This is the barograph by Fischer, makers of the world’s finest, most precise professional meteorological instruments since 1945. Preferred by art museums for its accuracy in detecting changes in temperature and humidity, key to the preservation of priceless works of art, this model is meticulously hand-crafted by engineers in Drebach, Germany, measuring barometric pressure between 955 and 1055 hPa using seven aneroid capsules. Operating between -22° F and 104° F, each capsule is made from two sheets of copper/beryllium alloy electron-welded together for an exact fit. Atmospheric pressure changes cause the capsules to expand or contract, and the polished brass linkages amplify the capsules’ changes into movements of a brass stylus, which inscribes barometric pressure readings onto a paper graph affixed to a rotating cylinder. The cylinder is precisely calibrated using quartz watch movement, and provides an accurate seven-day history of pressure trends. The drum removes for replacing the paper graph (one year’s supply included). Housed in a mahogany case with glass panels. Requires one AA battery. 13 1/4" L x 7 1/4" H x 7" D. (7 1/2 lbs.)