Classifications
pseudocylindric
equal-area
Graticule
Meridians: Central meridian is a straight line half as long as the equator. Other meridians are equally spaced semiellipses, concave toward the central meridian. The outer meridians (180° east and west of the central meridian) are semicircles.
Parallels: Unequally spaced straight parallel lines, widest separation near the equator. Perpendicular to the central meridian.
Poles: Lines half as long as the equator.
Symmetry: About the central meridian or the equator.
Aspects
Like most projections, transverse and oblique aspects can be prepared, although they are seldom used in this case.
Scale
True along latitudes 40°30′N/S. Constant along any given latitude; same for the latitude of opposite sign.
Distortion
Free of distortion only at latitudes 40°30′N/S. At the central meridian.
Usage
Thematic and other world maps in numerous atlases and textbooks and for sheet maps.
Similar projections
Eckert III has meridians positioned identically, but parallels are equally spaced. Putniṇš P2′ has meridians that are only portions of semiellipses, but parallels are also spaced for equal-area.
Origin
Presented by Max Eckert (1868-1938) of Germany in 1906.
Description adapted from J.P. Snyder and P.M. Voxland, An Album of Map Projections, U.S. Geological Survey Professional Paper 1453. United States Government Printing Office: 1989.