MULTIPLEX TELEPHONY AND TELEGRAPHY BY MEANS 
OF ELECTRIC WAVES GUIDED BY WIRES. 
[With 1 plate.] 
Dr. GEORGE O. Squier, 
Major Signal Corps, United States Army. 
I.—INTRODUCTION. 
Electrical transmission of intelligence, so vital to the progress of 
civilization, has taken a development at present into telephony and 
telegraphy over metallic wires; and telegraphy, and, to a limited 
extent, telephony, through the medium of the ether by means of 
electric waves. 
During the past 12 years the achievements of wireless teleg- 
raphy have been truly marvelous. From an engineering viewpoint, 
the wonder of it all is, that, with the transmitting energy being 
radiated out over the surface of the earth in all directions, enough 
of this energy is delivered at a single point on the circumference of a 
circle, of which the transmitting antenna is approximately the cen- 
ter, to operate successfully suitable receiving devices by which the 
electromagnetic waves are translated into intelligence. 
The “plant efficiency” for electrical energy in the best types of 
wireless stations yet produced is so low that there can be no com- 
parison between it and the least efficient transmission of energy by 
conducting wires. 
The limits of audibility, being physiological functions, are well 
known to vary considerably, but they may be taken to be in the 
neighborhood of 16 complete cycles per second as the lower limit 
and 15,000 to 20,000 cycles per second as the upper limit. If, there- 
fore, there are impressed upon a wire circuit for transmitting intelli- 
gence harmonic electromotive forces of frequencies between 0 and 16 
cycles per second, or, again, above 15,000 to 20,000 cycles per second, 
it would seem certain that whatever effects such electric-wave fre- 
quencies produced upon metallic lines, the present apparatus em- 
ployed in operating them could not translate these effects into audible 
signals, 
1A paper presented at the twenty-eighth annual convention of the American Institute of Electrical 
Engineers, Chicago, Ill., June 26-30, 1911. Copyright, 1911, by A. I. E. E. Reprinted by permission 
from Proceedings of the Institute for May, 1911, pp. 857-905. 
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