He also studied magnetic permeability at high temperature , and discovered what was later called the Hopkinson peak effect .
In 1883 Hopkinson showed mathematically that it was possible to connect two alternating current dynamos in parallel - -- a problem that had long bedevilled electrical engineers .
Hopkinson also studied magnetic permeability at high temperature , and discovered what was later called the Hopkinson peak effect .
In 1883 Hopkinson showed mathematically that it was possible to connect two alternating current dynamos in parallel - -- a problem that had long bedevilled electrical engineers .