Apeil 10, 1908] 



SCIENCE 



589 



by the speaker under the title "Evolution of 

 the Falls of Niagara." E. L. Faris, 



Secretary 



THE ELISHA MITCHELL SCIENTIFIC SOCIETY OP 

 THE UNIVERSITY OF NORTH CAROLINA 



The 176th meeting was held in the main 

 lecture room of the chemical laboratory, 

 Wednesday, February 12, 1908, at 7:30 p.m. 

 Professor Collier Cobb addressed the society 

 on " The Cause of Earthquakes in the Light 

 of Eecent Earthquake Action." The lecture 

 was fully illustrated with lantern slides. 

 A. S. Wheeler, 

 Recording Secretary 



DISCUSSION AND CORRESPONDENCE 



SOHAEBERLE, BECKER AND THE COOLING EARTH 



To THE Editor of Science: Professor 

 Schaeberle is certainly a bold man when, in 

 your current number (March 6, 1908, p. 392), 

 basing himself on his method of observing 

 stellar temperatures, he would upset modern 

 astronomy with one hand, and make the sun 

 the center of the sidereal cosmos, and with 

 the other would upset most modern theories 

 of geological climate! I hardly think that 

 Borrell, in the current number of the Journal 

 of Geology, Huntington, in the current vol- 

 lune of the Geological Society of America, 

 or most of the speakers at the Geological 

 Congress in Mexico, will at all agree that 

 Manson's hypothesis is " demonstrated as a 

 true theory"! They will agree with Cham- 

 berlin's strictures. But one can not yet go 

 into further criticism, save to urge those of 

 your readers who are neither geologists nor 

 astronomers not to accept Professor Schae- 

 berle's ipse dixit, but rather await the demon- 

 stration which he promises " later on." 



The object of this letter is rather to call 

 attention to the bearing which his work has 

 on that of Becker^ on the cooling earth. 

 Since Becker has kindly undertaken what I 

 had thought to do myself, when I had just a 

 few more facts, a few comments as to the 

 applicability of his conclusions may be ven- 

 tured. 



^ Science, February 7 and Marcli 8, Vol. 27, 

 pp. 231, 232, 392. 



Though Becker's concise method of deriving 

 his formulae (2) is not beyond criticism math- 

 ematically, the same may be derived from 

 Eiemann's and Byerly's^ more general and 

 rigid treatment. But Becker's discussion of 

 his formula obscures a most important limit 

 to its application, to wit, the temperature 

 must remain constant at the surface of the 

 cooling tody, which he assumes to he the rock 

 surface. Otherwise the solution applicable is 

 that given by Byerly {loc. cit.) on page 88, 

 following Eiemann. 



If we assume the temperature of the at- 

 mosphere at the surface to have varied appre- 

 ciably, and especially if we assume that its 

 temperature depends on that of the earth, as 

 Schaeberle says is largely the case (that two 

 thirds of its temperature is due to interior 

 heat), Becker's solution is inapplicable in the 

 form he gives it. In fact, if two thirds of its 

 heat comes from the ground now, originally, 

 at the time " hell froze over " and the waters 

 above the earth were separated from those 

 under, must not the temperature of the at- 

 mosphere near the earth have been much hot- 

 ter and much nearer that of the freshly con- 

 solidated rock than Becker assumes? Must 

 not the waters of the ocean have been then 

 largely up in the air and so the blanketing 

 effect and the atmospheric pressure much 

 greater? If so, Becker's conclusions are ut- 

 terly useless. For his fundamental formula 

 may be thus worded: 



y = original excess of surface rock \ 



temperature over atmospheric \ 



present geothermal gradient — ) 



original gradient / 



= 22/7 X diflFusivity X time elapsed. 



Now, Becker estimates the numerator as 

 something like 1,300° C, apparently assuming 

 this as the fusion point of a fairly silicious 

 rock, and the atmospheric temperature at 

 0° C. ? But all my work with grain indicates 

 lower consolidation temperatures for the acid 

 than the basic rocks, the former being in the 

 state of aqueo-igneous fusion of a sugar 

 syrup at 150° C. Moreover, as Day and Co. 

 have shown, quartz will not crystallize above 



- " Fourier's Series and Spherical Harmonics," 

 p. 84. 



