XXIV 
APPENDIX. 
Ill ascertaining the apparent time at Greenwich corresponding to the true 
distances, the first term of the proportion, being usually the difference 
between the next greater and the next less distance in the Nautical 
Almanac, has been corrected when necessary, by the method of second 
differences, to the actual change in the moon’s distance from the sun or star 
in the interval of three hours, of which the middle point is intermediate 
between the time of the observation, and that of the computed distance in the 
almanac, to which the portion of time sought is to be applied. 
Note. — The dates throughout this abstract are according to the astro- 
nomical method of reckoning; the times by watch, and the apparent 
Greenwich times, being carried on beyond twenty-four hours when necessary 
in longitudes west of Greenwich. 
