Swiss silver keyless lever tourbillon pocket watch Circa 1910

Silver open faced poor man’s tourbillon by Courvoisier Frères
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A Swiss silver open faced keyless lever pocket watch with patented one minute tourbillon, a poor man’s tourbillon, circa 1910. Gilded brass movement, inverted calibre, going barrel, straight line lever escapement, bimetallic compensated balance with gold poising screws and a blued steel flat hairspring set on the revolving carriage.
A polished case. Silvered dial, eccentric time indication in the upper half with radial Roman hour numerals and blue spade hands, a visible tourbillon with engraved balance bridge below. Movement signed. Accompanied by a copy of the invention patent.
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Diameter: 53 mm
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Weight: 94 g
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Signed: Courvoisier Frères La Chaux-de-Fonds
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The movement is based on Paul Loichot’s Swiss Patent No. 30754  from June 11, 1904.
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At the beginning of the 20th century, Paul Loichot from Charquemont in Doubs, France, invented and patented an interesting tourbillon design in Switzerland (Swiss Patent No. 30754 from June 11, 1904). He inverted the movement, allowing the carriage to be seen through the dial and placed the escapement in a straight line with a lever opening for the carriage arbour.
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Courvoisier Frères in La Chaux-de-Fonds, Switzerland registered trade name Mobilis on July 4, 1905 under No. 19062.