Central Meridian: Straight line 0.48 as long as the Equator.
Other Meridians: Equally spaced elliptical arcs concave toward the central meridian. The eccentricity of each ellipse changes at the Equator.
Parallels: Unequally spaced straight parallel lines, perpendicular to the central meridian. Spacing is not symmetrical about the Equator.
Poles: The North Pole is a line two-thirds the length of the Equator; the South Pole is a line three-fourths the length of the Equator.
Symmetry: About the central meridian but not the Equator.
This is an equal-area projection. Scale is true along 40º42'N and 38º27'S, and is constant along any parallel but generally not between pairs of parallels equidistant from the Equator. It is free of distortion only along the central meridian at 40º42'N and 38º27'S. This projection is not conformal or equidistant.
Because of the asymmetrical nature of this projection, two standard parallels must be specified. The standard parallels are by definition fixed at 40º42'N and 38º27'S.