VOL. I. PLATE II. 



FIG. 7. R. A rhombohedron. 



FIG. 8. P. An isosceles four-sided pyramid. 



FIG. 9. P. A scalene four-sided pyramid. 



FIG. 10. P. An isosceles six-sided pyramid. 



FIG. 11. (P) n . A scalene six-sided pyramid. 



FIG. 12. (P) n . A scalene eight-sided pyramid. 



