There was unusual weather last night, overcast with a squally westerly wind. Just laying our course North-North-West, at noon we were in latitude 29 degrees 11 minutes South, on the position assigned to a reef called the Turtle Dove. From the masthead I could see nothing indicating a shoal. Captain King passed near this position, and also remarks not seeing it. The Colonial schooner Champion, in beating to the southward, has passed over and near its assigned position, and I think we may fairly infer that there is no such reef as the Turtle Dove, and that probably it originated from the south end of the Abrolhos reef, ten miles North-North-West of it, being seen. We found 29 fathoms on this supposed shoal, with 35, twelve miles South by East of it, and 127, twenty-eight miles in the same direction. Between it and the south end of the Abrolhos Group the water deepened to 35 fathoms. In approaching the nearest island we passed close round the south-east end of a reef, running out about a mile from the south point, and then trending away round in a North-west by North direction, so as to form one side of a lagoon, whilst the island I have mentioned--a long narrow strip trending North-east by North--forms the other. The weather looking unsettled, the wind being from the south-west, with slight rain squalls, we were glad to find shelter, so near the commencement of our work, in a bight on the east side of the island, three quarters of a mile from the south point, where we anchored in 13 fathoms, scarcely a quarter of a mile from the shore. A coral patch, of two and a half fathoms, with only two on its northern extreme, confines this anchorage, which affords shelter from South-South-East round by West to North-east by North. The tide rose here 32 inches. From the masthead I got a tolerably good view of the island, in some places scarcely a cable wide, and a number of islets scattered to the north-west. The lagoon at this place was not more than three miles across, though marked twelve in the old charts; and I could trace the long line of white breakers rolling in on the other side in solemn grandeur, contrasting strongly in their foaming turbulence with the placid waters within the protection of the reef and island. I could clearly distinguish the limit of the danger in this direction, and that there was nothing to break the swell beyond. The surface of the lagoon was diversified by blue and grey patches, showing the alternations of shoal and deep water; near the centre there appeared to be a channel, which we afterwards found to be ten fathoms deep. In the head of the bight where we were anchored, there was a narrow low sandy neck, placed by our observations in latitude 28 degrees 58 minutes 26 seconds South and longitude 1 degree 47 minutes 32 seconds west of Swan River,* over which we hauled a boat to examine the opposite side of the lagoon.