A very good scarce aneroid US Army Signal Corps Aviation Section altimeter for aircraft by Tycos No 8431 c1917

Air altimeter having 3⅜” painted gilt-highlighted stepped dial, the outer concentrically-marked altitude scale calibrated in feet with a range from 0 – 25,000ft divided to 100ft. The upper part marked “Thousand Feet,” the inner “Altitude,” “Aviation Section, Signal Corps U.S. Army,” below, “Type C No. 8431,”and signed by the maker “Tycos, Rochester N.Y.” Aluminised alloy pointer with counterweight, flat glass.

Conventional high quality largely japanned Vidi pattern movement driven from a single 2” capsule raised over a brass chassis, pencil annotations to verso, possibly including a date of 13 Aug 1917. The whole contained within a flanged drum form alloy case, altitude setting knob, the verso with impressed instruction “Do Not Plug Vent on Underside or Break Gov’t Seal.”

Condition: The subject of a full service, conservation, and calibration under laboratory conditions, see performance chart from dynamic test. The American DH4, used for bombing and observation, could really only achieve ceiling heights of around 20,000ft by the end of the war, so these altimeters were rather over-confident, something possibly reflected in the drop-off in performance over 18,000ft.

Probably officially refurbished , presented in crisp working order.

Comments: An attractive and historically interesting item from the very early years in aviation. The US Army Signal Corps Aviation Section active between 1914 and 1918, mostly used Airco-built DH4s (DH stands for De Haviland) and the image shows a DH4 cockpit with a Type C air altimeter in situ. This air altimeter has an identical movement and case, and almost identical dial, to the British made Short & Mason aircraft altimeters of the same era, and as Taylor Instrument Co, the owner of the Tycos brand, was also the owner of Short & Mason, this altimeter would either have been made entirely in the UK, or the parts shipped to the US for assembly there.

Truly a collector’s piece.

Tycos & Taylor Instrument Company: George Taylor and David Kendall began making thermometers in 1851. By 1853 George was on his own and in 1872 he formed Taylor Brothers with his brother Frank. They morphed into Taylor Instrument Company in 1907 and began using the trade name Tycos in 1908. The Tycos name was used exclusively until 1932, when the Taylor name was used.

Short & Mason was established in England in 1845 and was a maker of high-quality weather instruments. Taylor Brothers bought Short & Mason in 1900 and Taylor marketed their made-in-England products in the USA.