After the discovery by Hans Christian Orsted (1777-1851) of the magnetic effect of an electric current in 1820, and the invention of electromagnets a few years later, many people tried to build crude electric motors or 'electromagnetic engines'. Many of them copied the action of a steam engine. This one, patented by T Allan in London in 1852, is unusually elaborate. All engines of this type were unsuccesful, because the principle of operation was inefficient for an electrical machine and the batteries that were the only source of electric power at the time were too expensive.
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