"Tis with our Judgments as our Watches none Go just alike yet each believes his own" - Pope, An Essay on Criticism,1711
Generally, noon was used to reset a clock or watch.
There were many almanacs with sunrise, noon and sunset published.
Try looking at the approach outlined in the middle of page 20 of:
Time's Telescope for 1816 or A Complete Guide to the Almanack
To adjust a watch clock . . .
Then there is the earlier (1731):
An Explanation of the Nature of Equation of Time and Use of the Equation Table for Adjusting Watches and Clocks to the Motion of the Sun
In part, this noon fixing of time caused the naval day to start at noon, rather than midnight. - R