684 SEC. 14. METEOROLOGY 



b. ANEROIDS. 



2810. Aneroid Barometer. The ends of the axle which 

 carries the index hand are jewelled like the pivots of a watch, 

 and the hand works under the cap. By this means greater 

 sensitiveness and especially greater definiteness of the indications 

 are obtained. This aneroid will show a difference in height of 

 2 feet. The Hon. Ralph Abercromby. 



2811. Aneroid Barometer, capable of measuring up to 5,000 

 metres from the level of the sea. With case, tables of comparisons, 

 instructions, &c. J. Goldschmid, Zurich. 



2812. Aneroid Barometer, capable of measuring from 9,000 

 to 10,000 metres from the sea level. With case, tables, and in- 

 structions, &c. J. Goldschmid, Zurich. 



2813. Pocket Aneroid Barometer, of German silver. With 

 case and instructions, &c. J. Goldschmid, Zurich. 



2814. Aneroid Barometer, W^eilenmann system. With 

 tables. J. Goldschmid, Zurich. 



2815. Aneroid Barometer, capable of measuring up to 

 5,000 metres. With tables, &c. J. Goldschmid, Zurich. 



The faces of the above aneroid barometers are of German silver. The 

 variations of reading are measured by a fine micrometer. A table, specially 

 prepared, accompanies each instrument, and gives the height of the barometer. 

 The correction for temperature, given in a second table, is founded on the 

 observation of a small thermometer applied to the instrument. 



2816. Miniature Aneroid Barometer, the dial measuring 

 f inch, the case f inch in diameter, the bearings set in jewelled 

 centres, compensated for temperature. Pillischer. 



This is believed by the maker to be the smallest instrument of the kind 

 ever constructed. 



2816a. Pocket and Watch-sized Aneroid Barometers. 



Negretti and Zambra. 



The patent for the aneroid having expired, the late Admiral Fitsroy urged 

 upon Negretti and Zambra the desirability of reducing its size as well as 

 improving its mechanical arrangement, and compensating it for temperature. 

 They after great labour and numerous experiments, succeeded in reducing the 

 dimensions to less than three inches in diameter and two inches in thickness. 

 These instruments have since been further reduced by Negretti and Zambra, 

 until they have at last reached the dimensions of an ordinary watch. These 

 very small instruments are found to act quite as correctly as the largest, and 

 are much more convenient ; they may be had with a range sufficient to measure 

 heights of 20,000 feet, with a scale of elevation in feet, as well as of pressure 

 in inches. 



2817. Two Aneroid Barometers, exhibitor's construction, 

 with visible movement. R. Deutschbcin, Hamburg. 



