Upon arrival in America, 1884, Tesla began working for Edison. In December of the same year, Tesla completed important improvements in the direct current generators, a task for which he had been promised a bonus of $50,000. When he heard that the promise had merely been a joke, he was deeply offended and decided to try his luck elsewhere.

The last date recorded in his diary was December 7. On the following page he wrote in large letters: „Good bye to the Edison Machine Works“.