1883 .] Earthquakes and Electricity , 703 
of Peru, where rain scarcely ever falls, and where hail, 
lightning, and thunder are unknown, these atmospheric ex- 
plosions are replaced by the subterranean thunder which 
accompanies the trembling of the earth ” (i., 205). Lastly, 
in respedt of the probable affinity between the heat, electri- 
city, and earthquakes : — “ If, on the one hand, the internal 
heat of our planet may be connected with the excitement of 
eleCtro-magnetic currents and the evolution of terrestrial 
light (aurorae) accompanying a magnetic storm, it is also a 
principal source of geological phenomena” (i., 189). 
A great name in seismological literature now claims our 
recognition. To the late Mr. Robert Mallet, F.R.S., Science 
is much indebted for his magnificent record of the earth- 
quakes that have occurred between B.C. 1606 and A.D. 1850 
— a list that comprises no fewer than 6831 instances of ter- 
ranean convulsion. This account, together with most of 
his researches in the field of earthquake physics, is contained 
in various Reports made to the British Association during 
the years 1850 to 1854 inclusive. Hereafter we shall pre- 
sent a selection from Mallet’s incidents ; let us now notice 
some of his dicta. In regard to particular shocks which 
have caused fissures to open in the earth, and fire and smoke 
to issue therefrom, he says : — “ The experiments of Bec- 
querel and other electricians have shown that when fradture 
in a solid takes place a powerful eledtrical disturbance is the 
consequence. This will be great in proportion as the surface 
and mass fradtured are in themselves large. When therefore 
a fradture of a mile long and of many feet in depth is formed, 
. . . the disturbance of eledtric equilibrium may be expedted 
to exceed that of a heavy thunderstorm, and may quoad this 
part of earthquake phenomena realise the dreams of the 
older philosophers who thought that an earthquake was a 
thunderstorm under ground. In this then I believe is to be 
found the usual source of the flame or flash seen suddenly 
to appear and vanish at the mouth of the rent ” (First 
Report, p. 54). He thinks that the smoke observed is pro- 
bably in all cases dust. On the subjedl of the malaise that 
frequently (as with thunderstorms) precedes earthquakes : — 
“ Animals, including pigs, oxen, horses, mules, dogs, geese, 
poultry, show presentiments of coming shocks by their un- 
easy manner. Human beings have sometimes a tendency 
before shocks to giddiness, headache, and nausea ” (First 
Report, p. 68). He quotes Von Hoff in the following im- 
portant passage : — “ In all relations between this earth and 
its atmosphere the former is to be considered as the principal 
and the latter only as its appendage. The atmosphere is 
