Barograph by Jakob Goldschmid, Zürich, Switzerland, 1873-1876.

Barographs are instruments for monitoring changes in air pressure over time. They contain a stack or series of aneroid capsules, which are chambers of thin metal, with the air inside partially removed. Changes in atmospheric pressure cause the aneroid capsules to move up and down. This small motion is mechanically enhanced by levers which adjust the position of the lightweight metal arm carrying a pen, which records onto a clockwork-driven recording drum.

This example was made by the Swiss maker Jakob Goldschmidt, who was renowned for his invention of a mechanical and portable aneroid barometer.