Use of public address system with telephone lines

The combination of the public address system and the telephone line makes it possible for a speaker to address simultaneously audiences located at a number of places. This paper discusses various applications of this combination, states the requirements for the lines, shows the circuit arrangements used and describes some of the important operating features. A description is given of the system used on Armistice Day, 1921, when large audiences at Arlington, New York and San Francisco joined in the ceremonies attending the Burial of the Unknown Soldier at the National Cemetery at Arlington, Virginia. The application of the public address system apparatus and methods to radio broadcasting is also briefly discussed.