216 



University of California Publications. [Geology 



effect of the linear orientation ; the end or macropinacoidal face 

 (containing B and C) shows the effect of the schistosity; and 

 the side or brachypinaeoidal face (containing A and C) shows 

 the effect of the schistosity superimposed upon that of the linear 

 orientation. The two effects were found in all cases to be super- 

 imposed in the same sense, — to have the same sign. However, 

 as the experiments indicate that the effect of structure in itself 

 is zero this coincidence is an accidental one and is to be explained 

 in terms of the thermal conductivities of the constituent minerals. 



THE ROCKS INVESTIGATED AND THE RESULTS OBTAINED. 



Four typical metamorphic schists were investigated. Each 

 specimen which was used possessed to a remarkable degree uni- 

 formity of distribution of mineralogical constituents, and uni- 

 formity in the strong development of the schistosity. Each rock 

 will be described in detail later. 



At the temperature of the melting point of the wax (63.6°) 

 C, the ratios of the three axes of the triaxial heat-conductivity 



ellipsoids were found to be as 



follows 











(Obse 



rved.) 



(Computed.) 





A 



B/A 



CIA 



C/B C/A^B/A 



Hornblende schist 



1.00 



.942 



.885 



. 961 . 940 



Glaueophane schist 



1.00 



.961 



.743 



.769 .773 



Quartzose schist 



1.00 



.906 



.860 



.947 .949 



Mica schist 



1.00 



.894 



.715 



.808 .800 



(Fort Wrangell). 



The fifth column is the quotient of the third by the second 

 and should equal the fourth column. 



These results are the average values for a large number of 

 observations, and a few words as to their probable accuracy are 

 in place here. There is no doubt that each individual reading 

 truly represents the length of that line, measured to 1/40 mm., 

 for the method of checking results showed that the lengths were 

 being measured accurately. The tube was racked across, read- 

 ings were taken at A and B, fig. 7, and the screw was given an- 



At 







1 1 ) 







Jc 





Fig. 7. 





