ON AQUEOUS AND IGNEOUS METEORS. 7J7 



Tlife shocks of earthquakes, and the eruptions of volcanos, are in all pro- 

 bability modifications of the effects of one common cause; the same coutitrie* 

 are liable to both of them; and where the agitation produced by an earth* 

 quake extends further than there is any reason tosuspectasubterraneousconimo* 

 tion, it is probably propagated through the earth nearly in the same manner a* A 

 noise is conveyed through the air. Vokanos are found in almost all parts of 

 the world, * but most commonly in the neighbourhood of the sea; and espe- 

 cially in small islands; for instance, in Italy, Sicily, Iceland, Japan, the 

 Caribbees, the Cape Verd islands, the Canaries, and the Azores: there are 

 also numerous volcanos in Mexico and Peru, especially Pichincha and Coto- 

 paxi. The subterraneous fires, which are continually kept up in an open 

 volcano, depend perhaps in general on suU'ureous combinations and decom- 

 positions, like the heating of aheap of wet pyrites, or the union of sul- 

 fur and iron filings: but in other cases they may perhaps approach more 

 nearly to the nature of common fires. A mountain of coal has been burning 

 in Siberia for almost a century, and must probably have undermined in some 

 degree the neighbouring country. Tlie immediate cause of an eruption 

 appears to be very frequently an admission of water from the sea, or from 

 subterraneous reservoirs; it has often happened that boiling water has been 

 discharged in great quantities from a volcano; and the force of steam i» 

 perhaps more adequate to the production of violent explosions, than any 

 other power in nature. The consequence of such an admission of water, into 

 an immense collection of ignited materials, may in some measure be under- 

 stood, from the accidents which occasionally happen in founderies: thus a 

 whole furnace of melted iron was lately dissipated into the air in Colebrook 

 Dale, by the effect of a flood, which suddenly overflowed it. 



The phenomena of earthquakes and volcanos are amply illustrated by 

 the particular accounts, transmitted to the Royal Society by Sir William 

 Hamilton, of those which have happened at different times in Italy. The 

 earthquake, which desolated Calabria, in 1783, was fatal to about 40000 

 persons, continuing its ravages for more than three months ; it destroyed 

 the towns and villages occupying a circle of nearly 50 miles in diame- 

 ter, lying between 33 and 39 degrees latitude, and extending almost 

 from the western to the eastern coast of the southernmost point of Italy, 

 besides doing considerable damage to places at much greater distances from 

 its origin, which is supposed to Imve been either immediately under the towa 



VOL. I. 4 u 



