EARTHQUAKE IN PERU, 1746. 269 as though they had run aground. Perhaps the most extraordinary circumstance which occurred during this earthquake was the subsidence of the new quay called Cacs de Prada, built entirely of marble, and at an immense expense. A great concourse of people had fled to this quay, as a spot where they might be safe from the falling ruins, when suddenly it sank down, with all the people on it, and not one of the bodies ever rose to the surface, and a great number of boats, and small vessels, anchored at the quay were swallowed up with it, as in a whirlpool, no fragments of them ever appeared, and the water at the place of the quay has now a depth of upwards of 100 fathoms. At the time of the subsidence of the quay, the bar was seen dry from shore to shore, then suddenly the sea came rolling in, in a wave about fifty feet high. About noon there was another shock, when the walls of several houses, which the preceding shocks had not overthrown, were seen to suddenly gape open, and then to close again so exactly that no fissure or joint could be perceived. The extent of country affected by this earthquake is almost incredible. The movement was most violent in Spain, Portugal, and the north of Africa, but slighter shocks were felt from Greenland and Iceland, to Norway, Sweden, Germany, Britain, Switzerland, France, Morocco, Fez, and even in the West Indies; and on Lake Ontario in America. The rate at which the undulatory movement was propagated was about twenty miles a minute, judging from the interval of time when the shock was first felt at Lisbon and the time of its occurrence at other distant places. In the year 1746, an earthquake occurred which overthrew Lima, in Peru, and inundated its port of Callao, so that only 200 out of 4000 persons escaped. Terrible as were these earthquakes yet they seem to have been inferior to some which have occurred at a more early date, in many parts of Asia. Earthquakes are by no means of uncommon occurrence, scarcely a year passes without several. They are now observed with great attention by philosphers, and are of the utmost importance in a geological point of view. Awful as it must appear to see the ground heaving and swelling like the troubled sea, hills tottering, and solid walls and towns tumbling into ruins, and the earth gaping open, suddenly swallowing thousands of terrified men, women, and children, yet the philosopher looks beyond this sight of human suffering; forgetting the momentary pain and terror, he sees here the origin of many of those mighty changes which he had before detected, and learns many new facts in regard to the former physical structure and condition of our planet, We have now considered somewhat at length the aqueous, and igneous, causes of change in the inorganic world, and we proceed to consider the agency of the atmosphere and of vital action. Have stooped with age the solid continents Have left their banks and man's imperial works- As if immortal have been swept away." Henry Ware. WE have before described the atmosphere as an elastic fluid encompassing the earth, and capable of absorbing large quantities of moisture, and have illustrated the formation of clouds and the origin of winds. We can easily perceive that so important an agent may be capable of effecting the most marked changes, and we do not now allude to those effects produced by a secondary agency. Thus, the moisture deposited from the air in the form of rain, or snow, upon lofty mountains, causes deluges of water to descend and overflow the plains below, or becomes the source of those mighty rivers which roll through thousands of miles, bearing their immense deposits down to the ocean's bed, Changes like these we have already considered, and do not therefore include them in our present description. The atmosphere acts as an agent in destroying rocks and changing the face of a country, mechanically and chemically. The formation of immense dunes, or downs, which are heaps of blown sand, is an illustration of the former action, and the disintegration and de, struction of rocks by the absorption of oxygen, and carbonic acid, is an example of the latter; both of these actions we will now briefly consider. The fine sands of the African desert for a long series of ages, have been blown by the westerly winds over all the lands capa ble of tillage on the western banks of the Nile, involving in the almost impalpable powder, ancient cities and works of art, except at a few places sheltered by the mountains. From the fact that these moving sands have only reached the fertile plains of the Nile in modern times, it was inferred by M. de Luc, that that continent was of recent origin. The same scourge he observes, would have afflicted Egypt for ages anterior to the time of history, had the continents risen above the level of the sea several hundred centuries before our era. But as Mr. Lyell very justly observes, there is no evidence that the whole African continent was raised at once, and it is possible Egypt and the neighboring countries might have been populated long before any sands began to be blown from the western portion, nor is there yet any evidence of the depth of this drift sand, in the various parts of the great Lybian deserts. Valleys of large dimensions may have been filled up, and may thus have arrested the progress of the sand drift for ages. The sand floods which have buried the works of art on the western countries of the Nile, have contributed greatly to their preservation. Nothing could be better adapted than this dry impalpable dust, to protect the features of the collossal sculptures of the temples, or the paintings upon their walls. Every mark of the chisel remains as perfect as though but yesterday from the sculptor's hand, and the colors of the paintings are as brilliant, as when first laid on, thousands of years ago. At some remote period, when the causes that now make the air move in sweeping winds across the Great Desert towards the Nile shall be removed, when the change of land and sea will perhaps open that desert to the ocean, after the pyramids shall have crumbled, towns and temples of higher antiquity, will be laid open, and a flood of light be shed upon the history of remote ages. Ere that time, the hieroglyphic writing will be thoroughly understood, and the years of the Egyptian dynasties as well determined as the reigns of modern kings. The great agent of decomposition in other places, moisture, is unknown there. The spectator who looks for the first time upon the immense cavern temple at Ipsambul in Nubia, might well imagine that the artists had just left their work. The walls are as white, the colors as perfect, and the outlines as sharp, as in the first hour of their ex istence, and when he surveys the tracings, and half-finished sculpture he might almost look for the return of the artists to complete their work. Such is the wonderful preservation of these works in the fine blown sand of the great deserts, that although the buildings have been roofless for two thousand years, the paintings are undefaced. "There are some small chambers in a temple at Abydos" says Sir F. Hennicker, "in which the color of the painting is so well preserved that doubts immediately arise as to the length of time that it has been done. The best works even of the Venetian school, betray their age; but the colors here, which we are told were in existence two thousand years before the time of Titian, are at this moment as fresh as if they had not been laid on an hour." The preservation of works usually esteemed as fugitive, being so perfect, we might expect that those executed in more durable materials the sienite, granite, basalt, and limestone, would be still more so, and we find fragments of temples leveled to the ground by Cambyses, five hundred years before the Christian Era still retaining their pristine polish. The north and east faces of the obelisk, still erect among the ruins of Alexandria, retain much of their original sharpness, but the south and west sides have been entirely defaced by the attrition of the minute particles of sand with which the air is charged, beating against them sixteen hundred years. The desolation brought upon those ancient cities by the irresistable encroachments of the desert, the remains of its immense temples and works of art, its silent chambers, where the wrapped-up dead have remained for two hundred centuries, who once trode the streets of ancient Thebes, with all the buoyancy of feeling and all the hope which animates men now, furnishes a striking instance of the influence of apparently insignificant causes, in producing the greatest results, and remind us of the prophet's declaration, "Wo to the land shadowing with wings." But the ancient cities of Nubia, and Upper Egypt, are not the only places buried in blown sand, there are numerous instances of towns and villages, in England and France, thus overwhelmed. For example, near St. Pol de Leon, in Brittany, a whole village was completely buried beneath drift sand, so that nothing but the |