About the McBryde-Thomas No. 4 Projection
F. Webster McBryde and Paul D. Thomas produced five equal-area pseudo-cylindrical projections in 1949 for use in world statistical maps by the US Coast and Geodetic Survey. The projection presented here is their No. 4 "flat polar quartic" projection. This projection has attracted some interest, and replaced the Hammer projection in some geography texts.
The McBryde-Thomas No. 4 projection is a pseudo-cylindrical projection. Ie. a mathematical projection with straight line parallels (like a cylindrical projection) but with curved meridians (unlike a cylindrical projection). With the exception of the central meridian, the meridians are all quartic (fourth order polynomial) curves. Unlike most of the pseudo-cylindrical projections presented here, the poles are represented as flat edges.
Author's Note: The McBryde-Thomas No. 4 Flat Polar Quartic projection is one of the better projections presented here at Equal-Area-Maps.com. Unlike the Mollweide projection, it has flat polar edges, which might be preferable for some applications. Unfortunately, it only has moderate software support. This McBryde-Thomas projection is supported by ESRI and the Proj4 library, but not Proj4JS.
See our interactive McBryde-Thomas 4 Projection world map (overlays disabled due to the lack of Proj4JS support).