CLARENCE KING. 



indispensability of more exact data in this branch of science for 

 a rational discussion of the fundamental problems of geology. 



This idea found a practical outcome a few years later in the 

 establishment of a physical laborator}^ immediately after his 

 assumption of the Directorship of the United States Geological 

 Survey. His earnestness and energy is shown by the fact that 

 instead of waiting for the slow action of Congress, he defrayed 

 the cost of the delicate apparatus necessary for this work out of 

 his own pocket. The credit of the brilliant physical investiga- 

 tions carried on in that laboratory is naturally due to Professors 

 Barus and Hallock, who conducted them, but it was King's 

 acumen and good judgment that was responsible for their selec- 

 tion, and his action that made it possible for them to carry on 

 their work. To himself, as he says ten years later in his paper 

 on the Age of the Earth (Am. Jour. Sci.,vol. xlv, January, 1893), 

 he reserved the privilege of "making geological applications of 

 the laboratory results." The experiments on the physical con- 

 stants of rocks contemplated were to be directed to the determina- 

 tion (a) of the phenomena of fusion, (b)of those of elasticity 

 and viscosity, and (c) of those of heat conductivity, each consid- 

 ered with special reference to their dependence on temperature 

 and pressure. 



The paper on the Age of the Earth, mentioned above, is his 

 only published result, and was but an earnest of what he had 

 planned to do. This was an attempt to advance to new precision 

 Kelvin's estimate of the earth's age deduced from terrestrial 

 refrigeration. It consists mainly of a mathematical discussion 

 of the earth's thermal age as determined from various postulates 

 presented by Laplace, George H. Darwin, and Lord Kelvin, and 

 based on Barus' determinations of the latent heat of fusion, spe- 

 cific heat, melted and solid, and volume of expansion between 

 the solid and melted state, of the rock diabase. This is followed 

 by a critical examination of other methods of determining the 

 earth's age — by tidal retardation, by sun-age, and by variations 

 of eccentricity. After a careful scrutiny of all the data on the 

 effect of pressure on the temperature of consolidation, King con- 

 cluded that, without further experimental data, "we have no 

 warrant for extending the earth's age beyond 24 millions of 

 years," an estimate which, as the result of a somewhat more ex- 



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