THE a 
AMERICAN sade 
JOURNAL OF SCIENCE, &c. 
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GEOLOGY, MINERALOGY, TOPOGRAPHY, &c. 
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Art. I1.—On Earihquakes—their causes and effects. By 
Isaac Lea. - e 
Tue nature of an earthquake is so well known, that Iwill 
describe it only as a vibrating or balancing motion of :the 
soil on which we tread, extending to various depths beyond 
our knowledge, and sometimes to an enormous extent. The 
wide-spreading devastation and ruin, which sometimes ac- 
company them, bring the mind to the contemplation of one 
of the most astonishing efforts of nature. The imagination, 
in seeking for its Se cause, is lost i in the “rath nr of its 
tered. 
My object is to endeavour to show aig are the pe 
ca ble sources from whence such large supplies o 
Bd ite bustible matter are drawn ; and to prove the entity ofthe 
volcano with the earthquake; by this I wish to be under- © 
stood that I believe carthquakes to be the effect of yélcanic 
eruptions, which accompany them as the thunder accom- 
panies the action of the electric fluid, and that the motion 
1s produced by a pre-existing cause. ‘L also deny that light- 
ning has the.power to produce the earthquake, as has been 
supposed—first by Dr. Stukely in 1749, and since by many 
philosophers. The electric as is frequently, nay most 
Vot. 1X.--No. 2. 
