/ 7. Conical, with rectified meridians and two | standard parallels (5 forms). | 8. Simple conical. | 9. Simple cylindrical (a special case of 8). | 10. Modified conical equal-area (Bonne's). | 11. Sinusoidal " " (Sanson's). | 12. Werner's conical " " Conical < 13. Simple polyconic. | 14. Rectangular polyconic. | 15. Conical orthomorphic with 2 standard parallels | (Lambert's, commonly called Gauss's). | 16. Cylindrical orthomorphic (Mercator's). | 17. Conical equal-area with one standard parallel. | 18. " " " " two " parallels. \ 19. Projection by rectangular spheroidal co-ordinates. / 20. Equidistant zenithal. | 21. Zenithal equal-area. | 22. Zenithal projection by balance of errors (Airy's). Zenithal < 23. Elliptical equal-area (Mollweide's). | 24. Globular (conventional). \ 25. Field sheet graticule. Of the above 25 projections, 23 are conical or quasi-conical, if zenithal and perspective projections be included. The projections may, if it is preferred, be grouped according to their properties. Thus in the above list 8 are equal-area, 3 are orthomorphic, 1 balances errors, 1 represents all great circles by straight lines, and in 5 one system of great circles is represented correctly. Among projections which have not been described may be mentioned the circular orthomorphic (Lagrange's) and the rectilinear equal-area (Collignon's) and a considerable number of conventional projections, which latter are for the most part of little value.