Ever since the building of the first practical automatic telegraph instruments by Vail in America in 1837, and Wheatstone in England in 1841, an ever-increasing amount of the world's high-speed communication has been carried on by the printing telegraph. While these early machines were built primarily for the use of the European Government Telegraphs or the large American telegraph companies, the developments of the last few years have produced an instrument which is a practical working tool for the service of modern commercial and industrial enterprises. This paper discusses some of the economic principles which determine the applicability of the automatic printing telegraph to present-day communication problems. Examples are given of the application of this type of apparatus to modern business conditions and the fundamental fact is demonstrated that whenever speed is essential in communication, consideration should be given to the automatic printing telegraph. The discussion is limited to those forms of light traffic load printing telegraph systems which have been developed particularly for linking together the departments of the factory, the terminal points of the railroad, the branches of the banking, the brokerage or the selling organization or the units of any other large corporation. A description is then given of the principle of operation of three such systems, somewhat in detail, as there is very little literature on the subject.