Jasper Brown Jeffries was an American physicist.
Jeffries was born in Winston-Salem, North Carolina, on April 15, 1912. He received a B.S. from West Virginia State College and an M.S. in physical sciences from the University of Chicago. From 1943 to 1946, Jeffries worked as a physicist on the Manhattan Project at the Met Lab at the University of Chicago. He was one of the only African-American scientists to work on the project.
Jefferies was one of seventy scientists and workers at the Met Lab to sign the Szilard Petition, a document written by Leo Szilard petitioning President Truman to avoid dropping the atomic bombs on Japan.
After the war, Jeffries taught as a professor of physics at the North Carolina Agricultural and Technical State University. He also worked as an engineer for the Control Instrument Company. Jeffries later taught as a professor of mathematics at Westchester Community College.
At the age of eighty-two, Jeffries died on July 16, 1994, in White Plains, NY.