers, if occasionally compared with a mercurial standard, are similar in their indications, and valuable ; but it must be remembered that for exact scientific observation, the Aneroid barometer cannot be put into comparison with the mercurial column for strict accuracy, although its con- venient size and great sensibility render it most useful for obtaining observations where a mercurial instrument is inconvenient to carry.
Col. Sir H. James, R.E., in his Instructions for taking Meteorological Obser- vations, says of the Aneroid : " This is a most valuable instrument, it is ex- tremely portable. I have had one in use for upwards of ten years."
One of the objects of Mr. Glaisher's experiments in balloons was "to compare the readings of an Aneroid barometer with those of a mercurial baro- meter." In the comparisons the readings of the mercurial barometer were corrected for index-error and temperature. Speaking of Aneroid indications,* Mr. Glaisher remarks : —
" A third (Aneroid) graduated down to five inches, and most carefully made
and tested under the air- pump before use, read the same as the Mercurial Barometer throughout the high ascent to seven miles, September 5th, 1862.f I have taken this instrument up with me in every sub- sequent high ascent, and it has always read the same as the Mercurial Baro- meter. These experiments prove that an Aneroid can be made to read correctly at low pressures.
" I may mention that on several occasions, Aneroid Barometers have been taken whose graduations have been too limited for the heights reached : these -p 24 have not broken or become
* Travels in the Air. By F. Glaisher. Page 89. The Aneroid Barometer, f Wolverhampton to Cold Weston, near Ludlow, September 5th, 18G2.
24
NEGBETTI AND ZAMBEA, HOLBORN VIADTJCT, E.G.,
FIG. 25. FIG. 26.
deranged by being subjected to a much less pressure than they were prepared for, but have resumed their readings on the pressure again coming within their graduations." The Aneroids used by Mr. Glaisher were made for him by Messrs. Negretti and Zambra.
Directions for using the Aneroid. — Aneroids are generally suspended with the dial vertical ; but if they be placed with the dial horizontal, the indications differ a few hundredths of an inch in the two positions. Therefore, if their indications are to be recorded, the instrument should be read off alivays in the same position.
As before observed, the Aneroid will not answer for exact scientific pur- poses, as its error of indication changes slowly, and hence the necessity of its being set from time to time with the reading of a Standard Barometer. To allow of this being done, at the base of the outer case is a screw in connection with the spring attached to the vacuum box. By applying a small screw-driver to this screw, the spring of the vacuum box may be tightened or relaxed, and the index hand adjusted to the right or left on the dial, as in correcting a watch.
28. Pocket Aneroid Barometers. — The patent for the Aneroid having expired, Admiral FitzRoy urged upon Messrs. Negretti and Zambra the desirability of reducing the size of the instrument as then made, as well as of improving its mechanical arrangement, and compensation for temperature. They accordingly at great expense, labour, and experiment, succeeded in reducing its dimensions to two inches in diameter, and an inch and a quarter thick. The exact size and appearance of these Aneroids is shown by fig. 24. For prices of Aneroid Barometers see page 29.
45, CORNHILL, E.G., AND 122, REGENT STREET, W., LONDON. 25
29. Watch Aneroid. — Negretti and Zambra have still further reduced the size of the Aneroid to that of an ordinary watch, our engravings, figs. 25, 26 showing their exact size. By a beautifully simple contrivance, a milled rim is constructed to move round, and carry with it the index or pointer over the scale engraved on the dial, for the purpose of marking the reading, so that any increase or decrease of pressure may be readily seen. These very small instru- ments are found to act quite as correctly as the largest, and are much more convenient. Besides serving the purpose of a weather-glass in the house or away from home, if carried in the pocket, they are admirably suited to the exigencies of tourists and travellers. They may be had with scale sufficient to measure heights of 20,000 feet ; with a scale of elevation in feet, as well as of pressure in inches, engraved on the dial. The scale of elevation, which is for the temperature of 50°, was computed by Professor Airy, late Astronomer Royal, who kindly presented it to Messrs. Negretti and Zambra, for publication.* Moderate- sized Aneroids, fitted in leather sling cases, are found very serviceable to pilots, fishermen, and for use in coasting and small vessels, where a mercurial barometer cannot be employed, because requiring too much space."
Negretti and Zambra' s Watch-sized Aneroid Barometers, figs. 25 and 26, have now for many years been fully tried and tested, as ordinary Weather Indicators, for obtaining Altitude Measurements, and also for Mining purposes. From the very extensive patronage afforded to them by Government authorities (for Military and Naval service), Engineers, Surveyors, and Scientific Observers, &c., N. and Z. feel justified in giving their unqualified recommendation to these instruments, for Travellers' use, as being both accurate and convenient.
30. Our woodcuts, figs. 24, 25, 26, show form and actual size of the most useful Aneroid Barometers. Fig. 24 being our Pocket size. Fig. 25 our Watch size, with the simple Barometer Scale of inches and20ths of an inch. This same size instrument is manufactured with Altitude Scales ranging from 10 to 20 thousand feet. Fig. 26 is of similar size to the preceding, but has the Altitude Scale arranged to revolve, so that the zero or 0 of this scale being set to the point occupied by the Index at the commencement of the ascent, the elevation attained above the starting point may be at once seen in a rough way on the scale. The divisions of this scale not being absolutely similar all round, causes an error in the reading, therefore, where exact observations are desired, the zero of the scale should be placed opposite to the 31 point, and the indications read off in the usual manner by inches and fractions, their value being known by reference to the Altitude Tables sent with the instrument, so that this form of Aneroid combines both methods of observing in one instrument.
* See List of Books on Meteorology at end of this seotiou.
26
NEGRETTI AND ZAMBRA, HOLBOKN VIADUCT, E.G.,
FIG. 27.
Our fig. 27 shows one of the most convenient arrangements yet introduced, viz., a Watch-sized Aneroid, with a reliable Thermometer and Compass. The hinged leather case containing the three instruments, being but little larger than an ordinary portemonnaie. Price, see page 29.
31. Measurement of Heights by the Aneroid. — The dial of the Watch Aneroid for determining altitudes is engraved with two scales in concentric circles, the inner circle being divided into inches and tenths of an inch, corre- sponding with the scale of the Mercurial column of a Standard Barometer. The outer circle is divided into spaces representing 100 feet, each tenth division being numbered as 1,000, 2,000, &c. The zero point of this circle corresponds with 31 inches of the Barometer scale, for this reason, that the Barometer never rises so high as 31 inches, consequently, our scale of feet is always outside the weather range. The zero of the feet scale has nothing whatever to do with the sea-level, that is a variable point and must be determined at the time of observation either by actual measurement at half tide level, or by computation from a known height.
32. Measurement of Altitudes above Sea Level. — In order to deter- mine the height of any station above the sea-level with this instrument, we must notice at what point it stands at the shore ; we then ascend, and on reaching the desired point, observe the position of the index on the dial. We then deduct the number of feet opposite the reading on starting from that against the reading at the elevated station, this gives the height above the level of the sea. Thus, if at sea-level, the barometer stands at 30 inches, and at the elevation it stands at 26 inches we get 900 feet, deducted from 4,800 feet, giving us a height of 3,900 feet, and so on for the other points of the scale.
When great accuracy is required, simultaneous observations must be taken at the two stations to obviate any error that might arise from a change of weather between the times of observation.
Further instructions for altitude measurement will be found in Negretti and Zambra's Treatise on Meteorological Instruments.
45, CORNHILL, E.G., AND 122, REGENT STREET, W., LONDON. 27
33. " Great storms are invariably preceded by a fall in the barometer of from '05 to '10 of an inch per hour. Storms from the eastward sometimes give loss local warning, but they are well foretold by the increase of statical force. Storms of a cyclonic character travel, it has been found, on an average about 20 miles an hour towards some point between NE. and SE., generally towards the former. They, therefore, take about twenty-four hours to traverse the British Isles, from the time of their commencement in the west of Ireland. The east coasts may thus be warned one day in advance by the telegraph ; and as the approach of a storm can be foreseen at the place threatened hours before its advent, noticev of gales may usually be given from one to two days in advance. As regards the exact time and locality, the prognostication of storms must necessarily present much difficulty. The forecaster must be guided in these respects rather by experience, to be gained by practice, than by princi- ples ; little information can be given without going into a complete examination of particular storms, each of which would present points of difference."
Strachan'Si Weather Forecasts.
NEGRETTI AND ZAMBRA'S SELF-RECORDING ANEROID BAROMETERS.
FIG. 28.
34. This instrument registers automatically with ink upon a ruled paper chart attached to a vertical cylinder revolved for seven days by means of a Clock movement inside it. The fluctuations of atmospheric pressure act upon seven Aneroid vacuum chambers, connected by an exceedingly simple mechanical con- trivance to a long lever arm carrying the Pen, by which a magnified diagram is produced upon the paper on the cylinder of the rise or fall or present height of the Barometric column. These papers are ruled to represent inches and tenths of the Mercurial Barometer Scale. A small Thermometer is mounted upon the
base of the instrument.
Price, in a Glazed Cabinet, as shown in fig. 28 .'.£7100
Kuled Papers, per Hundred, for above ... 18 0
NEGRETTI AND ZAMBRA'S SELF-RECORDING ANEROID BAROMETER.
FIG. 29.
35. These Instruments are arranged to show the various fluctuations that have taken place in the Barometer during the absence of the observer. They consist of a carefully finished Aneroid, and an eight-day Clock ; between these is placed in a vertical position, a revolving cylinder having a metallic paper attached to it ruled to coincide with the inches and tenths of the barometer scale. Close to this paper, is a pencil mounted on a metallic rod and is moved up 'and down as the variation of atmospheric pressure acts upon the vacuum chamber of the Aneroid ; at every hour this pencil is made to mark the paper by simple mechanism in connection with the clock.
By this means a black dotted curved line is produced on the paper, show- ing at a glance the present height of the barometer — whether it is falling or rising — for how long it has been doing so, and at what rate the change has taken place — if falling or rising at the rate of one-tenth of an inch per hour, or one-tenth in twenty-four hours ; all of which are particulars most essential to know when foretelling the weather, and which can only be obtained from an ordinary barometer by very frequent and regular observations.
Our engraving (fig. 29.) shows the full mounting of the Registering Aneroid, combining a reliable Timepiece with an exceeedingly interesting Meteorological Instrument, of a suitable and convenient size for a library or dining room mantel-shelf.
Recording Aneroid Barometer with Thermometer, ag shown fig. 29
Price, £22 0 0
Large size ditto ditto with more Ornamental Mounting . 27 10 0
Haled charts for the above, per Hundred ...',. 110
PRICES OF NEGRETTI AND ZAMBRA'S 29
STANDARD ANEROID BAROMETERS.
Compared and Corrected Scale Aneroid, Compensated for temperature, as supplied to the Royal Navy and Meteorological Department . . . . .-. . . . .550
Surveyors' or Engineers' Aneroid Barometer for Altitude Measurements, Compensated for temperature, with Revolving Ring, carrying Index, range of Scale, 10,000 feet, 4J inches diameter ...........770
Pull Range Engineers' Altitude and Surveying or Balloon Aneroid, corrected and Compensated for temperature, with 20,000 feet, Altitude scale (See engraving in Surveying Instru- ment Section) 880
Mining Surveyors' Aneroid Barometer, with a Scale reading
to 7,000 feet above the Sea Level to 2,000 feet below . 5 10 0
Leather Case with Sling Strap, for any of the above . . 0126
Pocket-Sized Aneroid, with Revolving Ring carrying Index
(size shown in fig. 24) . . . . . • . . .440
Mountain Aneroid Barometer, Pocket-Size, for measuring
Altitudes to 10,000 feet, Compensated for temperature 550
Ditto ditto ditto to 20,000 feet, fig. 24 . . .060
Watch-Sized Aneroid Barometer, of best Construction, Compensated for temperature, for Meteorological Observations or Altitude Measurements to 10,000 feet, (size shown in fig. 26) . . . . . . . .550
Watch-Sized Aneroid Barometer, to 20,000 feet . . .660
Watch-Sized Aneroid Barometer, with Devolving Altitude Scale
for 10,000 or 20,000 feet (Seepage 25) . . £5 10 0 6 10- 0
Watch-Sized Aneroid Barometers, with Thermometer and
Compass, in Morocco Pocket Case (fig. 27.) . £7 70 and 880 Watch-Sized Aneroid Barometers in Solid Gold Cases £15 15 0 to 21 0 0 Ditto ditto in Stout Silver Cases . . £6 6 0 and 770
Aneroid Barometers may be had with the French Metrical Scale, or with the English and corresponding French Scale engraved on the same instrument.
In the Section of our Catalogue " Household Barometers" — will be found an illustrated price list of Aneroid Barometers in Ornamental Mountings, suited for the Drawing Room, Library or Hall, Ships or Yachts, &c.
80
NEGUETTI AND ZAMBBA, HOLBOKN VIADUCT, E.C.,
FIG. 30.
36. Recording Mercurial Barometer or Barograph — for automatically recording the variations of atmospheric pressure by Photography. Recom- mended by the Meteorological Committee of the Royal Society, and used by many of the principal Meteorological Observatories.
Fig. 30. exhibits the general arrangement of this Barograph. B is a Standard Mercurial Barometer mounted upon a mahogany board and table, lacing it is a Drum D, to which is attached the sensitised Photographic Paper. This cylinder is revolved once in 24 or 48 hours by the clock C. A Condensing Lens, E, projects the light from the Gas Burner G through the space F over the edge of the mercurial column, and thence to the photographic combination lens P, by which an image of the mercurial column is formed upon the sensitive paper on the drum for a regulated space of time. A screen or shutter L acted upon by the clock cuts off this image for the space of four minutes every two hours, leaving white lines upon the photographic paper representing intervals of two hours. At the side of the barometer tube are placed two zinc rods attached to the barometer board at the lower ends at A. These rods are con- nected at their upper ends with a delicate mechanical arrangement H and K, so contrived as to compensate for varying Thermometric changes in the mercurial column, these variations of temperature being also recorded upon the sensitive paper.
Attached to the apparatus is, a glass cylinder, M, (of the same internal diameter as the Barometer tube), partly filled with mercury, into which is placed a sensitive Standard Thermometer for giving the temperature of the surround- ing air. B is an adjusting screw for regulating the height of the barometer upon its support. The apparatus when in action is enclosed in a light tight box.
The Barograph is constructed to special older, the cost varying from Sixty to Seventy Guineas.
45, COEKHILL, E.G., AND 122, REGENT STEEET, W., LONDON.
31
INSTRUMENTS FOR ASCERTAINING THE TEMPERATURE OF THE AIR.
THEEMOMETBES.
FIG. 31.
37. Undoubtedly there is no instrument the use of which has so greatly increased in the past few years as the Thermometer : not only is it now essential to the scientific observer, the meteorologist, the physician, and the chemist; but both for domestic uses and manufacturing processes a really accurate thermometer is indispensable. The following is a list of the various forms of Standard Thermometers manufactured by Negretti and Zambra ; all of these, to ensure extreme accuracy, have their scales divided by the Prize Dividing Engine (fig. 31) to which was awarded a Prize Medal at the Great Exhibition of 1851, and is described in the Report of the Jurors as follows : —
" This is a beautifully contrived Divider on Ramsden's principle, with a long fine steel screw. The novelties are — first, the wheel at the screw head, which is divided into 400 parts, and has cut upon its circumference (which is made broad) a helix screw, in the thread of which runs a detent, carried along by the run of the thread till it meets a stop clamped on the helix at a definite point. This arrests the screw at this point of the motion. A Prize Medal was awarded."
Messrs. Negretti and Zambra supply Dividing Engines made on the above principle both for circular and straight line divisions.
Price . . £35 to £150
NOTE.— From Report of the Juries of the Exhibition of 1851. " Negretti and Zambra are the only exhibitors in the British portion who have sent Thermometers with their stem* graduated — the only safe instruments for delicate experiments."
32
NEGRETTI AND ZAMBKA, HOLBORN VIADUCT, E.G.,
STANDARD THERMOMETERS.
Two important improvements in the Tubes and Scales of Thermometers and Barometers, first introduced by Negretti and Zambra, have become so extensively used that N. and Z. deem a short notice necessary to secure to themselves the credit of the inventions.
The first improvement is the introduction of a white Enamel at the back of Thermometer Tabes, which renders the mercury much more plainly visible both in large and small-bore tubes. Most of the extremely delicate Ther- mometers now in use would have been almost useless but for this enamelling. This invention has also been applied to the back of Barometer Tubes. The second invention is the use of Porcelain for Scales and Dials of Thermometers, Barometers, &c., in place of metal, ivory, or wood, all of which so soon become soiled and tarnished, and eventually the divisions and figures are obliterated by the action of the atmosphere, sea-water, or damp. The divisions and figures on these porcelain plates are etched in with fluoric acid, and the colour permanently burnt or melted in by fire. That these are important inventions may be inferred from their use in all thermometers and barometers supplied to the Board of Trade and other Government departments.
38. Independent Standard Thermometer (fig 32), with Negretti and Zambra's Enamelled tube, and Engine, divided into either Fahrenheit or Centigrade scales, the divisions engraved on its own stem and mounted on silvered brass, boxwood, or Negretti and Zambra's Patent Porcelain Scales.
Price, £550 Kew Certificate for above Thermometer 050
39. Comparative Standard Thermometers (fig. 33). These Thermometers are made by comparison with great care, from an accurate standard, correct to TV °f a degree. Engine-divided EnamelledTubes mounted on Silvered Brass or Negretti and Zambra's Patent Porcelain Scales, with Mahogany or Oak framing. Price, £220 and £2 10 0
FIG. 32.
N. & Z's Standard Thermometers are made from selected tubes, the internal diameter of which is ascertained by very carefully conducted experiments. They rrT(-, oo 'J are also strictly tested for index error, and a copy of the corrections, if any, furnished with each instrument, if required.
We recommend the Standard Thermometers not to be mounted in any way, but the tube to be enclosed in a strong outer glass jacket; the bulb dipping
45, COKNHILL, E.G., AND 122, BEGENT STREET, W., LONDON.
33
FIG. 34.
30-
70-
30-
•40
FIG. 35.
into a reservoir of mercury, and the whole hermetically sealed, as in our Standard Deep-sea Thermometers ; by these means the bulb is effectually protected from the pressure of the atmosphere, either from barometrical changes or difference in altitude, and the divisions on the stem are so covered by the outer glass tube that they cannot be effaced or become invisible. [
40. Board of Trade Thermometer. — It consists of a carefully compared thermometer with ISTegretti and Zambra's enamelled tube divided on its stem to degrees, which are sufficiently large to admit of sub-division into tenths of degrees and ranging from 0? to 130°. The scale is of Negretti and Zambra's Patent Porcelain, having the figures etched upon it, and burnt in a permanent black. It is a reliable comparative or reference thermometer, adapted for almost any ordinary purpose, and cannot be injuriously affected by any chemical action arising from air or sea- water. (Fig. 34). This thermometer is employed in
D
NEGRETTI AND ZAMBEA, HOLBORN VIADUCT, E.G.,
the Royal Navy and for the observations made at sea for the Board of Trade
and Meteorological Department.
Price, in Neat Japanned Case 0 10 6
Ditto Copper Case 0 12 6
A set of 6 Ditto ditto, in Copper Cases, fitted in a Mahogany Box . £2 10 0
41. Thermometers of Extreme Sensitiveness. — Negretti and Zambra's Instantaneous Thermometer, with Gridiron form of bulb, and divided upon the stem, as shown in the International Exhibition of 1862, used by Mr. Glaisher in his Balloon ascents to obtain very rapid thermometric readings. (Fig. 35) Price, £3 3 0 to £6 60
42. Thermometers, very delicate, with Spiral or Coiled bulbs, engine-divided upon the stem, mounted on
boxwood, metal, or opal glass scales. Fig. 36.
Price, £220 and £330
43. Earth Thermometer — for ascertaining the tem- perature of the soil at various depths. The tube is about five feet long, enclosed in stout wood, protected and strengthened by metal mountings and a pointed cap. The scale is of Negretti and Zambra's Patent Porcelain with enamelled and burnt-in divisions and figures. Figs. 37 and 38. Price, £1 15 0 and £220
44. Earth Thermometers in series for inserting into the ground at depths of 6 inches, 12 inches, 24 inches, 48 inches and 120 inches. These thermometers are arranged with a scale about 6 inches above the earth.
Price for the series £7 7 0
45. The temperature of the soil is a very important element in the consideration of climate especially in connection with the growth of vegetation. — " It has been calculated by Mr. Raikes, from experiments made at Chat Moss, that the temperature of the soil when drained averages 10° higher than it does when undrained ; and this is not surprising when we find that lib. of water evaporated from 1,000 Ibs. of soil will depress the whole by 10°, owing to the latent heat which it absorbs in its conversion into vapour."
Faraday has calculated that the average amount of heat radiated in a day from the sun on each acre of earth in the latitude of London, is equivalent to that which would be produced from the combustion of thirteen thousand four hundred and forty pounds of coal. FIG. 38. " The extremes of temperature in the different climates of the
FIG. 37.
45, COENHILL, E.G., AND 122, EEGENT STREET, W., LONDON.
35
earth are widely separated from each other, and the range of the thermometer is always greatest in the interior of the continents within the tropics. Mr Campbell, in the country of the Botchuanas, saw the thermometer at 8 a.m. at 28°, and at 84° at noon. Mr. Bruce records a temperature at Gondar of 113°. The thermometer at Benares rises to 118° ; at Sierra Leone the thermometer on the ground has been seen to rise to 138P, and Humboldt gives many instances of the temperature of the torrid zone rising to 118°, 120°, and 129°. At one time he found the temperature of a loose, coarse-grained granite, in the sun, 140'5. In the Dukhun at a height of 3,090 feet above the sea, Col. Sykes once saw the thermometer in the shade at 105°, the range of the thermometer generally being from 93°.9 to 40^.5."
Slightly beneath the surface of the earth in the tropics, Humboldt states temperatures of 162° and 134° are frequently noted, and in white sand at Orinoco 140°, whilst at the Cape of Good Hope under the soil of a bulb garden a temperature of 150° is recorded by Herschell. In China, the temperature of water of the fields was found to be by Meyer 113° and adjacent sand much hotter. These extremes of temperature, which would cause the specific gravity of the air to vary from 1167 to 863, may serve as a kind of measure of the dis- turbing causes which interfere with the velocity and local direction of atmos- pheric currents and other phenomena, the calculation of which has been founded upon mean results. — DanielVs Meteorology.
It is stated that below the layer of constant temperature (estimated at about 80 to 90 feet from the earth's surface), the temperature is found to increase one degree Centigrade for every 100 feet.
46. Earth Thermometer, Symons' Arrange- ment, with NEGUETTI & ZAMBBA'S Slow Action Thermometer. An iron tube closed at the lower end is forced down into the earth, and secured at the desired depth, and the thermometer lowered down into it by a cord or chain to the bottom, and allowed to remain a sufficient time ; when the temperature is to be noted, it is quickly drawn up and its indication observed. The great advantage of this method of obtaining Earth Temperatures is that the ther- mometer can at any time be compared with a Standard, which is a difficult if not almost impossible operation to be carried out with Thermometers of great length (fig 39). Also see fig. 49, page 42.
Price, according to length, £110 £150
£1 10 0, £2 2 0.
By means of these instruments it has been found that variations depending on the hour of the day are
D2
FIG. 39.
36 NEGRETTI AND ZAMBKA, HOLBOEN VIADUCT, E.G.,
scarcely sensible at a depth of 2 or 3 feet, and that those which depend on the time of year decrease gradually as the depth increases, but still remain sensible at the depth of 25 feet, the range of temperature during a year at this depth being usually about 2 or 3 degrees Fahr.
The mean rate of increase of temperature downwards is about 1 degree Fahr. for each 55 feet.
SELF-REGISTERING THERMOMETERS FOR HEAT.
Negretti and Zambra' s Patent Self-registering Maximum Thermometer.
The only Instrument of the kind adapted for transmission to India and the Colonies. 47. Previous to the Great Exhibition of 1851, all persons interested in meteo- rological observations were constantly annoyed by the inconvenience arising from, the imperfect construction of Maximum Thermometers ; and although Messrs. Negretti and Zambra at that time exhibited one or two new forms of instru- ments, nothing new in principle was brought forward. A thermometer, old in principle, greatly improved by Negretti and Zambra, wherein a bubble of air caused a separation in the mercurial column to form an index, was exhibited by them ; but as the air bubble at different temperatures assumed different lengths it was not approved by the Jury appointed to examine Meteorological Instru- ments. The instruments invented by Dr. Rutherford and Six, as Maximum Thermometers, had both proved inefficient for the purposes required ; and although the best and most correct forms of these were also exhibited by Negretti and Zambra, they still saw that a great want would be met if a perfect instrument could be invented to indicate Maximum temperatures, all the above being imperfect — Rutherford's from the tendency of the index to plunge in the mercury, Six's from the different expansive properties of the alcohol, mercury, &c., of which it is composed, and the one already alluded to, not only from the defects before noticed, but also from its liability to resolve itself into an ordinary thermometer when used, unless in the hands of a skilful manipulator. How far the New Patent Maximum Thermometer of Negretti and Zambra has supplied all these deficiencies may be judged from the fact that in all the principal Observatories throughout the world it is used, to the exclusion of all others, unless for the purposes of comparison. They are now in the hands of all our most scientific men, and have given universal satisfaction. The simplicity of their construction enables the most uninitiated in thermometers to use them with confidence and safety ; and another important feature in them is the impossibility of putting them out of order, for nothing short of actual breakage can in any way cause them to fail.
45, COBNHILL, E.G., AND 122, EEGENT STREET, W., LONDON. 37
FIG 40.
48. Negretti and Zambra's Patent Self-registering Standard Maximum Thermometer, consists of a tube of mercury mounted on an engraved scale, as shown in fig 40. The thermometer tube above the mercury is entirely free from air ; and at the point (A) in the bend above the ball, is inserted and fixed with the blow-pipe a small piece of solid glass, or enamel, which acts as a valve, allowing mercury to pass on one side of it when heat is applied ; but not allowing it to return when the thermometer cools. When mercury has been once made to pass the valve, which nothing but heat can effect' and has risen in the tube, the upper end of the column registers the maximum temperature. To return the mercury to the btflb, we must apply a force equal to that which raised it in the tube ; the force employed is gravity, and is applied by simply lowering the bulb end of the thermometer, when the gravity of the mercury in the tube will be sufficient to unite it with that in the bulb, and thus prepare the instrument for future observation.
Price, mounted with Negretti and Zambra's enamelled tube and Patent
Porcelain or Opal glass Scale, fig. 40 £110
The following is an extract from the Report of the Astronomer Royal, pub- lished shortly after the invention of the instrument — it, however, applies more strongly now, inasmuch as the intervening years have fully proved the efficiency and value of this invention : — -
Report of the Astronomer Royal, May, 1852.
" We have for several years baen very much troubled by the failures of the Maximum Self-Eegistermg Thermometers, especially those exposed to the sun: the part of the tube in which the index ought to slide becomes foul, apparently lined with* a coat of metal, and the index is immovable. A construction invented by Messrs. Negretti and Zambra appears likely to evade this difficulty. The mercury in its expansion is forced past an obstruction in the tube and does not return past in its contraction. No index is required in this construction. The specimens of this instrument which we have tried answer well."
In the Quarterly Report of the Registrar General, about the same time, there is the following annotation : —
l* The form of instrument adopted during the past quarter for maximum temperature is that of Negretti and Zambra, which is found to act admirably."
J. GLAISHEE, Esq., F.R.S., in his Lectures on the Results of the Great Exhibition, delivered at the Society of Arts, at the suggestion of his late Royal Highness the Prince Consort, when speaking of Meteorological Instruments (page 363) says : —
" In. maximum and minimum thermometers there was nothing new exhibited, although great need had long existed for an effective Maximum Thermometer. Thanks to the exhibition, however, this want has
* The whole of Negretti and Zambra's Standard Thermometers have their improved enamelled back tabes and are Engine-divided on the stem.
38 NEGBETTI AND ZAMBHA, HOLBOEN VIADUCT, E.G.,
since been supplied. Messrs. Negretti and Zambra have invented a thermometer, the construction of which is as follows : a small piece of glass is inserted in the bend, near the bulb and within the tube, which it nearly fills : at an increase of temperature, the mercury passes this piece of glass ; but on a decrease of heat, not being able to recede, it remains in the tube, and thus indicates the maximum temperature. After reading, it is easily adjusted. Pour of these instruments I have had at work for upwards of a month, two in ordinary observations, and two subject to severe tests, and all have answered admirably. Hitherto every series of meteorological observations has been more or less broken by the frequent plunging of the steel index into the mercury, or becoming otherwise deranged. Messrs. Negretti and Zambra have, in their Maximum Thermometer, supplied a want long felt." *
Extract from the Report of the Council of the British Meteorological Society, read at a General Annual Meeting of its Members, 1852 : —
" Negretti and Zambra's Thermometer, for the determination of maximum temperature, is "one of the good results of the Great National Exhibition, which proved itself, as regarded meteorological instruments, a most useful exponent of the insufficiency of those sold to the general public ; this Thermometer is the best which has yet been constructed for maximum temperatures, and particularly for sun observations ; for as the reading is determined by the entire mercurial column being detained at its highest point by a simple con- trivance within the tube, the necessity for an index is avoided, and with it the constant and distressing recurrence of derangement attendant upon the employment of those generally in use. This thermometer, constructed and brought into operation since the close of the Exhibition, has been for some time in the hands of Members of the Council, but only recently among its meteorological contributors, from its having been esteemed desirable that the Council should be well informed, by actual experiment, ot' the well-working of the instrument before sanctioning its general circulation. Accordingly, in the early part of the year, for some months several of Negretti and Zambra's Maximum Thermometers were subjected by our Secretary to severe tests, and as the results were highly satisfactory, the Council have not only viewed this instrument as an addition to the practical meteorologist, but strongly recommended its adoption and general use."
Copj from the Report of the Kew Committee of the British Association 1853-4:-
" The very ingenious instrument of Messrs. Negretti and Zambra has one quality, which, as regards durability, places it above every other form, of Maximum Thermometer, for when once well-constructed, it can never get out of order, — the observer having first satisfied himself as to its correctness, may ever after- wards use it with confidence, relying that his register will not be interrupted by any of those annoyances to which he may have been accustomed in other forms of this instrument."
From E. J. LOWE, Esq., F.R.A.S., F.G.S., &c., &c., to Messrs. NEGRETTI AND ZAMBRA.
" GENTLEMEN, — It affords me the greatest pleasure in being enabled to speak with praise regarding your Patent Maximum Thermometer. I have used a dozen of them for some time at both my observatories, and of these several since the date of their invention. In no single instance has there been any cause of complaint. Within the last few months I have carefully tested them in various ways, yet always with the most satisfactory results. I can therefore say with truth that your patent instrument is the best Self- Registering Maximum Thermometer which has ever passed through my hands; indeed, no observer can do without it."
HlGHFIELD HOUSE OBSERVATORY, NEAR NOTTINGHAM.
FIG. 41.
49. Negretti and Zambra's Patent Solar Radiation Thermometer (fig. 41). — Consists of a mercurial thermometer with a blackened bulb, the
* The thermometers have now been used with equal satisfaction for thirty-five years.
45, CORNHILL, E.G., AND 122, REGENT STREET, W., LONDON.
FIG. 42.
scale is engine-divided on the stem, and the divisions protected by a glass shield. In use, it should be placed horizontally, with its bulb in the full rays of the sun, resting on grass, and, if possible, so that lateral winds should not strike the bulb. The directions for use are identical with those for the determining of the temperature of the air. Fig. No. 41. Price, £1 10
50. Vacuum Solar Radiation Thermometer (fig. 42). — This instrument consists of Negretti and Zambra's blackened bulb Radiation Thermometer, enclosed in a glass tube and globe, from which all air is exhausted, as suggested by Sir John Herschel in the Admiralty Manual of Scientific Enquiry, in 1849. Thus protected from the loss of heat which would ensue if the bulb were exposed, its indications are from 20° to 30° higher than when placed side by side with a similar instrument with the bulb exposed to the passing air. At times when the air has been in rapid motion, the difference between the reading of a thermometer giving the true temperature of the air in the shade, and an ordinary solar radiation thermometer, has been 20° only, whilst the difference between the air temperature and the reading of a radiation thermometer in vacuo has been as large as 50°. It is also found that the readings are almost identical at distances from the earth varying from six inches to eighteen inches. By the use of this improved Solar Radiator the amounts of solar radiation at different places are rendered comparable ; with the exposed bulb Thermometer, (fig. 41) the results could not be compared, as the bulbs of the thermometers would be under very different conditions as to exposure and currents of air. This new arrangement gives the readings very much more uniform, and is found to be a decided improvement. Price, £150
Instructions for use same as No. 48.
FIG. 43,
40
NEGRETTI AND ZAMBRA, HOLBOEN YIADUCT. E.G.,
51. Negretti and Zambra's Patent Registering Maximum Thermometer with either black or bright bulbs for experiments on radiant or reflected heat, the scale divided on the stem, mounted on a brass stand.
Fig. 43. Price, £1 10 0
52. Negretti and Zambra's Improved Solar Radiation Vacuum Thermometer, with Mercurial Test Gauge. (Fig. 44.)
For some many years most important investigations have been in progress in connection with Solar Heat, and as it is evident that all such inquiry should
be carried out with the utmost precision, a question arose as to the perfection of the vacuum in different Solar Radiation Ther- mometers, and hence a ready means of testing these instruments became desirable for the purposes of comparison.
Although this want had been repeatedly pointed out, no attempt had been made to remedy the defect. At last, we produced a Solar Radiation Thermometer with a small mercurial vacuum gauge inside the outer covering, which gives the exact amount of vacuum, or, it might more properly be called, the exact amount of air left in the space around the thermometer. The insertion of this small test gauge in the manner that it has been effected, is one of the most beautiful arrange- ments ever effected by the skill of the glass- blower. As a matter of course, having pointed out the road, other tests were devised. Among others, an electrical test, by inserting metal wires and connections in the two ends of the glass shield, by which a current of electricity from a Rhumkorf 's Induction Coil can be passed through the tube, and the colour, &c., &c., of the electric discharge be observed. This test has two defects, viz., that coils and batteries are not always available, and also that the metal connections in the glass tube are very liable to fracture, and consequent leakage of air into the tubes from the cracking of the glass around the wires.
We need hardly observe that this is a most important invention and improvement, for, without satisfactory evidence of the perfection of the vacuum, strict experiment cannot be carried out. Price, £1 16 0
53. Wood Stand for Negretti and Zambra's Patent Vacuum Solar Radiation Thermometer, for experiments at four feet from the
FIG. 44.
45, COBNH1LL, E.G., AND 122, REGENT STREET, W., LONDON.
41
FIG. 47.
FIG. 46.
FIG. 45.
ground. Suggested and recommended by the Rev. F. W. Stow, who advises that the bulb end of the thermometer should be placed facing the S.E., and in such a manner that the air may circulate freely round it. Strict shade temperature should also be noted by a good Thermometer, so as to obtain the Maximum in sun and shade, and from these the amount of Solar Radiation may be deduced. Fig. 45. Price, £110
54. Fig. 46 shows a new arrangement of Negretti and Zambra's Patent Solar Radiation Maximum Thermometer in vacuo. It will be seen in the woodcut that the bulb of the Thermometer is exposed to the sky in a vertical position, with its stem enclosed by a light case or box. The scale is on the stem of the Thermometer, but, as in No. 57 the scale is figured the reverse of an ordinary instrument, the reading commencing from the end of the tube and not at the bulb. This arrangement has been introduced by N. and Z. to meet some requirements in connection with observations on solar temperatures where it has been supposed that a perfect sphere presented to the solar rays would give far more accurate indications than a projecting bulb such 'as seen in figs. 41 and 43. Fig. 46. Price, £1 15 0
55. Negretti and Zambra's Patent Registering Clinical Thermometers of various sizes and forms will be described in future sections with prices and illustrations.
56. Babinet's Apparatus, Sling Thermometer or Thermometer Fronde, for ascertaining the temperature of the Air by the rapid rotation of two sensitive Thermometers, Price with Thermometers. (Fig. 47.) £2 10s.
42
NEGRETTI AND ZAMBRA, HOLBORN VIADUCT, B.C..
57. Negretti and Zambra's Patent Self-Registering Maximum Thermometer, for recording the Temperature of Mines, Thermal or Boiling Springs, Atmospheric or Earth Temperature, &c., &c.
This Thermometer has its scale divided and figured upon the stem, the REVERSE of an ordinary Thermometer — the reading commencing from the end of the tube and not at the bulb. The stem or tube is mounted in and protected by a stout glass shield, the bulb of the Thermometer being uppermost, and all mercury passing the bend or contraction in the tube will by gravity fall to the opposite end, and be detained and measured. The whole instrument is conveniently mounted in a round copper or brass case, with a handle or ring attached to the top for suspending the Thermometer. Fig. 48.
FIG. 48.
FIG. 49.
In use, the Instrument is suspended by the ring attached to the top of the metal mounting, and as it enters a heated atmosphere the mercury in the bulb expands into the tube, passing the bend or contraction* near the bulb ; whatever quantity of mercury passes the bend will remain in the tube, and not recede when the temperature cools ; should thirty or forty degrees of mercury pass, it will of its own weight, fall to the end of the tube ; should it not do so, hold the Thermometer in an oblique position, the bulb end being lowest so that the mercury in the tube may very gradually descend until it touches any mercury at the bend,f if now the bulb end be raised the mercury will again descend carrying with it any small particles that have passed the bend- When the mercury has all been collected at the end of tube, read off in degrees on the thermometer scale its indication, and that will be the Maximum Temperature.
To re-set the Thermometer hold it bulb downwards, and swing it back- wards and forwards, to force back the excess of mercury, beyond the present temperature, into the bulb. This precaution should always be observed before commencing to take an observation.
Price, in Strong Metal Mountings. £1 10 0
57*. In our Section, " Thermometers for Special Purposes," will be found woodcuts of several other forms of these Instruments, with details as to their construction and use, and of fig. 49, for obtaining the temperature of Springs or Wells or Earth Temperatures, see also No. 46.
* Sometimes a bend and sometimes a contraction is used to separate the indicating mercurial column, t The tube should not be held upright, or portions of the mercury may pass by the bend into the bulb.
45, CORNHILL, B.C., AND 122, REGENT STEEET, W., LONDON.
The following extract from the Fourth Report of the Committee on Under- ground Temperature, British Association for Advancement of Science, 1871, will sufficiently prove the advantages of Negretti and Zambra's Patent Maximum Thermometer without further comment : — -
" The Thermometer which the Committee have been employing for the last three years is a Phillips's Maximum, having so fine a bore that the detached column of mercury which serves as the index is sustained in the vertical position by capillary action, and will bear a moderate amount of shaking without slipping down. Numerous instances, however, have occurred in which the index has slipped in consequence of jerks or concussions sustained by the thermometer in hauling it up from a depth. During the past six months the Secretary has been in correspondence with Messrs. Negretti and Zambra respecting a proposed modifi- cation of the Maximum Thermometer known by their name, which occurred to him more than a year ago, and was described by him privately to some meteorological friends at the last Meeting of the Association. It was then supposed to be new, but it now appears that Messrs. Negretti and Zambra have made something of the kind for the last fifteen years. Several changes, however, were necessary before the thermometer was adapted to the uses of the Committee, and the first complete instruments were received in June last. They are enclosed, like the thermometers previously used, in hermetically sealed tubes, for protection against pressure, and they have the advantages (1) of Icing able to bear severe jolts without derangement of their indications, and (2) of presenting to view a mucli broader column of mercury, so as to be more easily read in a dim light.
58. Mercurial Thermometer, with large Cup shaped Bulb, (fig. 50), convex on the one side and concave on the other, exposing a very large surface, suited for experiment on Radiant or Accumulated heat.
Price, Engine-divided on the Stem £150
59. Negretti and Zambra's Patent Marine Maximum Thermometer, (fig. 48.) As all other marine thermometers are liable to give false indications from the movements of the vessel in rough weather, this instrument becomes a most important improvement. It is constructed and used in a similar manner to No 57, the bulb of the thermometer being uppermost; and no oscillation, however violent, can disturb the indications. It is mounted in a strong wood or metal frame, suitable for sea service. Price, £110
60. Helio-Pyrometer. Mr. T. Southall, of Birmingham, has published some very remarkable results obtained with a Standard Maximum Registering Thermometer, having a Blackened Bulb placed within a shallow box lined through- out with black velvet, and having a soft cushion of the same material in the bottom. Upon this cushion the Thermometer
is to be placed, and covered over as closely as possible by a piece of plate glass. Thus arranged, Accumulated Sun Temperatures have been noted by
FIG. 50.
NEGEETTI AND ZAMERA, HOLBOEN YIADUCT, F.C.,
Mr. Southall varying from 216 to nearly 232 degrees of temperature. In fact Mr. S. states he has, with this apparatus, caused Water to loil rapidly by Solar Heat.
Negretti and Zambra's Patent Maximum Thermometer will be found eminently suited for experiment with the Helio-Pyrometer, as there is no fear of the thermometer being spoilt by derangement of the index, as is the case with both Rutherford's and Phillips's instruments.
Price of complete Apparatus with N. and Z.'s Patent Maximum Thermometer £220 Extract from the Report of the Council of the British Meteorological Society, read at a General Annual Meeting of its Members, 1852 : —
" Negretti and Zambra's Thermometer, for the determination of maximum temperature, is one of the good results of the great National Exhibition, which proved itself, as regarded meteorological instruments, a most useful exponent of the insufficiency of those sold to the general public ; this Thermometer is the best which has yet been constructed for Maximum temperature, and particularly for Sun observations.
FIG. 51.
FIG. 52.
61. Pyrheliometer (Pouillett's) (fig. 51), for ascertaining the effect of the sun's heat upon a given area by the number of degrees of heat imparted to mercury in five minutes. Price, £550
This instrument is composed of a shallow cylinder of steel, A, fig. 51, which is filled with mercury. Into the cylinder a thermometer, D, is introduced, the stem of which is protected by a piece of brass tubing. We thus obtain the temperature of the mercury. The flat end of the cylinder is to be turned towards the sun, and the surface, B, thus presented is coated with lamp black.
45, CORNHILL, E.G., AND 122, BEGENT STEEET, W., LONDON. 45
There is a collar and screw, C, by means of which the instrument may be attached to a stake driven into the ground, or into the snow, if the observations are made at considerable heights. It is necessary that the surface which receives the sun's rays should be perpendicular to the rays ; and this is secured by appending to the brass tube, which shields the stem of the thermometer, a disk, ^7, of the same diameter as the steel cylinder. When the shadow of the cylinder accurately covers the disc, we are sure that the rays fall, perpendicular, on the blackened surface of the cylinder.
" The surface on which the sun's rays here fall is known ; the quantity of mercury within the cylinder is also known ; hence we can express the effect of the sun's heat upon a given area, by stating that it is competent, in five minutes, to raise so much mercury so many degrees in temperature." — Dr. TyndaWs il Seat considered as a Mode of Motion"
62. JSthrioscope (Leslie's) (fig. 52.) The celebrated philosopher, Sir John Leslie, was the inventor of this instrument, the purpose of which is to give a comparative idea of the radiation proceeding from the surface of the earth towards the sky. It consists, as represented in fig. 52, of two glass bulbs united by a vertical glass tube, of so fine a bore that a little coloured liquid is supported in it by its own adhesion, there being air confined in each of the bulbs. The bulb, J., is enclosed in a highly polished brass sphere, D. The bulb, B, is blackened and placed in the centre of a metallic cup, C, which is well gilt on the inside, and which may be covered by a top, F. The brass coverings defend both bulbs from solar radiation, or any adventitious source of heat. When the top is on, the liquid remains at zero of the scale. On removing the top and presenting the instrument to a clear sky, either by night or by day, the bulb, B, is cooled by terrestrial radiation, while the bulb, A, retains the temperature of the air. The air confined in B, therefore, contracts ; and the elasticity of that within A forces the liquid up the tube, to a height proportionate to the intensity of the radiation. Such is the sensitiveness of the instrument, that the smallest cloud passing over it checks the rise of the liquid. Fig. 52. Price, £1 10 0
SELF-REGISTERING THERMOMETERS FOR COLD.
FIG. 53.
63. Negretti and Zambra's Standard Minimum Thermometer. (Fig. 53.) consists of an enamelled glass tube, the bulb and parts of the bore of which is filled with perfectly pure colourless Spirits of Wine, in which floats freely a
46
NEGRETTI AND ZAMBRA, HOLBORN VIADUCT, B.C.,
black glass index. The tube is engine divided and mounted as shown in fig. 53. on either N. and Z.'s patent Porcelain or Opal Glass Scales.
Directions for using Minimum Thermometers, for the Determination of the Minimum Temperature of the Air. — Having caused the black index to flow to the end of the column of spirit, by slightly tilting the Thermometer, bulb uppermost, suspend the instrument, (in the shade with the air passing freely to it on all sides) by the two plates attached for that purpose, — in such manner that the bulb is about half an inch lower than the end of the Thermometer furthest from the bulb, — then on a decrease of temperature, the spirit will descend, carrying with it the index towards the bulb ; on an increase of temperature, the spirit will ascend in the tube beyond the index, leaving that end of the index furthest from the bulb indicating the extreme of cold or Minimum temperature. To re-set the instrument, simply raise the bulb end of the Thermometer a little, as before observed, and the index will again descend to the end of the spirit, ready for future observation.
Price, in mounting as fig, 53 £1 1 0
FIG. 54.
64. Negretti and Zambra's Standard Terrestrial Radiation Thermometer, (fig. 54).— The bulb of this instrument is transparent, with the divisions engraved on its stem similar to that for solar radiation. In use, to be placed with its bulb fully exposed to the sky, resting on grass, with its stem supported by little forks of wood. Price, £110
FIG. 55.
65. Negretti and Zambra's Link shaped Bulb Minimum Thermometer, mounted either as a Terrestrial Radiation irstrument, fig. 55, or on a Porcelain scale as fig. 53. This peculiar form of bulb was devised by Negretti and Zambra to obtain extreme sensitiveness by the large surface exposed to air.
Price, £150
45, CORNHILL, E.G., AND 122, REGENT STREET, W., LONDON.
47
FIG. 57.
FIG. 56.
Brass Stand for use with Price, 5s. 6d.
66. Negretti and Zambra's Minimum or Terrestrial Radiation Thermometer with Brass Stand, (fig. 56). Price, £150
67. Concave Metallic Reflector on a Terrestrial Radiation Thermometer (fig. 57).
N.B. — As Alcohol Thermometers have a tendency to read lower by age, owing to the volatile nature of the alcohol allowing particles in the form of vapour to rise and lodge in the tube, it becomes necessary to compare them occasionally with a Mercurial thermometer whose index error is known ; and if the difference be more than a few tenths of a degree, examine well the upper part of the tube to see if any alcohol is in the bore, if so, detached por- tions can be joined to the main column by swinging the thermometer sharply backwards and forwards with a pendulous motion, keeping the bulb down- wards. When all the detached portions are joined, allow it to stand upright for an hour before again suspending it for observations.
68. Negretti and Zambra's Patent Mercurial Minimum Thermometer, represented by fig. 58, has a cylindrical bulb of large size. The reason for having the bulb large is to allow the internal diameter of the thermometer tube to be greater than that generally used for thermometrical purposes, so that a steel index, pointed at both
ends, may move freely within when required.
FIG. 58*.'
In use, the Thermometer is suspended perpendicularly with the steel index resting on the surface of the mercurial column. As the mercury in the cylinder contracts from the effect of cold, that in the tube descends, and the index, of its own gravity, follows it ; on the contrary, as the mercury expands and rises in the tube, it passes the index on one side, and in rising, exerts a lateral pressure on the needle, and jambs it to one side of the tube, where it* remains firmly fixed, leaving the upper
FIG. 58.
48 NEGRETTI AND ZAMBEA, HOLBOEN VIADUCT, B.C.,
point of the needle indicating the minimum temperature. In this thermometer the reading is always from the upper point of the needle, and not from the mercury itself.
To extricate the needle from the mercury, a magnet is used, when, if the needle is embedded only a few degrees, it can readily be withdrawn without altering the position of the instrument. Should the magnet not be sufficient for the purpose, we simply turn the thermometer from the upright position, slightly elevating the bulb (58*2). The mercury and index will then flow into the small reservoir (58®). Should the index not freely leave the tube with the mercury, assist it with a magnet and when the mercury and index are in the upper bulb (58*2), apply a magnet outside, which will attract and hold fast the index ; and whilst thus holding it, again bring the thermometer to the upright position, when the mercury will immediately fall back into the tube, leaving the index attached to the magnet (fig. 4), with which it is guided down to the surface of the mercury, ready for another observation.
Price, £2 10 0
The value of these instruments may be estimated from the following letters, received from gentlemen by whom the thermometers have been tested since their invention. —
LEWISHAM, 1856, February 27.
" GENTLEMEN,— In reply to your note just received, I beg to say that your new Mercurial Minimum Ther- mometer was suspended by the side of two Minimum Thermometers of the best kind of the ordinary con- struction, on the day I received it from you, viz., 1855, November 21, and it has been examined and read every day since, during which interval of time the temperature has varied from 15° to 60°. It has acted equally well within this range. In the course of the experiments, it was found that at times differences amounting to 2° and 3° existed in the minimum readings between those of the new mercurial and old spirit thermometers. These differences were found due to two causes. The one occurred at low temperatures, and on reference to independent registers, it was found that the readings of the mercurial were right, the difference being attributable to the sluggishness of the alcohol; and, in the other case, it was found that the index of the ordinary thermometer had unduly moved towards the bulb, the instru - ment having been shaken by the wind.
"I consider the new Minimum Thermometer a very important addition— indeed a more important one than the Maximum Thermometer of your invention, as by its means we can register all observations of temperature by the use of one fluid, and that the recognised standard for the measurement of heat.
"With respect to your Maximum Thermometer, it acts admirably, and leaves scarcely anything to be desired. It has never been out of order during the four years* I have had it in constant use, and it does not seem possible to put it out of order, except by the destruction of the instrument. " I am, Gentlemen, your obedient Servant,
"JAMES GLAISHEE, F.E.S. " Messrs. NEGRETTI and ZAMBRA, Opticians." " Secretary to the British Meteorological Society.
The following is an extract from a letter to the inventors, Messrs. NEGRETTI and ZAMBRA, from E. J. LOWE, Esq., dated Observatonj, Beestrm, near Nottingham :
"Your Patent Mercurial Thermometer is an admirable invention. I have worked it to my entire satisfaction. I have tested its usefulness in many different ways, every one of which has been perfectly satisfactory. It is certainly a meteorological triumph for which meteorologists must return you thanks."
Care must be taken not to withdraw the magnet until the index is in contact with the mercury, for, if released before touching, it might plunge too deeply and give a false indication. The rule for re-setting it will be to bring
* It is now more than twenty -nine years, and still the thermometer is perfect.
45, CORNHILL, B.C., AND 122, EEGENT STREET, W., LONDON.
49
the needle-point in contact with the mercury, and then withdraw the magnet, having previously ascertained that no particles of mercury are attached to the index.
It may sometimes, though rarely, happen that, from the time a minimum temperature is registered by the index, and the time an observation is made, .the mercury may have risen so high in the tube as to completely pass the index, as shown (fig. 3). Should it so happen, the space which the index occupies will readily be observed, as it will be pressed to one side of the tube, causing a different appearance in that part, although the point of the needle may not be seen. If such be the case, apply a magnet to the spot where you see the index is fixed : this will hold the needle firmly. Then, by slightly tilting the thermometer bulb uppermost, the mercury will flow into the top bulb, leaving the index attached to the magnet, and quite uncovered. Having taken the reading, draw the needle into the top bulb, and hold ifc there whilst you adjust the thermometer by again bringing it to the upright position.
So \ 70 I £31 $9
NEC PETTI & 2 AM BRA-, LONDON.
FIG. 59.
68. Negretti and Zambra's Patent Mercurial Minimum Thermo- meter. The Patent Mercurial Minimum Thermometer is constructed as follows : A is the thermometrical or indicating tube, and B is a small vertical tube connected to it at right angles, about one inch from the bulb. In the tube B, at the point C, is inserted a platinum plug, which does not entirely fill the bore, as may be seen by elevating either end of the instru- ment, as the mercury will then flow in the tube A, either to or from the bulb, depending upon which end of the thermometer is elevated or depressed.
To set for Observation, and use the Patent Mercurial Minimum Thermometer. — Hold the thermometer with the bulb downwards until the bulb and tube B are quite full of mercury ; then raise the bulb end of the thermometer, and the mercury will flow from the tube B into the tube A, until it reaches the plug C, where it will be checked by the mercury adhering to the platinum plug — the affinity of platinum for mercury being sufficient to arrest the flow of mercury, if not allowed to flow too rapidly. Should it overshoot the mark and go to the end of the tube A repeat the operation more carefully.
Suspend the thermometer horizontally, and on a decrease of the tem- perature the mercury will fall in the tube A until it attains its minimum
f>0 NEQEETTI AND ZAMBRA, HOLBORN* VIADUCT, E.G.,
temperature ; and on an increase of temperature the mercury will rise in the tube B, leaving the indicating column in A, registering the extreme degree of cold, or minimum temperature. To re-set the instrument for future obser- vation, simply raise the bulb end of the thermometer until the mercury again comes in contact, and is checked, by the platinum plug.
This form of Mercurial Minimum Thermometer has one very great advantage over the preceding instrument, viz., it is much less liable to injury or breakage in transit. Price, fig. 69. £220
69. Actinometer, Sir John HerschelPs (fig. 60), for ascertaining the absolute heating effect of the solar rays, in which time is considered one of the elements of observation. The Actinometer consists of a large cylindrical thermometer bulb, with a scale.considerably lengthened, so that minute changes may be easily seen. The bulb is of transparent glass, filled with a deep blue liquid, which is expanded when the rays of the sun fall direct on the bulb. To take an observation, the Actinometer is placed in the shade for one minute, and read off, it»is then exposed for one minute to sunshine, and its indication recorded ; it is finally restored to the shade, and its reading noted. The mean of the two readings in the shade, subtracted from that in the sun, gives the actual amount of expansion of the liquid pro- duced by the sun's rays in one minute of time. For further information see " Report of the Royal Society on Physics and Meteorology." Price, £770
70. Negretti and Zambra' s improved Isolated Glass Mountings for protecting Thermometer Scales from moist- ure. Many observers having found much trouble in reading the indications of Terrestrial Radiation and exposed Thermometers from the condensation of moisture on the inside of the protect- ing glass tubes or shields, Messrs. Negretti and Zambra have succeeded in perfecting a method of mounting up such instru- ments that quite obviates the difficulty. This improvement con- sists in so melting an external glass cylinder round both ends of the thermometer as to render the shield perfectly air-tight, in fact, to hermetically seal up the instrument in it — so that no moisture can possibly accumulate inside the tube, whilst the bulb
FIG 60 °^ *^e thermometer is perfectly exposed to the air.
Negretti and Zambra are now applying this improvement with great advantage to Thermometers, Hygrometers, and many other instruments required for out of door exposure. These isolating mountings will make a slight addition to the cost -of such Thermometers.
45, COBNHILL, B.C., AND 122, KEGENT STREET, W., LONDON. 51
FIG. 61.
71. Portable Patent Maximum and Minimum Registering Thermo- meters.— Negretti and Zambra's Small Patent Maximum and Minimum Registering Pocket Thermometers, fitted into a secure and convenient pocket case, special for travellers, (fig. 61.) Price . . . .£220
Larger Standard size ditto 2 10 0
The construction and use of the Portable Registering Thermometers is identical with N. and Z.'s larger Standard instruments, Nos. 40 and 53. These are the only Registering Thermometers that will travel without dera-ngement. Explicit printed instructions for use accompany each set.
72. Marie Davy's Actinometer, consisting of two Thermometers in vacuo, one with a bright and the other with a black bulb, both divided on the stems and mounted upon a suitable stand for out-door exposure. Price, £330
RULES FOB CONVERTING THERMOMETER READINGS. . To convert Fahrenheit readings to Centigrade.
Subtract 32 and multiply the remainder by -
y
e.g. 68° P.=( 68— 32)x- = 20° C. y
To convert Fahrenheit readings to Reaumur.
Subtract, 32 and multiply the remainder by -
e.g. 68° F.=( 68— 32) X - = 16° R.
To convert Centigrade readings to Fahrenheit.
Multiply by f and add 32. o
To convert Reaumur degrees to Fahrenheit. Multiply by | and add 32.
To convert Centigrade to Reaumur.
Multiply by - 5
To convert Reaumur to Centigrade. Multiply by |
NOTE.— All of Negretti and Zambra's Standard Thermometers may be had with. Centigrade or Reaumur Scales to order.
E2
52
NEGRETTI AND ZAMBRA, HOLBOEN VIADUCT, E.G.,
NEGRETTI & ZAMBRA'S
PATENT
BURLY RECORDING THERMOMETRICAL APPARATUS.
20
FIG. 62.
73. Negretti and Zambra's Patent Atmospheric Eecording Thermometer (fig. 62). For any hour determined upon, the clock carrying the Thermometer is -set (similar to an alarum clock), and when the hands arrive at this point of time, the movement of the
£l«
clock. releases a catch or detent, and the Thermometer* with its scale is revolved, the mercury then records the temperature of the air for that exact moment in a similar manner to those mentioned in the next page. These Recording Instruments are found to be a most important addition to our Meteorological Instruments, and no slight boon to observers in many parts of the world who are engaged in taking simultaneous observations with our own at fixed hours. ~ Price, as fig. 62. £440
* The Thermometer used with this apparatus is shown ly fig. 62a, and is fully described on page 53.
45, CORNHILL, B.C., AND 122, REGENT STREET, W., LONDON. 53
NEGRETTI AND ZAMBIA'S
PATENT HOURLY RECORDING THERMOMETRICAL APPARATUS.
An instrument for obtaining automatic thermometer readings at stated intervals of time having long been sought for — after many experiments, NEGRETTI & ZAMBRA have invented and constructed one both simple and accurate.
74. Negretti & Zambra's Patent Hourly Recording Thermometrical Apparatus. This new instrument consists of twelve Thermometers, mounted on a suitable stand, a good Clock, and a Galvanic Battery. The advantages are — simplicity of manipulation, both in taking the recorded readings and setting the thermometers for future observations ; the most important one, being able to expose the thermometers at any distance from/ the clock and battery — the only limit being the length of the conducting wires and the strength of the battery.
Before describing the mechanical and electrical arrangements of the apparatus, we proceed to explain the construction and action of the thermometers themselves. This will be best understood by reference to the engraving, fig. 63.
The bulb is cylindrical, and Mercury is the thermometrical fluid. The neck of the bulb is contracted at A, and upon the shape and fineness of this construction the success of the instrument depends. Beyond A the tube is bent, and a small catch reservoir is formed at B, for a purpose to be presently explained. At the end of the tube a small r.eceptacle, C, is provided. When the bulb is downward it contains sufficient mercury to fill the tube and a part of the reservoir, 0, leaving suf- ficient space in C for the expansion of the mercury. In this position no scale would be possible, as the apparent movement of the mercury would be con- fined to the space C. When the thermometer is held bulb upward, the mercury breaks off at A, and by its own weight flows down the tube, filling C and a portion of the tube above C, in relation to the existing temperature. The scale accordingly is made to read upwards from C. To set the instrument for observation, it is only necessary to place it bulb downward, then the mercury takes the temperature just as an ordinary thermometer. Whenever the existing temperature is required, all that has to be done is to turn the thermometer bulb upward ; the mercury will then break off at A, falls to
54 NEGRETTI AND ZAMBRA, HOLBORN YIADUCT, E.G.,
end C, and in this position the temperature can be noted. The engraving, fig. 63, shows the thermometer after it has been inverted.
This reading may be taken at any time after the thermometer has been turned over, for the quantity of mercury in the lower part of the stem, which gives the reading, is too small to be sensibly influenced by a change of tempera- ture, while that in the bulb will continue to contract with greater cold and to expand with greater heat, and in the latter case some mercury will pass the contraction A, and may fall down and lodge at B, but it cannot go further so long as the bulb is upward, and thus the temperature to be read off will not be vitiated. It must be clearly understood that the thermometer is only intended to give the temperature at the time when it turned over. The divisions and figures are engraved upon the stem of these thermometers.*
It will be seen in the accompanying drawing that twelve thermometers are mounted on the stand ; each one is sustained upon a metal arm in such a man- ner that it will fall over and become inverted by the release of a stop or detent from the joint action of the clock and galvanic battery.
In the drawing, six of the twelve thermometers are shown inverted, the bulbs being upwards, the clock at each of the six successive hours having made contact and completed the galvanic circuit, and by the action of an electro- magnet released the detents, and allowed the thermometers to fall over and record the temperature for that moment. This action is produced by simple mechanism on the back of the clock dial, the contact being made at each hour It will be evident that the thermometers could be made to record half-hourly, or they might, by increasing the number, be made to register every fifteen minutes, or less, the only limit being the number of thermometers used.
When the thermometers are all reversed, the readings may be quickly taken and the thermometers re-turned to their original positions, bulbs down- wards.
Attached to the back of the clock dial, and in its centre, is a disc of ebonite, about two inches in diameter, with a hole in the centre to allow the spindle to pass on which the clock hands are fixed. Round the edge of this disc are twelve platina studs, one being opposite each hour on the clock dial ; each stud is separately connected to one of twelve terminals in the order of 1 to 12 at back of clock, viz. : The stud opposite 12 o'clock on the dial is carried to No. 12 terminal, &c., &c. Immediately behind the hour hand, at the back of the dial, and attached to the same spindle, is a metal spring which touches each stud in succession as the hour hand travels round. This spring is not insulated from the metal work of the clock ; consequently the current runs to the clock.
* These Thermometers are divided with either Fahrenheit or Centigrade Scales, and their number may be increased to special order.
45, COBNHIU,, E 0., AND 122, REGENT STREET, W., LONDON.
55
Negretti and Zambra's Patent Apparatus for Recording Hourly Temperatures. (FiG. 64.)
56 NBGRETTI AND ZAMBEA, HOLBOEN YIADUCT, E.G.,
Fixed at the back of the clock dial, near its outer edge, are two little glass cups containing mercury, one of which is connected to the metal work of the clock ; the other glass cup is connected to the thirteenth terminal on the back of the clock. Immediately over these two cups, and fixed to an arm or lever, is a forked piece of platina wire, which, when depressed into the cups, forms a connecting bridge from one to the other. The lever is depressed when one end is lifted by the minute hand of the clock. This is accomplished by means of a wedge-shaped piece of steel brought through to the front of the dial, and acted upon by the minute hand directly over twelve o'clock ; when the minute hand approaches twelve, it presses the left angle of the wedge and lifts it.
A terminal at the outside of a box containing twelve magnets is connected to a metal bar running the entire length of the same, to which is attached one end of a wire from each of the twelve electro-magnets ; the other ends of the wires from the electro-magnets are separately connected to the twelve terminals under the box containing the magnets, thence by separate wires to the twelve terminals on the clock, in the order of from 1 to 12 as marked.
We will now suppose the time to be six o'clock. The battery is connected as follows : — One pole to the thirteenth terminal on the clock, the other pole to the terminal at end of box on the Recording apparatus. The electric circuit is now complete. From the battery to the thirteenth terminal on clock, then to one of the glass cups, over the little bridge of wire to the other glass cup, thence through metal work of the clock to the spring, which spring touches upon the stud at the back of the hour hand (at, say six o'clock), from thence to No. 6 terminal on the back of the clock, from there to No. 6 terminal under the box containing the electro-magnets, through No. 6 magnet to the bar above, then to the terminal at the end of the box, and back to battery. In its circuit, No. 6, magnet attracts its keeper, the catch falls, and allows No. 6 thermometer to turn over, and in like manner throughout the series.
Price, fig 64. £52 10 0
NEGRETTI AND ZAMBRA'S SUNSHINE RECORDER.
75. This instrument shown by fig. 65 consists of a glass sphere ground perfectly true, mounted upon a brass frame, with suitable adjustments for placing its axis parallel with the axis of the earth ; it has also a divided semi-circle arranged to adjust the apparatus for use in any latitude.
Surrounding one-half of the glass sphere is placed a concentric metal plate, for holding the prepared and divided paper cards, upon which the record is burned by the concentrated Solar rays.
45, COENHILL, E.G., AND 122, BEGENT STEEET, W., LONDON. 57
FIG. 65.
Two grooves are formed upon the concentric plate, by which the position of the divided cards can be varied to suit the elevation of the sun at different seasons of the year.
In use, the Sunshine Recorder should be placed geographical North and South, similar to a sun dial.
Price, fig. 65. £12 12 0 A supply of prepared cards sufficient for one year's use . . . • £1 12 0
FIG. 66. FIG. 67.
76. Jordan's Sunshine Recorder (Patent), made and supplied only by Negretti and Zambra.
58
NEGRETTI AND ZAMBRA, HOLBOEN VIADUCT, E.G.,
Since the indention in 1853 of Mr. CAMPBELL'S instrument for automatically registering the duration of Sunshine, the subject has become of increasing interest, and improved forms of his instrument have been generally adopted at the principal Observatories and Meteorological Stations where the hours of bright Sunshine are regularly observed and registered. These ingenious instruments are perfect recorders of Sunshine so long as the sky is clear, but are too costly to come into general use by the greater number of observers now- interested in the subject. It is to meet this difficulty that the instrument now introduced has been designed. We believe that it meets all the requirements ; it is accurate in its action, of simple construction, and sufficiently cheap to come within the means of all those who are interested in this comparatively new branch of meteorological science.
Half Size.
FIG. 68.
The action of Mr. JORDAN'S Sunshine Recorder differs entirely from that of the instrument above referred to, inasmuch as the results are obtained by means of photography, instead of by the burning power of the concentrated solar rays ; it is, however, only on days when the atmosphere is a little hazy, or the sun slightly obscured by thin, filmy cloud, that there is any important difference in the record of the two instruments ; at such times the photographic registering instrument will probably show an excess of sunshine, as under certain conditions the thin film of cloud or haze interferes more with the action of the heat rays than it does with the actinic rays.
The new instrument — which is figured on the other side — consists of a dark cylindrical chamber, on the inner circumference of which is placed a carefully prepared photographic paper. The ray of sunlight being admitted into this chamber through small apertures in the side, is received on the sensitized paper or chart, and travels around it by virtue of the earth's rotation, leaving a distinct trace of chemical action, thereby registering its duration, and the degrees of its intensity, varied by every passing cloud. The cylinder is mounted on a suitable stand, having simple means of adjustment, for the different seasons of the year, and for the use of the instrument in any latitude.
Price. Sunshine Recorder— Fig. 66 £330
Ditto — Fig. 67, with rackwork adjustment and
clamping screws 550
A Box containing 100 prepared CHARTS, with instructions- Fig. 68 100
45, COBNHILL, E.G., AND 122, REGENT STREET, W., LONDON. 59
The Charts are printed upon sensitized paper, ruled with vertical lines, representing the hours and minutes of the day; they are supplied, ready for use, in boxes containing 100 each. The records obtained are rendered permanent by simply washing the papers for a few minutes in cold water and afterwards drying them between blotting-paper.
INSTRUCTIONS FOR FIXING- JORDAN'S SUNSHINE RECORDER.
77. Select a suitable position which has the full range of the sun at all seasons of the year. Provide affirm support with a perfectly level top, place the Instrument upon it (the lid of the cylinder facing north), and when the sun is on the meridian (12 o'clock) turn the instrument on its base until the shadow of the pin on the lid of the cylinder coincides with the vertical line on the white glass behind it. When this adjustment has been correctly made, the instrument may be permanently screwed down to its support, then incline the cylinder on its horizontal axis, by means of the milled head at the side, until the point of the shadow of the aforesaid pin falls on the point of intersection of the two lines, and clamp securely by means of the opposite milled head, the ray of sunlight passing through the central aperture will then fall on the twelve o'clock division of the chart. This adjustment will require to be altered occasionally as the seasons vary, the necessity for alteration being shown by the position of the trace above or below the central line of hour divisions on the «hart.
The charts should be inserted in the cylinder each day after sunset, ready for the following day, the ends being placed against the stops provided for the purpose. On removing the charts from the instrument after the day's observa- tion the number of hours recorded should at once* be tafadated, the trace may then be rendered permanent by immersing the chart for a few minutes in cold water, until the surface becomes white and the trace a bright blue colour ; it should then be removed and dried between blotting paper. Care must be taken not to expose the sensitized charts to the daylight longer than is necessary for removing and inserting them in the cylinder. The cylinder being held in position on the frame by a clamping screw can be easily removed for the purpose of changing the chart, which may be done either at the place of observation or indoors
* This precaution is necessary that any very faint traces on the chart may not be lost before registering, by too long immersion in water, or it may be advisable to mark with a pencil the limits of the trace before placing in water.
GO NEGEETTI AND ZA.MBRA, HOI/BORN VIADUCT, B.C.,
NEG-BETTI & ZAMBEA'S RECORDING DEEP SEA THERMOMETERS.
78. Deep Sea Sounding Thermometers, Self-Registering, the original double tube principle, invented by Negretti and Zambra, specially- constructed for the Board of Trade and Admiralty. Warranted to stand a pressure of 450 atmospheres. Price £2 10 0
This manner of protecting the bulb was invented by Messrs. Negretti and Zambra in 1857, and is described by the late Admiral R. FitzRoy, in the first number of Meteorological Papers, p. 55, published July 5th. 1857, as follows :
" Referring to the erroneous readings of all thermometers, consequent on their delicate bulbs being compressed by the great pressure of the ocean, he says : — ' With a view to obviate this failing Messrs. Negretti and Zambra undertook to make a case for the weak bulbs, which should transmit temperature, but resist pressure. Accordingly a tube of thick glass is sealed outside the delicate bulb, between which and the casing is a space all round, which is nearly filled with mercury. The small space not so filled is a vacuum, into which the mercury can be expanded, or forced by heat or mechanical compression, without doing injury to or even compressing the inner or much more delicate bulb.'"
The bulb of the Thermometer thus protected resists the pressure of the ocean, which varies according to its depth — that of three thousand fathoms being something like three tons pressure upon the square inch.
79. Negretti and Zambra's Small Deep Sea Sounding Thermometers, the so-called Dr. Miller's pattern in Copper. Case.
Price £2 10 0 £330
R. H. SCOTT, Esq., F.R.S., in a paper published in the Journal of the Meteo- rological Society, January 17th, 1872, speaking of Negretti and Zambra's Deep- Sea Thermometers, described by Admiral FitzRoy in the first number of Meteorological Papers, published July 5th, 1857, says : —
" The number of the thermometers of this particular pattern, which was supplied to the Meteorological Department of the Board of Trade by Messrs. Negretti and Zambra, the makers, was upwards of fifty, and they were supplied to several ships in the Royal Navy, especially those employed on certain well-known deep-sea sounding expeditions. I was not able to find any record of any of these thermometers having been tested in an hydraulic press, and, accordingly, as soon as the Miller pattern thermometer had been definitely adopted by the Hydrographer, it was resolved to subject one of the old thermometers (Negretti and Zambra's) in the Meteorological Office to the same test as that which the new instruments were made to undergo, in order to see whether or not the construction of the original instruments offered sufficient security against alteration of the shape of the bulb, owing to pressure. The experiments were carried out on the 28th of September, 1869, in
45, COBNHILL, B.C., AND 122, EEGENT STREET, W., LONDON. 61
the presence of Capt. Toynbee and Mr. Strachan, and the results of the testing have been published in the report of the Meteorological Committee of the Royal Society for 1869. The concluding sentence of this report was as follows (page 32) : —
"'The foregoing experiments are sufficient to show that the original thermometers described by Admiral FitzRoy were good and trustworthy instruments, in so far as regards their capability of resisting pressure.' "
NEGRETTI AND ZAMBRA'S NEW RECORDING DEEP-SEA THERMOMETERS.
80. These Instruments differ from all other Recording Thermometers in the following important particulars :— I. The Thermometer contains pure mercury only, without any alcohol or other fluid. II. It has no indices or springs, and its indications are by the column of mercury only. III. It can be carried in any position, and cannot be put out of order except by breakage. And chiefly, it will indicate and record the exact temperature at any depth of the sea, irrespective of either warm or cold currents or stratum through which the Thermometer may have passed in its descent or ascent. This last very special quality renders N. and Z.'s Thermometers superior for Deep Sea tempera- ture to any others ; for those used in the Challenger expedition are liable to give erroneous indications, owing to their indices slipping, and otherwise getting defective (this was proved by Messrs. Negretti and Zambra at a Meeting of the British Meteorological Society) ; and under certain conditions of temperature it is not possible by these old Thermometers to obtain true temperatures at certain depths which might be required.
The construction of Negretti and Zambra's original Deep Sea Thermometer is as follows : —
In shape it is like a syphon with parallel legs, having a continuous communication, as seen in the annexed figure, 69. The mounting of the Thermometer is pivoted on a centre, and being attached in a perpendicular position to a simple apparatus (which will be presently described), is lowered to any depth in the water that may be desired. In its descent the Thermometer acts as an ordinary instrument, the mercury rising or falling according to the temperature of the stratum through which it passes ; but so soon as the descent ceases, and a reverse motion is given to the line, so as to pull up the apparatus towards the surface, the Thermometer turns once on its centre, first bulb uppermost, and afterwards bulb downwards. This causes the mercury, which was in the left-hand column, first to pass into the dilated syphon bend at the top, and thence into the right hand tube, where it remains, indicating on a graduated scale the exact temperature at the time it was
62
NEGEETTI AND ZAMBRA, HOLBORN TIADUCT, K C.
turned over. Fig. 69 shows the
position of the mercury after the
instrument has been thus turned on
its centre. A is the bulb ; B the
outer coating or protecting cylinder ;
C is the' space of rarefied air, which
is reduced if the outer casing be
compressed ; D is a s mall glass plug
on the principle of Negretti and
Zambra's Patent Maximum Ther- mometer, which cuts off, in the
moment of turning, the mercury in
the tube from that of the bulb,
thereby insuring that none but the
mercury in the tube can be trans- ferred into the indicating column ;
E is an enlargement made in the
bend so as to enable the mercury
to pass quickly from one tube to
another in revolving ; and F is the
indicating tube or Thermometer
proper. In its action, as soon as the
Thermometer is put in motion, and
immediately the tube has acquired
a slightly oblique position, the
mercury breaks off at the point D,
runs into the curved and enlarged
portion E, and eventually falls into the tube F, when this
tube resumes its original perpendicular position.
The contrivance for turning the Thermometer over
may be described as a metal frame with a vertical screw
propeller; to this frame (fig. 70) the instrument is attached-
In its descent through the water the screw is lifted out of
gear and revolves freely on its axis ; but so soon as the
apparatus is pulled up towards the surface the screw falls
into gear and revolves in the contrary direction, turning the Thermometer over once, and then becoming locked and immovable, the temperature is recorded for that moment. Price £10 10 0
This arrangement of Deep Sea Thermometer (fig. 70) having been found defective, Negretti and Zanibra have abandoned its manufacture — it being norc quite superseded by their recently improved Thermometers, particulars of which »vill be found in the following pages. Our description is therefore only inserted as a matter of history in connection with the invention of Deep Sea Recording Instruments.
FIG. 69.
45, COENHILL, E.G., AND 122, KEGENT STREET, W., LONDON. 63
NEGRETTI & ZAMBRA'S
NEW PATENT STANDARD
MARINE REGISTERING THERMOMETERS.*
81. " The most'successful Deep- Sea Thermometer hitherto has been Six's Thermometer, with the bulb protected from pressure, as invented by NEGRETTI AND ZAMBRA in 1867. Nevertheless there are several disadvantages inherent in the principle of construction of Six's instrument. The indices are unreliable, as, however carefully fitted, they may slip down by gravity, and even shift upward by sudden lifting motion ; so that the observations are always more or less liable to error : the index error also is very liable to alter by the shifting of the spirit, or by bubbles of spirit getting among the mercury ; and unless the observer is well-trained in its management, and takes care to compare it with a correct ordinary ther- mometer every time it is used, there is no guaranteeing1 its accuracy of indication. Further, its accuracy in its best condition does not attain to fractions of a degree, as it cannot be read off closer than about half a degree. Then it must be kept in the vertical position, or it is certain to become more or less deranged in transit.
" However, so long as it sufficed to observe the nearest degree of temperature, the improved protected Six's answers the purpose of a deep-sea thermometer, with careful management and checking ; but lately the bottom temperature of shallow seas and of rivers has come under investigation, and for this purpose Six's instrument is unsuitable.
" Between the temperature of the surface of the sea and that at the depth of a few fathoms, the differences to be determined are found to be not degrees of the thermometer, but fractions of a degree ; hence, the observations to be worth anything at all, must be made with an undoubtedly accurate thermometer.
" During the last two or three years systematic observations of the surface and bottom temperatures have been taken from the various lightships off the British coasts, under the direction of the Meteorological Office. This investigation of the temperatures of the British seas has been urged upon the Government by naturalists and physicists interested in the question of the food supply of the people as affected by the take of fish. What is required to be made evident is, whether any, and what, effect temperature has upon the habits and migrations of fish, so as to tend to a right understanding of the conditions favourable for the development of the various species of fish, and the best seasons and temperature indi- cations for their capture. This investigation, commenced with Six's Thermometers, has at present only shown that such instruments are not sufficiently reliable for the purpose ; and it was represented by the Government to Messrs NEGRETTI AND ZAMBRA, that a more perfect and stable deep-sea thermometer was a desideratum. They accordingly turned their attention to the matter, and the result is the new STANDARD DEEP-SEA THERMOMETER.
" The construction of this thermometer will be readily understood by reference to the sketch diagram fig. 71. The bulb is cylindrical, and mercury is the thermometrical fluid. The neck of the bulb is contracted in a peculiar manner at A, and upon the shape and fine- ness of this contraction the success of the instrument mainly depends. Beyond A the tube is bent, and a small catch reservoir is formed at B, for a purpose to be present/I^ explained. At the end of the tube a small receptacle, C, is provided. When the tube is downward, the glass contains sufficient mercury to fill the bulb, tube, and a part of the reservoir C, if the temperature is high, leaving sufficient space in C for the expansion of the mercury. In this position no scale would be possible, as the apparent movement of the mercury would be confined to the space C. When the thermometer is held bulb upward, the mercury breaks off at A, but by its own weight flows down the tube, filling C and a portion of the tube above C, in relation to the resisting temperature. The scale accordingly is made to read upwards from C. To set the instrument for observation it is only necessary to place it bulb down-
* Description condensed from " ENGINEERING," Mai-ch 22iid, 1878.
64 NEGRETTI AND ZAMBRA, HOLBORN VIADUCT, E.G.,
DESCENDING. ASCENDING.
FIG. 72.
FIG. 71.
FIG. 73.
ward, then the mercury takes the temperature just as an ordinary thermometer. When at any time or at any place the temperature is required, all that has to be done is to turn the thermometer bulb upward, and keep it in this position until read off.
" The reading may be taken at any time after, for the quantity of mercury in the lower part of the stem which gives the reading is too small to be sensibly influenced by a change of temperature, unless it is very great, while that in the bulb will continue to contract with greater cold and to expand with greater heat, and in the latter case some mercury will pass the contraction A, and may fall down and lodge at B, but it cannot go further so long as the bulb is upward, and thus the temperature to be read off will not be vitiated. Now, when- ever the thermometer can be handled, it can readily be turned bulb upward for reading off the existing temperature. At a depth in the sea, some contrivances must be provided for turning the thermometer bulb upward. For this purpose the thermometer is fitted into a hollow wooden frame, loaded with shot, free to move from end to end of it, and sufficient to render the whole instrument just vertically buoyant in sea-water.
" In using the thermometer a cord is rove through the hole in the frame nearest the bulb, and the instrument is fastened by this cord to the sounding line. In descending the thermometer will be pulled down with the bulb downwards ; but upon being pulled up, the instrument, owing to the resistance through the water, and consequent displacement of its centre of gravity, will turn over and come up bulb uppermost, the temperature of the spot where it turned over will then be indicated, as shown in the illustrations. See figures 72 and 73.
" As regards the thermometer itself it was necessary, in order to make it perfectly satisfactory, to protect it against pressure, even if intended for shallow seas, as well as for
45, CORNHILL, E.G., AND 122, REGENT STREET, W., LOKDON. 65
the deepest. For whether used in deep or shallow water, unless withdrawn from pressure, its indications would always be more or less in error. Like an ordinary thermometer it is devoid of air, and so quite different from Six's, which, containing compressed air, has a certain internal resistance. Hence it would be more affected by pressure than Six's, how- ever thick the glass of the bulb. By the simple expedient of placing the thermometer entirely in a shield of glass hermetically sealed (see fig. 4 on next page), the effect of external pressure is entirely eliminated. The shield must of course be strong, but need not be exhausted of air. It must, however, render the enclosed thermometer more difficult to be affected by changes of temperature ; in other words, it will make it sluggish.
" To counteract this sluggishness, in that portion of the shield surrounding the bulb, some mercury is introduced, and confined there by a partition cemented in the shield around the neck of the thermometer bulb. This mercury acts as a carrier of heat from the exterior of the shield to the interior of the thermometer : and the efficacy of this arrangement has been experimentally determined, the instrument thus protected being, in fact, far superior in sensibility to Six's thermometer.
" So long as the shield withstands the pressure, that is, does not break, the thermometer will be unaffected by pressure, and there is abundant experience to show that such a shield will stand the pressure of the deepest ocean. The greatest pressure can never affect a thermometer so protected. Doubtless the shield will be compressed a little under great pressure, but this can never exert an internal pressure sufficient to have an appreciable effect upon the thermometer. This method of shielding is quite efficacious, and deep-sea thermometers so protected do not require to be tested for pressure in the hydraulic press. The thermometer will simply require to be tested for sensitiveness and for errors of gradu- ation very accurately ; because it is a standard instrument adapted to determine very small differences of temperature as well as large ones, even one or two- tenths of a degree in shallow waters. The test for sensitiveness should determine how many seconds the instru- ment requires to take up a change of 5 deg. rise or fall ; and the time has been found from 5 to 10 seconds.
" A considerable number of these instruments have already been tested at the Kew Observatory with perfectly satisfactory results, which place beyond doubt their value as Standard Deep-sea Thermometers.
" This instrument possesses great advantages. It has no attached scale, th'e figuring and graduations are distinctly marked on the stem itself, and the shield effectually preserves them from obliteration by sea-water. The part of the stem which forms the background to the graduations is enamelled white,* to give distinctness to the mercury.
" The hole at the top of the frame is for the purpose of lowering and keeping the thermometer upright until it has reached the water. This is effected by putting a cord through the hole, and both ends of it kept in the hand until the thermometer has reached the water, then one end is let go and the cord pulled on board ; this operation is not imperative, but it saves the thermometer from being knocked about previous to reaching the water." Negretti and Zambia's Patent Standard Marine Thermometer (fig. 72) . Price £2 10 0
* Enamelling the bac/c of Thermometer Tubes is on important invention by Negretti and Zambra. Most of the extremely sensitive Thermometers that are now made (such as Clinical Thermometers) would have been almost useless but for this improvement.
1 cubic foot of Sea Water weighs 62*425 lbs.=557 cwt , or 0-028 of a ton.
Sea Water freezes at 28°. Boils at 213 2 ; variable with the density.
80 miles from the Island of St. Thomas, at a depth of 3 875 fathoms, the temperature of the Sea was found to be 34£° Fahrenheit ; the pressure at this depth 4* tons to square inch.
The pressure at 100 feet is found by Divers difficult to bear for any lengthened period. Man cannot sustain a greater pressure than 6 Fathoms, or 120 feet. Weights of 6 or 8 hundredweight require two Hours to fall through 3 miles of Sea Water, owing to the friction of the water on the rope or wire. — Dr. CARPENTER.
F
C6 NEGEETTI AND ZAMBEA, HOLBOEN YIADUCT, B.C.
NEGRETTI & ZAMBRA'S PATENT IMPROVED-FRAME STANDARD DEEP-SEA THERMOMETER.
H c
FIG. l.
FIG. 3.
FIG 4.
FIG. 2.
82. NEGRETTI & ZAMBRA'S Improved Standard Deep-sea Thermometer has been abundantly proved to be the only thermometer that ought to be used in researches into the temperature of the sea below the surface. It is quite applicable for testing the temperature of the sur- face water, but merely for this purpose a less expensive instrument would usually be employed. For taking temperatures at moderate depths, from a few feet to a few hundred fathoms, NEGRETTI AND ZAMBRA'S Wooden Float form amply suffices and is quite suitable. The only objection that has been raised to this wooden float is, that in sounding to great depths a check upon the line, caused by the motion of the ship due to the heave of the sea, may make it turn over and register, so that the temperature at the desired depth is not obtained. In very deep soundings it is often desirable to have a series of thermometers
45, COBNHILL, E.G., AND 122, REGENT STREET, W., LONDON. 67
upon the line at different depths ; and in this case the frequent checks and stoppages upon the line during the hauling up, either from the pitching of the ship or in detaching the thermometers as they arrive at the surface, lead to some uncertainty in the results. To do away with all doubt as to the accuracy of the record brought up by each thermometer is the object of the new form of the Standard Deep-sea Thermometer. The improvement is due to suggestions kindly furnished to NEGBETTI AND ZAMBBA by Commander MAGNAGHI, of the Royal Italian Navy. By means of it the thermometer may be attached to any part of the line during the descent ; and after the first regular haul in of from 10 to 80 feet, according to adjustment, any number of stoppages or any amount of line may be afterwards run out without altering the temperature obtained at the commencement of hauling up. Several thermometers can now be fastened upon the line and serial temperatures obtained at any required depth with certainty.
The apparatus will be best understood by reference to the accompanying figures (Nos. 1 and 2). A is a metallic frame in which the case B, containing the thermometer, is pivoted upon an axis H, but not balanced upon it. C is a screw-fan attached to a spindle, one end of which works in a socket D, and on the other end is formed the thread of a screw E, about half an inch long, and just above it is a small pin or stop P on the spindle. G is a sliding stop-piece against which the pin F impinges when the thermo- meter is adjusted for use. The screw E works into the end of the case B the length of play to which it is adjusted. The number of turns of the screw into the case is regulated by means of the pin and stop-piece. The thermometer in its case is held in position by the screw E, and descends into the sea in this position (Fig. 1), the fan C not acting during the descent because it is checked by the stop F. When ascent commences the fan revolves, raises the screw E, and releases the thermometer, which then turns over and registers the temperature at that spot, owing to the axis H being below the centre of gravity of the case B as adjusted for the descent. Each revolution of the fan represents about 10 feet of move - ment through the water upwards, so that the whole play of the screw requires 70 or 80 feet ascent ; therefore the space through which the thermometer should pass before turning over must be regulated at starting. If the instrument ascends a few feet by reason of a stoppage of the line while attaching other thermometers, or through the heave of the sea, or any cause whatever, the subsequent descent will cause the fan to carry back the stop to its initial position, and such stoppages may occur any number of times provided the line is not made to ascend through the space necessary to cause the fan to release the thermometer. When the hauling-in has caused the turnover of the thermometer the lateral spring K forces the pin L into a slot in the case B and clamps it (as seen in fig. 2) until it is received on board so that no change of position can occur in the rest of the ascent from any cause. The case B is cut open to expose the scale of the thermometer, and is also perforated to allow the free entry of the water.
The construction of the Thermometer will be understood by referring to Figs. 3 and 4 and also to the description given on page 63 (fig. 71)
Price for NEGEETTI AND ZAMBEA'S New Patent Improved Frame Standard Deep-Sea Thermometer, as fig. 1.
The Hydrographic Bureau at Washington published lately the following results of a series of observations carried out in order to determine the length, depth, and duration of ocean waves : —
The longest wave hitherto observed is said to have had a length of half-a-mile, and to have spent itself in 23 seconds. During storms in the North Atlantic waves sometimes extend to a length of 500 ft. and 600 ft., and last from 10 to 11 seconds.
The most careful measurements of the height of waves give from 44 to 48 feet as an extreme limit ; the average height of great waves is about 30 ft.
These measurements refer to ordinary marine action, and do not relate to earthquake action or other exceptional agencies.
F 2
68 NEGRETTI AND ZAMBKA, HOLBOJiN VIADUCT, E.G.,
INSTRUMENTS FOR ASCERTAINING THE HUMIDITY OF THE ATMOSPHERE.
THE instruments used for observing the amount of moisture contained in the atmosphere are called Hygrometers. They are without doubt of all Meteorological instruments the most useful and valuable.
To ascertain with exactness the Hygrometric condition of the air is of the utmost importance both to the Physician and Agriculturist. By observing the varying amount of vapour or moisture in the air, the one is enabled to regulate its condition as best suited to his patient's requirements, and the other by closely watching the movements of the Barometer in connection with the Hygrometer can anticipate probable atmospheric changes that may prove beneficial or injurious to his crops.
There are many Hygrometers constructed as Weather Indicators only, simply showing the approximate condition of the air if it be wet or dry. Such instruments, however ingenious, are not of any scientific value. For more exact and precise observation the Hygrometers of Daniell, Regnault, and Mason are chiefly used — the latter, viz., Mason's, from its extreme simplicity is now universally in use, and in connection with the valuable tables compiled by James Grlaisher, Esq., F.B.S., the dew point can be ascertained with great exactness and ease.
In connection with the Hygrometer, the dew point will be frequently spoken of. This may be described in a few words as the amount of water which the air can sustain in an invisible form increasing with the temperature ; but for every definite temperature there is a limit to the amount of vapour which can be thus diffused. When the air is cooled the vapour present may be more than it can sustain ; part will then be condensed either in the form of dew, rain, hail, or snow. The temperature which the air has when it is so fully saturated with vapour that any excess will be deposited as dew, is called the dew-point.
" To measure the quantity of dew deposited each night, an instrument is used called a Drosometer. The most simple process consists in exposing to the open air bodies whose exact weight is known, and then weighing them carefully when covered with dew. According to Wells, locks of wool, weighing about eight grains, are preferred, divided into spherical masses of the diameter of about two inches.'' — Kcemtz.
45, COBNHILL, E.G., AND 122, BEGENT STEEET, W., LONDON. 69
83. Saussure's Hygrometer (fig. 74), for showing changes in the hygrometric condition of the atmosphere on a graduated arc, by the contraction and elongation of a human hair, this acting the reverse of string or cord, stretching when moist and contract- ing when dry. A thermometer is attached to the scale.
Price, £1 10 0
Although a most elaborate Treatise on the construction and use of this Hygrometer was written by its inventor, M. Horace Benedict de Saussure, Professor of Philosophy, at Geneva, in 1783, this instrument may be regarded more as an ornamental curiosity than of any scientific value. FIG 74.
84. Leslie's Thermometric Hygrometer (fig 75). It will be seen that Leslie's instrument is the elementary form of Mason's Wet and Dry Bulb Hygrometer, by which it is entirely superseded.
This instrument consists of a glass tube, terminated with a bulb at each end, as fig. 75. The tube is partly filled with sulphuric acid, tinged by carmine. One of the balls is covered with muslin, and kept continually moistened with water, drawn from a vase placed near it by the capillary attraction of a few strands of cotton- wick. The descent of the coloured liquid in the other stem will mark the diminution of temperature caused by the evaporation of the water from the humid surface. The drier the ambient air is, the more rapidly will the evaporation go on ; and the cold produced will be greater. When the air is nearly saturated with moisture, the evaporation goes on slowly ; the cold produced is moderate, because the ball regains a large portion of its lost heat from surrounding bodies. The degree of refrigeration of the ball is an index of the dryness of the air.
When this hygrometer stands at 15°, the air feels damp ; from 30° to 40°, we reckon it dry ; from 50° to 60°, very dry ; and from 70° upwards, we should call it intensely dry. A room would feel uncomfortable, and would probably be unwholesome, if the instrument in it did not reach 30°. In thick fogs it keeps almost at the beginning of the scale. Price, £110
85. Daniell's Hygrometer, for ascertaining the dew-point by direct observation (fig. 76), invented about the year 1820, by the late Professor Daniell, of King's College, London.
It consists of a glass tube, bent twice at right angles, and terminating, at each end, in a bulb. In the long limb of the tube is enclosed a delicate thermometer, which descends to the centre of the bulb, which is about three- parts filled with sulphuric aether. All the other parts of the tube are carefully freed from air, so that they are occupied by the vapour of the aether. This bulb is made of black glass ; the other bulb on the shorter limb is transparent, and
70
NEGEETTf AND ZAMBKA, HOLBORN VIADUCT, E.C.,
FIG. 75. FIG. 76. FIG. 77.
covered with a piece of fine muslin. The support for the tube has a delicate thermometer attached, to show the temperature of the external air.
This instrument gives the dew-point by direct observation, and is to be used at an open window facing the north in the following manner : — Having fixed the tube upon the stand, with the bulbs vertically downward, the ^Ether is all caused to flow into the lower ball by inclining the tube. The temperature of the air is noted by the exposed thermometer. Then some ^Efcher is poured upon the muslin-covered bulb. The rapid evaporation of this ^Ether cools the bulb and causes condensation of the ^Ethereal vapour in its interior. This gives rise to rapid evaporation of the Mtlaer in the lower bulb, whereby its temperature is greatly reduced. The air in the vicinity is deprived of its warmth by the cold bulb, and is soon cooled to the temperature at which it is perfectly saturated with the vapour which it contains. Cooled ever so little below this temperature, some aqueous vapour will be condensed, and will form a dew upon the black- glass bulb. At the first indication of the deposit of dew the reading of the internal thermometer is taken : which is the dew-point. In very damp or windy weather the .^Ether should be slowly dropped on the bulb, otherwise the descent of the mercury in the Thermometer is so rapid as to render it difficult to be certain of the temperature. Should this occur, the observation may be repeated by watching the temperature at which the ring of dew disappears, the mean of the two readings will be the correct point of precipitation. The greatest differ- ence observed by Mr. Daniell in the course of four months' daily experiments between the external thermometer and the internal one at the moment of
45, COKNHILL, E.G., AND 122, EEGENT BTRKET, WM LONDON. 71
precipitation in the natural state of the atmosphere was twenty degrees. When Darnell's Hygrometer is required to act merely as a weather-glass, to predict the greater or less probability of rain, &c., the difference between the con. stituent temperature of the vapour (shown by the interior thermometer), and the temperature of the air (shown by the exterior thermometer), is all that is necessary to be known. The probability of rain or other precipitation of moisture from the atmosphere, is in inverse proportion to this difference. There are several difficulties connected with the use of Daniell's Hygrometer that are in a great measure overcome in Regnault's Instrument. Fig. 76 Price, £330
86. Jones's Hygrometer (fig. 77). This instrument is the same in principle as Daniell's Hygrometer, but simpler in its construction. The tube of the Mercurial Thermometer is bent so as to bring its bulb vertical and parallel with its stem. This bulb is one inch long, and of a conical shape, with a flattened top or surface of black glass projecting a little beyond the sides. Below the flat surface this bulb is covered with black silk. The Hygrometer is mounted and supported on a brass stand in such a manner that the black surface can be inclined towards the light. When used the temperature of the air is first to be noted. ./Ether is to be poured on to the silk cover of the bulb, and the condensation of moisture takes place upon the black surface of the bulb. Then, by again noting the temperature, the dew point may be known.
Price, £2 10 0
87. Regnault's Condenser Hygrometer, (fig. 78), for ascertaining by direct observation the dew-point, is superior to Daniell's, from its being more certain in its indications, and economical in use. It consists of two highly- polished silver cylinders, into the upper part of which are cemented thin glass tubes ; these have brass covers, arranged to receive and support two delicate Standard Thermometers, the bulbs of which descend nearly to the bottom of the silver portion of these chambers. Each chamber has a small internal tube carried down from the brass cap to within a short distance of the bottom, to admit the passage of the air, which is drawn through both chambers by an Aspirator, (fig. 78*) connected to the base of the hollow upright and arms supporting the cylinders.
To use this Hygrometer, aether is poured into one chamber sufficient to cover the bulb of the thermometer, and then the thermometers being inserted into both cylinders the instrument is now connected to the aspirator, and by it the air is drawn through both cylinders down the internal tubes, passing in one chamber in bubbles through the aether, and in the other chamber simply around the thermometer. The tube in this empty cylinder is of such a diameter as to ensure similar quantities of air passing through each chamber.
After a short time the passage of the air through the aether will cool it down to the dew-point temperature and the external portion of the silver chamber containing the aether will become covered with moisture. The degree shown
72
NEGRETTI AND ZAMBRA, HOLBORN VIADUCT, E.G.
FIG. 78.
FIG. 79.
by the thermometer in the aether at that instant will be the temperature of the dew-point ; the second thermometer showing the temperature of the air at the time of observation.
Price, in case .... £5 5 0
Aspirator for ditto (fig. 78*) £1 15 0 to 2 15 0
88. Regnault's Condenser Hygrometer (fig. 56), of simpler form, only one cylinder or chamber being nsed. The air in this arrangement is blown through the aether by the mouth. A small thermometer is attached to the stand to show the temperature of the external air.
Price, in Case, with ^Ether Bottle (fig. 79) £3 10 0
For practical utility and convenience in use the Wet and Dry Bulb Hygro- meter is vastly superior to all others. The engravings, N"os. 80 to 86, will show the various forms of Negretti and Zambra's Hygrometers from the simplest to the Standard instruments as manufactured by Negretti and Zambra for the various Scientific Observatories and Societies, the Government Meteorological Stations, the Metropolitan and County Hospitals, &c., &c. Most of these Hygrometers ' have Negretti and Zambra's Patent Porcelain Scales and Enamelled Tubes.
89. Wet and Dry Bulb Hygrometer, simple form, on a stand (fig. 80) for table or shelf. Price, 12s. 6d., 16s., and £110
90. Ditto Ditto Ditto plain, portable, brass stand and metal cover (fig. 81). Price, £1 10 0
45, CORNHILL, E.G., AND 122, REGENT STREET, W., LONDON.
73
FIG. 80. FIG. 82. FIG. 83.
91. Wet and Dry Bulb Hygrometer with Wood or Zinc Scales, mounted in a Japanned Metal Case, suited for out-door use, the Greenhouse or Conservatory (fig. 82). Price, £0 14 0
92. * Ditto Ditto with Negretti and Zambra's Patent Porcelain Scale, in Japanned Case, as fig. 82. Price, £110
93. Mason's Hygrometer, portable brass-jointed tripod-stand and metal cover (fig. 83). Price, £3 3 0
94. Negretti and Zambra's Standard Dry and Wet Bulb Hygrometer, or Psychrometer (fig. 84), consists of two parallel Thermometers, as nearly identical as possible, mounted on a wooden bracket, one marked dry, the other wet. The bulb of the wet thermometer is covered with thin muslin and round the neck of the stem is twisted or tied, as seen in fig. 84*, conducting-threads of lamp-wick, or common darning- cotton, these pass down into a vessel of water, placed at such a distance as to allow a length of conducting-thread of about three inches ; the cup or glass being placed on one side, and a little beneath, so that the water within may not affect the reading of the Dnj Bulb Thermometer. In observing, the eye should be placed on a level with the top of the mercury in the tube, and the observer should refrain from breathing whilst taking an observation. The temperature of the air and of the evaporation is given by the readings of the two thermometers, from which can be calculated the dew point, Tables being furnished for that purpose with the instrument.
The dry bulb thermometer indicates the temperature of the air itself ; while the wet bulb, cooled by evaporation, shows a lower temperature according to the amount of and rapidity of evaporation.
This instrument is used by the Members of the British Meteorological
Society, and supplied to them by Negretti and Zambra (fig. 84) Price £220
Glaisher's Tables for ditto 026
NEGRETTI AND ZAMBBA, HOLBOKN VIADUCT, E.G.,
FIG. 85.
FIG. 84.
95. Wet and Dry Bulb Hygrometer for external Window use, with engraved Opal Glass or Porcelain Scales, mounted on a substantial and Ornamental wood and metal bracket, fitted with a clamping screw for setting the scale at any convenient angle for observation, as fig. 85.
Price £2 10 0 and £330
96. Portable Wet and Dry Bulb Hygrometer, (fig. 86.) A most compact and convenient form of Hygrometer, invented by Negretti and Zambra, as a companion instrument to their Small Patent Maximum and Minimum .Registering Thermometers and Pocket Aneroid Barometer (figs. 26 and 61), pages 26 and 51. The Hygrometer, with stand and water cistern, is fitted into a neat Pocket case. Price . . . .£220
Larger Standard size . 2 10 0
45, CORNHILL, E.G., AND 122, REGENT STREET, W., LONDON.
75
FIG. 81. FIG. 86.
97. Dines* Hygrometer. We notice this apparatus chiefly as a matter of record. It is fully described along with an account of some remarkable results obtained from its use by its inventor, George Dines, Esq., in the Journal of the Meteorological Society ; but, like Daniell's, Regnault's, and Jones's Hygrometers, it is not self-acting, and not so simple in its use as the Wet and Dry Bulb Instrument. Therefore, this Apparatus will only be supplied to special order. Price, £2 12 6 to 3 3 0
98. Registering Hygrometer, constructed with Negretti and Zambra's Patent Maximum and Minimum Registering Thermometers, each fitted up as a wet-bulb thermometer, to record the highest and lowest temperature of evaporation during any interval of time. Price, £330
99. Hygrometer Screen. The engraving (fig. 89), page 79, shows one of the best methods of fixing up and protecting the Hygrometer, the louvre boarded case affording free passage to the air and at the same time protection from rain, suow, the sun's rays, or radiated heat from surrounding bodies. This Screen should be fixed at about four feet from the ground, the door facing due North. If fixed against a wall, there should be left a space between the back of the Screen and the wall, at least three or four inches, to insure a free circulation of air. It need hardly be pointed out that the Screen must be securely fastened to its support, wherever used, to prevent vibration or injury from wind. This arrangement is specially recommended by the Board of Trade for Marine Service both for Hygrometers and Thermometers.
Price, £1 1 0, or made to Order.
100. From the readings of the two thermometers, the dew-point can be deduced by formulae (that known as Apjohn's is considered the most theoretically true), or from the valuable Hygrometric Tables by J. Glaisher, Esq., F.R.S.
76 NEGRETTI AND ZAMBEA, HOLBORN VIADUCT, E.G.,
101. For practical purposes in estimating the comparative humidity, the annexed table, which is a reduction from Mr. Glaisher's elaborate work, will be sufficient.
|
Temperature by the Dry Bulb Thermometer. |
Difference between Dry-Bulb and Wet-Bulb Readings. |
|||||
|
2° |
4° |
6° |
8° |
10° |
12° |
|
|
Degree of Humidity. |
||||||
|
34° |
79 |
63 |
50 |
|
__ |
|
|
36 |
82 |
66 |
53 |
__ |
|
|
|
38 |
83 |
68 |
56 |
45 |
|
|
|
40 |
84 |
70 |
58 |
47 |
__ |
___ |
|
42 |
84 |
71 |
59 |
49 |
|
|
|
44 |
85 |
72 |
60 |
50 |
|
|
|
46 |
86 |
73 |
61 |
51 |
|
|
|
48 |
86 |
73 |
62 |
52 |
44 |
|
|
50 |
86 |
74 |
63 |
53 |
45 |
, |
|
52 |
86 |
74 |
64 |
54 |
46 |
|
|
54 |
86 |
74 |
64 |
55 |
47 |
|
|
56 |
87 |
75 |
65 |
56 |
48 |
|
|
58 |
87 |
76 |
66 |
57 |
49 |
|
|
60 |
88 |
76 |
66 |
58 |
50 |
43 |
|
62 |
88 |
77 |
67 |
58 |
50 |
44 |
|
64 |
88 |
77 |
67 |
59 |
51 |
45 |
|
66 |
88 |
78 |
68 |
60 |
52 |
45 |
|
68 |
88 |
78 |
68 |
60 |
52 |
46 |
|
70 |
88 |
78 |
69 |
61 |
53 |
47 |
|
72 |
89 |
79 |
69 |
61 |
54 |
48 |
|
74 |
89 |
79 |
70 |
62 |
55 |
48 |
|
76 |
89 |
79 |
71 |
63 |
55 |
49 |
|
78 |
89 |
79 |
71 |
63 |
56 |
50 |
|
80 |
90 |
80 |
71 |
63 |
56 |
50 |
|
82 |
90 |
80 |
72 |
64 |
57 |
51 |
|
84 |
90 |
80 |
72 |
64 |
57 |
51 |
|
86 |
90 |
80 |
72 |
64 |
58 |
52 |
The total quantity of aqueous vapour which at any temperature can be diffused in the air being represented by 100, the percentage of vapour actually present will be found in the table opposite the temperature of the dry-bulb thermometer, and under the difference between the dry-bulb and the wet-bulb temperatures. The degree of humidity for intermediate temperatures and differences to those given in the table can be easily estimated sufficiently accurately for most practical purposes.*
This table will be found serviceable to Horticultarists, since it will enable them to estimate the chilling effect of dew or hoar-frost on tender plants.
In England the usual difference between the thermometer readings, — in the open air, shaded from the sun, reflected heat, and currents of air, — ranges from one to twelve degrees. In hot and dry climates, as India and Australia, the range out of doors has been found as much as 30°.
A. still more comprehensive but simple Dew-Point or Humidity Table has been recently published by William Marriott, Esq., F.M.S., price 6d.
45, CORNHILL, E.G., AND 122, REGENT STREET, W,, LONDON. 77
The Summer and Autumn of the year 1859 were specially remarkable for a most unusual Thermometric and Hygrometric condition of atmosphere, and Londoners will long remember the state of the River Thames during that period. Deficiency of water supply during 1858 and 1859, and great evaporation (often to fourteen degrees of thermometrical difference in Mason's Hygrometer), caused a condition of its stream excessively offensive, if not actually pestilential and unhealthy. Everywhere a want of water was felt, and this had been of considerable duration. In August the heat reached 92° (in places where usually summer heat is not above 80Q), and the temperature of evaporation was 78°, by the same hygrometer.
INSTRUCTIONS FOR THE USE OF THE WET AND DRY BULB
HYGROMETER.
102. The muslin on the bulb of the Hygrometer should be washed occasionally by pouring water over the bulb ; and it should be replaced by a fresh piece at least once a month. Accuracy depends very much upon keeping the wet bulb clean, free from dust, and not too wet.
When the bulb is frozen, some cold water should be taken from nnder ice, being cautious to raise its temperature as little as possible, and the thermometer bulb should be wetted with it by means of a camel-hair brush or feather. After waiting a few minutes, the temperature of evaporation may be observed. The water should be either distilled or rain water, or if this be not procurable, the softest pure water which can be had. The water vessel should be replenished after, or some little time before, observing ; because observations are incorrect if made while the water is either colder or warmer than the air.
In connection with the barometer, the Wet and Dry Bulb hygrometer is very useful, not only on land, but especially at sea, where other kinds of hygrometers cannot be practically used. A fall in the Barometer is indicative of coming wind or rain ; if the hygrometer shows increasing dampness by the difference of the readings becoming smaller, — rain may be anticipated. On the contrary, if the hygrometer shows continuing or increasing dryness, a stronger wind is probable, without rain.
The Hygrometer is eminently useful in regulating the moisture of the air of apartments ; a difference in the thermometer readings of from 5° to 8° being considered healthy. Many diseases require that the temperature and humidity of the air which the invalid breathes should be very carefully regulated. In a room, the hygrometer should be placed away from the fire, but not exposed to draughts of air.
78
NEGKETTI AND ZAMBEA, HOLBOBN VIADUCT, B.C.,
FIG. 87.
103. Negretti and Zambra's Self-Kecording Hygrometer, fig. 87. The Thermometers in this Hygrometer are similar in construction to those used in Negretti and Zambra's Patent Hourly Recording Thermometric Apparatus. No. 64, Page 55. It will be seen by the drawing (fig. 87) that two Thermometers are, with a Water Cistern, mounted upon a metal frame in; such a manner that they will fall over and become inverted from the joint action of a Clock and Galvanic Battery.
The most important improvement in this Self- Recording Hygrometer is that it can be freely exposed at any distance from the regulating clock. Our wood engraving exhibits the Clock, A, with an adjusting index upon its dial, enabling the observer to arrange the release of the detent, B, at any appointed time, thus allowing the frame supporting the Hygrometer to turn over, and by inverting the Thermometers record the temperature of both the Wet and Dry bulb instruments at the moment.
The escapement is an Electro Magnet, seen at B, in connection with a Galvanic Battery, B, the Clock at C and C, and the Wire A and A. At the arranged time the circuit is completed by the clock, and the electrical current acting upon the soft iron magnet releases the detent and the Hygrometer turns over.
The instrument is re-set for another observation, by turning back the frame with the Thermometers into its original vertical position (as shown in the engraving) and by adjusting the index of the Clock. Price £10 10 0
The peculiar construction of the two Thermometers is fully described on page 63, and fig. 71.
45, COKNHILL, E.O., AND 122, BEGENT STREET, W., LONDON.
79
FIG. 88.
FIG. 89.
FIG. 91.
FIG. 90. 104 Screens for Thermometers and Hygrometers-.
80
NEGRETTI AND ZAMBRA, HOLBOEN YIADUCT, B.C.,
FiG. 92.
104. Beckley's Thermograph and Eecording Hygrometer.^— As recommended by the Meteorological Committee of the Boyal Society for pro- ducing Photographic records of the variations of temperature and moisture in the atmosphere.
In the engraving (fig 92) the Wet and Dry Bulb Thermometers are shown at W and T. freely exposed to the external atmosphere, at H is a screw for adjusting these Thermometers ; C is an accurate clock for rotating the cylinder D (upon which is stretched the sensitised photographic paper) once in 48 hours ; G G are gas lamps, the rays of light from them being concentrated by two condensers, E E, upon reflectors M M and thence projected by the Photographic Combination Lenses P P, through perforated screens and the air bubbles in the tubes of the Thermometers upon the prepared paper. Upon the drum D the movements of the air bubble in both tubes are hereby recorded with precision, a screen in connection with the clock movement is arranged to intercept the light for 4 minutes every two hours, this producing white lines (time spaces) upon the paper when the record is developed.
The room in which the Thermograph is placed should be most carefully darkened when the apparatus is in action.
Price, £125, complete with two Standard Thermometers, two Bent Thermometers, Clock Movement, Sec., fyc.. complete, made to order.
RAIN GAUGES
81
105. It is hardly possibly to over-estimate the value and importance of carefully compiled statistics of the Rainfall. The two great sanitary questions of the day, viz., the Water supply and Sewage of large towns, are in a very great measure connected with the amount of rain falling during a given period, and reliable particulars of the rainfall are specially valuable both to the Civil and Hydraulic Engineer.
The Farmer and commercial Financier are also both deeply interested in the results of a probable dry or wet season influencing the growth, amount, and value of various crops and produce of the earth. We subjoin a few facts we think may prove useful and interesting.
Fall of Rain at the Royal Observatory, Greenwich.
Taking December, January, and February as the winter months ; March, April, and May as the spring months ; June, July, and August as the summer months ; September, October, and November as the autumn months, the quantities which fell in the different seasons were as follows :
|
— |
1842. |
1843. |
1844. |
1845. |
1846. |
1847, |
Mean. |
|
Winter . Spring Summer . Autumn . |
Inches. 2-81 4-42 5-69 9-65 |
Inches. 4-14 5-98 7-34 7-01 |
Inches. 5-16 359 6.63 9-58 |
Inches. 5-33 4-27 6-84 5-90 |
Inches 5-42 5-43 6-00 8-44 |
Inches. 4-77 3-16 4-12 5-56 |
Inches. 4-60 4-47 6-10 7-69 |
|
Total . |
22-57 |
24-47 |
24-96 |
22-34 |
25-29 |
17-61 |
22-86 |
The quantity of rain which fell at the Royal Engineers' stations during
the year 1853-4, was as follows :
Edinburgh Guernsey St. John's Gibraltar Malta . Jamaica
Inches. 23-15 32-77 55-05 47-29 28-08 34-31
Barbadoes . Ceylon Mauritius . Fremantle . New Zealand
Inches. 68-24 71-63 39-52 33-94 48-42
Lincoln is the dryest recorded station in England, the mean annual rain- full being 20 inches. The wettest recorded station is Stye, at the head of Borrowdale in Cumberland, where the mean annual rainfall amounts to 165 inches. A fall of rain measuring a tenth of an inch in depth is equal to a deposit of about forty hogsheads per acre.
82 NEGRETTI AND ZAMBRA, HOLBORN VIADUCT, B.C.,
POSITION FOR RAIN GAUGES
106. From the observations made at the Royal Observatory at Greenwich, the fact is clearly established that in the lower regions of the atmosphere, the quantity of rain which falls diminishes with the altitude above the ground.
The height for placing the receiving surface of a rain gauge is somewhat open to a difference of opinion. Mr. Glaisher's gauge is directed to be ** half sunk in the ground." This would place the edge of the gauge about 8 inches from the surface of the ground. Mr. Symons gives 12 inches as most correct, 10 inches as a mean between these will be perhaps the best to adopt. Rain gauges should be placed on a level piece of ground, and not on a slope or terrace, away from walls or trees, as many feet from their base as their height, the edge of the funnel should be set quite level. Unless for special observa- tions Rain Gauges should not be placed on roofs or any very elevated position. It is very important that Rain Gauges be occasionally examined to see that the Receiving Funnel be not choked up by dust or leaves, and that at very wet stations the receiving portion of this Gauge be sufficiently large to hold any possible rainfall ; — even the probable occurrence of a water-spout might be provided for in hilly or very exposed situations. Gauges should be well supported to prevent their being knocked down or blown over by the wind, and after «riow or frost the gauges should be placed in a warm room until the collected contents are melted and can be measured. In measuring off the quantity of collected rain, the graduated glass should be held quite upright, and the reading taken midway between the two apparent surfaces of the water. The rain should never be collected in the graduated measure, especially in winter, to avoid risk of breakage by frost.
107 Measurement of Rain. The Rain Gauge should be examined every day, at nine a.m., and the amount of water collected by it entered in the register, as having fallen on the previous day ; for if we measure at nine a.m. to-day, it is probable, under ordinary conditions, that more of the Rain collected by the Gauge will have fallen during the fifteen hours of the previous day up to midnight than during the nine hours extending from midnight to nine o'clock of the following morning.
A vast amount of interesting and most valuable information respecting Rain Gauges and the Rainfall will be found in Negretti and Zambra's Treatise on Meteorological Instruments, and Mr. G. J. Simons' eminently useful publications as enumerated in our list of books at the end of this section.
45, CORNHILL, B.C., AND 122, REGENT STREET, W., LONDON. 83
INSTRUMENTS USED FOR MEASURING THE RAINFALL
FIG. 93.
FIG 94.
FIG. 95
108. Howard's Rain Gauge,* (fig. 93). The simplest form of the in- strument constructed 'and used by the celebrated meteorological writer, Luke Howard, from whom it derives its name ; it has a 5-inch Copper Funnel, with a turned brass Rim, fitted to a stoneware or glass bottle, with a glass graduated measure divided to hundredths of an inch. Price, £0 10 6
109. Symons' Rain Gauge, (fig. 94). This instrument has a glass receiving bottle protected by a metal case, with openings at the side for the convenience of observing the collected rainfall without disturbing the frame, which is firmly supported in the ground by strong spikes. The measure holds half an inch of rain for a 5-inch area subdivided into hundredths.
Price, with graduated measure . . £0 10 6
Ditto, in Copper 0 15 0
See also Symons1 Snorvdon Rain Gauge, No. 118, Page 85.
110. Glaisher's Rain Gauge, (fig. 96). — This gauge is eight inches diameter, and arranged for the reception of the water only which falls upon its receiving surface, and for the prevention of loss by evaporation. The rain is first collected in a funnel, the receiving surface of which is accurately
* Pluviometer, Ombrometer, Udometer.
G 2
84
NEGRETTI AND ZAMBRA, HOLBORN VIADUCT, F.C.,
FlQ. 96.
FIG. 97.
turned in a lathe, and terminated at its lower extremity in a bent tube of small aperture, in which the last few drops of rain remain as shown in the engraving. The glass receiving vessel is graduated to hundred ths of inches according to the calculated weight of water, as determined by the area of the receiving surface. In use, the gauge is partly sunk below the surface of the soil, so that the receiving surface is about eight inches above it. Thus situated, no water escapes by evaporation in any month of the year. If placed differently, the readings must be taken daily.
Price t in Japanned Tin . £1 1 0
in Copper . . 1 10 0
RECEIVING VESSEL FOE GLAISHER'S GAUGE. — Price, in Japanned Tin or Copper, 2s. <k 3s. 6d.
As some meteorologists have objected that the curved tube at the base of the funnel is liable to be choked up with dust, Messrs. Negretti and Zambra, if desired, supply these Rain Gauges with a straight tube of sufficient length to reach very nearly the bottom of the receiving vessel, thus obviating this diffi- culty, and at the same time preventing evaporation.
111. Glashier's Rain Gauge, with extra large receiving vessel, mounted with a convenient tap for drawing off the water, suited for Tropical countries or stations where there is an excessive rainfall. Price, in Copper, £330
The 8-inch Glaisher's and the Meteorological office Rain Gauges are now considered by scientific men the best, and consequently are almost universally adopted as Standard instruments, but at the same time we would observe that most valuable results have been obtained by the use of Mr. Symons' 5-inch gauge in many parts of the United Kingdom.
45, CORNHILL, E.G., AND 122, BEGENT STEEET, W., LONDON. 85
112. Rain Gauge (fig 97), having a receiving surface of 12 inches diameter, arid graduated glass tube divided to inches, tenths, and hundredths of an inch, showing by simple inspection, without the use of a graduated measure, the amount of rain fallen. In japanned metal, with tap for emptying the gauge.
Price . . . £2 10 0 Ditto, ditto, in Copper . 3 10 0
113. Rain Gauge, a similar but rougher form of No. 112, without brass mountings, and instead of the graduated glass tube, it is fitted with a boxwood scale, attached to a metal float inside the gauge, on which can be read off, by simple inspection,