Later on, after the automatic was completed, and Edison was installing the system for the Atlantic and Pacific Telegraph Company he says: "About this time I invented a district messenger call-box system, and organized a company called the Domestic Telegraph Company, and started in to install the system in New York. I had great difficulty in getting subscribers, having tried several canvassers, who, one after the other, failed to get subscribers. When I was about to give it up a test operator named Brown, who was on the Automatic Telegraph wire between New York and Washington, which passed through my Newark shop, asked permission to let him try and see if he couldn't get subscribers. I had very little faith in his ability to get any, but I thought I would give him a chance, as he felt certain of his ability to succeed. He started in, and the results were surprising. Within a month he had procured two hundred subscribers, and the company was a success. I have never quite understood why six men should fail absolutely, while the seventh man should succeed. Perhaps hypnotism would account for it. This company was sold out to the Atlantic and Pacific Company."
This was not the first time that Edison had worked on district messenger signal boxes, for as far back as 1872 he had applied for a patent on a device of this kind. Although he was not the first, he was a very early inventor in this field.
It will be seen, therefore, that not all of his problems and inventions were connected with telegraphy. He seemed to find relief in working on several lines that were quite different and distinct, but all were useful and capable of wide application. For instance, when we take a piece of paraffin paper off candy, chocolate, chewing-gum or other articles, we scarcely realize that it owes its introduction to Mr. Edison. Yet such is the fact, and we relate it in his own modest words: "Toward the latter part of 1875, in the Newark shop, I invented a device for multiplying copies of letters, which I sold to Mr. A. B. Dick, of Chicago, and in the years since it has been introduced universally throughout the world. It is called the mimeograph. I also invented devices for making, and introduced, paraffin paper, now used universally for wrapping up candy, etc."
In the mimeograph a stencil is prepared by writing with a pointed pencil-like stylus on a tough prepared paper placed on a finely grooved steel plate. The pressure of the stylus causes the letters to be punctured in the sheet by a series of minute perforations, thus forming a stencil from which hundreds of copies can be made.
Edison accomplished the same perforating result by two other inventions, one a pneumatic and the other an electric motor. The latter was the one which came into extensive use, and was called the "Edison electric pen." A tiny electric motor was mounted on a pencil-like tube in which a pointed stylus (connected to the motor) traveled to and fro at a very high rate of speed. Current from a battery was supplied to the motor through a flexible cord, and the tube was held and used like a pencil, as in the other case. As many as three thousand copies have been made from such a stencil.
[1] The sand battery is now obsolete. In this type the cell containing the elements was filled with sand, which was kept moist with an electrolyte.
XI
THE TELEPHONE, MOTOGRAPH, AND MICROPHONE
It is well known that to Mr. Alexander Graham Bell belongs the credit for transmitting the articulate voice over an electric circuit by talking against a diaphragm placed in front of an electromagnet. But after Mr. Bell brought out the telephone Mr. Edison made some remarkable improvements.