Rare French Atmos — Barometer Joins the Collection
An unsigned French Atmos — Barometer of about 1890, tentatively attributed to the Paris workshop of Jules Richard, has entered the collection.
Where a conventional aneroid conceals its movement behind a dial, the Atmos displays it entirely. Turned brass pillars, knife-edge bearings, a profiled beam, a steel helical spring and a stack of two corrugated Vidie capsules are mounted in the open on a brass plate and enclosed in a glazed mahogany case with a carrying handle. In place of a dial there are two silvered brass plates: a barometric scale graduated in London inches from 28 to 31, and a thermometer plate carrying paired Fahrenheit and centigrade arcs, the maker's mark BREVETÉ S.G.D.G. and the inscription MADE IN FRANCE.
The transmission is the instrument's chief rarity. There is no fusee chain, no hairspring and no bell-crank on pivots — the assemblies that have defined aneroid movements since Vidie. The long arm of the beam connects by a short link directly to the pointer arbor, and the required reading span comes from the length of the pointer rather than from a gear ratio.
The instrument is unsigned. The attribution to Jules Richard rests on correspondences with a dated barograph from that workshop: the carrying handle, the finger-jointed case, the turned profile of the brass pillars and the overall layout. The attribution is probable rather than documented. A full catalogue description, covering the attribution, the trade name and the movement in detail, accompanies the entry.