Bullitt was an authority on insurance law and wrote a number of important pamphlets in actuarial mathematics. He was a personal friend of a number of important figures in twentieth-century mathematics, including G.D. Birkhoff, G.H. Hardy, and Albert Einstein.

The Bullitt family had already compiled collections of rare books in history, horticulture, and other field when William Marshall Bullitt decided to pursue acquisitions of rare mathematical editions. Bullitt began by seeking the aid of mathematicians and historians of mathematics in determining a list of ``25 Greatest Mathematicians (Excluding all Living Mathematicians)”. Prior to World War II, Bullitt and his wife traveled extensively in Europe; his cousin, William Christian Bullitt, was the American Ambassador to France at the time. Bullitt put together a magnificent collection of rare and significant mathematics. “Strangely enough, anyone wishing to write about Galois in Paris would do well to journey to Louisville, Kentucky,” wrote Leopold Infeld, author of Whom the Gods Love, a fictionalized biography of the celebrated French mathematician Evariste Galois. A well-written account of Bullitt and his efforts to obtain rare mathematics manuscripts is given in ``William Marshall Bullitt and His Amazing Mathematical Collection”, by Richard M. Davitt (Professor of Mathematics at the University of Louisville), in The Mathematical Intelligencer, Vol. 11, No. 4, 1989.

In 1958, Bullitt’s wife gave the entire mathematics collection and related correspondence to the University of Louisville, where today it is the William Marshall Bullitt Mathematical Collection. Visitors from around the world visit the Collection. Members of the Bullitt family are frequent Lecture attendees. The mathematics and astronomy communities—indeed, the entire Louisville community—gratefully and gladly acknowledges the debt to the family for the inestimable contribution

Text adapted from the University of Louisville Dept. of Mathematics Bullitt Lecture website.