greater than their diameters.” That the great power in operation in the formation of basaltic columns is heat, appears to be indisputable. There is, for example, a bed of sandstone in furnaces for smelting metals, and, in the course of time, it requires to be repaired. Portions, taken out, on such occasions, have been found to have a columnar appearance: the heat of the furnace having changed the form of the substance, not by any fusion of its parts, but by a peculiar arrangement of them, thus giving them the specified figure. Another astonishing result of this natural power is seen in the eruption of a volcano. The eye of a traveller, perhaps, as it is turned towards Vesuvius, discerns a dark red spot on the mountain’s side, issuing from an orifice near to the crater. But soon, that deep burning light apparently spreads out, or flows on into a long wide stream, descends the entire length of the great cone, and reaches to the plain below. But, as the first light was seen through and behind the mists which follow the departure of the sun, so now its extended influence is only rendered visible by the increasing gloom. But, as the eye is still attracted towards this remarkable eminence, a pillar of fire is seen rising up from the crater high into the air; while innumerable lights appear, like so many natural fire-works rushing upwards, and falling in a glowing shower, on the outer sides of the crater, which soon present the aspect of a heap of fire. Large and red-hot stones are flung forth from time to time, from the same troubled source, to fall, roll down the sides of the crater, and lose their brightness. Mountains that are liable to volcanic action, before an eruption takes place, are generally the most fertile, and the most attractive of all eminences. Illustrations of this remark are found upon a magnificent scale in Mexico; and, among the rest, that of Jorullo, in the extensive intendency of Valladolid, lying on the west coast of America, between the intendencies of Mexico and Guadalaxara, (pronounced Quadalahàra.) Mechoacan, a part of it, is an expanse of table-land which enjoys a fine and temperate climate, and is intersected with hills and charming valleys, presenting an appearance unusual in the torrid zone, of extensive and well-watered meadows. On the twenty-ninth of September, 1759, from the centre of a thousand burning cones was thrown up the volcano of Jorullo; a mountain of scoriæ and ashes, seventeen hundred feet high, in an extensive plain, and covered with most luxuriant vegetation. When plains, hills, and valleys, are thus spoken of, the reader should remember, that all of them are reared upon the lofty chain of the Andes, for volcanic eruptions only, so far as we know, take place in mountainous regions.