and its Connection *with Magnetism. 183 



be produced by " currents of electricity circulating about 

 from east to west," then the conclusion seems inevitable, that 

 either the electrical and magnetic fluids are identically one 

 in essence, though, perhaps, liable to certain modifications ; 

 or, that the electric fluid is derived primarily from the sun, 

 and induces the several magnetic phenomena, by an energy 

 exerted upon certain substances vv'ithin the earth's surface : in 

 either case, the sun must be referred to as the prime actuating 

 cause. 



Mr. Ritchie's farther remarks are pertinent to the idea 

 above suggested ; for he says, in reference to the questions, 

 " Hovi^ are these (electro-magnetic) currents generated ? — 

 Are they voltaic or thermo-electric ? — from the constitution 

 of our globe, "we can scarcely doubt that they belong to the 

 latter class. The earth abounds with metalliferous veins, and 

 these veins are undoubtedly of different temperatures : con- 

 sequently, thermo-electric effects must take place. The rapid 

 change in the magnetic equator, when approaching South 

 America, renders this supposition highly probable." [Journal 

 of the Royal Institution, Aug. 1831, p. 130.) 



5. The sun's rays, for the most part, strike the surface 

 of the earth, and produce the develojiement of heat, varying 

 in intensity according to the then existhig state of the atmo- 

 spheric medium through which they pass; and, perhaps, 

 according to the nature and extent of the electrising processes 

 induced within that surface upon which the rays impinge. 

 The light thus radiated must be either reflected, absorbed, or 

 extinguished. 



That a portion of it is reflected, no one acquainted with 

 astronomical facts can entertain a doubt. That another and 

 considerable portion is absorbed is proved, almost to a de- 

 monstration, by the increase of temperature at a considerable 

 depth below the surface of the ground ; and by numerous 

 electrical and magnetic phenomena. That any portion is 

 extinguished or destroyed, is contradicted by the direct ana- 

 logy of facts ; for all nature affords irrefragable evidence that 

 not an iota of her productions ever was or can be lost. 



From the foregoing and many other considerations, I have 

 arrived at the conclusion that, as the surface of the earth is 

 the grand absorbing medium of the rays of light, the portion 

 absorbed, not being extinguished, must inevitably be produc- 

 tive of many stupendous phenomena, some of which I shall 

 now endeavour cursorily to point out. 



Without entertaining, to its full extent, the theory of Pro- 

 fessor Leslie, that the globe is cavernous, its central cavern 

 being replete with light, " shining with intense refulgence, 



N 1 



