A rare early 19th Century thermometer by Breguet in a gold oval ring. Oval gilt plate with bimetallic strip and quadrant gears linked to a central pinion. Fine signed engine turned gold dial marked "Thermometre". Circular chapter marked in degrees and at the quarters "Glace – Tempere – Chaleur – Fievre". Gold oval case, engine turned middle, glazed on both sides to reveal the mechanism. Reeded gold swivel band to allow use as a ring or perhaps as a fob. Accompanied by a certificate from the archives showing it was sold in 1810 for 336 Francs.