WRIGHT: CHANGE IN ANGLES OF QUARTZ 



491 



The agreement between the values computed from the first 

 equation and the data of observation is indicated in Table 2. 



A check on these values was obtained from the data on the 

 expansion of quartz parallel to the principal axis as determined by 

 RandalP and the specific volumes of quartz kindly furnished me by 

 Dr. Sosman of this Laboratory. These values are listed in Table 

 3. In Randall's paper the true expansion coefficients only are 

 given. From them the total expansion listed in Table 3 was 

 found by Euler's method of mechanical quadrature. 



TABLE 3 



The changes in the crystal angle p of the unit rhombohedron 

 with temperature as calculated from these data are given in column 

 5, the observed values in column 6 and the differences in column 7. 

 The agreement between observation and theory is excellent, 

 better in fact than might well have been expected from the data 

 used. Such close agreement should be considered more or less 

 accidental. ' 



* Phys. Rev., 20: 10-37. 1905. 



