1776. THE PACIFIC OCEAN. 131 



clock, &c. By a mean of the several results of the 

 equal altitudes of the sun, taken with the astronom- 

 ical quadrant, the astronomical clock was found to 

 lose on sidereal time, V 8", 368 each day. The pen- 

 dulum was kept at the same length as at Greenwich, 

 where the daily loss of the clock on sidereal time, 

 was 4". 



The watch, by the mean of the results of fifteen 

 days' observations, was found to be losing 2" 261, on 

 mean time, each day ; which is 1" 052 more than at 

 Greenwich : and on the 21st, at noon, she was too 

 slow for mean time by l h 20'57" 66. From this, 

 6' 48", 956, is to be subtracted, for what she was too 

 slow on the 11th of June at Greenwich, and her daily 

 rate since; and the remainder, viz. l h 14/ 08" 70*, 

 or 18 M' 10", will be the longitude of the Cape 

 Town by the watch. Its true longitude, as found by 

 Messrs. Mason and Dixon, is 18 23' 15". As our 

 observations were made about half a mile to the east 

 of theirs, the error of the watch, in longitude, is no 

 more than 8' 25". Hence we have reason to con- 

 clude, that she had gone well all the way from Eng- 

 land, and that the longitude, thus given, may be 

 nearer the truth than any other. 



If this be admitted, it will, in a great measure, 

 enable me to find the direction and strength of the 

 currents we met with on this passage from England. 

 For, by comparing the latitude and longitude by 

 dead reckoning, with those by observation and the 

 watch, we shall from time to time, have, very accu- 

 rately, the error of the ship's reckoning, be the cause 

 what it will. But as all imaginable care was taken 

 in having and keeping the log, and every necessary 

 allowance made for lee-way, heave of the sea, and 

 other such circumstances, I cannot attribute those 

 errors that did happen, to any other cause but cur- 

 rents ; but more particularly when the error was 

 constantly the same way, for several days succes- 

 sively. 



k2 



