The Vintage Wrist Watch Company has dated this Antique Brass Pocket Altimeter to the 1910s.
It is believed that an altimeter of this size would have been used aboard an observation balloon during the first World War… the observer would have worn thick gloves so a larger altimeter would have been easier to handle.

Identical altimeters were manufactured by Thomas Watson Scientific Instruments Ltd, a London based optical and scientific instrument manufacturer and this is probably one of their pieces.
The altimeter is functioning although has not been tested for accuracy.
The Vintage Wrist Watch Company has dated this Antique Brass Pocket Altimeter to the 1910s.
Specialists in antique and vintage wrist watches and pocket watches
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