Organized Telegraph

Until Thomas Alva Edison tackled the problem of multiple telegraph messages, the most that could be sent over one wire at a time was two. Edison increased the number to four. Later, Western Union engineers developed the "Multiplex" system which enabled them to transmit four communications simultaneously in each direction. "Voice carrier" currents of different frequencies, in Multiplex groups of four, recently made possible 32 messages in each direction over a four-wire circuit. Last week, Western Union announced that an electrical tone generator borrowed from a musical instrument had tripled the figure to 96.

The Hammond Electric Organ, first marketed three years ago, is no larger than a piano, has no reeds or pipes. Pressing a key on the Hammond keyboard generates a minute electric current with an oscillation frequency corresponding to the pitch of the desired note. The current is relayed into a reproduction cabinet where it becomes a musical tone.

Hearing and studying the Hammond, Western Union engineers decided that its tone generator was well suited for producing carrier currents of different electrical frequencies, tried it out with gratifying success. The currents are separated in pitch by 300 cycles. A generator adapted to Western Union's purposes costs about $1,000. By this technique the company sends telegrams from Manhattan to Chicago, Washington, Buffalo, Atlanta. Practical effect of the Hammond-type generator will be to reduce the number of wires necessary for intercity service, thus saving a sizable chunk of maintenance costs as the unnecessary wires are retired from service.

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