A very rare and particularly fine early German aviation altimeter by Otto Bohne, Berlin.
Circa - 1913.
In excellent untouched original condition retaining the three metal outer fixing rings and large adjustment wheel - used to 'set' the instrument before flight.
Originally having a leather case it would have been strung between the bracing wires of an early 'monoplane' within sight of the pilot.
The outer case is aluminium, making the instrument very light. Weight being the enemy of these early fragile machines.
A highly collectable early aviation instrument.