NavList:

An addendum to my post: an excerpt from a Jack Aubrey novel:

Patrick O’Brian, The Mauritius Command, p. 46

His telescope was a disappointment. It was not that he could not see Jupiter: the planet gleamed in his eyepiece like a banded gold pea. But because of the ship’s motion he could not keep it there long enough or steadily enough to fix the local time of its moons’ eclipses and thus find his longitude. Neither the theory (which was by no means new) nor the telescope was at fault: it was the cleverly weighted cradle slung from the maintopgallantmast stay that he had designed to compensate for the pitch and roll that did not answer, in spite of all his alterations: and night after night he swung there cursing and swearing, surrounded by midshipmen armed with clean swabs, whose duty it was to enhance the compensation by thrusting him gently at the word of command.

Best
Wolfgang