447 
THE ERUPTIOlSr OF ETNA. 
BY S. J. MACKIE^ F.G.S. 
*o« 
I N one of tL.e most important of recent papers upon the 
origin of volcanos, one of our best Vulcanists — if such 
a heathen term may be allowed — comments on the high 
interest of volcanic phenomena, and on the prevailing igno- 
rance of their causes, in these remarkable words : — 
Now, although the study of the laws of volcanic action is a branch of 
geology which has not attracted much attention in this country, yet every one 
will, on consideration, admit that, among all the forces of nature which may 
be seen in activity on the surface of the earth, the volcano is by far the most 
striking in its phenomena, and the most directly demonstrative of the cha- 
racter and mode of operation of those (as yet little understood) subterranean 
agencies by which the crust of our globe has been unquestionably from time 
to time modified, and was in all probability in a large degree elaborated. 
What was here true in Mr. Scrope^s remarks in 1859 is true 
still. We do not yet know either the cause or the source of 
volcanos. Before, however, we can hope to comprehend the 
scientific bearings of volcanic phenomena in respect to exist- 
ing theories, we must briefly understand what those principal 
theories are. No one would now dream of looking upon the 
flame and smoke-belching crater of the Sicihan mountain as 
the ancients did, in their wonderment and afiright, as the 
entrance to hell or Hades ; or of giving full faith to those sub- 
lime and poetic 'notions which they conceived, amidst the 
rumblings and resoundings of the dreadful district, of the 
deep-seated smithery of the Cyclops forging, under the fire- 
god Vulcan, the thunderbolts of Jove. And so we may only 
use these romantic mythological fantasies as an embellishing 
vignette to our chapter. 
The earliest geologists attributed volcanic action to the igni- 
tion of beds of coal, sulphur, and other inflammable materials ; 
but the first who went any way to practically or experimentally 
support this view was Lemery, who, in the Memoms of the 
French Academy for 1700, in order to account for the spon- 
taneous firing of such substances notified certain mixtm^es of 
