Aneroid barometers have no liquid inside and the reading is displayed by means of dial and a needle - a heavy spring inside expands and compresses with the changes in the air pressure.

A blued needle indicates the present pressure; a brass needle indicates a previous observation. The “U.S. Signal Service – 1101” inscription on the back of the case refers to the organization that ...

M. Teisserenc de Bort has sought to obtain an aneroid barometer which will give precise observations at sea, especially in rough weather, when it is impossible to read the mercury barometer.

James Pitkin received a British provisional patent (#2947) for “Improvements in Aneroid Barometers” in 1861. In 1870, together with Thomas W. Short, his partner at that time, he brought out an ...