G. P. Merrill — Composition of Stony Meteorites. 469 



Art. XL1I. — The Composition of Stony Meteorites com- 

 pared with that of Terrestrial Igneous Rocks, and, con- 

 sidered with reference to their efficacy in World-Making • 

 by George P. Merrill. 



[Read before the Geological Society of Washington, March 24, 1909. J 



Speculation relative to subjects the actual proof of which 

 lies entirely beyond his reach, has ever been a favorite pursuit 

 of the thinking man. Nowhere is this more manifest than in 

 questions relating to the age and origin of the earth. Of all 

 the theories which have been evolved, and which have stood 

 the test of any considerable length of time, only that known as 

 the Kant-Laplacean, and the more recent hypotheses of 

 Professor Chamberlin of Chicago, need our present considera- 

 tion. Any and all of these call for the world-making materials, 

 whether gaseous or solid, from sources beyond our immediate 

 universe. It is but natural, therefore, that those substances 

 which reach our earth from space in a solid form, and which 

 give the only really tangible illustrations of what materials of 

 space may be, should be regarded as of value in aiding our 

 arrival at the desired conclusions. This fact was recognized 

 over one hundred years ago (1794) by Chladni, who regarded 

 meteorites as remnants of cosmic materials employed in the 

 formation of worlds, or, as he expressed it, as "Weltspane." 

 The idea, with various more or less important modifications, 

 has been repeated by subsequent workers,* and is brought up 

 for consideration with renewed force by the recent papers of 

 Professor Chamberlin, which have been so clearly summarized 

 under the heading of the "Origin of the Earth" in his work on 

 geology.f 



It should be stated, however, that Professor Chamberlin is 

 not an advocate of the meteoric theory of the earth ; in fact, 

 he states definitely that the origin of meteorites is but an 

 incidental result of stellar and planetary action, their genesis 

 being wholly a secondary matter, and furnishing no grounds 

 for regarding them as the parent material of great nebulse or 

 of stellar systems. Chamberlin inclines rather to what he calls 

 the "planetesimal hypothesis," which assumes that the solar 

 system was derived from a spiral nebula consisting of finely 

 divided solid or liquid materials, which revolve independently 

 about a common nucleus, and which are gathered into larger 

 aggregates through the crossing of the elliptical orbits of the 



* See Lockyer's Meteoric Hypothesis for discussion. Arrhenms' Worlds 

 in Their Making is perhaps the latest work in which the matter is seriously 

 considered. 



f Geology, vol. ii, Earth History, pp. 1-81. 



Am. Jour. Sci.— Fourth Series, Vol. XXVII, No. 162.— June, 1909. 

 32 



