II.*- -BAROMETERS. 573 



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, Weilenmann 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. M. Pillischer. 



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

 ever constructed. 



2817. Two Aneroid Barometers, Reitz system, with visible 

 movement. R. Deutschbein, Hamburg. 



2818. Two Metal Barometers, exhibitor's construction, with 

 visible movement. R. Deutschbein, Hamburg. 



2819. Two Spring Barometers, Reitz system, with visible 



movement. R. Deutschbein, Hamburg. 



The first four pieces are house barometers, distinguished by good work- 

 manship, shape, and cheapness. The last two instruments are spring -baro- 

 meters, specially adapted to meteorological observations, determination cf 

 heights, &c. 



The aneroid barometers of the Reitz system are metal barometers with a 

 vacuum box according to Vidi. The movements of the box are read off by 

 means of a microscope on a scale which is divided into hundredths of milli- 



