Aluminium surveying altimeter having 3” silvered and finely engraved dial, the upper portion marked “Surveying Aneroid” and “Compensated,” the lower signed by the maker “Negretti & Zambra, London” and no. “3183.” Barometric scale from 50–79 centimetres of mercury, outer rotating altitude scale 0–3,000 metres. Fine blued-steel pointer set beneath bevelled glass, slip ring mounted extendable scale magnifier. Case mounted post with altitude scale setting crown, heavy suspension ring. Conventional first quality movement with bi-metallic temperature compensation. The verso with calibration port at 8 o’clock. The whole contained within its original internally-sprung oxblood Moroccan leather over wood, blue velvet-lined drum form case, the lower part with four suspension strap loops, button closure, the inside lid with maker’s cartouche in gold “Negretti & Zambra, Surveying Instrument Makers, London.”
A truly special antique scientific instrument. Top maker, top condition and complete, surveying barometric altimeters are by no means rare – this though, metric and of uncommon size, is a scarce pattern, aluminium-cased (the expensive carbon fibre of the time), a best quality movement and finely engineered overall. The leather transit case is unusual and would have been an optional additional expense at the time of purchase. The aluminum case has had the lacquer restored.
Dimensions: 4¾” diameter x 2″ deep
Stock No: BA0409