A very rare WW1 French Spad, or similar aviation altimeter by the renowned makers Naudet & Co, Paris.
The instrument is in excellent original condition and retains the outer leather case. When in use it was fixed within a sprung cradle to reduce vibration from the engine.
It responds well to atmospheric pressure variations and can be set to the correct altitude.
This altimeter would make a fine addition to any early aeronautical collection.
A Similar Instrument Fitted Within A Sprung Cradle
A Very Rare Early Aviation Instrument.