July 30.

The next day, the 30th, was spent in examining some bights in the narrow part of the channel near Gap Island, so named from a remarkable division in its centre, through which the high-tide flows, and gives it the appearance of being two islands.  It was on this occasion that we explored Halfway Bay, where we were fortunate in finding good anchorage, and in which we also discovered a strait, that on a subsequent examination was found to communicate with Munster Water, and to insulate the land that forms the north-west shore of the bay:  this island was called after the late Right Honourable Charles Greville, whose name has also been given to a family of plants (grevillea) that bears a prominent rank in the botany of this country.  The strait, in which the tide was running at the rate of six or seven knots, was not more than one hundred and fifty yards wide; but in one part it was contracted to a much narrower compass, by a bed of rocks that nearly extended across the strait, and which must originally have communicated with the opposite shore.

We landed under the flat-topped hill, at the south end of Greville Island, among the mangroves which skirt the shore, and walked a few hundred yards round the point, to examine the course of the strait; but the way was so rugged, and we had so little time to spare, that we soon re-embarked and returned into Halfway Bay.  The geological character of the island is a red-coloured, coarse-granular, siliceous sandstone, disposed in horizontal strata, and intersected by veins of crystallised quartz.  The surface is covered by a shallow, reddish-coloured soil, producing a variety of shrubs and plants.

After this we crossed the river, and examined the two bays opposite to Gap Island, but found them so shoal and overrun with mangroves that no landing could be effected in any part.  In both bays there is anchorage between the heads; but all the inner part is very shoal, and perhaps at low water there is not more than nine feet water within the heads.  In the mid-stream of the river the bottom is deep, and is formed entirely of shells over which, on account of its being very narrow, the tide runs with great strength; and from the irregularity of the bottom forms numerous eddies and whirlpools, in which a boat is quite unmanageable.

During our absence, Mr. Bedwell examined our former watering-place, at the back of St. Andrew’s Island, and on his return landed upon the sandy beach of a bay on the south-west side of the basin, but was unsuccessful in his search for water at both places.

The sea breeze freshened towards sunset, and fanned up the fires that had been burning for the last three days in several places upon the low land, and on the sides of the hills to the westward of Mount Trafalgar; before night they had all joined, and, spreading over the tops of the hills for a space of three miles, produced a singularly grand and magnificent effect.