A good brass aneroid barometer by Naudet No 9065 retailed by Abraham Van Emden, Amsterdam c1870

Aneroid barometer having 4½” silvered and die struck dial, the barometric scale calibrated in inches of mercury with a range from 25” – 31” and divided down to 1/50th”. The upper part with standard meteorological terms, the centre with boldly marked retailer’s details, “A. van Emden, Amsterdam.” The lower marked “Compensated,” “Holosteric Barometer,” and serial no. “9065.” Blued steel pointer, gilt brass index, flat glass held within a knurled ‘Dent style’ brass bezel. Substantial 1st quality movement driven from an early pattern 3” diameter x ⅜” deep capsule and tensioned on a C spring, static mass/counterweight. Inside of case with inscribed name or place (illegible) and the date “Mai 1870.”

All contained within a spun brass drum form case with belled shape. The verso with calibration port and Naudet “PHNB” logogram, mounting screws set at 3 and 9 o’clock. Extension post and suspension loop.

Condition: The subject of a full overhaul, service, conservation, and calibration under laboratory conditions, see performance chart. The movement working extremely well over the standard meteorological range, some dispersion at lower pressures though this is a common characteristic of early capsules. The dial crisp and clean, faint mark from 9 0’clock to 12 o’clock, being well marked to the centre. The case with traces of external original finish, though crisp and bright, minor impressions to verso.

Comments: In 1860, Naudet patented a variation of the Vidi design for aneroid barometers which incorporated the C spring instead of the coil spring utilised by Lucien Vidi (see image to side). Over the next few years, the design was improved by the addition of a bimetallic strip to compensate for temperature fluctuations. This barometer contains the enhanced movement and, as can be seen by the performance chart, is an exceptionally well-engineered instrument, still performing well after more than 150 years.

A good and early instrument, presenting as clean, crisp, working very well and really quite attractive, especially so for its unusual retailer marking to dial centre. 

Certainly collectable.