INTRODUCTION. 9 



led with the dust. The same atmosphere, although invariably the 

 residence of the electric fluid, exhibits, only occasionally, decisive 

 proof of an energy, which pervades the material world. Excited 

 by causes, which, except in their proximate operation, are unknown 

 to us, the electric fluid fills the atmosphere with thunder and light- 

 ning. It was reserved for Dr. Franklin to prove, that lightning is 

 identical with the spares which are obtained by friction from glass 

 or resin, or from dry fur, from our apparel of silk or woollen, and 

 from many other sources. In short, we now know that all things are 

 full of the electrical influence ; that we can bring it down from the 

 clouds by kites, metallic rods and wires ; that we can evolve it by our 

 machines of glass and metals, and that by the power called Galvan- 

 ism, using certain arrangements of metals, acids, and other substances, 

 we can produce it at pleasure, connected more or less with the other 

 imponderable fluids, in entire independence of the weather, and of 

 the state of the atmosphere ; and at the same time we can render 

 sensible the attraction and repulsion, which are inseparable from its 

 excitement. 



Although the experiments, exhibiting these facts, are sufficiently 

 curious, the importance of the subject has, only within a few years, 

 been perceived in its full extent ; for it is now believed, that the par- 

 ticles of matter are constantly under the influence of these attractions 

 and repulsions, and that they are producing, without cessation, de- 

 compositions and new arrangements. 



Associated, every where, with electricity, HEAT both modifies its 

 effects, and produces peculiar phenomena. The mild radiations of 

 the sun, and the gentle fluctuations of temperature are subjects of 

 common experience, and excite no particular surprise. But the 

 amazing energy of VOLCANIC ACTION, far surpasses every other ex- 

 ample of natural heat. Science is now in a condition to reason, with 

 considerable probability, as to the causes of volcanic heat, and still 

 more, regarding those of the accompanying phenomena of earth- 

 quakes : but leaving these for the present out of view, our attention 

 is arrested by the grandeur of the events, associated with volcanic 

 agency. 



The convulsion of the ground, not only in the immediate vicinity, 

 but often in distant countries ; the subterranean noises, like internal 

 thunder, and the grating sound produced by the rending of the solid 

 strata ; the violent emission of gases, steam, ashes, sand, ignited 

 stones and rocks, and eventually of the current of lava, which flows 

 in a stream of fire down the mountain, and over the nether country ; 

 the overthrow of the structures of man, or their inhumation beneath 

 the lava and ashes ; the lightning and thunder, in and above the cra- 

 ter ; the violent flux and reflux of the tides and the strong agita- 

 tion of the sea, alternately inundating and draining the adjacent 



