. 87. OF THE CONNEXION OF FORMS. 71 



nal faces or the base, the limit of the series on the other. 

 Hence they are not simple, but compound forms ; and this 

 is the reason why they have not been enumerated among 

 the simple forms. The whole series is comprised within 

 the two limits. The particular mode in which the limits 

 of the series of different forms result, depends upon the 

 quality of those forms themselves, and will be explained in 

 particular in every series. 



Forms of several axes cannot have limits of this descrip- 

 tion. However, if we suppose the different varieties of ho- 

 mogeneous simple forms of variable dimensions (. 70. 71 73. 

 77) to constitute series ; the limits of these series will be 

 represented by those forms of many axes, whose dimen- 

 sions are constant (. 58. 59. 63.). 



. 87. FUNDAMENTAL FORM. 



That form, which serves as the base of the de- 

 rivation (. 81.), is termed the Fundamental Form. 



The idea of the Fundamental Form in the present me- 

 thod, is well defined, and perfectly determined. Hence 

 mere simple forms, or such as have hitherto been common- 

 ly called fundamental, primitive or primary forms, must 

 not be confounded with this idea. 



Fundamental forms must possess the following proper- 

 ties. They must be, 



1. Simple forms; 



2. Forms not derivable from another fundamental form ; 



3. Forms which do not possess infinite axes; and 



4. Forms contained under the least possible number of 



faces, provided the form itself be not objectionable 

 from other considerations. 



According to these characters, the fundamental forms of 

 the mineral kingdom will be, 



1. The Scalene Four-sided Pyramid, 



2. The Isosceles Four-sided Pyramid, 



3. The Rhombohedron, and 



4. The Hexahedron. 



