Hence the peculiarity all through the Journal of the p.m.
coming before the a.m.It results that any events recorded as occurring in the p.m.of January 1st in the log, would, if translated into the ordinary system, be given as happening in the p.m.of December 31st; while occurrences in the a.m.of January 1st would be equally in the a.m.
of January 1st in both systems.
This puzzling mode of keeping the day at sea continued to a late period, and was common to seamen of all nations.
The astronomical day, again, begins at noon AFTER the midnight at which the civil day begins, and hence is a whole day later than the ship's day.
This does not enter into Cook's Journal, but one of the logs of the Endeavour, extant, that of Mr.Green the astronomer, was kept in this time, and the events of say Thursday, June 24th, of Cook's Journal, are therein given as happening on Wednesday, June 23rd.

These differences of reckoning have been a fertile source of confusion in dates in many voyages.
Besides Cook's Journals there are other Journals and Logs of the voyage extant.

Perhaps it may be necessary to state that a Log is the official document in which the progress of the ship from hour to hour is recorded, with such official notes as the alteration in sail carried, expenditure of provisions and stores, etc.

A Journal contains this information in a condensed form, with such observations as the officer keeping it may feel inclined to insert.
The ship's Log Book of the Endeavour is in the British Museum.

Mr.R.M.
Hudson of Sunderland possesses Cook's own log, not autograph however, presented by Cook to Sir Hugh Palliser, the ancestor of his wife.
The Journals of all the officers of the Endeavour are preserved at the Public Record Office.