David Nelson Crosthwait Jr. was born in Nashville, Tennessee, on May 27, 1898. His interest in mechanics led him to Purdue University, where he studied mechanical engineering. After graduation, he took a job with the C.A. Dunham Co. conducting innovative research. There, he designed the heat system for New York City’s Rockefeller Center and Radio City Music Hall. On Oct. 16, 1934, he patented his invention. Crosthwait held 119 patents — 39 in the U.S. and 80 internationally — all in relation to heating, cooling and temperature-regulating technology.