9. Six glass models, representing the six systems 

 of crystallography. 



1860. Exhibited by J. R. LarJcin. 



The fundamental forms or combinations are formed through- 

 out of sheet glass, and the crystallographic axes marked by red 

 wires. 



1. Cubic. The octahedron is marked by orange-coloured 



wires, and the edges of fche two tetrahedra are marked 

 on the faces of the cube by blue and white lines respec- 

 tively. 



2. Tetragonal. The square prism of the second order with 



the basal planes in glass. A long pyramid marked by 

 yellow wire, and a short one by white. The square 

 prism of the first order is marked by dark lines on the 

 surface of the glass, and the corresponding short prism 

 of the second order by white lines. 



3. Rhombic. The rectangular prism is in glass, the corre- 



sponding rhombic prism is marked by dark lines on the 

 glass, and the rhombic pyramid by yellow wires. 



4. Hexagonal. The hexagonal prism is in glass, the corre- 



sponding rhombohedron is marked by white wires, and 

 the derived scalenohedron by blue wires. 



5. Oblique. The oblique rhombic prism of the second order 



is in glass. The corresponding prism of the first order 

 is marked by dark lines on the glass, and the oblique 

 rhombic pyramid corresponding to the latter by brown 

 wires. 



6. Doubly oblique, the oblique prism of the second order is in 



glass. The corresponding prism of the first order is 

 marked by dark lines on the glass, and the corresponding 

 oblique pyramid by brown wires. 



10. A glass cube, containing a cardboard model of a 

 combination of a tetrahedron in blue, with a three-faced 

 tetrahedron truncating its edges in green. 



1876. Lent by Rev. N. Brady, M.A. 



11. Models in glass (20) to illustrate the simple 

 crystallographic forms. In cardboard box. 



1886. Exhibited by Messrs. Townson fy Mercer. 



12. Glass models of crystals (30). ij in. size. In 

 two leather cases. 



E. 14. 1887. 



Bought of Steeg $ Renter, Homburg vor der Hohe. 



