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 <albertson.ch...@gmail.com>wrote: > On Tue, Jan 24, 2012 at 3:16 AM, Attila Kinali <att...@kinali.ch> wrote: > > On Tue, 24 Jan 2012 11:04:08 +0000 > > "Poul-Henning Kamp" <p...@phk.freebsd.dk> wrote: > > > >> In message <20120124115848.312d60bd4fccce4f3e71c...@kinali.ch>, 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 > > -- > > Chris Albertson > Redondo Beach, California > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.