This is a summary of a talk given at the Logic Institute on July 9. Theoretical studies of computing machinery are usually based on an idealized type of machine, known as a Turing machine. On the basis of a comparison of Turing machines with actual machines, it is concluded that this sort of theoretical study is justified.Research supported with funding from the United States Air Force, Mathematics Division of the Office of Scientific Research, under Contract No. AF 18(600)-685, performed by Cornell University.Prepared for Project Code(s) and/or No.(s): R354-10-37.Report No. 71."AD 136 615.""October, 1957."This is a summary of a talk given at the Logic Institute on July 9. Theoretical studies of computing machinery are usually based on an i...