The observations on the state of the weather, taken with much difficulty, are not intended to include the regular observations on the exterior of the island, and in like manner some of those taken in the harbour, or basin of the crater, must be accepted with a certain limitation. For similar reasons, we were unable to fix the rate of the current setting from the sea into the basin, although we secured most extraordinary results considering the circumstances. The amount of specimens of natural history which was procured, was very limited, but on that account was the more valuable. To the geologist, it must be of the very highest interest to find that St. Paul has been classified, with scientific precision, and by dint of personal examination and research, in one of the four main divisions in which, according to the scheme of Alexander Von Humboldt, the volcanic formations of the earth may be divided. Measured by the latest distribution of the volcanic strata by the description of stone found, as laid down by the greatest of German naturalists, St. Paul belongs to the same class as Chimborazo, Popocatepetl, Teneriffe, &c., in a word, to what is known as the Chimborazo formation. A section of the east-side, taken in profile, lays bare its entire geological history, and forms one of the most instructive means of coming to direct conclusions as to its geological structure.
The birth of this island from the bosom of the deep, combined with eruptions of lava and scoriæ, was the last effort of the subterranean forces. Since that period it has been subject wholly and solely to the various terrestrial influences, although the lapse of centuries has not been able to extirpate the last traces of the volcanic fire which once poured forth its currents of molten lava. A large proportion of the level ground is hot, and at the lower edge of the rim of the crater appear several hot springs, the temperature of which, as already remarked, is so high that fish, eggs, potatoes, &c., can be cooked on them in a few minutes. The highest point of St. Paul rises 870 feet above the basin of the crater. Its walls rise abruptly at an angle of about 85°, while the upper surface of the island (with the single exception of a small plateau of about 400 feet on the north side) stretches, at first level from the periphery of the upper margin of the crater, gradually falling away towards the sea-coast, at an angle of about 13°. On its North-west coast, where it is from 100 to 200 feet in perpendicular height, the island presents several small pyramids of pumice, like parasitic warts on the principal mass.