Processes applied to a ship to alter its state of magnetization

As an alternative measure to coiling certain vessels for their protection against mines, processes known as ¿wiping¿ and ¿flashing¿ have been used. The process known as ¿deperming¿ has been developed to remove or compensate the permanent longitudinal and athwartship magnetisms, which frequently lead to dangerous fields even in the case of coiled vessels. These three processes are separately described, and the various techniques which have been employed are briefly discussed. Particular attention is paid to the methods developed for ensuring the maximum stability for the treatment.