To contemplate the dynamo with its clumsy, enormous spools, it suggests to the imagination of the average observer the gigantic toy of some Brobdingnagian boy--but the dynamo is no toy. It is the most compact, business-like, and dangerous of all utilitarian devices. To touch its brushes may be instant death, for the dynamo is the prison house of the lightning, and resents intrusion. Hidden away from public gaze in some sequestered power house, and working night and day like some tireless, dumb, and mighty genii, it sends its magnetic thrills of force silently through the many miles of wire extending like radii from some great nerve center through the conduits in our streets, and stretching from pole to pole like giant cobwebs through the air. Responding to its force, thousands of little incandescent threads leap into radiant brightness and shed their mellow and genial light in our offices, our stores, hotels, and homes. Brilliant arc lamps, rivaling the sun in power, make night into day, and produce along our streets coruscations, silhouettes, and dancing shadows in spectacular and unceasing pageants. From the towering lighthouses of our coasts its beams are thrown seaward, and a beacon for the mariner shines beyond all other lights. The great search light of our ships is in itself but a hollow mockery until the dynamo whispers in its ear the word “light!” and then its beam, reaching for miles along the horizon, discovers a stealthy enemy, or signals the safe return to port. The mighty force of the dynamo entering the electric motors on the street cars turns the wheels and transports its load with scarcely a passenger inside realizing how it is all done. The same energy turns the electric fan, and with kindly service soothes the weary sufferer, and at another place remorselessly takes the life of the condemned criminal. The dynamo is one of the great factors of modern civilization, and its potential name, like that of “dynamite,” rightly defines its character. [Illustration: FIG. 25.--MODERN MULTIPOLAR DYNAMO.] CHAPTER VI. THE ELECTRIC MOTOR. BARLOW’S SPUR WHEEL--DAL NEGRO’S ELECTRIC PENDULUM--PROF. HENRY’S ELECTRIC MOTOR--JACOBI’S ELECTRIC BOAT--DAVENPORT’S MOTOR--THE NEFF MOTOR--DR. PAGE’S ELECTRIC LOCOMOTIVE--DR. SIEMENS’ FIRST ELECTRIC RAILWAY AT BERLIN, 1879--FIRST ELECTRIC RAILWAY IN UNITED STATES, BETWEEN BALTIMORE AND HAMPDEN, 1885--THIRD RAIL SYSTEM--STATISTICS ELECTRIC RAILWAYS AND GENERAL ELECTRIC CO.--DISTRIBUTION ELECTRIC CURRENT IN PRINCIPAL CITIES.