Special trend barometer according to the sympiesometer system. Invented by Mr. Adie from England in the early 19th century. Antique copies are very rare and expensive. This reproduction is a mercury-free liquid barometer with which one can predict the weather by correcting the temperature influences. The reading is done by looking at the difference between the thermometer and the liquid-filled barometer tube. With this difference one can read on the auxiliary scale at the top right, the current weather type, red liquid under blue is nice weather, above blue is bad weather. The hand serves as a memory for the last measured position in order to indicate the weather change {trend hand) The cabinet is made of mahogany and is finished with a glass pane. The scale plate is made of brass Dimensions: 48 x 14 x 5 cm Please take a good look at the photos, these are part of the description