November 29, 1907] 



SCIENCE 



749 



due to the same law operating with a dif- 

 ferent velocity. 



Hknet Fairfield Osboen 



SCIENTIFIC BOOKS 



Temperatur und Zustand des Erdinnern — • 

 eine Zusammenstellung und kritische Be- 

 leuchtung oiler Hypothesen. Von Herr- 

 mann Thiene. Jena, Fischer. 1907. Pp. 

 107. Price two and a half marks. 

 This useful paper is the result of a prize 

 offered by the Jena philosophical faculty for a 

 critical review of the literature and theories as 

 to the temperature and state (solid, fluid or 

 gaseous) of the earth's interior — a useful 

 undertaking since the literature is much scat- 

 tered. Astronomers, mathematicians and phys- 

 icists as well as geologists, have contributed to 

 it. The conclusions of the author, an as- 

 sistant in the Jena Mineralogical Institute, 

 are that the earth has an outer crust, of the 

 composition of diorite, and an iron core. The 

 surface density is about 2.8; the mean density 

 is between 5.4 and 5.7. The density at the 

 center according to Stieljes must be between 

 7 and 12.16, having due regard to all the facts, 

 including the moment of inertia (resistance to 

 change in its axis of rotation and the effect of 

 the attraction of the sun and moon on the 

 equatorial bulge) and the difference of gravity 

 at pole and equator. Thiene does not describe 

 the methods, but the results and assumptions 

 merely of the different writers. The reviewer 

 would note that our knowledge of the density 

 must be the more inaccurate the nearer the 

 center since the density of any ellipsoidal layer 

 has less and less importance and effect either 

 on the mass or the moment the nearer the 

 center respectively the axis of rotation it is. 

 Laplace's law of density is shown by the author 

 to agTee with the known facts. But any law 

 in which the constants were so taken as to be 

 consistent with the known data would, if ex- 

 pressed and expanded in a series in which the 

 density is a function of the ratio of the dis- 

 tance from the surface of the earth to its 

 radius, according to Maclauvin's theorem, re- 

 duce to Laplace's law for the first two terms. 

 It is obvious, though Thiene does not re- 



mark it, that other things being equal the law 

 of density will be different and the densities 

 at the center less if the temperature keeps on 

 increasing clear to the center than if it in- 

 creases less rapidly or attains a maximum. 



Thiene leans to the view that the tempera- 

 ture increases toward the center more and 

 more slowly from a rate of something like 

 1° C. in thirty-three meters to begin with so 

 that the greatest heat reached is probably from 

 2,000° C. to 10,000° C. He is not aware of 

 the arguments of See and Chamberlin for an 

 increase in temperature clear to the center and 

 a possible increase in the gradient. He would 

 attribute the heat to the original warmth of 

 condensation. The Kant-Laplace theory is 

 taken as established. 



The interior he believes a plastic crystalline 

 (anisotropic) solid mass, which would, how- 

 ever, turn into a fluid or possibly a gas were 

 the pressure removed. 



A list of references at the end and an alpha- 

 betical list of authors are valuable additions 

 and enable one to grasp the scope of the work 

 which seems fairly full for Gennany. An 

 American can hardly think that the hope of 

 the author that nothing essential has been 

 overlooked is fulfilled. He mentions the 

 metallic interior without mentioning Durocher. 

 He could not, of course, have had access to so 

 recent a work as Chamberlin and Salisbury's 

 geology, but many of the thoughts therein col- 

 lected have appeared in the Journal of Geol- 

 ogy, to which he seems also not to have had 

 access.^ He discusses and turns down theories 

 of a gaseous interior without mentioning See. 

 And by the way he does not note that a 

 temperature of 10,000° C, together with the 

 theory of an iron core favored by him, and the 

 critical temperature of iron and platinum 

 which he cites, from 5,000° to 7,000°, would 

 needs imply the possibility of a gaseous center. 



The bearing of theories of isostasy is but 

 mentioned. Neither Dutton nor Gilbert's 

 work with Putnam is mentioned nor that 

 with WooSward, only one of the least im- 

 portant of whose papers is cited. To the 



'■ Other writers too recent to be mentioned are 

 Hayford, Gregory, and those cited by Love in 

 ScnsNCE, N. S., Vol. XXVI., No. 669, Oct. 25, 1907. 



