Open scale barograph by Short & Mason Ltd., London. MO 2278/-/41 in glazed carrying case, dated 1941
This open scale barograph in a glazed carrying case was made by Short and Mason. Changes in atmospheric pressure cause the series of 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. The charts normally run for a week.