More complicated, of course, are the mathematical machines which work out involved equations, but they are all based on simple mechanical operations. In the Weather Bureau at Washington there is a tide-predicting machine, which has been called a “great brass brain.” Its brass gears may be set to allow for all the varying factors of apparent solar and lunar motions, and they will work out the tide for any past or future data in a few moments, solving mechanically a mathematical problem that, by hand, would take hours and hours of weary figuring.
HEARING AND TALKING WITH A MECHANICAL “EAR”
It was in 1877 that Edison startled the world with a machine that could actually talk. Others had been working on this problem for years, but they had been trying to copy the human mouth and organs of speech. Edison attacked the problem from a new angle. He was not aiming to produce speech but to reproduce it. Let the human vocal organs modulate the sound waves so that they would produce spoken words; he would provide a machine with no mouth but only an ear and a very retentive memory which would listen to these sound waves and make an impression of them on its soft tinfoil or wax brain. Then, at any time by the principle of “reversal,” the record could be made the transmitter instead of the receiver of sound waves, and it would actuate the ear so that it would repeat the sound vibrations it had formerly received. Thus Edison made the ear of his machine serve the double office of hearing and talking. When Edison’s phonograph was listening it had a sharp needle attached to the ear-drum or diaphragm of the sound box, which cut a hill and dale groove in the brain or cylinder record of the machine; when reproducing, a blunt needle was used which faithfully followed the hills and dales of the groove without cutting a path of its own.
The next notable improvement in the phonograph was that of Emile Berliner, who in 1887 invented the laterally vibrating needle which cut a zigzag groove in the record instead of a hill-and-dale groove. In other words, instead of having his recording needle move in and out as in the Edison machine, it moved sidewise. He also invented the flat-disk record, which has almost completely supplanted the cylindrical record.