MONTAGU SOUND extends from Cape Voltaire to the north end of Bigge's Island, a distance of thirty-one miles, and is from eleven to twenty miles deep. It is fronted by a range of islands; the outer range, which is eight miles within the Montalivet Isles, was called PRUDHOE ISLANDS; besides which there were several scattered about the sound, and some of larger size near the main: of the latter are KATER'S and WOLLASTON'S. They are of a very rocky character, and furnished with but a poor and shallow soil, although the surface is thickly covered with small trees, growing most luxuriantly. WATER ISLAND, to the north-east, in latitude 14 degrees 21 minutes, and longitude 125 degrees 32 minutes 25 seconds, was visited by us, as was also CAPSTAN ISLAND, in the south-west corner of the sound. The latter island is in latitude 14 degrees 35 minutes 20 seconds, and longitude 125 degrees 16 minutes 20 seconds. They are both rocky, and destitute of any soil but what is formed by the decomposition of the vegetables that grow upon the island. The channels between them appeared to be clear and free from hidden danger. The depth among the islands is from ten to fifteen fathoms on a muddy bottom; but the anchorage is better between Kater Island and the promontory that separates it from Walmesly Bay, than any other part. It is a very fine port, particularly near the bottom, in SWIFT'S BAY, where the depth is from four to five fathoms at low water, It is high water at full and change in Swift's Bay at twelve o'clock, which is two hours and a quarter later than in Vansittart Bay: the tide rose eighteen feet, whereas in Port Warrender its rise was only six. The islands off the north-east end of Bigge's Island are more numerous than in other parts of the sound: they were only seen at a distance, and too numerous to give correct positions to. BIGGE'S ISLAND is fourteen miles long, and from six to seven broad; it is of moderate height, and rocky character: its south end appeared to be thickly wooded. A flat-topped hill near the shore of Scott's Strait is a remarkable object, and may be seen six or seven leagues off. It is in latitude 14 degrees 39 minutes 20 seconds, and longitude 125 degrees 10 minutes 20 seconds.