Posted by JLabaree on October 26, 2007 at 22:33:00 from 74.75.130.147 user JLabaree.
In Reply to: Re: Time Ball, was Signal Stations posted by Adam Quinan on October 26, 2007 at 16:34:03:
Another reason for the noon sighting of the sun to determine local noon is to establish longitude, isn't it? Comparing the difference between local noon and the time on a ship's chronometer (kept at GMT) tells you how far around the globe you have traveled (if the difference is four hours, then you have traveled 4/24 of the way around globe from the meridian).
It's been a while since I've done any celestial navigation, but I seem to remember that modern tables allow you to shoot your position (latitude, that is) pretty much any time of day. But it seems likely that declination and refraction tables in days of yore may have been limited to certain times of day - noon being one of them. Does that sound reasonable?