Signedon center dial: J. Goldschmid Zürich / No. 620
case marked: J. GOLDSCHMID IN ZÜRICH
Inscribedvarious scales, marked on the face of the instrument, plus information all in German
in center: Aneroid Barometer / No. 620
FunctionAneroid barometers were used to measure atmospheric pressure and altitude, and were much more convenient than mercury barometers since they did not use any kind of liquid. The Goldschmid anaeroid barometer was invented in the middle of the 19th century, and had the advantage of a partially evacuated capsule which was was affected only by the resistence of the spring. The metal capsule, which reacts to tiny changes in air pressure by contracting and expanding, is connected by internal clockwork to the dial on the face of the barometer, from which a measurement of air pressure can be taken.
One of the major benefits of this kind of barometer was its portability. They could be made extremely small, and were much more easily transportable since they did not contain mercury. The downside of their size, however, was the fact that scales had to be considerably contracted in order to fit on the instrument, but extend far enough to be useful. This problem was here rectified by using a spiraling scale, which can extend the scale much further.
ProvenanceFrom the Geographic Institute Collection, Harvard University.
Related WorksOn the Goldschmid aneroid: W. E. Knowles Middleton, The History of the Barometer (Baltimore: Johns Hopkins University Press, 1964), 418-420.