Denoyer semi-elliptical

Classifications

archaic
compromise

Graticule

Meridians: Central meridian is a straight line half as long as the equator. Other meridians are curves that are nearly elliptical areas and nearly equally spaced, with some spreading near the outer limits; all are concave toward the central meridian.
Parallels: Equally spaced straight parallel lines. Perpendicular to the central meridian.
Poles: Lines about 0.31 times the length of the equator.
Symmetry: About the central meridian or the equator.

Scale

True along the central meridian and the equator.
Constant along any given latitude; same for the latitude of opposite sign.

Distortion

Free of distortion along the equator.

Usage

By Denoyer-Geppert in thematic maps and atlases of the early and middle 20th century.

Origin

Developed by L. Philip Denoyer of Chicago about 1920. Exact design basis not known. Empirical approximations are used for computer plots.

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.