FIG. 16.—SIPHON RECORDER MESSAGE.
To-day there lie in submerged silence, but pulsating with the life of the world, no less than 1,500 submarine telegraphs. Their aggregate length is 170,000 miles; their total estimated cost is $250,000,000, and the number of messages annually transmitted over them is 6,000,000. Thirteen cables work daily across the Atlantic, and an additional one is being laid from Germany. Messages now go across the Atlantic and are received on the siphon recorder at the rate of fifty words a minute, and at a cost of twenty-five cents a word. Our guns may thunder in the Philippines, and the news by cable, traveling faster than the earth on its axis, may reach the Western Hemisphere under the paradoxical condition of several hours earlier than it occurred. Cablegrams to Manila cost $2.38 a word, and the cable tolls for our War Department alone are costing at the rate of $325,000 a year. The logical outcome is a Pacific cable, a bill for which, connecting San Francisco and Honolulu, has already passed the United States Senate.
Messages from the Executive Mansion at Washington to the battlefield at Santiago were sent and responses received within twelve minutes, while a message dispatched from the House of Representatives in Washington to the House of Parliament in London, in the chess match of 1898, was transmitted and a reply received in thirteen and one-half seconds.
To-day the cable with the still small voice, more divine than human, speaks with one accent to all the nations of the earth. Differing though they may in tongue and skin, in thought and religion, in physical development and clime, the telegraph speaks to them all alike, and by all is understood. Truly it fulfils the prophecy so gracefully expressed in the verses quoted, and has become the common bond of union among the nations of the earth.
[CHAPTER V.]
The Dynamo and Its Applications.
[Observations of Faraday and Henry]—[Magneto-Electric Machines of Pixii and of Saxton]—[Hjorth’s Dynamo of 1855]—[Wilde’s Machine of 1866]—[Siemens’ of 1867]—[Gramme’s of 1870]—[Tesla’s Polyphase Currents].
In the last thirty-five years of the Nineteenth Century there has grown up into the full stature of mechanical majority this stalwart son of electrical lineage. As the means for furnishing electrical power it stands to-day the great fountain head of electrical generation, and in its peculiar field ranks as of equal importance with the steam engine. Until about 1865 the voltaic battery, which generated electricity by chemical decomposition, was practically the only means for producing electricity for industrial and commercial purposes. It was through its agency that the telegraph, the electric light, and many other discoveries in electricity were made and rendered possible. Its cost and limited amount of current, however, restricted the limits of its practical application, and although its current could furnish beautiful laboratory experiments, its mechanical work was more in the nature of illustration than utilization. But with the advent of the dynamo electricity has taken a new and very much larger place in the commercial activities of the world. It runs and warms our cars, it furnishes our light, it plates our metals, it runs our elevators, it electrocutes our criminals; and a thousand other things it performs for us with secrecy and dispatch in its silent and forceful way. But what is a dynamo? To the average mind the most satisfactory answer would be—that it is simply a machine which converts mechanical power into electricity. Attach a dynamo to a steam engine, and the power of the steam engine will, through the dynamo, become transformed or converted into a powerful electric current. Any other source of mechanical power, such as a water wheel, gas engine, wind wheel, or even a horse or man, will serve to operate the dynamo; its primary and sole function being to take power and convert it into electricity.
The stepping stone to the dynamo in its development was the magneto-electrical machine. This is a machine founded upon the general principle observed by Faraday in 1831 and 1832, and also by Prof. Henry about the same time, that when a magnet is made to approach a helix of insulated wire it causes a current of electricity to flow in the helix as long as the magnet advances. If the magnet is passed through the helix, the current is reversed as soon as the magnet passes the middle point. The principle is the same if the magnet be made to approach and recede from the poles of an electro-magnet having a helix wound around a soft iron core. Likewise the same result occurs if the electro-magnet with its helix is made to approach and recede from a permanent magnet, the current in the helix flowing in one direction when it approaches the permanent magnet, and in the opposite direction when leaving the said magnet. The movement of the two elements in relation to each other requires some force to overcome the repellent and attractive actions, and this force is converted into electrical energy. This is the principle of the magneto-electric machine.