Posted by Jock on October 27, 2007 at 10:44:41 from 87.105.81.146 user Jock.
In Reply to: Re: Longitude, was Time Ball, was Signal Stations posted by JLabaree on October 26, 2007 at 22:33:00:
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?
Let me declare at once that, at although I reckon myself reasonably competent in the field of applied mathematics, I have not yet tackled the field of celestial navigation. So what follows may be complete rot!
It strikes me that nautical tables giving the apparent declination of celestial bodies only at certain times of day would be of limited practicality - if the weather was cloudy you would want to take a sight when a window appeared in the clouds and tables restricted to certain times of day or night would be of little use. I seem to remember that, instead of a marine chronometer, Slocum took an old alarm clock. Isn't it the case that the trigonometry is a lot easier at noon?