Charlie, or "CJ" as he later became known, was a strong and far-sighted builder at SRI. He started in 1954 as a physicist in the Chemical Physics Department under Clint Kelley, who made him Manager of the Molecular Physics Group in 1956. He first built an electron scattering apparatus to examine properties of sodium azide, a highly unstable explosive, for the Army. He was responsible for several important hirings as new work was acquired, and in 1962 became head of the Molecular Physics Department. Following a year spent in the famous Applied Mathematics Department at Queens University, Belfast, Northern Ireland, he invited three well known theorists from England and Northern Ireland to spend sabbaticals at SRI. These visits and the attendant lectures on atomic and molecular theory were very beneficial to the development and growth of the young Molecular Physics Department, and the action was typical of Cook's long-range outlook.
He was appointed Executive Director of Chemical, Theoretical, and Applied Physics in 1965 and of Physics and Chemical Physics in 1967. He became Executive Director of Plans and Programs, Physical and Life Sciences Division, in 1968 and of the Physical Sciences Division in 1969. He was the first to lead this division to a profitable operation. He became Vice President of the Office of Research Operations in 1976 and Senior Vice President, Office of the President, in 1981.
As he rose in responsibilities at SRI, his interests expanded from atomic and molecular physics to applications work, which included one of the first efforts to develop a magnetically levitated, very high speed, rail transit system and the use of automation in manufacturing.
Among his primary legacies to SRI is the Molecular Physics Laboratory, which ultimately gained international renown and has retained that stature today. He also turned Physical Sciences into a robust and healthy division for the first time.