THE 



JlMERICAJS 



JOURNAL OF SCIENCE, &c. 



GEOLOGY, MINERALOGY, TOPOGRAPHY, &c. 



Art. L — On Earthquakes — their causes and effects. By 

 Isaac Lea. 



The nature of an earthquake is so well known, that I will 

 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 etforts of nature. The imagination, 

 in seeking for its original cause, is lost in the labyrinth of its 

 own efforts, and we find ourselves, after a fruitless labour, 

 but a short distance from the threshold at which we en- 

 tered. 



My object is to endeavour to show what are the proba- 

 ble sources from whence such large supplies of com- 

 bustible matter are drawn ; and to prove the identity of the 

 volcano with the earthquake ; by this I wish to be under- 

 stood that 1 believe earthquakes to be Ihe effect of volcanic 

 eruptions, which accompany them as the thunder accom- 

 panies the action of the electric fluid, and that the motion 

 is produced by a pre-existing cause. I 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 fluid is fre<juently> nay most 

 Vol. IX.— No. 2. 27 



