A very rare and most interesting "atmos barometer," made in France and retailed by J Stevenson, Optician, Aberdeen

French Atmos Barometer c1875 – SOLD

Antique atmos barometer of grained and lacquered brass construction with silvered and engraved brass twin dial/registration plates of rectangular form: the outer having calibrations from 28-31 inches of mercury with divisions set at 1/20th of an inch, annotated “Stormy,” “Rain,” “Change,” “Fair,” and “Very Dry,” and bearing the legend “Atmos – Barometer;” the inner raised on a single turned pillar with twin curved thermometers, at left a reddened spirit type with plate marked “Fahrenheit” and calibrated 30–110 degrees, at right a Mercurial type, the plate marked “Centigrade” and calibrated 10-50 degrees, the plate further marked “Atmos – Barometer” to top, “Made in France” to lower left and “Brevete S.G.D.G,” a French non-government backed form of patent.

Heavy main chassis plate, the principal lever of L-shaped form raised on twin turned pillars with ‘knife-edge pivots’ and bearing upon a single steel coil spring in compression raised on a turned pillar and seated on a threaded adjustment platform, the spur acting through short levers driving a grained, white metal indicator arm raised upon a turned pillar. The mechanism driven by twin 2½” capsules. Attractive grained and laquered brass telltale with short operator’s extension running in a nickeled escutcheon.

The whole contained within its original polished mahogany single-glass case, finger jointed corners, the top set with nickeled brass carry handle. Base set with screw adjustment port and with retailer’s paper roundel affixed, marked “J. Stevenson, Optician, Aberdeen” with pen annotation “AH/-, OE/-.”

Image of French Atmos BarometerThe instrument, having the benefit of light conservation, remains in original condition. Setting a date of manufacture is not easy. There is little doubt that this originates from the later half of the 19thcentury – the glass, clearly original, is uneven with flaws atypical of later manufacture, and the mechanism reflects very much the Vidi movement, suggesting a date nearer 1850. The jeopardy here, though, is that, although the original Vidi patent was improved upon very quickly after 1850, some makers probably continued to replicate it well into the last quarter. Reasons for this may have had as much to do with practice as ease of manufacture, a coil spring arrangement being a far simpler mechanism to produce than a tempered C-type spring arrangement. The instrument may have been influenced by the introduction of the drum barograph recorder in 1867, as it seems very much a half-way house. On balance, the evidence would suggest a date of manufacture circa 1870-1880.

Very much a collector’s piece and a fascinating commentary on the development of the aneroid barometer. See Banfield, Edwin, “Barometers: Aneroid and Barographs,” p51 and p53, fig. 39 for description and image of a similar barometer.

Dimensions: 7″ wide x 6″ high x 4¼” deep

Stock No: BA0231

Price: SOLD

Image of French Atmos Barometer c1875
Image of French Atmos Barometer c1875