I think James Burke discussed these clocks in one of his documentary series. Besides not using a pendulum, they were temperature compensated by using materials with opposite temperature coefficients of expansion and then gimbaled for use on a rolling and pitching ship.
Oddly enough, the phase locked loop came significantly earlier when a clock maker used it to regulate pendulum clocks overnight to quickly calibrate a new clock to a reference clock. On Tue, 24 Jan 2012 17:50:54 +0100, Azelio Boriani <[email protected]> wrote: >Yes, the first real push was the Longitude Act (1714) and the Harrison's >clocks. > >On Tue, Jan 24, 2012 at 5:36 PM, Chris Albertson ><[email protected]>wrote: > >> On Tue, Jan 24, 2012 at 3:16 AM, Attila Kinali <[email protected]> wrote: >> > On Tue, 24 Jan 2012 11:04:08 +0000 >> > "Poul-Henning Kamp" <[email protected]> wrote: >> > >> >> In message <[email protected]>, Attila >> Kinali w >> >> rites: >> >> >> >> >All this talk about telling the time using stars or the sun made me >> wonder >> >> >how did people tell what position their telescopes had back in the days >> >> >before GPS? >> >> Sailingships and trade was what pushed this. At the time of Columbus >> he was able to know his latitude within a few 10s of miles but even >> after returning to Europe he did no know how far around the world he >> had sailed. Was it 1/3rd or 2/3rds? They had no way to know. The >> problem was that on one had a clock that should keep time well enough. >> They used hour glasses on board ship for short duration time keeping >> but those were of no use on a longer ocean crossing. >> >> Later they discovered the idea of common view of the moons of Jupiter >> and they could measure the time from local noon some even on Jupitor >> while a person back home did the same thing. Later when he got back >> home they compare notes and then know the difference in longitude. >> Good ocean going clocks were still centuries away. But in the >> 1500's they could only know the location after the fact when they >> returned _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
