Inventions in the Century

by William Henry Doolittle

In the generation of this mighty force improvements have been made, but those of greatest power still involve the principles discovered by Faraday and Henry seventy years ago. The ideas of Faraday of the “lines of force”—the magnetic power streaming from the poles of the magnet somewhat as the rays of heat issue on all sides from a hot body, forming the magnetic field—and that a magnet behaves like an electric current, producing an electric wave by its approach to or recession from a coil of wire, joined with Henry’s idea of increasing the magnetising effect by increasing the number of coils around the magnet, enter into all powerful dynamo electric machines of to-day. In them the lines of force must flow around the frame and across the path of the armature; and there must be a set of conductors to cut the lines of force twice in every revolution of the cylinder carrying the armature from which the current is taken.

When machines had been produced for generating with some economy powerful currents of electricity, their use for the world’s business purposes rapidly increased. Among such applications, and following closely the electric lighting, came the electric railway. A substitute for the slow animal, horse, and for the dangerous, noisy steam horse and its lumbering locomotive and train, was hailed with delight. Inventors came forward with adaptations of all the old systems they could think of for the purpose, and with many new ones. One plan was to adapt the storage battery—that silent chemical monster which carries its own power and its own machine—and place one on each car to actuate a motor connected to the driving wheels. Another plan was to conduct the current from the dynamo machine at its station along the rails on one side of the track to the motor on the car and the return current on the opposite track; another was to carry the current to the car on a third rail between the track, using both the other rails for the return; another to use an overhead wire for the current from the dynamo, and connect it with the car by a rod, one end of which had a little wheel or trolley running on the overhead wire, to take up the current, the other end being connected by a wire to the car motor; another plan to have a trench made leading from the central station underneath the track the whole length of the line, and put into this trench conducting wires from the dynamo, to one of which the car motor should be connected by a trolley rod or “brush,” extending down through a central slot between the rails of the track to carry the electric supply into the motor. In all these cases a lever was supplied to cut off communication between the conducting wire and the motor, and a brake lever to stop the car.

All of these plans have been tried, and some of them are still being tried with many improvements in detail, but not in principle.

The first electrical railway was constructed and operated at Berlin in 1879, by Messrs Siemens and Halske. It was two thousand seven hundred feet long and built on the third rail system. This was an experiment but a successful one. It was followed very soon by another line near Berlin for actual traffic; then still another in Saxony. At the Paris Exposition in 1881, Sir Wm. Siemens had in operation a road about one thousand six hundred feet in length, on which it is estimated ninety-five thousand passengers were conveyed in seven weeks. Then in the next year in London; and then in the following year one in the United States near New York, constructed by Edison. And thus they spread, until every important town and city in the world seems to have its electric plant, and its electric car system, and of course its lighting, telephone and telegraph systems.

In 1882 Prof. Fleeming Jenkin of England invented and has put to use a system called Telpherage, by which cars are suspended on an overhead wire which is both the track and electrical conductor. It has been found to be advantageous in the transportation of freight from mines and other places to central stations.

With the coming of the electric railway, the slow, much-abused horse, the puffing steam engine blowing off smoke and cinders through the streets, the great heavy cars, rails and roadbeds, the dangerous collisions and accidents, have disappeared.

The great problems to solve have related to generation, form, distribution and division of the electric current at the dynamos at the central stations for the purposes of running the distant motors and for furnishing independent supplies of light, heat, sound and power. These problems have received the attention of the keenest inventors and electrical engineers and have been solved.

The description of the inventions made by such electrical magicians as Thomas Edison and Nikola Tesla would fill volumes.

The original plan of sending but one message over a wire at a time has also been improved; and duplex, quadruplex and multiplex systems have been invented (by Stearns, Farmer, Edison and others) and applied, which have multiplied the capacity of the telegraphs, and by which even the alleged all-talk-at-the-same-time habit of certain members of the great human family can be carried on in opposite directions on the same wire at the same time between their gatherings in different cities and without a break.

To understand the manner of multiplying messages or signals on the same line, and using apparently the same electric current to perform different operations, the mind must revert to the theory already referred to, that a current of electricity does not consist of a stream of matter flowing like water through a conductor in one direction, but of particles of subtle ether, vibrating or oscillating in waves from and around the conductor which excites them; that the vibration of this line of waves proceeds at the rate of many thousand miles per second, almost with the velocity of waves of light, with which they are so closely related; that this wave current is susceptible of being varied in direction and in strength, according to the impulse given by the initial pressure of the transmitting and exciting instrument; and that some wave currents have power by reason of their form or strength to penetrate or pass others coming from an opposite direction. So that in the multiplex process, for instance, each transmission having a certain direction or strength and its own set of transmitting and receiving instruments, will have power to give its own peculiar and independent signal or message. Apparently there is but one continuous current, but in reality each transmission is separated from the others by an almost inconceivably short interval of time.