Pocket altimeter having 2½” silvered and die struck dial, the outer altitude scale with a range from 0- 5,000ft, stations at 1,000ft and divided to 10ft, the inner dual concentric barometric scale calibrated in inches of mercury with a range from 26 to 31, stations at the inch and divided 1/20th”.
Marked “Compensated” to the centre, blued steel pointer, flat bevelled glass, rotating bezel with index. First quality movement driven from a single 1½” nickel alloy cell, frosted gilt finished chassis, finely executed component parts, the bridge dated “19/7/10” and signed by the finisher. All contained within a semi barrel form case, calibration port to verso, extension post and suspension ring.
Together with its original tan pig skin over timber, cream silk and purple velvet lined case, the lid silk with applied retailer’s label “J. Trotter, Manufacturing Optician, 40 Gordon Street, Glasgow.” Snap closure on a button release.
Condition: The subject of a complete service, conservation, and calibration under laboratory conditions, see performance chart below. The altimeter barometer in good condition, good sensitivity and progression, more than passably accurate within the normal barometric range, the dial clean and bright lacking any obvious signs of oxidation, the brass case retaining virtually all its gilded finish, minor marks and slight wear. The suspension ring replaced. The leather case structurally sound, the leather outer with good colour and retaining its covering over the release button, minor abrasions, patches of discolouration. The fabric interior, the lid silk partially perished, some staining and discolouration, the velvet retaining much of its vibrancy and in good condition.
The principle here is for accuracy. In expanding the scale there was a requirement for the pointer to traverse the dial twice – this in itself might appear a simple matter, however the engineering required greater accuracy in making and the matching of component parts. The wider scale, of course, enabled better resolution. Few makers attempted this, Watkin Hicks being one such other.
Offering wonderful aesthetic qualities, this instrument exudes quality from the pig skin case to the gilt finish. A lovely item and very collectable.
Dimensions: 3¼” diameter x 1¼” deep
Stock No: PB1618