A difference was also noticed between the day and night tides at Rat Island, where the time of high-water at the full and change of the moon was ten o'clock, and the rise varied from 8 to 32 inches, from the result of twenty-five observations; by which I found, moreover, that the tides ebbed five hours and a half in the night, and six hours and a half during the day, and the water fell 9 inches with the night, and 18 with the day ebb. The difference between the length of the night and the day floods was an hour; the duration of the former being six hours, whilst that of the latter was seven; whilst the difference in the rise was 7 inches, the greatest general height, which was during the night tides, being 20 inches. We were detained in Recruit Harbour until May 21st, determining the position of the number of small islands and detached reefs to the south-east of Wallaby Islands; but at length, after completing the soundings on the north-east and north side and ascertaining the extent of the reef to the north-west, we proceeded to the isolated patch of land before mentioned as seen from Flag Hill, and which, from its relative position to the remainder of Houtman's Abrolhos, we called North Island. An anchorage was found in 12 fathoms, three quarters of a mile from a bay on the north-east side, and half a mile from the reef extending to the northward. The island was about a mile across, and nearly circular. It was surrounded by a range of hills, with a flat in the centre, covered with coarse grass, where a great many quails were flushed, affording good sport, but not a single wallaby. RECORD HILL. The highest hill on the south-west point, measuring 42 feet, received the name of Record Hill, from our leaving a paper in a bottle, giving an account of our cruise. A contiguous reef stretched out from the west side of the island for the distance of a mile, beyond which was the open sea. This reef extended two miles and a half to the North-North-West and four miles and a half to the southward. Our observations were made on a sandhill 36 feet high, immediately over the bay, which they placed in latitude 32 degrees 18 minutes 5 seconds South longitude 2 degrees 9 minutes West from Swan River. LEAVE HOUTMAN'S ABROLHOS. May 23.