Pocket Barometer by Short & Mason, London
Silvered dial signed ‘Short & Mason, London’ made for A & N.C.S. Ltd, Westminster..
The outer chapter ring is marked from 0- 8,000 feet and indicates the height above sea level. The inner ring is marked from 23 to 31 inches and indicates atmospheric pressure in inches of mercury,
To measure your height you rotate the outer chapter ring until the hand is aligned with the zero (assuming you are at sea level), then as you climb, the hand moves due to the fall in air pressure and you will be able to read off the height you have reached.
The word ‘compensated’ indicates that this barometer adjusts the reading for changes in temperature, thereby giving a more accurate reading.
The barometer retains it’s original morrocan leather travelling case decorated with green silk lining. C.1910
Short and Mason were founded in 1845 by Thomas Short and James Mason at 40, Hatton Garden, London. They quickly established themselves as leaders in the field of precision instruments specialising in Barographs and Barometers. The firm among many other famous names supplied the scientific instruments for the ill fated Scott and Shackleton Polar expeditions. They continued to trade until 1969 when the company was merged with the Taylor instrument company (Europe). C.1910
A & N.C.S. is the mark for the Army and Navy Co-operative society, Francis Street, Westminster, London.