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