The Electrical Experimenter, June, 1916, page 99:

High  Speed  Radio  Telegraphy
By C. V. Logwood
THE first attempt toward perfecting a rapid transmission system for radio telegraphy was that made by the Poulsen Wireless Telephone and Telegraph Company of San Francisco, California. In June, 1910, the company erected two experimental stations, one at Sacramento and the other at Stockton. These stations were erected for both radio telephone and telegraph work and were especially located at these points so that atmospheric interference would be minimized so far as possible. Fig. 1
    The initial high speed radio telegraphic system was installed and supervised by Mr. Schow of Copenhagen, Denmark, with Mr. V. Poulsen as chief engineer. The stations were in charge of Mr. Albertus and Mr. Jensen, both of Denmark.
    The first system tried out employed a tape transmitter, as shown in Fig. 1. The tape consisted of a perforated sheet of paper containing the (code) message and this was passed between two contacts, one of which was a roller, as perceived. The tape and the two contracts operated a relay, which in turn controlled the antenna wavelength. At the other end the receptor consisted of a standard form of circuit, in which the telephone circuit was linked to a fine gold wire A-B, Fig. 2. This was about four inches long and had a resistance of about 360 ohms. The wire was placed between the poles of a powerful electro-magnet NS, which were excited by 110 volts D.C. A condensing lens P was placed on one side of the gold wire, while in front of it was mounted a Nernst lamp L. The light developed by this lamp was focused on the wire. The light passing through the microscope indicated was caused to fall upon a moving photo film, as depicted at the right. It is then obvious that if the gold wire is made to vibrate it will cause the continuous ray of light to oscillate and thus a wavy image or line will be photographed on the film. The film, which moves continuously, passes through a developing and fixing chamber. Fig. 2
    A great deal of experimental work has been conducted on this system, but it finally proved unsuccessful. The first defect that had to be eliminated was that of the breaking of the fine gold wire and the second was that the signals were not clearly recorded on the moving film. This latter was overcome by placing a small slit about 1/32"x½" before the film, so that the light received by it would be equally distributed. The other defect which had to be remedied was that of the detector. The first detector utilized was that having graphite in contact with galena. It is obvious from this description that any direct current impulse through the crystal detector would cause the gold wire to be attracted by the electromagnet poles.
    After extensive trials and research along this line, the experiments proved total failures, but the object was not entirely abandoned. Mr. Christensen of Copenhagen, noting the difficulties which were observed in the previous experiments, began to work on the problem, but after trying for a year without results, he decided to give some other engineer a chance to develop a high speed telegraphic instrument and finally Mr. Elwell, Chief Engineer, assigned the author the task of solving this interesting problem. Fig. 3
    Complete installations were made at Los Angeles and San Francisco, using the last improved type of rapid transmitters and receivers. After six weeks of constant, laborious work it was demonstrated that the system was a complete failure.
    The author had previously made some promising experiments with the telegraphone and microphonic relay, which had all the "ear-marks" of a new system. The following scheme was installed by Dr. De Forest and myself. At first a Wheatstone transmitter was employed for translating the perforated paper strip containing the (code) message into dots and dashes. It consisted of a circular, toothed metallic wheel, as perceived at W, Fig. 3, which revolved by means of a motor. Upon the surface of the wheel was placed a strip of paper. A fine brush contact B was then placed on top of the paper strip so that it made contact with the metallic wheel W, when a punched mark in the paper was under the brush contact B. The Wheatstone transmitter was connected to the relay, as indicated. Now it is quite evident that whenever the strip of paper traveled across the wheel that it would automatically operate the relay. The first problem encountered in this work was that of finding a proper telegraph relay, which would handle heavy currents at high speed. At last this was overcome by making a powerful, stocky key; one which would act instantly and at the same time withstand heavy amperages. Fig. 4
    When the transmitter was finally perfected our minds turned to the development of a receiver which would record the high speed "incoming" signals. The problem was eventually solved by employing a tikker of my rotary type, to break up the sustained waves and then lead them to a three-step audion amplifier ; a two-step one of the same type is depicted at Fig. 4. The highly amplified signals were then brought to a single sensitive receiver R. This was arranged against a microphonic transmitter M, the diafram of which was tuned to the receiver's diafram, and thus the greatest amount of sensitiveness was obtained. The microphone was connected in series with a battery and a small telephone induction coil C, Fig. 4, the secondary of which was linked to a telegraphone.
    Owing to the coarse sounds produced by the tikker, it was impossible to receive signals having a speed greater than seventy-five words per minute. This was due to the following reasons: the signals coming in at seventy-five words per minute could be readily recorded on the moving steel wire of the telegraphone, but in order to reproduce them at normal (thirty or thirty-five words per minute) speed, it was necessary to run the steel wire slowly and in doing so the tone of the signals was not very clear. This resulted from the harsh sounds developed in the telegraphone receiver due to the slow speed of the moving steel wire. However, this was readily eliminated by employing a higher pitch than the tikker's "paper-tearing" note. The Federal Telegraph Company has operated successfully with this system for a whole season, but signals were transmitted at somewhat slower speed than seventy-five words per minute. Finally it was abandoned as this company installed several duplicate stations.
    Apparatus for use in rapid radio transmitters and receivers are still in their infancy and there is a wide field of research for those who are interested in the commercial end of radio telegraphy, as it is patent that a great deal of money can be saved if an all around, thoroughly reliable system can be evolved.