A very rare early WW1 " Admiralty Air Dept " (R.N.A.S) altimeter. This instrument was most probably destined for one of the first heavy bombers, rather than a fighter or reconnaissance aircraft -  due to the low height range of 10,000 Ft. 
This low height would also link it to early airship use.

The altimeter is in excellent original condition, and unusually has a silvered dial -  manufactured by Short & Mason Ltd, London.

Most interestingly the aneroid movement is dated:
21 / 01 / 1915. The instrument also has a very low serial number - 105.

A unique opportunity.

      This early altimeter is extremely rare.