Among the trees seen in the course of this ramble, I had almost forgotten to mention one which struck me more than any other from its resemblance to a kind of cotton tree, used by the natives of the South Sea islands in building their canoes. February 7. The day following we secured several boat-loads of rainwater, deposited in the holes of the rocks, near our temporary observatory, and were the better pleased with our success, as our well-digging had proved unsuccessful. GEOLOGY OF THE CLIFFS. There was something particularly striking in the geological formation of the cliffs that form the western side of this bay: and which rise from 70 to 90 feet in height, their bases apparently resting amid huge and irregular masses of the same white sandstone as that which forms the cliffs themselves, and from which this massive debris, strewn in all conceivable irregularity and confusion around, appears to have been violently separated by some great internal convulsion. Some of these great masses, both of the living cliff and ruined blocks beneath, are strangely pierced with a vein or tube of vitreous matter, not less in some instances than 18 inches in diameter. In every place the spot at which this tube entered the rock was indicated by a considerable extent of glazed or smelted surface; but I am not sufficiently versed in the science of geology to offer any specific theory to account for the appearances I have described: the cliffs were rent and cracked in a thousand different ways, and taking into consideration their strange and wrecked appearance, together with the fact that lightning is known to vitrify sand, may we not thus get a clue to the real agency by which these results have been produced?* (*Footnote. Since this was written, I have consulted my friend, Mr. Darwin, who has kindly examined a specimen I brought away. He pronounces it "a superficial highly ferrugineous sandstone, with concretionary veins and aggregations." The reader should, however, consult Mr. Darwin's work on the Geology of Volcanic Islands page 143.) WEIGH AND GRAZE ON A ROCK. February 10. The weather was thick and gloomy, and it rained fast; but, having completed our survey and observations, and the wind being favourable, it was resolved to get underweigh without further loss of time. In the very act of weighing, the ship's keel grazed a sunken rock, of the existence of which, though we had sounded the bay, we had been, till that moment, in ignorance! He only who has felt the almost animated shudder that runs through the seemingly doomed ship at that fearful moment, can understand with what gratitude we hailed our escape from the treacherous foe.