Overhead projector
French scientist Edmund Becquerel developed the first known overhead projection machine in 1853. It was used by Jules Duboscq in 1866. During World War II, overhead projectors started to be used in U.S. military training. After that, they were used at schools. Overhead projectors began to be widely used in schools and businesses in the late 1950s and early 1960s. As the need for overhead projectors grew, a company named Bruhl Industries was founded in 1953, which created more overhead projectors than anyone else.