Classifications
cylindric
Graticule
Meridians: Equally spaced straight parallel lines 0.73 as long as the equator.
Parallels: Unequally spaced straight parallel lines, closest near the equator, but spacing does not increase poleward as fast as it does on the Mercator. Perpendicular to meridians.
Poles: Straight lines equal in length to the equator.
Symmetry: About any meridian or the equator.
Aspects
Normal aspect is commonly used.
Oblique aspect has been used by the National Geographic Society.
Scale
True along the equator in all directions.
Constant in any given direction along any other given latitude; same scale at the latitude of opposite sign.
Changes with latitude and direction.
Distortion
None at the equator. Shape, area, and scale distortion increases moderately away from the equator but becomes severe at the poles.
Other features
Parallels are spaced from the equator by calculating the distance for 0.8 of the same latitude on the Mercator and dividing the result by 0.8. Therefore, the two projections are almost identical near the equator.
Usage
World maps in numerous American atlases and some other atlases, as a projection resembling the Mercator but having less distortion of area and scale, especially near the poles.
Similar projections
Gall projection has different spacing of parallels. The lines of no distortion are at latitudes 45°N and S. Rather than at the equator. Miller proposed other alternates in 1942, including one identical with his preferred cylindric but using two-thirds instead of 0.8.
Origin
Presented by Osborn Maitland Miller (1897–1979) of the American Geographical Society in 1942.
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.