Central Meridian: A straight line.
Meridians: Complex curves connecting points equally spaced along each parallel and concave toward the central meridian.
Parallels: Concentric circular arcs spaced at true distances along the central meridian.
Symmetry: About the central meridian.
This is an equal-area projection. The curvature of the standard parallel is identical to that on a cone tangent at that latitude. The central meridian and the central parallel are free of distortion. This projection is not conformal.
This projection has one standard parallel, which is 30ºN by default. It has two interesting limiting forms. If a pole is employed as the standard parallel, a Werner projection results; if the Equator is used, a Sinusoidal projection results.
This projection dates in a rudimentary form back to Claudius Ptolemy (about A.D. 100). It was further developed by Bernardus Sylvanus in 1511. It derives its name from its considerable use by Rigobert Bonne, especially in 1752.