It is clear that the wave which traversed the Pacific in May, 1876, was somewhat inferior in size to that of August, 1868, which therefore still deserves to be called (as I then called it) the greatest sea-wave ever known. The earthquake, indeed, which preceded the oceanic disturbance of 1868 was far more destructive than that of May, 1876, and the waves which came in upon the Peruvian and Bolivian shores were larger. Nevertheless, the wave of May, 1876, was not so far inferior to that of August, 1868, but that its course could be traced athwart the entire extent of the Pacific Ocean. When we consider the characteristic features of the Peruvian and Chilian earthquakes, and especially when we note how wide is the extent of the region over which their action is felt in one way or another, it can scarcely be doubted that the earth’s Vulcanian energies are at present more actively at work throughout that region than in any other. There is nothing so remarkable, one may even say so stupendous, in the history of subterranean disturbance as the alternation of mighty earth-throes by which, at one time, the whole of the Chilian Andes seem disturbed and anon the whole of the Peruvian Andes. In Chili scarcely a year ever passes without earthquakes, and the same may be said of Peru; but so far as great earthquakes are concerned the activity of the Peruvian region seems to synchronize with the comparative quiescence of the Chilian region, and _vice versâ_. Thus, in 1797, the terrible earthquake occurred which is known as the earthquake of Riobamba, which affected the entire Peruvian earthquake region. Thirty years later a series of tremendous throes shook the whole of Chili, permanently elevating its long line of coast to the height of several feet. During the last twelve years the Peruvian region has in turn been disturbed by great earthquakes. It should be added that between Chili and Peru there is a region about five hundred miles in length in which scarcely any volcanic action has been observed. And singularly enough, “this very portion of the Andes, to which one would imagine that the Peruvians and Chilians would fly as to a region of safety, is the part most thinly inhabited; insomuch that, as Von Buch observes, it is in some places entirely deserted.”