In 1931, Blair initiated Project 88, “Position Finding by Means of Light.” Here “light” was used in the general sense of electromagnetic radiation, including infrared and the very-short radio waves with line-of-sight transmission characteristics (microwaves). Some success was made with detection of thermal radiation from aircraft engines, but Blair was soon convinced that detection could best be done using reflected microwave signals.U.S. Department of the Army; Historical Report: Sgnal Corps Engineering Labs: 1930-1943, Government Printing Office, 1943
