I20 A. A. MICHELSON 



It would be interesting to confirm this important conclusion, 

 even qualitatively, by experiments on the effect of such relatively 

 small pressures as we are able to obtain in the laboratory. 



Such experiments are now in progress; and while the highest 

 pressures obtainable are a thousand times smaller than the pressure 

 in the interior of the earth, it may be stated that there are distinct 

 indications of an increase in the coefiicient of rigidity, and a marked 

 increase in the coefficient of viscosity of the few materials thus far 

 investigated. 



I would take this opportunity of expressing my appreciation of 

 the interest taken in this work by Professor T. C. Chamberhn, at 

 whose instigation the investigation was undertaken, and of tender- 

 ing thanks to him and to President H. P. Judson for their efforts 

 in securing the necessary funds. I would also gratefully acknowl- 

 edge the friendly co-operation of Professor Frost and the members 

 of the staff o" the Yerkes Observatory. 



