Editing Degaussing (section)

=== Early experiments ===
With the introduction of [[iron]] ships, the adverse effect of the metal hull on steering [[compass]]es was noted. It was also observed that [[lightning]] strikes had a significant effect on compass deviation, identified in some extreme cases as being caused by the reversal of the ship's magnetic signature. In 1866, [[Evan Hopkins]] of London registered a patent for a process "to depolarise iron vessels and leave them thenceforth free from any compass-disturbing influence whatever". The technique was described as follows: "For this purpose he employed a number of [[Grove cell|Grove's batteries]] and electromagnets. The latter were to be passed along the plates till the desired end had been obtained... the process must not be overdone for fear of re-polarising in the opposite direction." The invention was, however, reported to be "incapable of being carried to a successful issue", and "quickly died a natural death".<ref>{{cite book |first=Commander S.T.S. |last=Lecky |title=Wrinkles in Practical Navigation |publisher=George Philip & Son |location=London |date=1917 |isbn= |pages=36 |url= |edition=19th |orig-year=1881}}</ref>
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