George Warlick, of Kingston, TN, worked at the Oak Ridge National Laboratories (ORNL) Health Physics Division in the production of documents in the late 1940s. He worked with Karl Z. Morgan and helped develop the colors of the Radiation Warning Sign. The "father of health physics" (the study of the risks of ionizing radiation to people and the environment), Karl Z. Morgan (1908-1999), studied physics at the University of North Carolina and Duke, earning his Ph.D. in 1934. He chaired the Physics Department at Lenoir Rhyne College until 1943, when he joined the Metallurgical Laboratory of the University of Chicago. Transferring to Oak Ridge National Laboratory in 1944, he became Director of the Health Physics Division, leading studies on the detection of ionizing radiation. Dr. Morgan was founder of the Health Physics Society and the International Radiation Protection Association, edited Health Physics Journal and coauthored the first textbook on health physics, and became an authority on the safe limits for radionuclides in the human body. After retiring in 1972, he continued his work as a professor at the Georgia Institute of Technology.