Воткните артикль где нужно.When Edison was boy of fifteen he

Воткните артикль где нужно.When Edison was boy of fifteen he worked as telegraph operator. He had to be on duty from 7 p.m. to 7 a.m. and give signal every hour to prove that he did not sleep. signals were мейд with stonishing exactness. One night inspector arrived and saw Edison sleeping on chair. He was about a to shake him when he caught sight of mechanism on table near telegraph instrument. He waited to see what would happen. When hand of clock pointed to hour, instrument got busy and one level threw open key while other sent signal over wire. inspector seized sleeping boy, roused him and fired him. That is why first of Edisons numerous inventions was never patented.