SOLD This is a late 19th century pocket high altitude altimeter barometer most likely used by balloonists or mountain climbers In their expeditions. Was made by the well-known scientific instruments maker Negretti & Zambra from London. The silver barometer dial goes from 15-31 in/mercury and the altimeter scale from zero to 20,000 feet adjusted by a bezel. The fine calibration is made with the back bezel locked by a small screw. The body of the altimeter is made of sterling silver and is in excellent condition with nice patina. Dimensions: 50 mm diameter and 15 mm height.