Datei:F. Hauth, St. Petersbourg, Nr. 43, circa 1850 (1).jpg

Inventé par F(riedrich) Hauth, Horloger de la Marine Impèriale à St. Petersbourg, Nr. 43, 115 x 63 x 130 mm, circa 1850.

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Historisch bedeutende, seltenes Schiffschronometer mit Federchronometerhemmung mit konstanter Kraft und 8 Tagen Gangreserve Geh.: Mahagonikasten, Gehäuseschlüssel, Messing-Zylinderform-Gehäuse, zweiteilig. Ziffbl.: versilbert, signiert, nummeriert, zentrale arabische Minute, kleine röm. Stunde, kleine arabische Senkunde, gebläute Spade-Zeiger. Werk: Messingwerk, 68 mm, Zierschliff, signiert, nummeriert, massive Werkspfeiler, 2 Federhäuser, Federchronometerhemmung nach Thomas Earnshaw, bimetallische Chronometer-Unruh nach "Pennington" mit 6 Schrauben und 4 Muttern, freischwingende, gebläute, zylindrische Unruhspirale mit Endkurven, zwei übereinander liegende, leicht versetzte Chronometerräder für die Hemmung und den Zwischenaufzug mit zusätzlicher zylindrischer, gebläuter Spirale, chatonierter Diamantdeckstein auf Unruh.

A historically important ship's chronometer with constant force spring detent escapement and 8 days power reserve Case: mahogany, case key, brass bowl type case, two-body. Dial: silvered, signed, numbered, central Arabic minutes, auxiliary hours, auxiliary seconds, blued spade hands. Movm.: brass movement, 68 mm, decorated, signed, numbered, solid movement pillars, 2 barrels, spring detent escapement according to Thomas Earnshaw, bimetallic "Pennington" chronometer balance with 6 screws and 4 nuts, freesprung blued helical balance spring with terminal curves, two chronometer wheels lying slightly shifted upon another for the escapement and the remontoir with additional blued helical spring, chatoned diamond endstone on balance.

Friedrich Hauth, Nevskii, St. Petersburg, 1828-1849
The instrument is fitted with an unusual constant-force escapement that Hauth had invented himself, according to his inscription on the dial. The impulse comes from a pivoted lever spring-loaded via a helical hairspring; at a certain point of time the lever releases one of the two concentric escape wheel locking detents. Hauth used a double escape wheel to synchronise the unlocking levers. Each wheel has 15 teeth and is easily adjustable with regard to the other wheel, so that they control the length of the impulse. Hauth set them off half a tooth (12º) to give them a suitable amplitude.

Friedrich Hauth was a very talented chronometer and watch maker and received a great number of honours and awards during his working life. He was listed with his business on Nevskii Prospect in St. Petersburg between 1828 and 1849. Between 1836 and 1837 he created an astronomical clock for the St. Petersburg University; when he had completed the clock he immediately started working on a similar clock for the Pulkova Observatory. In 1843 Hauth supplied nine chronometers for research on the different longitudes of Altona (Hamburg) and the Pulkova Observatory, two of which are listed at the Royal Observatory in Greenwich in 1854. Between 1845 and 1849 Hauth looked after the chronometers of the St. Petersburg Academy of Sciences.