Western Union Telegraph Company

Annotation

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. These specifications are issued primarily for the use of testing and regulating forces assigned to the care and operation of Multiplex equipment.<br><br>A knowledge of the fundamental principles of electricity and magnetism and an understanding of the operation of the duplex are necessary for the proper understanding of the theory and operation of the apparatus described.<br><br>Those not already familiar with these subjects are advised to first study some standard work on Principles of Electricity and Magnetism, also one of the many books which take up the development of Duplex Telegraphy. This will enable them to obtain a much better understanding of the operation of the Multiplex System.