euclid The Time Traveler's Clock, Руководство пользователя

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wooden box, gimbals, chronometer case, and a clockwork which incorporates a fusee
mechanism for near-constant winding force as the mainspring winds down, a detent
escapement, and a temperature-compensated balance wheel fitted with a helical
hairspring.
When the US Navy realized the upcoming need for thousands of such chronometers in
the years prior to World War II, the only company which could fill the need was
Hamilton Watch Company of Lancaster, Pennsylvania. Hamilton could meet the need if
the basic design of a Ulysse-Nardin chronometer was exactly copied, except for the
balance wheel assembly. Hamilton had developed a better way to create a
temperature-compensated balance wheel that would not require the time-consuming
and laborious process of regulation that was required by the Swiss-pattern
chronometers.
Figure 9: Ulysse-Nardin Marine Chronometer, Predecessor to Hamilton 21
By making the balance wheel an unbroken ring of stainless steel supported by a simple
two-spoke arrangement made from Invar (a metal alloy with near-zero change in
dimension with temperature change), a Hamilton could manufacture a balance with
built-in temperature compensation not requiring many days of regulating. Hamilton
produced about 10,000 such chronometers prior to and during the war, and these were
found to be the most reliable and precise chronometers manufactured until that time.
The advantages of a mechanical, manual-wind chronometer are its reliability and
trustworthiness. As long as the chronometer is wound each day, accurate time is