1864. | Mauuxr on Harthquakes. 69 
Thus, we see that in an Earthquake whose origin is beneath the 
sea, there may be a series of waves, all arriving in the following order, 
differently, and at different times, to an observer standing on the land. 
Ist. The great Earthquake wave of shock. 
2nd. The forced sea-wave (of which we have as yet not spoken); it is 
the roll of water forced up by, and carried along with, the earth-wave, 
which raises the sea-bottom, and with it the water upon its back as it 
were, and at its own rate of motion, after it has got into shallow water. 
This is but occasionally perceptible, and only in great Earthquakes. 
ord. The sound-wave through the earth, which may or may not be 
before. 
4th. The sound-wave through the sea. 
5th. The sound-wave through the air. 
All these except the second are elastic waves. 
6th, and lastly. The great sea-wave, or wave of translation, rolls in 
and completes the catastrophe, often hours after the shock has done its 
work of destruction ; or portions of it may roll in upon shores that 
have felt no shock at all. Thus in the great Harthquake at Japan, 
which a few years ago wrecked a Russian frigate in one of the harbours 
there, the great sea-wave produced in the deep seas, near those great 
Islands, hours afterwards, reached the opposite shores of the Pacific, 
at St. Diego and Francisco, and gave the first intelligence at those 
places of the disaster that had occurred at the further side of that great 
ocean. 
Space forbids us now to pursue the subject further. At some 
future opportunity we may be enabled to revert to it; and to develope 
the relations between the movements of the elastic-wave particle and 
the wave’s transit to which we have in the preceding pages almost 
confined our remarks. It remains also to be shown by what methods 
the position and depth, and even the form and magnitude of the 
deep-seated focus of an Earthquake, may be ascertained by deciphering, 
with the help of science, the terrible handwriting left by the destroyer 
upon the country it has overthrown. ‘To these should be added some 
description of the secondary effects of Earthquakes, in moulding anew 
the features of the lands they pass over, and how those affect and 
modify the shocks that reach them. Something, too, might be said as 
to the distribution of Earthquakes in time and in space upon our 
Earth’s surface ; what are the conditions originating within our planet ; 
the impulses on which their existence depends; and, lastly, what is the 
function of Earthquakes, and what uses they fulfil as parts of the great 
cosmical machine. 
