The next thing to interest Thomas was the system of telegraphing. He had not lost the habit of asking questions and quizzed the operator at Mt. Clemens, Mr. McKenzie, every chance he had. As he stood on the station platform one day, asking Mr. McKenzie something, he noticed the operator's little child playing on the tracks right in front of a coming train. And that train was an express! Thomas rushed out and seized the child just as the train almost touched his coat. Mr. McKenzie was so grateful that he said: "Look here, I want to do something for you. Let me teach you to be a telegraph operator." Thomas was delighted and after that used to take four lessons a week. At the end of three months he was an expert. Thomas could not have learned so quickly if he had not worked very steadily. He always put his heart and mind on whatever he was learning, and he did not sleep more than four or five hours at night all the time he was studying the dots and dashes that are used in sending telegraph messages. At the age of sixteen, Thomas Edison took his first position as telegraph operator. He did not earn very much at this work, at first, and usually tried to get places where he had night hours. This was so that he would have part of the daytime to read in public libraries and to try experiments. There were so many wonderful things to learn or to understand in this world that it was a pity, he thought, to waste much time in eating or sleeping. When Thomas was twenty-two, he had made his ideas worth three hundred dollars a month. Probably the school teacher who thought the little Edison boy was "addled" never earned that much at any age! From that time until now Thomas Edison's experiments have meant a fortune to him and no end of pleasure and comfort to the world. You cannot go into a city in the United States that is not fitted with electric lights--_Edison_ lights. When you hear a phonograph, remember it is an Edison invention; when you go sight-seeing in a new city, the guide of the motor carriages will shout the names of places to you through a megaphone,--another Edison idea. He has patents on fourteen hundred ideas. No wonder he has had to keep busy! There is no telling how many more patents his brain will win, for he is only sixty-seven, and that is young in the Edison family. Thomas's great-grandfather lived to be a hundred and four, and his grandfather lived to be a hundred and two. And he himself is just as busy to-day as he was when he drove every one but his mother nearly crazy with his questions. Only to-day he stays in his workshop, getting answers to them.