210 



University of California Publications. [Geology 



do in such a case, and within what extremely wide limits the 

 results of good experimenters varied with this method. The 

 last point will be brought up again in discussing the probable 

 error of the results on the thermal conductivities of schists. 



A fairly comprehensive list of ratios of thermal conductivi- 

 ties to the one-half power (this gives the ratios of the axes of 

 the isothermal ellipsoids) is appended herewith for future refer- 

 ence. Many of these have been checked by measurements of 

 absolute conductivities by the method of Forbes and in other 

 ways. 



For the monoclinic minerals, c will be replaced by "parallel 

 to that axis of elasticity which lies nearest c " ; and the fourth 

 row shows by its sign in which quadrant this axis lies. The sign 

 -)- indicates that it lies in the obtuse angle between the c axis 

 and the elinodiagonal. The numbers show how far from the 

 c axis this axis lies. The third column will still indicate values 

 parallel to b. 



Then the second column must indicate values along a line 

 perpendicular to b and to the direction indicated in the first 

 column. 



The list includes no triclinic minerals. 



Isometric 



Tetragonal 



Hexagonal 



Orthorhombic 



Monoclinic 



c a 



All minerals 1.00 1.00 



Eutile 79 1.00 



Zircon 90 1.00 



Scapolite 85 1.00 



Vesuvianite 95 1.00 



Quartz 76 1.00 



Specularite 1.10 1.00 



Dolomite 1 . 05 1.00 



Apatite 96 1.00 



Tourmaline 1.15 1 . 00 



Caleite 91 1.00 



Barite 1.00 1.06 



Anhydrite 1.00 .971 



Staurolite 1.00 .97 



Tremolite 1.00 .60 



Hornblende 1.00 .71 



Epidote 1.00 .93 



Gypsum 1.00 .80 



.00 

 .00 

 ,00 

 .00 

 .00 

 .00 

 1.00 

 1.00 

 1.00 

 1.00 

 1.00 

 1.03 

 .943 

 .901 

 .75 

 .80 

 1.09 

 .65 



—14? 5 

 + 17° 



