490 FRANK D. ADAMS 



experimental study was thus secured, the phenomenon of the flow 

 of marble was further studied, and the investigation was extended 

 to other rocks and to various rock-making minerals. 



In the present paper it is proposed to describe briefly the results 

 obtained in a single line of the investigation — that in which a method 

 suggested many years ago by Professor Kick was followed. This 

 method, however, while giving certain interesting results, especially 

 with the softer and more plastic rocks, has proved to be less suitable 

 for the development of high differential pressure and for otherwise re- 

 producing the conditions which obtain in the deeper parts of the 

 earth's crust, than the method suggested by the present writer and 

 employed in the research into the flow of marble to which reference 

 has been made. A brief statement of the results obtained by the lat- 

 ter method will appear elsewhere shortly,' while the full and detailed 

 results of the whole investigation will eventually be issued by the 

 Carnegie Institution of Washington in a special publication. 



In carrying out experiments on the action of differential pressure 

 with a view to reproducing more or less accurately the conditions of 

 pressure which obtain in the deeper parts of the earth's crust, where 

 flow is developed, it is manifestly quite useless to attempt to reproduce 

 these conditions by simply submitting the materials to be investi- 

 gated to compression in a testing machine, as is done in testing the 

 strength of building stones. ~ Differential pressure is certainly 

 developed in such cases, but it consists merely of the ordinary atmos- 

 pheric pressure on the sides of the test-piece while the enormously 

 greater pressure exerted by the testing machine acts in the vertical 

 direction. It is necessary to increase the lateral pressure and make 

 it in some degree at least approach the measure of that exerted in a 

 vertical direction if the pressure conditions of the zone of flow in the 

 earth's crust are to be reproduced. 



DESCRIPTION OF KICK'S METHOD 



To secure this lateral pressure experimentally Kick^ devised his 

 method. This consists in making a box of some strong and at the 

 same time ductile metal, such as copper, placing in it a specimen of 



1 See Amer. Jour. Sci. (June, 1910), and following numbers. 



2 "Die Principien der mechanischen Technologie und die Festigkeitslehre," Ze/7. 

 des Ver. Deut. Ingen. (1892), XXXVI, 919. 



