When was it proposed that electricity and magnetism were distinct effects by scientists William Gilbert ?
He was the first ( 1838–42 ) to produce high frequency AC electrical oscillations , and to point out and experimentally demonstrate that the discharge of a capacitor under certain conditions is oscillatory , or , as he puts it , consists "" of a principal discharge in one direction and then several reflex actions backward and forward , each more feeble than the preceding until equilibrium is attained "" .