Among the metallic substances, the one best adapted by its low conductivity to such resistance and transformation of force, is platinum. The high degree of heat necessary to fuse this metal adds to its usefulness and availability for the purpose indicated. When an electrical current is forced along a platinum wire too small to transmit the entire volume, it becomes at once heated—first to a red, and then to a white glow—and is thus made to send forth a radiance like that of the sun. Of the non-metallic elements which offer similar resistance, the best is carbon. The infusibility of this substance renders it greatly superior to platinum for purposes of the electric light.
Near the beginning of the present century it was discovered by Sir Humphry Davy that carbon points may be rendered incandescent by means of a powerful electrical current. The discovery was fully developed in the year 1809, while the philosopher just referred to was experimenting with the great battery of the Royal Institution of London. He observed—rather by accident than by design or previous anticipation—that a strong volume of electricity passing between two bits of wood charcoal produces tremendous heat, and a light like that of the sun. It appears, however, that Davy at first regarded the phenomenon rather in the nature of an interesting display of force than as a suggestion of the possibility of turning night into day.
For nearly three-quarters of a century the discovery made by Sir Humphrey lay dormant among the great mass of scientific facts revealed in the laboratory. In the course of time, however, the nature of the new fact began to be apprehended. The electric lamp in many forms was proposed and tried. The scientists, Niardet, Wilde, Brush, Fuller, and many others of less note, busied themselves with the work of invention. Especially did Gramme and Siemens devote their scientific genius to the work of turning to good account the knowledge now fully possessed of the transformability of the electric current into light.
The experiments of the last named two distinguished inventors brought us to the dawn of the new era in artificial lighting. The Russian philosopher, Jablokhkoff, carried the work still further by the practical introduction of the carbon candle. Other scientists—Carre, Foucault, Serrin, Rapieff, and Werdermann—had, at an earlier or later day, thrown much additional information into the common stock of knowledge relative to the illuminating possibilities of electricity. Finally, the accumulated materials of science fell into the hands of that untutored but remarkably radical inventor, Thomas A. Edison, who gave himself with the utmost zeal to the work of removing the remaining difficulties in the problem.
Edison began his investigations in this line of invention in September of 1878, and in December of the following year gave to the public his first formal statement of results. After many experiments with platinum, he abandoned that material in favor of the carbon-arc in vacuo. The latter is, indeed, the essential feature of the Edison light. A small semicircle, or horseshoe, of some substance, such as a filament of bamboo reduced to the form of pure carbon, the two ends being attached to the poles of the generating-machine, or dynamo, as the engine is popularly called, is enclosed in a glass bulb, from which the air has been carefully drawn, and is rendered incandescent by the passage of an electric current. The other important features of Edison's discovery relate to the divisibility of the current, and its control and regulation in volume by the operator. These matters were fully mastered in the Edison invention, and the apparatus rendered as completely subject to management as are the other varieties of illuminating agencies.
It were vain to speculate upon the future of electric lighting. The question of artificial illumination has had much to do with the progress of the human race, particularly when aggregated into cities. Doubtless the old systems of lighting are destined in time to give place altogether to the splendors of the electric glow. The general effect of the change upon society must be as marked as it is salutary. Darkness, the enemy of good government and morality in great cities, will, in great measure, be dispelled by the beneficent agent, over which the genius of Davy, Gramme, Brush, Edison, and a host of other explorers in the new continents of science has so completely triumphed. The ease, happiness, comfort, and welfare of mankind must be vastly multiplied, and the future must be reminded, in the glow that dispels the night, of that splendid fact that the progress of civilization depends, in a large measure, upon a knowledge of Nature's laws, and the diffusion of that knowledge among the people.
THE TELEPHONE.
Perhaps no other great invention of man has been within so short a period so widely distributed as the telephone. The use of the instrument is already co-extensive with civilization. The cost at which the instruments are furnished is still so considerable that the poor of the world are not able to avail themselves of the invention; but in the so-called upper circles of society the use of the telephone is virtually universal. It has made its way from the city to the town, from the town to the village, from the village to the hamlet, and even to the country-side where the millions dwell.