All About Inventions and Discoveries
The Romance of modern scientific and mechanical Achievements

i66 All About Inventions tion. He promptly acquired an interest in the competitor, and at last secured working control of it. Under his direction it was likewise rejuven- ated, although this work was summarily interrupted by the Government declaring the combination illegal and compelling the Western Union to trade under its separate and distinct individuality as before. Few people have any tangible conception of the principles governing the transmission of speech over a wire. We say that the voice is transmitted in- stantly, but, speaking from the strictly rigorous scientific point of view, a certain period of time is occupied in the transmission, although it is so minute as to be practically negligible. We all know that sound is caused by vibrating the air, and that by varying the tones the vibrations or waves are changed. When we speak into the transmitter of the telephone we set up a series of vibrations of the air. These air-waves have to be converted into elec- trical waves to flash along the wire. But the elec- tiical waves travel at a far higher speed than the sound waves. The latter are sluggish, moving only at 1,160 feet per second, whereas the electrical waves travel about 56,000 miles per second. Thus, if a person were to climb to the top of St. Paul’s Cathe- dral and, turning towards Birmingham, were to hail a companion in the latter city, and supposing that the human voice would carry so far through the open air, seven and a half minutes would pass before the hail reached the friend in Birmingham. But when the hail is given over the telephone the no J miles between the two cities are traversed in the sio part of a second.