256 CARNEGIE INSTITUTION OF WASHINGTON. 



lected, but the work of carefully comparing them with the results 

 obtained in {b) and {c) still remains. This will take much time. 

 For example, a thorough review of Darwin's works or of Ritter's 

 can not be done inside of six months. Nearly all of this work is 

 entirely unverified and should be gone over. Besides, I am planning 

 to make every conceivable cross-test on every theory. The work 

 brought out in somewhat separate lines after the publication of many 

 of the original papers makes this a serious task. 

 Very truly yours, 



F. R, MOULTON. 



The Work of Dr. Lunn. 



Chicago, September jo, igo^. 

 Dear Professor Chamberlin : After making the progress pre- 

 viously reported to you, I was compelled by the strain of other work 

 to lay the geological problem aside almost entirely for several months, 

 but during the 'past two months it has been constantly before me. 

 I think it will ser\'e the purpose of your report of progress if I set 

 forth the way in which the matter has developed. The sketch may 

 be brief, because at least part of the manuscript will be ready for 

 publication so soon. 



Our object was to determine the total amount and distribution of 

 heat due to the gravitational energ>' resulting from the contraction 

 to its present condition of an earth originally homogeneous and 

 having the density of the present surface rock. It was thought that 

 this would represent fairly the thermal effects that would arise from 

 the formation of the earth by aggregation. There is not the slight- 

 est difficulty in determining the total amount of that energy for any 

 assigned law of density ; but the question of its localization in the 

 mass antecedent to its transfer, by conduction or by extrusion 

 through volcanic processes, can not be answered without recourse to 

 hypothesis as to the thermodynamic properties of the substance at 

 the high temperatures and pressures met with. The resijlts which I 

 have already furnished you refer to the energy generated by what 

 might be called static compression, each portion of the mass being 

 conceived as heated by local compression from the surface density 

 to its present density, the work done being assumed to produce a 

 proportionate rise of temperature. The form of the original tem- 

 perature curve corresponding to this and the main features of the 



