Page:A Voyage to Terra Australis Volume 2.djvu/101

Cumberland Isles.]

with the swinging of the ship, and took place one hour before the moon's passage, as it had done amongst the barrier reefs; from ten to fifteen feet seemed to be the rise by the shore, and the flood came from the northward.

We returned on board the ship at noon; but I deferred getting under way till next morning, on account of the wind blowing fresh, and some business to be executed which could not be attended to whilst among the reefs. This gave an opportunity of making further observations by the time keepers, from which it appeared that they gave only 8′ 36″,3 of longitude west from Upper Head, with the rates there found; whereas by the survey, we had made 12′ 37″. The time keeper No. 520, taken alone, gave 11′ 35″,8; and when the correction, afterwards found necessary in the Gulph of Carpentaria, is applied, the difference becomes 12′ 41″, almost exactly as by survey. The previous positions of the ship amongst the reefs, and wherever I had not any bearings of fixed points, have therefore been deduced from this time keeper. but it differed on the north head of the island, from 7° to 9° 23′ east, in the space of a few yards.

The variation amongst the Barrier Reefs has not been mentioned; but five azimuths and amplitudes were taken between the 6th, p.m. and the 15th a.m. When corrected to the meridian, the extremes were 7° 53′ and 7° 11′; and the mean, in latitude 20° 44′, longitude 150° 32′, will be 7° 30′ east.

At daylight on the 17th, the breeze was moderate at E. by N., with fine weather; and in steering northward, close to the wind, we passed three miles to leeward of a dry bank of rocks and sand.