Antique aneroid barometer having 4¼” silvered, engraved and engine divided dial calibrated in inches of mercury with a range from 21 – 31 divided to 1/100th”, the upper part signed “Elliott Bros, London,” the lower marked “Compensated for Temperature,” silvered reflector ring with dial attachments and case lip, blued steel pointer with added knife at tip, gilt index with knob, deep bevelled glass, plain style bezel.
High quality movement driven from an early pattern 3” nickel alloy capsule tensioned on a C spring mounted to cast and machined bridge supported on integral extensions. The short cross shaft with adjustable end shake knurled gain adjuster, the primary lever subject of modification by Elliott Brothers with the addition of adjustable metallic compensation. All raised over a circular iron chassis.
All contained within a bell top drum form case, extension post and suspension ring, the verso with compensation port. The verso engraved “Elliott Brothers” and dated “February 1864.”
Condition: The subject of a complete overhaul, conservation and calibration under laboratory conditions. The dial clean and crisp, the bezel slightly deformed, original glass with minor and one slightly deeper abrasion, the case retaining some of its original lacquered finish, areas of oxidation, some wear and minor dents. The movement working well across the range with excellent sensitivity and good progression, see performance chart.
Comments: This antique barometer is a good comparison to that example numbered “180” also shown on the site. It is clearly earlier as the numbers would suggest, and dated positively on the verso “1864.” There are too many similarities between the two for there to have been latter modifications or additions, and they provide good evidence of the work undertaken by Elliott Brothers in the application of temperature compensation. The general engineering and appearance of this movement lacks the refinement of the later instrument.
Undoubtedly originating from the French maker Pertuis Hulot & Naudet, this was a wise choice since Naudet were amongst the finest instruments of their class at the time. The intention here is clear – take a very fine movement and modify it further to produce an instrument of the most reliably accurate nature, evidenced by the finely divided dial, the knife addition to the pointer helping eliminate parallax and enabling the highest resolution, and the well-engineered modifications for temperature compensation. Interestingly, the temperature compensation arrangement added to the primary lever does appear to be made in brass entirely – it is likely though that metallurgical analysis would show a variation in the two metals used, affording the benefit of a differing coefficient of expansion causing a warping of the primary lever.
A very important and unusual instrument, a fascinating commentary on the development and innovation of the aneroid system, in well above average condition. A collector’s piece.
Stock No: BA1051
Price: Vavasseur Archive – not currently for sale