This item is an ENGLISH POCKET BAROMETER with LINED LEATHER CASE. The barometer is in good working order and comes with a lined leather case. The barometer measures slightly over 3" in diameter. It fits snugly into the silk and velvet leather case. There are a series on numbers - 6522/1 - written on the lid that have no relevance as far as we can tell. The case holds tightly and the clasp works and holds well. The barometer is marked - CASELLA, LONDON, COMPENSATED. It registers in millibars on the barometer face and in feet on the outer bezel ring which revolves to be used as an altimeter.
Pocket barometers were used by hikers, explorers, balloonists, etc since they not only served as a weather instrument but were also altimeters. 1/10th of an inch of barometric pressure translates into 90 feet of altitude. Pocket barometers allowed a user to easily determine altitude.