1864. | Mazer on Harthquakes. 61 
Between 1820 and 1841, Von Hoff, Kries, Hoffmann, and one or 
two others, had laboriously collected and digested into order a large 
mass of facts, or reputed facts, of earthquakes, and to the first belongs 
the credit of having, in a masterly discussion,* shown what are the 
relations (so far as then known) between Meteorological and Harth- 
quake Phenomena—and pointed out, that all the supposed meteoro- 
logical presages were devoid of reality, and that Harthquakes belong 
to Physics and Geology and not to Meteorology. 
But none of these men made the slightest advance towards a_ 
physical theory of Earthquake motions. 'The only true hint even, 
that was to be found before 1846, as to the true nature of the Earth- 
quake motion, is found in a paper on Volcanoes, by Gay Lussac, in 
the ‘Ann. de Chim., vol. xxii. p. 429, who quotes from Dr. Young’s 
Lectures, and concurs in his opinion, that “ Earthquakes were of the 
nature of vibrations in solids.” Even Darwin—who of all men had had 
the finest opportunity of seeing the effects of Earthquake on the most 
extensive scale in South America—rendered no better account of the 
then accepted Vorticose displacement of objects, than by asking, ‘‘ Might 
it not be caused by a tendency in each stone to arrange itself in some 
particular position with respect to the lines of vibration, in a manner 
somewhat similar to pins on a sheet of paper when shaken ? ” 
He, too, like Parish, had recorded the circumstances of the great 
sea-waves that roll in, after South American and other Earthquakes, but 
neither rendered any solution of the facts. Nor was an attempt made 
by anyone, as yet, to connect these sea-waves and the sounds heard in 
great Earthquakes with the other parts of the phemomena. 
A considerable advance had been made in a branch of science 
apparently remote enough from Earthquakes, which, however, greatly 
prepared the way for solving one part of their true history. The 
brothers Weber, in Germany, and Scott Russell after them, i England, 
had experimentally developed the science of certain classes of liquid 
waves; and the latter had, in 1844, shown the laws of propagation 
of one class of these, viz. waves of translation. 
In February, 1846, a paper was read to the Royal Irish Academy, 
and .then published in its Transactions, vol. xxi. part 1, “‘ On the 
Dynamics of Earthquakes,’ which (we quote the words of the Presi- 
dent, Dr. Chas. Graves, on presenting the Cunningham medal) fixed 
upon an immutable basis the real nature of Earthquake phenomena, 
and, for the first time, showed that the three great classes of phenomena 
—1, Shocks; 2, Sounds; 3, Great Sea Waves—were all reducible to 
a common origin, and formed parts of a connected train, and were 
explicable upon admitted laws. This paper also, for the first time, 
explained the true nature of the movements that had been called 
“-vorticose,’ and viewed as proofs of circular movements, by showing 
that they were the result of rectilinear motions. 
It also pointed out the important uses that might be made of Earth- 
quakes, as instruments of cosmical research, enabling us not only to 
discover the depth beneath the surface of the origin of these shocks, 
and hence of volcanic foci, but ultimately of ascertaining the nature, 
* Geschichte der natiirlichen Veranderungen der Erdoberfliche. 
