of the arches as uninjured as if freshly laid.”  The stranger had hardly concluded this sentence when he was interrupted by Onuphrio, who said, “I have always supposed that in every geological system water is considered as the cause of the destruction or degradation of the surface, but in all the instances that you have mentioned it appears rather as a conservative power, not destroying but rather producing.”  “It is the general vice of philosophical systems,” replied the stranger, “that they are usually founded upon a few facts, which they well explain, and are extended by the human fancy to all the phenomena of Nature, to many of which they must be contradictory.  The human intellectual powers are so feeble that they can with difficulty embrace a single series of phenomena, and they consequently must fail when extended to the whole of Nature.  Water by its common operation, as poured down from the atmosphere in rain and torrents, tends to level and degrade the surface, and carries the material of the land into the bosom of the ocean.  Fire, on the contrary, in volcanic eruptions usually raises mountains, exalts the surface, and creates islands even in the midst of the sea.  But these laws are not invariable, as the instances to which we have just referred prove, and parts of the surface of the globe are sometimes destroyed even by fire, of which examples may be seen in the Phlegraean fields, and islands raised by one volcanic eruption have been immerged in the sea by another.  There are, in fact, no accidents in Nature; what we call accidents are the results of general laws in particular operation, but we cannot deduce these laws from the particular operation or the general order from the partial result.”  Ambrosio said to the stranger:  “You appear, sir, to have paid so much attention to physical phenomena that few things would give us more pleasure than to know your opinion respecting the early changes and physical history of the globe, for I perceive you do not belong to the modern geological schools.”  The stranger said, “I have certainly formed opinions or rather speculations on these subjects, but I fear they are hardly worth communicating; they have sometimes amused me in hours of idleness, but I doubt if they will amuse others.”  I said, “The observations which you have already been so kind as to communicate to us, on the formation of the travertine, lead us not only to expect amusement but likewise instruction.”

The Stranger.—­On these matters I had facts to communicate; on the geological scheme of the early history of the globe there are only analogies to guide us, which different minds may apply and interpret in different ways; but I will not trifle with a long preliminary discourse.  Astronomical deductions and actual measures by triangulation prove that the globe is an oblate spheroid flattened at the poles, and this form we know, by strict mathematical demonstrations, is precisely the one which a fluid body revolving