of certain Crystals, ^7 



of his temper left unintelligible at the time they were written, 

 and which, notwithstanding his indefatigable industry, were 

 subsequently lost to the public, for want of being fully deve- 

 loped. 



We have seen, that by due application of spheres to each 

 other, all the most simple forms of one species of crystal will 

 be produced, and it is needless to pursue any other modifica- 

 tions of the same form, which must result from a series of 

 decrements produced according to known laws. 



Since then the simplest arrangement of the most simple 

 solid that can be imagined, affords so complete a solution of 

 one of the most difficult questions in crystallography, we are 

 naturally led to inquire what forms would probably occur from 

 the union of other solids most nearly allied to the sphere. And 

 it will appear that by the supposition of elementary particles 

 that are spheroidical, we may frame conjectures as to the origin 

 of other angular solids well known to crystallographers. 



The obtuse Rhomboid, 



If we suppose the axis of our elementary spheroid to be its 

 shortest dimension, a class of solids will be formed which are 

 numerous in crystallography. It has been remarked above, 

 that by the natural grouping of spherical particles, fig. lo, 

 one resulting solid is an acute rhomboid, similar to that of 

 fig. 2, having certain determinate angles, and its greatest 

 dimension in the direction of its axis. Now, if other particles 

 having the same relative arrangement be supposed to have 

 the form of oblate spheroids, the resulting solid, fig. 12, will , 

 still be a regular rhomboid ; but the measures of its angles » 

 will be different from those of the former, and will be more 



MDCCCXIII. I 



