Those three murals, completed in 1936, were installed beneath the rotunda in the Roosevelt Memorial Hall of the American Museum of Natural History in New York.
Less known but also important, he was a major contributor to the development of ship camouflage in the United States during World War I. Mackay was born in 1876 in Philadelphia to Elizabeth J. and Frank F.
As a muralist, he completed projects for the Library of Congress, the American Museum of Natural History, the Minnesota State House of Representatives, and other locations.
Mackay played a major role in the development of U.S. ship camouflage during World War I, although there are conflicting accounts of the extent of his contributions.
After the U.S. entered World War I in 1917, a scheme devised by Mackay was one of five camouflage “measures” approved by the U.S. Navy Consulting Board for official use on merchant ships.