l66 REPORTS ON INVESTIGATIONS AND PROJECTS. 



GEOLOGY. 



Chamberlin, T» C, University of Chicago, Chicago, IlHnois. Grant No. 241. 

 Study of fzindamental problems of geology. (For previous reports see 

 Year Book No. 2, pp. 261-270; Year Book No. 3, pp. 195-258, and 

 Year Book No. 4, pp. 1 71-190.) $6,000. 



The work of Dr. Chamberlin and his collaborators during the past year 

 followed essentially the lines set forth in previous reports. The personal 

 studies of Dr. Chamberlin were rather widely distributed over the group 

 of cosmogonic and geologic problems outlined in the report of last year, but 

 embraced some special studies on the former rates of rotation of the earth, 

 on the reversal of deep-sea circulation, and on the fourfold organization of 

 typical atmospheres. The special nature of these is, in a measure, indi- 

 cated in the synopses of his papers given below. 



Prof. F. R. Moulton continued his computations of the orbits of mate- 

 rials ejected from one sun under the differential attraction of a second sun 

 passing near it, the endeavor being to test mathematically the working 

 value of some of the more basal propositions of the hypothesis that spiral 

 nebulse have arisen from the ejections and perturbations attendant upon 

 stellar approaches. These computations were carried forward continuously 

 during the whole year. Forty-eight cases, in addition to those reported last 

 year, were mathematically treated. The courses of the orbits were followed 

 by computation for an average period of about five years. The perturba- 

 tions were found so great that it was necessary to use short intervals in 

 most of the computations, and this entailed very large amounts of numeri- 

 cal work in which Mr. Elton James Moulton assisted. Most of the cases 

 selected were such that the disturbing sun at its nearest approach to the 

 disturbed sun was still at a distance of five astronomical units. In eight of 

 the cases the orbits of the two suns were hyperbolas with an eccentricity of 

 1.2. A sufficient number of cases have now been worked out to give a fair 

 basis for general treatment and provisional deductions. It appears already 

 that in a considerable percentage of assignable cases the ejected material 

 will be left by the disturbing sun revolving in orbits whose eccentricities are 

 of the same general magnitude as those of many of the planetoids. 



Dr. A. C. lyUnn continued his mathematical inquiries into the application 

 of geophysical theory to accretion under the planetesimal hypothesis, particu- 

 larly in its relations to the temperatures and other physical states of the 

 earth's interior. Following his treatment of a theory initiated by Fisher — 

 but worked out by Dr. Lunn on the basis of the Laplacian law of density — 

 and the application of the results under alternative secondary postulates, 

 which was essentially completed last year, he entered upon a study of the 

 effects of changes in the secondary hypotheses thus entertained, and upon a 

 critical examination of them. The previous inquiry was traversed by the 



