Hi They were doing accurate enough measurement of other astronomical phenomena in the late 1500's to have a framework to work against. By the early 1600's the data had been published and was pretty well accepted. You could have figured it out much earlier, but you would not have missed it past then. Of course you had to go looking, and believed what you saw.
Bob On Nov 5, 2010, at 4:31 AM, Rob Kimberley wrote: > I thought the ball dropped at noon. Perhaps you were there in the summer, > and they had advanced 1 hour for summertime (daylight savings). > > Rob K > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of WB6BNQ > Sent: 05 November 2010 12:11 AM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Setting clocks 100 years ago > > OK Bob, > > I'LL bite ! Why is it 1:00 pm for the ball ? > > Bill....WB6BNQ > > > Bob Marinelli wrote: > >> Hi Murray, >> >> Actually, the ball at Greenwich drops at 1:00 pm every day. For >> everyone who can get to London, the observatory is well worth at least >> a half day visit, they have several working Harrison clocks and yes >> you can set your wristwatch at 1:00 when the ball drops :) there is >> also a wonderful transit. >> >> Cheers, >> >> Bob >> >> On Nov 4, 2010, at 4:30 PM, Murray Greenman wrote: >> >>> Navigators used chronometers to determine their longitude. If they >>> were stopped in one place long enough, they could work out longitude >>> by a complicated process of star and lunar observations; however, >>> when they left an established port, they usually took with them a >>> time standard based on local measurements of the sun and the known >>> location of the port. >>> >>> These measurements used a device called a 'Transit', which was a >>> simple telescope mounted so that it pivoted in elevation, but was >>> fixed N-S in azimuth. Midday was marked by the time at which the sun >>> transited the telescope. It thus had higher resolution than a >>> sundial. Getting N-S axis correct involved determining by iteration >>> and surveying the axis that gave maximum elevation at time of >>> transit. >>> >>> Once the transit was observed, a large ball on top of the building >>> was dropped, indicating midday, and in some locations a cannon was >>> also fired. Ships in port could observe the ball drop and hear the >>> cannon. To this day the ball drops at midday at Greenwich. >>> >>> >>> 73, >>> Murray ZL1BPU >>> >>> >>> _______________________________________________ >>> 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. >> >> _______________________________________________ >> 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. > > > _______________________________________________ > 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. > > > > _______________________________________________ > 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. _______________________________________________ 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.
