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Electrical Lecture.

Hon. Thomas D. Lockwood, of the American Bell Telephone Company, delivered a lecture last night, before a large audience, on "The Progressive Evolution of the Telephone System of today." Mr. Lockwood said that the first appearance of the telephone in anything like its present shape was in 1876, when a very simple apparatus, which could transmit a few words and phrases, was placed on exhibition at the Centennial Exhibition by its inventor, Mr. Alexander Graham Bell. The first form was what is known as the magneto telephone, which consisted of an electro magnet at each end of the line in front of which were placed armatures. When one of these armatures was vibrated the same vibrations were observed in the other. Mr. Bell then found that by means of a small diaphragm he could transmit the sound waves made by the voice to a diaphragm at the other end of the line. He now gave all his attention to perfecting this diaphragm transmitter and in 1877 brought it to the familiar form in which it has remained ever since. When the magneto telephone had been perfected, a new difficulty arose as to how the man at one end of the line was to call the man at the other. At first the simple push button was used, but this frequently failed to work, and finally the present method of ringing a bell by means of a mechanical generating machine was adopted.

The next difficulty was that when these bells were used the regular line had to be cut off, and restored when a person had been called. This difficulty was met by the invention of the automatic switch, by means of which the hanging up to transmitter on the side of the telephone closed the regular line, so that the bell could be rung.

The first business telephone line erected was that between New York and Philadelphia. The lines were gradually made longer and longer until the present line between New York and Chicago, was completed. This line is 950 miles long, has 44,247 poles, and contains 826,800 lbs. of copper.

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