On the 19th we left Port Western, passing out by keeping an isolated piece of tableland, called Tortoise Head, on the South-East extremity of French Island, open of the North-East point of Grant Island. The only danger is a sandbank, lying in the centre of the channel, four miles within the entrance. It may always be avoided by keeping a cable's length from the eastern shore. The western half of the south side of Grant Island, is a line of cliffs, from one to three hundred feet in height. A remarkable pyramidal rock marks the point where this terminates, after which a long range of low hills, covered with scrub, stretches to Cape Wollami, the helmet-shaped headland before-mentioned. A light North-East wind rendered our progress slow towards Cape Patterson, we reaching it by daylight of the 20th. It is a low point, covered with scattered sand hillocks; a few rocky patches here and there front its sand beach. Finding from the succession of dense fogs that we could not prosecute an easterly examination of the coast, we returned towards Port Phillip, and experienced some unusual swells off Port Western. EXTRAORDINARY SOUNDINGS. The soundings were in general tolerably regular; but in the same neighbourhood we had some extraordinary ones--SEVENTY FATHOMS, on a gravelly bottom. This was nearly one third of the way across from Grant Island to Cape Shanck, seven miles from the latter. The same strange depth was likewise found three miles south from Cape Wollami, with the same kind of gravel bottom, or a very fine kind of shingle. It was a single cast of the lead. On either side in this last case were 39 and 33 fathoms fine sand and shells. Had it not been for the change in the quality of the bottom, I should have doubted so great a depth, which is the more remarkable from its being the greatest within the Strait. The next day towards evening we again anchored in Hobson's Bay, where we stayed till the 23rd. This time in getting out of Port Phillip through the southern channel, we met with an accident. I have before mentioned the difficulty of seeing the eastern part of the north bank, which, on this occasion, combined with the dazzling effect of the sun's rays ahead, was the cause of our grounding for a short time near the inner entrance. It was, therefore, noon next day before we were again outside, when we steered across for the north end of King Island. January 26. In passing Franklin Road the next morning, we saw a cutter at anchor, doubtless the colonial vessel which is occasionally allowed to visit Captain Smith, and afford him supplies. We passed down four miles from the western side of King Island, carrying an outer line of soundings, varying from 40 to 50 fathoms; and in the evening anchored in Fitzmaurice Bay. BELL ROCK.