Pocket barometer having engraved and silvered 1¾” dial, the upper portion marked with the retailer “Braham, Optician,” the lower portion marked “Bath” and “Compensated.” Outer rotating altitude ring having a scale in feet set from 0 – 10,000, barometric scale set to inches of mercury with a range from 21 – 31. Fine blued steel pointer beneath bevelled glass. Instrument constructed around an early first quality Negretti & Zambra coil-spring pattern single 1¼” capsule driven lacquered brass movement with decorated chassis, marked “21″ to verso.
Lacquered brass barrel form case with ribbed detail, knurled barometer bezel, suspension ring, calibration port to verso. Lightly hand-marked “440” to upper edge of verso. The whole contained within its original leather over wood, green velvet and silk lined case. Snap closure on button release.
An instrument of obvious high quality, the pocket barometer altimeter with good sensitivity and progression, working well. The unusual Negretti & Zambra movement capable of great accuracy unrivalled for its type – stamped “21”, we have come across another six such movements, all with serial numbers in the low double digits.
Retaining almost all its original lacquered finish, with losses to suspension loop, the crystal chip-free, the case restored, with losses to leather to top and verso, the side leather replaced. The silk and velvet linings with good colour and integrity.
A very attractive pocket barometer from a top maker for a respected firm of West Country opticians and scientific instrument makers. Very collectable.
John Braham, recorded as working in Bristol, Bath, Cheltenham and Torquay from 1830 on, was a leading maker of mathematical, nautical and optical instruments. The business was sold to Matthew William Dunscombe, a former apprentice, who kept the Braham name until 1874 when the company was renamed M.W. Dunscombe Ltd.
Dimensions: 2¼” diameter x 1¼” deep
Stock No: PB0935