B. Glass Models. 



5. Four glass models, showing the principal crystal- 

 line forms contained in the cube (as arranged by Dr. 

 Leeson) 3 in. size. 



1857. Exhibited by J. E. Larkin. 



These are cubes formed by sheet glass. The crystallographic 

 axes are all marked by red wire. The derived forms are re- 

 presented by wire edges within the cube. 



1. The four-faced cube is shown by green wire, the rhombic 



dodecahedron by blue, the octahedron "by yellow, the 

 trapezohedron by orange, and an inner cube by red. 



2. The rhombic dodecahedron in blue, 3-faced octahedron in 



yellow ; the edges of the octahedron contained in the same 

 are marked inside by white, and an inner cube in red. 



3. The two derivative tetrahedra are marked by blue and 



white lines respectively on the glass, the octahedron by 

 yellow wire, an inner cube by red and a combination of 

 the cube and octahedron by white. 



4. The trapezohedron in white, the hexakis-octahedron in 



blue, an inner cube in red. The edges of the rhombic 

 dodecahedron contained in this are marked on the inside 

 in white, and those of the octahedron in yellow. 



6. Glass cube, 3 in. size. 



1866. Exhibited by J. R. LarJcin. 



The crystallographic axes are marked by red wire ; one 

 derived tetrahedron by dark lines on the glass, the octahedron 

 by yellow wire, the rhombic dodecahedron by blue, and an 

 inner cube by red. 



7. Glass cube, 2 in. size. Under small shade. 



1857. Exhibited ly J. R. Larkin. 



The crystallographic axes and an inner cube are marked by 

 red wire, the octahedron by yellow, and the rhombic dode- 

 cahedron by blue. 



8. Hexagonal prism. Under small glass shade. 

 1857. Exhibited by J. R. Larkin. 



The prism faces are formed of sheet glass, as are also the basal 

 planes ; the crystallographic axes are marked by red wire ; 

 the rhombohedron by white, and the corresponding scaleno- 

 hedron by blue, 



