Those were indeed busy days, when, at one time, Edison, besides directing the work of his shops, was working on no less than forty-five separate inventions of his own. He had thus entered definitely upon that career as an inventor which has left so deep an imprint on the records of the Patent Office.
Soon after he commenced manufacturing he was engaged by the Automatic Telegraph Company, of New York, to help it out of its difficulties. An Englishman named George Little had brought over a system of automatic telegraphy which worked well on a short line, but was a failure when put upon the longer circuits, for which automatic methods are best adapted.
This principle of automatic telegraphy, briefly described, was somewhat as follows: A narrow paper ribbon was perforated with groups of holes corresponding to Morse characters. This ribbon was passed over a cylinder, and a metallic pen was so connected that it would drop into the holes as they passed. The pen and cylinder being connected with the telegraph line, a current would pass over the line whenever the pen touched the cylinder. At the other end of the line the electrical impulses passed through another metallic pen, which rested upon another ribbon of paper chemically prepared, and, through electro-chemical action, would mark dots and dashes upon the paper.
There were a great many very serious difficulties to be overcome in order to make this system practical on long lines, but Edison applied himself to the work with tremendous energy. His laboratory note-books of the period show many thousands of experiments in the three years that he was working on his problem, and during this time he also took out a long list of patents on the subject.
So successful were his efforts that with his apparatus it became possible to send and record one thousand words a minute between New York and Washington, and thirty-five hundred words a minute between New York and Philadelphia.
Later on, Edison improved this system by further inventions, by means of which the message at the receiving end was automatically printed upon the paper ribbon in Roman letters instead of dots and dashes. Thus, the paper on which the message was received could be torn off and sent out immediately to the person for whom it was intended. This saved time and expense, for under the previous system a clerk must first translate the dots and dashes into words and write it out before delivery. The apparatus worked so perfectly that three thousand words a minute were sent between New York and Philadelphia and recorded in Roman letters.