Early Swiss gold independent lever chronograph Circa 1860

Gold hunting cased two-train lever chronograph attributed to P.H. Doret 
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An early and fine Swiss 18 carat gold hunting cased two-train pocket watch with independent chronograph without return to zero function and 1/4th second diablotine made for the American market, circa 1860. Rhodium-plated movement, two-train, 25 jewels, Geneva striping decoration, counterpoised straight-line lever escapement, cut bimetallic compensation balance, blued steel Breguet balance spring, index regulator. Hinged gold cuvette with engine-turned border. White enamel dial with Roman numerals, outer minute track, outermost fourths of a second ring, subsidiary quarter-second diablotine and original blued steel Breguet hands. Plain case, master mark J.T.S. & Co, reeded band, button at 12 for the start/stop of the chronograph and diablotine.
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Diameter: 55 mm
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Signed: No name
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This piece can be considered a true chronograph with an independent train. It is interesting because it probably dates from just before the Adolphe Nicole patent of 1862 and is therefore one of the early developments of the mechanism for chronographs. Unlike the Adolphe Nicole patent, the hands of the present watch cannot be reset to zero.
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The feature known as a diablotine is a small subsidiary dial on a chronograph or independent centre seconds pocket watch, the hand of which moves in a jumping manner at intervals of 1/4 or 1/5th of a second. The term literally means ‘little devil’. The diablotine is halted when the chronograph or centre seconds is stopped and the fractions of a second can be read.