In 1943 the Signal Corps began the development of a travel aid which was to be used to help the blinded of World War II in their rehabilitation program. The scope of the problem soon developed to include all blind people, civilians as well as veterans. The research on a suitable guidance device went through several stages and finally reached the point where RCA was contracted by the Signal Corps to manufacture 25 prototypes for test and evaluation. Subsequently, a contract was entered into between the Veterans Administration Research Division and Haverford College for the express purpose of giving the Signal Corps Sensory Aid a realistic series of field tests. Before describing the results of these tests let us say a few words about the instrument itself.