Rare French square one handed verge pocket watch Circa 1670-75

Gold rock crystal pocket watch by F. L. Meybom
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An extremely rare, square and one handed French verge pocket watch, circa 1670-1675. The case is covered with panels of blued steel overlaid with openwork floral designs of gold. It has a hinged cover of rock crystal with bevelled sides set within a silver and diamond bezel that permits an unobstructed view of the white enamel chapter ring with its black numerals for the hours and decorative marks at the quarters. The dial’s centre is a circle of dark blue basse taille enamel, and the spandrels are painted with pink and blue floral ornament, completing the extraordinarily rich effect.
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Square gilded brass full plate movement, partly blued steel and silver, key wind, signed, chain/fusee, baluster shaped movement pillars, four arm steel balance, fine florally engraved and pierced balance cock. Gold case, blued steel, rock crystal, partly gilded silver, and diamonds. Struck twice on the side of the case below III and IV position: owl (French mark for gold articles imported from countries without customs conventions, 1893 to present). Painted enamel dial with basse taille enamel on gold. Signed on the top plate of the movement. Case attributed to Isaac Bergeron dit d’Argent French.
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Dimensions: 38 x 32 x 16 mm
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Signed: F. Meybom, Paris, St. Germain
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Watchmaker: F. L. Meybom (active ca. 1650–80)
Almost nothing is known about the watchmaker who signed the movement of this watch, F. Meybom A Paris/St. Germain, except that he made at least three of these unusual square plated movements.
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The Paris watchmaker Auguste Bretonneau (recorded working 1638–58) and Balthazar Martinot (recorded working 1661–97), better known than Meybom, also made them.  All three provided movements for cases that are almost identical to this one, and one of these has been plausibly attributed to the Paris goldsmith Isaac Bergeron.
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Bergeron is recorded as a maker of watchcases in 1671, but as a Protestant, he was never allowed to become a master goldsmith in Paris. In 1686, he was probably the goldsmith on whose behalf King Louis XIV intervened by ordering that he be allowed to continue making watchcases. In 1694, he fled with his family to London.