1801.
September.
Wednes. 23.
down the latitude of the south-east point at 20° 31′ south, and longitude from lunar observations, 28° 37′ west of Greenwich. The latitude appeared to agree with our observations; but in the longitude there is some difference. According to Earnshaw's two time keepers, No. 465 and 543, which kept better rates than the remaining four, the longitude of the Nine Pin is 29° 25½′ west; which being reduced to the south-east point, will place it in 29° 23′, or 46′ west of the French navigator.[1] The longitude in captain D'Auvergne's plan of Trinidad, constructed 1782, is 29° 55′, or 32′ still further west. From two sets of distances of the star Altair to the west, and two of Aldebaran east of the moon, I made the longitude of the south-east point to be 29° 19′ west; the difference from the time keepers, which I consider to have given the best longitude, being no more than 4′.
Azimuths taken upon the binnacle in the morning, with three compasses, and the ship's head at S. W. by S., gave variation 3° 54′; and in the evening, at S. W., 3° 50′; but next morning,Thurs. 24. when Trinidad was just disappearing from the deck in the N. 60° E., other azimuths then showed the variation to be 1° 35′ west, the ship's head being S. S. W.; it therefore appears, that there is a difference off the north, and off the south-west sides of the island. From the first observations I deduce the true variation to be 4° 14′ west, and from the last 1° 50′ west. Captain D'Auvergne marks the variation 0° 45′ west, in 1782; but under what circumstances it was ascertained, does not appear.
The trade wind having again arisen from east-south-east, we were enabled to make between eighty and ninety miles a day. It afterwards veered gradually round, by the north-east and north, to
- ↑ The error of No. 465 was found, at the Cape of Good Hope, to be 10′ 57″,2 to the east, and of No. 543, to be 39′ 21″,5 east, contracted in 96 days upon their English rates. To obtain the above longitude, a proportional part of these errors according to the number of days, has been applied to the keepers; and the difference between them is no more than 2″.
