Swiss split-second chronograph with diablotine Circa 1860

Gold chronograph with seconde foudroyante by Ami LeCoultre
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An extremely rare Swiss split-seconds chronograph with direct seconde foudroyante, circa 1860. This is a top-quality watch that is quite heavy. It features an 18K gold à goutte hunting case, with its case and movement bearing the same matching number. The watch also has a glazed gold-rimmed cover over the movement. What makes this watch extremely rare is its calibre, which flaunts Geneva stripes, screwed gold chatons, a fine adjusting device, a special lever, and a bridge that is numbered and inscribed with Pat and applied for. The watch’s dial is white enamel and has Arabic numerals, outer minute and chronograph divisions, outer red Arabic five-minute/seconds numerals, and quarter-second diablotine. The blued steel hands add to its elegance. The watch is in very good condition, although it requires cleaning. It is intact and ready to be used.
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Diameter: 52 mm
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Weight: 150 g
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Signed: Ami LeCoultre
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This is an extremely high-quality watch attributed to Ami LeCoultre. The company filed the patent for these ultra-fine split-second chronographs with so-called direct diablotine in 1887 and signed movements with Pat before that date. applied for.
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Charles Ami Lecoultre (1843-1921) was a highly skilled watchmaker who, from 1881, worked with the renowned Louis Elisée and Henry Daniel Piguet. He specialized in creating complex watches and developed a patent in 1887 for a mechanism that connects the split-second hand and its train operating mechanism with the second-hand or with the second-hand and minute-hand. This invention allowed these hands to move in unison with the split-second hand. The hands and their connecting gears were all started simultaneously by the first movement of a push-pin and stopped by a brake lever that is brought in contact with the surface of one of the gears. The second movement of a push-pin operated the brake lever, and a lever and heart cam were employed to return the second and minute hands simultaneously to their normal or zero position. They were operated by the third movement of a push-pin simultaneously with the disengagement of the split-second mechanism.
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Seconde foudroyante
Seconde foudroyante refers to a specific type of complication found in mechanical watches, particularly high-end luxury timepieces. It is a French phrase that translates to lightning second in English. This complication allows the watch to display the seconds with exceptional precision, typically measuring up to 1/8th, 1/6th, or even 1/5th of a second.
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The seconde foudroyante mechanism is characterized by a rapidly rotating hand or disk that completes one full revolution in a single second. This hand or disk is usually located on a sub-dial or placed centrally on the watch face, making it easy to read the precise fraction of a second.
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The complication is considered a technical marvel in watchmaking as it requires intricate craftsmanship and precise engineering to achieve such high-speed accuracy. It is often associated with chronographs, which are watches designed for precise timekeeping and measuring elapsed time.
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The seconde foudroyante adds an element of visual fascination to a watch as the rapidly moving hand or disk creates a dynamic and captivating display of time. However, this complication is typically found in exclusive and expensive timepieces due to its complexity and the high level of expertise required to create it.
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Diablotine 
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 means little devil. The diablotine is halted when the chronograph or centre seconds is stopped, and the fractions of a second can be read.