7 02 THE POPULAR SCIENCE MONTHLY. 



In like manner, the geologist, looking into the bowels of the 

 earth, and finding here and there the remains of a tree or a saurian, 

 presumes that they once lived and grew in the same localities, and 

 were buried and petrified under the rock-grindings of after-ages. 

 But he really has no absolute proof of any such thing. They may 

 have been created in the fossil state and laid away in the strata on 

 the same day the earth was made. But I think the scientist, know- 

 ing laws of Nature by which, with sufficiently long periods of time, 

 all these geologic results might have been gradually brought about, 

 is justified in believing that they too were the slow product of Nature 

 and of time. 



So we, finding that the world has certainly at some time been 

 subjected to a heat at least sufficient to volatilize nearly every known 

 substance, and that there are laws of Nature by which, through 

 periods of time immensely long, the earth and the planets might 

 have been rolled up from a gaseous nebula and bowled off in their 

 mighty revolutions, have just as much right to say that it was so, as 

 we have to say that the American forests grew, or that the Triassic 

 beds were deposited. 



Geology has proved that the earth, up to the primary rocks, was 

 once a molten mass. The crystalline structure of the unstratified 

 rocks compels to this conclusion ; for minerals insoluble in water can 

 only become crystallized in large masses by cooling from a state of 

 fusion. If, then, the earth was once an incandescent globe of melted 

 rocks for everything above the granite beds must then have been in 

 a state of vapor it is not unreasonable to suppose that it may have 

 existed prior to that time in a still more highly-heated condition 

 even volatilized, and diffused through space as rare and attenuated 

 gases ; for this is the condition which all matter assumes under 

 sufficient degrees of heat. In fact, we must either suppose that the 

 earth was created as a fiery liquid globe, for which we have no war- 

 rant, or we must follow back to the time when its vapors were scat- 

 tered in space, unreflecting and impenetrable to light when the earth 

 was " without form and void, and darkness was upon the face of the 

 deep." 



Let us start, then, with that condition of things which it is now 

 very generally conceded must once have existed the diffusion of 

 matter in a nebulous form throughout all space. Calculations easily 

 made show that the nebula must have been of extreme tenuity 

 such that the few grains taken up on the point of a knife-blade must 

 have been expanded to fill several cubic miles. A heat so powerful 

 for we know of no other force which could thus hold apart the atoms 

 of matter would doubtless be sufficient to resolve every known sub- 

 stance into its simplest elementary constituents, perhaps into a very 

 few primordial elements ; for chemists are far from being satisfied 

 that they have arrived at the ultimate forms of matter in their list of 



