Vintage English aneroid compensated pocket barometer in original condition, with outside altitude ring marked from 0 to 10000 feet, patina silver dial, signed by Dollond and numbered. Coin edge bezel rotates to set the altitude. Superficial scratches due to normal wear and age. Working condition unknown. Approximate diameter is 51.1mm.

Dollond was undoubtedly one of the finest and most innovative of all meteorological instrument making firms, achieving the highest international reputation as early as the 1750’s. It continued to prosper throughout the 19th Century but was acquired by Aitchison in 1913, following financial difficulties.

An aneroid barometer is a device that measures atmospheric pressure. It`s often specially calibrated for use as an altimeter, consisting of a box or chamber partially exhausted of air with a hand to indicate the degree of compression of the top caused by the external air.