Abstract :
In 1946, the author read a paper before this Institution on the ¿Electrical Control of Dangerous Machinery and Processes.¿ A little earlier, Mr. H.A. Hepburn had read a paper on ¿The Fencing of Dangerous Parts of Machinery¿ to The Institution of Mechanical Engineers, and he suggested to the author that the interlocking of such guards and fencing would prove an appropriate subject for a useful continuation of both papers. The present critical study, which is a development of one Section of the 1946 paper, arises from that suggestion; its subject matter is sufficiently indicated by its title, and it is only necessary to add that, in it, an attempt has been made to deduce a number of guiding principles of design and not to describe particular mechanisms in detail.
