leapsecs-boun...@leapsecond.com wrote on 02/18/2009 09:56:10 AM: > 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 time > and instead designed a clock that kept uniform time, which he could > calibrate before a journey. This is often not well explained inthe potted > histories.
I didn't trim enough when I quoted. I was reacting to the complaint about navigation problems in 1707. I think you're right about the history of Harrrison's clocks. It wasn't until 1730 that Harrison achieved sufficient accuracy. Joe _______________________________________________ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
