1803.
April.
Lieutenant Flinders took altitudes from the sea horizon, between April 1 p.m. and 8 a.m., for the rates of the time keepers; the mean of which, with the errors from mean Greenwich time at noon there on the last day of observation, were as under:
| Earnshaw's No. | 543, | slow | 2ʰ | 57′ | 14″,56 | and losing | 16′,73 | per day. |
| 520, | fast | 1 | 57 | 19, 28 | - | 33, 99 |
the rate of No. 543 differing only 0″,2 from that with which we had left Caledon Bay. The longitude given by this time keeper on April 1, p.m. with the Caledon rate, was 123° 39′ 8″,4 east, or 3′ 22″ more than the lunars; and when the Caledon rate is accelerated, the difference is only 2′ 3½″ east. This quantity, if the longitudes of Caledon and Coepang Bays be correct, is the sum of the irregularities of No. 543, during the fifty-one days between one station and the other. The time keeper No. 520 had been let down on the passage, and its rate being now more than 3″ greater than at Caledon Bay, its longitude was not attended to at this time.
In laying down the coasts and islands of Arnhem's Land, the bearings and observed latitudes were used, with very little reference to the time keepers; but No. 543, when corrected, did not differ so much from the survey as 1′ in twenty-five days. The rest of the track, from Wessel's Islands to Coepang, is laid down by this time keeper with the accelerated rate, and the application of a proportional part of 2′ 3½″, its irregularity during fifty-one days.
Variation of the surveying compass, 0° 46′ west, observed when the ship's head was E.S.E., or corrected to the meridian, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . |
0° 37′ east; |
but this variation seems to apply only to Coepang Bay; for about two degrees to the eastward it was 1° 4′ west, corrected, and one degree to the south-west it was 1° 41′ west.
The flood tide comes from the southward, through Samow Strait, and rises from three to nine or ten feet; high water usually took place as the moon passed under and over the meridian, but the winds make a great difference both in the time and rise of the tide.
