'. S. Dana — Ifonazite from North (Jarolu 



1*1 110^110 = 86° 34' 20" 



a^e 100 ~ 011 = 79° 53' 3" 



Each of these is the mean of a considerable number of inde- 

 pendent measurements, whose extremes varied not more than 

 •'><!" from the mean given. The axial ratio obtained from them 

 may be regarded as reasonably exact, viz : — 



The following table contains a list of the more important angles 

 (supplement angles) calculated from the above data, and also 

 such measured angles as could be obtained with sufficient ac- 

 curacy to make them of interest. The agreement between the 

 measured and calculated angles is close in the cases where the 

 former gave good reflections, but the planes 

 which give the prismatic habit to the crystals (v) afforded 

 angles on which no dependence at all could be placed. 



Measured angles. Calculated angles. 



of the Alexander County monazite with those of the 



