A scarce WWI nickel plated brass wrist compensated Aero Hypsometer or air altimeter No 5037 by J.H. Steward Ltd, London, c1915

Rare WWI Wrist Hypsometer or Air Altimeter by Steward No 5037 c1915


Wrist air altimeter having 1⅝” silvered and die struck dial, crown operated rotating altitude scale calibrated in feet with a range from 0 -10,000ft and divided to 100s, annotated “FEET” with increasing altitude direction arrow, the centre at 5 o’clock position with “0,” denoting mean sea level (29.92”Hg). The upper part marked with maker’s name and address, “J.H. Steward Ltd, 406 Strand & 457 West Strand, London,” the lower part annotated “Aero Hypsometer, Compensated” and serial no. “5037.” Blued steel pointer, rotating bezel with engine turned gripping ring, coloured index (faded) to bevelled glass. Conventional Vidi pattern movement driven from a 1.105” nickel pressure sensing capsule tensioned on a C spring, all contained within a semi barrel form case, strap lugs and large bronze altimetric adjustment crown.

Complete with its correct original long pattern leather strap for fixing over flying suits or leathers.

Condition: The subject of a complete mechanical overhaul, conservation, and calibration under laboratory conditions. The dial crisp and clean, minor marks, annotations clear. The glass chip free and clear. The plated case clean with some wear and light points of oxidation. The leather strap complete, some perishing but remaining sound. The movement working well with excellent sensitivity, good progression, and very good levels of accuracy, though seeing some dispersion at higher altitudes, a normal characteristic of these antique instruments. The crown operated altitude scale runs smoothly with no discernible backlash. The bezel with index rotating smoothly. The red painted index faded but discernible.

Comments: Very rarely seen especially in this condition, remaining original in all respects. Very much for the aviation collector or connoisseur alike.

Dimensions: 1⅞” x ⅝” deep

Stock No: PB1810

Price: £1400






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