On Tue, 17 Feb 2009, Joseph M Gwinn wrote: > > > The navigators who used marine chonometers knew perfectly well that > > those chronometers did not keep the "right" time as measured by clocks > > on land being reset by telescopes. Instead they knew that if their > > chronmeters were treated well they kept uniform time, and those > > navigators knew that getting the "right" time meant keeping a log of > > the difference between the "right" time of the clocks on land and > > their chronometer. > > They used the best cronometers then available. Harrison's first attempt > at a chronometer was in 1730, and success came many years later, in 1760 > or so.
Steve is right. The key difference between H4 and Harrison's previous clocks is that he gave up trying to make a clock that keeps correct tims and instead designed a clock that kept uniform time, which he could calibrate before a journey. This is often not well explained in the potted histories. Tony. -- f.anthony.n.finch <d...@dotat.at> http://dotat.at/ GERMAN BIGHT HUMBER: SOUTHWEST 5 TO 7. MODERATE OR ROUGH. SQUALLY SHOWERS. MODERATE OR GOOD. _______________________________________________ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
