 In the prototype of the single-pole electric starter (finished between 1852 and 1854) both the stationary and the revolving parts were electromagnetic.It was also the discovery of the principle of dynamo self-excitation, which replaced permanent magnet designs.He also may have formulated the concept of the dynamo in 1861 (before Siemens and Wheatstone) but didn't patent it as he thought he wasn't the first to realize this.