The latitude of Observation Island, from two meridian altitudes to the north and south, is 15° 36' 46" S.
Longitude from six sets of distances of the sun east of the moon, given in Table IV. of Appendix No. 1, 137° 6' 42"; but by the time keeper No. 543 corrected, it is preferably 137° 3' 15" E.
The rates of the time keepers were found from afternoon's altitudes in an artificial horizon, between the 16th and 26th; and the means, with their errors from mean Greenwich time, at noon there on the last day of observation, were as under:
Earnshaw's No. 543, slow 2h 29' 11.17" and losing 14.93" per day Earnshaw's No. 520, slow 4h 11' 37.59" and losing 28.25" per day
This rate of No. 543 is only 0.19" more than that found at Sweers' Island, and so far as the six sets of lunars may be relied on, the longitude by this time keeper was not far from the truth; the letting down on the passage therefore did not seem to have produced any change; but in No. 520, the rate is more than 8" greater, and the longitude was getting 1½' per day too much to the east, as well before as after it was let down. The coast from Sweers' to Observation Island is consequently laid down by No. 543, with the small accelerating correction arising from the 0.19" increase of rate in 16.4 days.
Variation of the theodolite, observed on the east side of South-west Island, 2° 22' east.
In the bearings taken at different parts within the group, the variation seemed to differ from 2° 30' to l° 30'. The largest variations were on the east sides of the islands, and the smallest on the west sides; seeming to show an attraction of the land upon the south end of the needle. On board the ship, when coasting along the east side of Vanderlin's Island, and the whole group lay to the west, the variation appeared from the bearings to be as much as 4° east.
The best observation made on the tide, was on the 23rd, during my boat excursion to the south end of Vanderlin's Island. On that morning the moon passed over the meridian at sixteen minutes past ten, and the perpendicular movements of the tide were as follows. At seven o'clock, when I left the shore, the tide was falling; on landing at nine it was stationary, and appeared to be low water; at noon it rose fast, and at three was still rising, and continued so to do, but slowly, until seven in the evening, The tide then began to fall; but after subsiding one foot, it rose again until ten o'clock, and had then attained its greatest height. Low water took place therefore about an hour before, and high water at eleven hours and a quarter after the moon passed the meridian: the rise appeared to be from four to seven feet. At Wellesley's Islands high water had taken place an hour and a half earlier, which seems extraordinary, if, as it necessarily must, the flood come from the northward. I think it very probable, that the tide in both places will follow what was observed in King George's Sound on the South Coast; where high water, after becoming gradually later till midnight, happened on the following day before seven in the evening, and then later as before.
The break of three hours in the tide here, is somewhat remarkable: it was not observed amongst Wellesley's Islands, where the tide ran twelve hours each way; but was found to increase as we proceeded west and northward until it became six hours, and the tides assumed the usual course.