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. This unit is in amazing condition, as is in the photo. I don’t have the paper for it, and it will need to have someone that knows what there doing work the unit. Its been collecting dust on a shelf forever. I will answer what questions I can, but seeing as its older than may grandparents your getting a piece of history. Thank you for your consideration.