At first sight seems to be a clock with a missing hand and 12 hours dial continued by a second 24 hours round, is actually a tachometer.
This Instrument used to measure engine revolutions per minute, has in it´s interior a clock.
The propeller spin movement is transmitted to this instrument and the rotating movement charge the power spring power of the clock wich it has power reserve just for a several seconds, these is inside the the piece in the photo below
It has 4 jewels and a swiss pallet escapement, the rest is the mechanism for the indication per minute.
100 % ORIGINAL. SERVICED, FULL WORKING CONDITION.
PRICE 1.200 EUROS
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This instrument was used before WW I and in WW I aircrafts as:
BLERIOT XI
NIEUPORT 28
MORANE SAULNIER A-I
