254 CARNEGIE INSTITUTION OF WASHINGTON. 



In my last report mention is made of the preliminary stages of an 

 inquiry relative to changes in the form of the earth growing out of 

 hypothetical changes in the rate of rotation due to tidal action. The 

 inquiry as originally planned could easily have been carried out, as 

 Professor Slichter had contributed the necessary computations and 

 it only remained for me to add the geological discussion. This would, 

 however, only have introduced a conflict between geological deduc- 

 tions and the well-known tidal deductions of G. H. Darwin. It 

 seemed therefore desirable that the influence of tidal attraction should 

 be recomputed on the assumption of a rigid earth instead of a viscous 

 one, not only, but on the assumption of increasing rigidity toward 

 the center — an assumption that seems to be required by several recent 

 lines of evidence relating to the state of the earth's interior. It 

 seemed also desirable that the assumption should involve high elas- 

 ticity of form, which seems also to be indicated by the rates of trans- 

 mission of transverse seismic oscillations through the deeper parts of 

 the earth. I have not as yet been able to arrange for this rather 

 laborious work, owing to the engagement of the available parties 

 competent to undertake it. 



I append herewith statements of the collaborative work of Doctors 

 Moulton, Lunn, and Stieglitz, the general nature of which was 

 outlined in my last report. 

 Respectfully submitted. 



T. C. Chamberlin. 

 Chicago, September ^o, igo^. 



The Work of Dr. Stieglitz, 



Chicago, October 26, 1904. 

 Dear Professor Chamberlin : I beg to report that I have made 

 considerable progress on the problem of possible relation of the de- 

 posits of pure gypsum beds, free from calcium carbonate, to the 

 carbon dioxide content of the atmosphere and the climate at the 

 period when the deposits were laid down ; but I think it is advisable 

 to pursue the subject further before reporting any specific results. 

 Yours respectfully, 



Julius Stieglitz. 



