A paper issued by Siemens-Halske of Germany in January of 1917[1] states that the Siemens Pendel Telegraph “is among the forerunners of the eventual worldwide start-stop system for intercommunication by the printed word.” The following excerpt translated from that description briefly explains the operation:
The Pendel Telegraph uses the five-unit permutation code to select characters, and operates on a start-stop principle. It is intended for station-to-station, one-way operation, the line current normally being closed to the positive side of the line battery. Transmission is under control of a keyboard with keys arranged as in a typewriter. Upon the depression of a key, the line battery is reversed, thereby transmitting a negative pulse to line which effects the start of both transmitter and receiver at the same time. Thereafter, five-code-combination pulses are transmitted, followed by positive current to line, thus restoring the circuit system to a normally closed line condition.
The name “Pendel Telegraph” would make one think that the timing of the transmitter and receiver were under control of a swinging pendulum. This is not the case. However, it does have a plan for simulating the action of a pendulum by an arrangement of springs and semi-rotating weights to effect synchronism for each printing cycle; and energy is derived from a motor which intermittently winds a power mainspring to an even tension. This arrangement is started in operation at both terminals at the same time and provides isochronal motion at both transmitter and receiver for each transmitted character. Due to multiple operations of the springs and weights used to provide synchronous action, the operating speed is limited to four or five letters per second.
In England, too, there was work being done along these same lines. Mr. H. H. Harrison, who is so well known for his contributions over the years in the telegraph field, devised printer apparatus using the five-unit code which is described in Herbert’s Telegraphy,[2] as follows:
The instrument is provided with a Baudot 5-key keyboard, and has a step-by-step distributor which is mounted inside the casing. The standard Baudot alphabet is used, but each letter or character is prefixed by a positive starting impulse. Every time a key is depressed a universal bar is actuated which closes contacts giving the starting impulse and the distributors at both ends of the line step through six spaces. The combiner is of the electrical type invented by Baudot, and is similar to that used in Siemens’ new automatic printing telegraph. Five relays of the class used for telephone purposes are set at the receiving end, according to whether some of the stepping impulses are positive or negative. The distributor is a trunk hunting switch as used in automatic telephony, and consists of a ratchet wheel and stepping electromagnet. On the shaft of the ratchet wheel is fixed a wiper which sweeps over a semi-circular bank of contacts in response to the stepping impulses. Two-way working is secured by means of the differential balance.
(The article ends with the statement that a typewriter keyboard is being constructed to replace the five keys.)
It appears that all of these telegraph engineers and inventors envisioned a start-stop system and experimented with the idea of operating all transmitting and receiving apparatus at identical speeds by inserting a start signal before each group of letter code signals, to start both transmitter and distant receiver at the same time, and a stop condition between code groups.
In the following chapters will be shown the contributions made by both the Kleinschmidt and the Morkrum companies in the printing telegraph field, and finally their joint efforts which were to lead up to the establishment of that now worldwide intercommunicating system, the TELEX.
CHAPTER 2
KLEINSCHMIDT
Edward E. Kleinschmidt’s first direct contact with telegraph apparatus was during his employment as a young man, in 1893, by John E. Wright, whose firm had developed and was then manufacturing printing telegraph equipment known as the Wright-Negron bulletin printer for the Havas News Agency in Paris. These printers operated on the step-by-step principle at 30 words per minute. (To attest to their ruggedness, as late as 1951 some of these machines were reported to be still in use!)
Five years later, in 1898, Kleinschmidt started an experimental shop at 122 Fulton Street in New York City. A sign over the door read, “Inventions Developed,” and he did experimental and developmental work for various customers (individuals as well as companies—including Western Union) on a time-and-material basis. In the beginning he had a project of his own going—a facsimile telegraph system. He submitted the system to Western Union in 1900 with the suggestion that it might be valuable for customer services, since a customer could write his telegram in longhand and insert the written message in the transmitting unit for transmission in facsimile to the telegraph central. The idea, however, was rejected. At that time the photoelectric cell for scanning the written message and electronic means for amplifying signals had not yet been developed; while the apparatus operated quite well over short circuits, evidently the time had not arrived for commercial facsimile telegraphy.
The first telegraph apparatus job for the shop was brought in by Dr. George A. Cardwell, a dentist by profession. It was a partially developed printing telegraph using a three-unit code made up of combinations of plus-minus-high-and-low-voltage pulses (the code we have already discussed). The work for Dr. Cardwell was carried on until 1903 when a working model was completed. It had a typewheel for printing and stops arranged in a circle; magnets under control of relay selection were used to set the stops according to the received code combinations. This arrangement operated well, and on a test over a Western Union circuit from New York to Baltimore it gave satisfactory results. As we have seen, however, the code arrangement proved unsatisfactory for general telegraphic use.