Note 40 — Chapter II
Reading edition
The right ascensions, declinations, longitudes, &c., stated in these memoranda—which were noted at the time of observation—are only approximations to the truth; perfect accuracy in these respects being of no importance in such observations. They are, however, in general, within a minute or two of the truth. The times of the observations, too, are noted in reference—not to the astronomical, but to the civil day. The astronomical day commences at 12 noon, and the hours are reckoned, without interruption, to the following noon. The civil day commences at 12 midnight.