Edward Stonestreet Lamar, 73, a retired senior scientist with the Navy Department died Thursday at Arlington Hospital. He had a heart ailment.

Dr. Lamar was born in Rockville. He joined the Navy Department as a scientific consultant during World War II and remained in government service until his retirement in 1975.

His wartime assignments took him to Pearl Harbor and London, where he worked with the British Admiralty as a civilian on the staff of the U.S. naval attache.

After the war, Dr. Lamar was chief scientist at the Naval Electronics Laboratory in San Diego and was assigned to the operations and evaluation group at the Center for Naval Analysis.

In 1955, he returned to Washington as a manager of naval research programs. He was, successively, chief scientist at the Navy's Bureau of Ordnance, the naval weapons command and the naval air systems command. On his retirement, he was awarded the Navy's Superior Civilian Service Award.

Dr. Lamar was a graduate of Montgomery High School in Rockville. He later attended Washington & Lee University in Lexington, Va., and then graduated from George Washington University. He also earned a master's degree in physics at George Washington and a doctorate in physics at Princeton University.

He taught at the Massachusetts Institute of Technology from 1936 until beginning his government career in 1941.

Dr. Lamar was a member of the Society of Sigma XI, an honorary scientific fraternity, the Optical Society of America and the Operations Research Society of America. He published papers on chemical knietics, optics, operations research and other topics.

He was a member of the Cosmos Club.

Survivors include his wife, Mary Beth Wood Lamar, of tE home in Arlington; a daughter, Mrs. Ralph Glenn Lendsey, of Dale City; a brother, George, of Dundalk, Md.; three sisters, Mrs. Nolan B. Harmon, of Atlanta, Edith Waters, of Carson City, Nev., and Mrs. Charles Schley, of East Providence, R.I., and one grandchild.