The Progress of the Century

by Unknown

In modern dynamos and motors the armature, usually constructed of sheet-iron punchings, is a ring with projections as in Paccinotti’s machine, and the coils of wire are in most cases wound separately and then placed in the spaces between the projections, constituting in fact a form of drum winding. In the early 70’s a few Gramme ring and Siemens drum machines had been applied to the running of arc lights, one machine for each light. There were also some Gramme machines in use for electroplating.

At the Centennial Exhibition, held at Philadelphia in 1876, but two exhibits of electric-lighting apparatus were to be found. Of these one was the Gramme and the other the Wallace-Farmer exhibit. The Wallace-Farmer dynamo machine is a type now obsolete. It was not a good design, but the Wallace exhibit contained other examples reflecting great credit on this American pioneer in dynamo work. Some of these machines were very similar in construction to later forms which went into very extensive use. The large search-lights occasionally used in night illumination during the exhibitions were operated by the current from Wallace-Farmer machines. The Gramme exhibit was a remarkable exhibit for its time. Though not extensive, it was most instructive. There were found in it a dynamo running an arc lamp; a large machine for electrolytic work, such as electroplating or electrotyping, and, most novel and interesting of all, one Gramme machine driven by power was connected to another by a pair of wires and the second run as a motor. This in turn drove a centrifugal-pump, and raised water which flowed in a small fall or cataract. A year or two previously the Gramme machine had been accidentally found to be as excellent an electric motor as it was a generating dynamo. The crude motors of Jacobi, Froment, Davenport, Page, Vergnes, Gaume, and many others, were thus rendered obsolete at a stroke. The first public demonstration of the working of one Gramme machine by another was made by Fontaine at the Vienna Exhibition of 1873.

Here, then, was a foreshadowing of the great electric-power transmission plants of to-day; the suggestion of the electric station furnishing power as well as light, and, to a less degree, the promise of future railways using electric power. Replace the centrifugal pump of this modest exhibit by a turbine wheel, reverse the flow of water so as to cause it to drive the electric motor so that the machine becomes a dynamo, and, in like manner, make of the dynamo a motor, and we exemplify in a simple way recent great enterprises using water-power for the generation of current to be transmitted over lines to distant electric motors or lights.

The Centennial Exhibition also marks the beginning—the very birth, it may be said—of an electric invention destined to become, before the close of the century, a most potent factor in human affairs. The speaking telephone of Alexander Graham Bell was there exhibited for the first time to the savants, among whom was the distinguished electrician and scientist Sir William Thomson. For the first time in the history of the world a structure of copper wire and iron spoke to a listening ear. Nay, more, it both listened to the voice of the speaker and repeated the voice at a far-distant point. The instruments were, moreover, the acme of simplicity. Within a year many a boy had constructed a pair of telephones at an expenditure for material of only a few pennies. In its first form the transmitting telephone was the counterpart of the receiver, and they were reversible in function. The transmitter was in reality a minute dynamo driven by the aërial voice waves; the receiver, a vibratory motor worked by the vibratory currents from the transmitter and reproducing the aërial motions. This arrangement, most beautiful in theory, was only suited for use on short lines, and was soon afterwards replaced by various forms of carbon microphone transmitter, to the production of which many inventors had turned their attention, notably Edison, Hughes, Blake, and Hunnings. In modern transmitters the voice wave does not furnish the power to generate the telephone current, but only controls the flow of an already existing current from a battery. In this way the effects obtainable may be made sufficiently powerful for transmission to listeners 1500 miles away.

There is no need to dwell here upon the enormous saving of time secured by the telephone and the profound effect its introduction has had upon business and social life. The situation is too palpable. Nevertheless, few users of this wonderful invention realize how much thought and skill have been employed in working out the details of exchange switchboards, of signalling devices, of underground cables and overhead wires, and of the speaking instruments themselves. Few of those who talk between Boston and Chicago know that in doing so they have for the exclusive use of their voices a total of over 1,000,000 pounds of copper wire in the single line. There probably now exist in the United States alone between 75,000 and 100,000 miles of hard-drawn copper wire for long-distance telephone service, and over 150,000 miles of wire in underground conduits. There are upward of three-quarters of a million telephones in the United States, and, including both overhead and underground lines, a total of more than half a million miles of wire. Approximately one thousand million conversations are annually conveyed.

The possibility of sub-oceanic telephoning is frequently discussed, but the problem thus far is not solved. It involves grave difficulties, and we may hope that its solution is to be one of the advances which will mark the twentieth century’s progress.

The advent of the telephone in 1876 seemed to stimulate invention in the electric field to a remarkable degree. Its immediate commercial success probably acted also to inspire confidence in other proposed electric enterprises. Greater attention than ever before began to be given to the problem of electric lighting. An electric arc lamp, probably the only one in regular use, had been installed at Dungeness Light-house in 1862, after a long set of trials and tests. It was fed by a Holmes magneto-electric machine of the old type, very large and cumbrous for the work. Numerous changes and improvements had before 1878 been made in arc lamps by Serrin, Duboscq, and many others. But the display of electric light during the Paris Exposition of 1878 was the first memorable use of the electric light on a large scale. The splendid illumination of the Avenue de l’Opéra was a grand object-lesson. The source of light was the “electric candle” of Paul Jablochkoff, a Russian engineer. It was a strikingly original and simple arc lamp. Instead of placing the two carbons point to point, as had been done in nearly all previous lamps, he placed them side by side, with a strip of baked kaolin between them. The candle so formed was supported in a suitable holder, whereby, at the lower end, the two parallel carbons were connected with the circuit terminals. By a suitable device the arc was started at the top and burned down. The electric candle seemed to solve the problem of allowing complicated mechanism for feeding the carbons to be discarded; but it survived only a short time. Owing to unforeseen difficulties it was gradually abandoned, after having served a great purpose in directing the attention of the world to the possibilities of the electric arc in lighting.

Inventors in America were not idle. By the close of 1878, Brush, of Cleveland, had brought out his series system of arc lights, including special dynamos, lamps, etc., and by the middle of 1879 had in operation machines each capable of maintaining sixteen arc lamps on one wire. This was, indeed, a great achievement for that time. Weston, of Newark, had also in operation circuits of arc lamps, and the Thomson-Houston system had just started in commercial work with eight arc lamps in series from a single dynamo. Maxim and Fuller, in New York, were working arc lamps from their machines, and capital was being rapidly invested in new enterprises for electric lighting. Some of the great electric manufacturing concerns of to-day had their beginning at that time. Central lighting stations began to be established in cities, and the use of arc lights in street illumination and in stores grew rapidly. More perfect forms of arc lamps were invented, better generating dynamos and regulating apparatus brought out. Factories for arc-light carbon making were built. The first special electrical exhibition was held in Paris in 1881. In the early 80’s, also, the business of arc lighting had become firmly established, and soon the bulk of the work was done under two of the leading systems. These were afterwards brought together under one control, thus securing in the apparatus manufactured a combination of the good features of both. Until about 1892 nearly all the arc lamps in use were worked under the series system, in which the lights are connected one after another on a circuit and traversed by the same current. This current has a standard value, or is a constant current. Sometimes as many as a hundred lamps were on one wire. As the mains for the supply of incandescent lamps at constant pressure, or potential, were extended, attention was more strongly turned to the possibility of working arc lights therefrom.

Within a few years of the close of the century this placing of arc lamps in branches from the same mains which supply incandescent lamps became common, and the enclosure of the arc in a partially air-tight globe, a procedure advocated by Staite, in 1847, was revived by Howard, Marks, and others for saving carbons and attention to the lamp. The enclosed arc lamp was also found to be especially adapted to use in branches of the incandescent lamp circuits, which had in cities become greatly extended. The increasing employment of alternating currents in the distribution of electric energy has led also to the use of alternating current arc lamps, and special current-regulating apparatus is now being applied on a large scale to extended circuits of these lamps. It can be seen from these facts that the art is still rapidly progressing and the field ever widening. A little over twenty years ago practically no arc lamps were used. At the close of the century, they were numbered by hundreds of thousands. The annual consumption of carbons in this country has reached two hundred millions.

Almost simultaneously with the beginning of the commercial work of arc lighting, Edison, in a successful effort to provide a small electric lamp for general distribution in place of gas, brought to public notice his carbon filament incandescent lamp.