— se ov oe ee ee ee T ESTN ae a 
1886.] Recent Literature. 951 
Peru. The sea-wave of the Iquique earthquake of May ọ, 1877, 
like many of its predecessors, was felt across the basin of the whole 
Pacific, from New Zealand in the south to Japan and Kamschatka 
in the north, and but for the intervention of the Eurasian and 
American continents would have made itself appreciable over the 
whole of our globe. At places on the South American coast it 
has been stated that the height of the waves varied from twent 
to eighty feet. At the Samoa islands the heights varied from six 
to twelve feet. In New Zealand the sea rose and fell from three 
to twenty feet. In Australia the heights to which the water oscil- 
lated were similar to those observed in New Zealand. In Japan 
it rose and fell from five to ten feet. In this latter country the 
phenomena of sea-waves which follow a destructive earthquake 
on the South American coast are so well known that old residents 
ave written to the papers announcing the probability of such 
occurrences having taken place some twenty-five hours previously 
in South America. In this way news of great calamities has been 
anticipated, details of which only arrived some weeks subse- 
quently, Just as the destructive earthquakes of South America 
have announced themselves, in Japan; in a like manner, the de- 
Structive earthquakes of Japan have announced themselves upon 
€ tide gauges of California. 
Similarly, but not so frequently, disturbances shake the other 
oceans of the world. For example, the great earthquake of Lisbon 
Propagated waves to the coasts of America, taking on their jour- 
ney nine and a half hours. 
The complete set of phenomena which may accompany a vio- 
lent sub-marine explosion is as follows (p. 174): 
2 By the initial impulse of explosion or lifting of the ground, a 
reat sea-wave” is generated, which travels shorewards with a 
velocity dependent upon its size and the depth of the ocean; at 
the same instant a “ sound-wave ” may be produced in the air, 
which travels at a quicker rate than the “ great sea-wave.” A 
third wave which is produced is an “earth-wave,” which will 
reach the shore with a velocity dependent on the intensity of the 
'mpulse and the elasticity of the rocks through which it is propa- 
gated, This latter, which travels the fastest, may carry on its 
back a small “ forced sea-wave.” On reaching the shore and 
Passing inland, this “ earth-wave” will cause a slight recession of 
_ S Water as the “ forced sea-wave ” slips from its back. 
As these “forced sea-waves” travel they will give blows to 
ships beneath which they may pass, being transmitted from the 
. tom of the ocean to the bottom of the ships like sound -waves 
‘0 water. At the time of small earthquakes, produced, for exam- 
ple, by the explosions of small quantities of water entering vol- 
canic fissures, or by the sudden condensation of steam from such 
= a fissure entering the ocean, aqueous sound-waves are produced 
YOU. XX.—wo. xy. é 
