1 86 PLEASANT WA YS IN SCIENCE. 



with those of August, 1868, and perceive their exact similarity, 

 we can no longer reasonably entertain any doubt of the 

 really stupendous fact that the throes of the earth in and near 

 Peru are of sufficient energy to send oceanic waves right across 

 the Pacific, waves, too, of such enormous height at starting, 

 that, after travelling with necessarily diminishing height the 

 whole way to Hawaii, they still rose and fell through thirty-six 

 feet The real significance of this amazing oceanic disturb- 

 ance is exemplified by the wave circles which spread around 

 the spot where a stone has fallen into a smooth lake. We 

 know how, as the circles widen, the height of the wave grows 

 less and less, until, at no great distance from the centre of 

 disturbance, the wave can no longer be discerned, so slight 

 is the slope of its advancing and following faces. How 

 tremendous, then, must have been the upheaval of the bed 

 of ocean by which wave-circles were sent across the Pacific, 

 retaining, after travelling 5000 miles from the centre of dis- 

 turbance, the height of a two-storied house ! In 1868, indeed, 

 we know that the wave travelled very much further, reaching 

 the shores of Japan, of New Zealand, and of Australia, even 

 if it did not make its way through the East Indian Archi- 

 pelago to the Indian Ocean, as some observations seem to 

 show. Although no news has been received which would 

 justify us in believing that the wave of May, 1876, produced 

 corresponding effects at such great distances from the centre 

 of disturbance, it must be remembered that the dimensions 

 of the wave when it reached the Sandwich Isles fell far 

 short of those of the great wave of August 13-14, 1868. 



It will be well to make a direct comparison between the 

 waves of May, 1876, and August, 1868, in this respect, as 

 also with regard to the rate at which they would seem to have 

 traversed the distance between Peru and Hawaii. On this 

 last point, however, it must be noted that we cannot form an 

 exact opinion until we have ascertained the real region of 

 Vulcanian disturbance on each occasion. It is possible that 

 a careful comparison of times, and of the direction in which 

 the wave front advanced upon different shores, might serve 



