288 APPENDIX CALCULATION OF THE 



bulk, a row of molecules to have been abstracted 

 at the angle A of the primary form, from the first 

 plate of molecules added to the plane P, and an 

 additional row to have been abstracted from each 

 succeeding plate. 



As the three plane angles which concur to produce 

 the solid angle at A, are similar, a similar abstraction 

 of molecules would take place simultaneously from 

 the plates superimposed on each of the three adjacent 

 planes, and the result would be the production of a 

 tangent plane, presenting at its surface the terminal 

 solid angles of the molecules belonging to those 

 plates which had been added to the smaller rhomb- 

 oid.* 



Let us next suppose that instead of any abstraction 

 of molecules from the superimposed plates, those 

 plates had been added entire, and a perfect enlarged 

 rhomboid had been produced. 



* It will be recollected that the molecules are so small, as to occasion 

 no perceptible difference iu the character of the secondary plane, 



