On the 22d, we passed the entrance of the Straits of San Bernadino. It would have been my most direct route to follow these straits until I had passed Mindoro, and it is I am satisfied the safest course, unless the winds are fair, for the direct passage. My object, however, was to examine the ground for the benefit of others, and the Apo Shoal, which lies about mid-channel between Palawan and Mindoro, claimed my first attention. The tender was despatched to survey it, while I proceeded in the Vincennes to examine the more immediate entrance to the Sooloo Sea, off the southwest end of Mindoro. Calavite Peak is the north point of Mindoro, and our observations made it two thousand feet high. This peak is of the shape of a dome, and appears remarkably regular when seen from its western side. On approaching Mindoro, we, as usual, under high islands, lost the steady breeze, and the wind became light for the rest of the day. Mindoro is a beautiful island, and is evidently volcanic; it appears as if thrown up in confused masses: it is not much settled, as the more southern islands are preferred to it as a residence. On the 23d, we ascertained the elevation of the highest peak of the island by triangulation to be three thousand one hundred and twenty-six feet. The easternmost island of the Palawan Group, Busvagan, [42] was at the time just in sight from the deck, to the southwest. It had been my intention to anchor at Ambolou Island; [43] but the wind died away before we reached it, and I determined to stand off and on all night. On the 24th, I began to experience the truth of what Captain Halcon had asserted, namely, that the existing charts were entirely worthless, and I also found that my native pilot was of no more value than they were: he had evidently passed the place before; but whether the size of the vessel, so much greater than any he had sailed in, confused him, or whether it was from his inability to understand and to make himself understood by us, he was of no use whatever, and we had the misfortune of running into shoal water, barely escaping the bottom. These dangers were usually quickly passed, and we soon found ourselves again floating in thirty or forty fathoms water. We continued beating to windward, in hopes of being joined by the Flying-Fish, and I resolved to finish the survey toward the island of Semarrara. [44] We found every thing in a different position from that assigned it by any of the charts [45] with which we were furnished. On this subject, however, I shall not dwell, but refer those who desire particular information to the charts and Hydrographical Memoir. Towards evening, I again ran down to the southwest point of the island of Mindoro, and sent a letter on shore to the pueblo, with directions to have it put on board the tender, when she should arrive. We then began to beat round Semarara, in order to pass over towards Panay.