356 



Proceedings of the Boyal Physical Society. 



The following Table gives all the commoner indices up to 

 49.50.0, 49.0.50 in the form of fractions, together with 

 their decimal equivalents, which represent the pro- 

 portional lengths to radius as unity, and are the natural 

 tangents to the angles represented by the indices. The 

 nearest angular measurement in degrees and minutes to 

 these is given in the first column. 



The Table is taken partly from Griffin's " Principles of 

 Crystallography," with some extensions, and with some 

 omissions of the parts not needed for the present 

 purpose. 



