establishment or to furnish light to a town of 20,000 inhabitants, and the importance of this step will be appreciated. It shows how the forces of nature may be used in the service of man. It suggests the great change our civilization will experience when our light, heat, and mechanical power are obtained directly from waterfalls, the wind and ceaseless energy of the ocean, and the heat and light of the sun, instead of through the costly mediation of coal and the steam engine.

The telephone is steadily enlarging its powers by the establishment of long-distance lines for the transmission of speech and music. Indeed, it does not seem unlikely that Europe and America will soon be within speaking range of each other. A telephonic cable has just been laid across the English Channel, connecting conversationally Paris and London with very satisfactory results. Musical tones have been sent more or less distinctly through the Atlantic cable; but the best results in this department have been achieved through systematic efforts to convey orchestral music over long-distance wires.

Not long since a band of musicians playing in New York City entertained an audience of more than one thousand persons in Newton, Massachusetts, some 250 miles away; the musicians conscientiously executing their parts in full view of the large if not inspiring funnels of the separate transmitters for each instrument in one room; the delighted listeners, in another state, hearing the sweet sounds as they came from six loud-speaking receivers dependent from the chandeliers; an unpoetic telephone wire many miles long the only bond of harmony between them. Similar results have been obtained over a distance of 450 miles. These interesting experiments assign an important part to the telephone in our future entertainment both public and private.

The attention of the scientific world, however, is absorbed at present in the most important discovery of recent years. The experiments of Henri Hertz, a young German physicist and mathematician, have shown that light is identical with electricity or, scientifically speaking, that light is an electrical phenomenon.

One highly interesting conclusion drawn from his work is that all the energy radiated from the sun is really electrical energy; as such it is transmitted to the earth and there

transmuted into all the forms of power and motion that go to make up the activity of our globe. The vitality of growing plants, the muscular power in animals derived from vegetable food, the heat and light stored in coal, the mechanical power of the steam-engine, and the capacity for work in wind-mills and waterfalls, originally existed as electric waves quivering along the beams of solar light.

The most famous physical laboratories of the world are now entering the new domain opened by Hertz and it is not too much to say that every day brings new additions to our knowledge of the real nature of electricity.

These simple experiments so valuable, so fruitful, grow naturally out of our previous knowledge of light and electricity. They involve the greater part of what is characteristic of the present state of electrical science. Their full significance can be appreciated only when examined by the help of the researches of Faraday and the complete theory constructed by Maxwell out of their results.

In 1831, while pursuing his investigations of the relations between electricity and magnetism, Faraday discovered that a current of electricity was produced in a wire made to move in the neighborhood of a magnet. Although he fully realized the practical value of this principle, the principle of the modern dynamo, he nevertheless regarded its discovery as only a step in his progress toward establishing definite relations between electricity, magnetism, and light. Undiverted from his main purpose of unraveling the mystery of electricity, he concluded a remarkable paper before the Royal Society of London, giving a full account of his discovery with these words: "I have rather, however, been desirous of discovering new facts and new relations dependent on electro-magnetic induction than of exalting the force of those already obtained; being assured the latter would find their full development hereafter." The full development industrially of his principles by others gave to the world the dynamo and the telephone. Faraday's steadfast de-votion to experimental electricity made him, as a most eminent authority* says, the origin of nearly all we now know. Faraday next sought to connect the phenomena of electricity and light. Indeed, some of his very

Sir William Thomson.

first experiments were directed to this end and the last years of his long life found him still engaged upon the same problem. His only result, a most important one, was to effect a change in the character of a ray of light by the influence of a powerful magnet, to rotate the plane of polarization of light by magnetism. This experiment constituted the basis of Maxwell's theory.

In order to understand the place of this experiment in present views of electricity let us study briefly the undulatory theory of light, accepted in Faraday's time, and the properties of the luminiferous ether.

Light is known to be a form of energy and to consist of exceedingly rapid vibrations of some kind or other. These vibrations are propagated in the form of waves or undulations with a certain definite velocity which has been measured experimentally and found to be 186,330 miles per second. The motions constituting light are very similar to the disturbances set up in a flexible, extended cord when one end is shaken rapidly and steadily up and down. The wave-form is sent onward while each part of the cord swings in the same place up and down across the length of the line. The more rapid the shake, the shorter are the waves. In the case of light the simple cord is replaced by a continuous medium called the luminiferous ether and the vibrations are not simply up and down but in all directions transverse to the ray. Some crystals possess the property of suppressing the vibrations in one direction allowing only the vibrations at right angles to them to pass through; the light is then said to be polarized in a plane. Faraday's experiment changed the position of this plane by electro-magnetism, showing some connection between electricity and light. The motions constituting radiant heat, light of different colors, and the chemical rays are all of the same kind, differing only in rate of vibrations or wave-length and are now included in the term radiant energy.

The ether, the most important factor in modern electrical theory, was proposed by Huygens originally to explain light only. It is now regarded as a material substance many billion times lighter than hydrogen but not so rare as our own atmosphere would be at a height of 250 miles. This ether fills all space not occupied by grosser matterthe interstellar and interplanetary spaces and surrounds the molecules of bodies as the

air does the earth. The best vacuum science can obtain is full of it. Its properties are derived from the undulatory theory of light, which requires it to be highly elastic, continuous, and possessed of some degree of rigidity, although it allows the planets to move through it undisturbed. A globe, the size of the earth, filled with this ether cannot weigh less than 250 pounds. It has been compared to "an impalpable and all-pervading jelly, through which light and heat waves are constantly throbbing, which is constantly being set in local strains and released from them, and being whirled in local vortices, thus producing the various phenomena of electricity and magnetism." Although its existence is as well established as the law of gravitation, its nature and constitution are somewhat of a mystery and many scientists are engaged in devising mechanical models illustrating its action in conveying light and electricity. Positive and negative electricity are almost regarded as opposite phases of this ether and a somewhat speculative tendency is manifest to make it not only the seat of all the known forces of light, heat, electricity, and magnetism, but of gravitation as well.

Faraday's discovery of the change in light due to magnetism diverted his attention from the magnet and electrified bodies to the spaces surrounding them. The old views of electricity, whose forms of expression we still retain, regarded electricity as a fluid contained in conductors and flowing through wires. Faraday's chief contribution to our present knowledge was in showing that the forces of attraction and repulsion were the real things and that they were external. He overturned the idea, derived possibly from the heavenly bodies, of action at a distance and believed that the attractions were exerted through the intervening space. The magnet did not act at a distance on its armature but by means of something in the space between them, which space he invested with what he called lines of force. In the case of a current, the electricity did not flow through the wire, but some motion or state of the medium surrounding was propagated outside the wirethe wire being the only place where the electricity was not. And he showed the current to be different in the cases where the wire was surrounded by air, sulphur, or glass. He was led to conjecture that the ether in the air, the glass, or the sulphur, in the space ex

ternal to the magnet and electric charge, was the medium of transmission, but whether the effect was instantaneous or took time for its propagation he was unable to say.

Maxwell entering into the labors of Faraday boldly assumed that the luminiferous ether was the seat of all electrical and magnetic forces. On this hypothesis, with Faraday's experiment as a basis, he formulated a complete and elaborate theory of electrical waves, expressing in mathematical language a large group of hypothetical facts, which for subtlety and ingenuity have never been surpassed. Even now his work on Electricity and Magnetism is a magnificent hieroglyph only partially deciphered, awaiting the advent of some Champollion to unfold its implicit record of unknown electrical facts. He showed that if electrical waves were conveyed through the ether they would behave like light waves and travel with a certain velocity depending on electrical considerations alone. This velocity he measured experimentally and found nearly equal to the velocity of light.* He therefore not only declared the ether to be the medium that conveyed electrical forces but advanced the very original proposition that light itself is an electro-magnetic phenomenon; the proofs of this hypothesis being the identity of the velocities and the agreement of another relation depending on both the optical and electrical properties of all substances. These proofs although they gained a considerable degree of acceptance for his theory were nevertheless indirect.

Hertz's method is to produce electrical waves and show that they are practically identical with those of light, thus affording a direct proof of Maxwell's theory. To do this he takes advantage of a principle discovered in 1842 by our own Professor Joseph Henry of the Smithsonian Institution: that the discharge of a Leyden jar is oscillatory. The discharge of a Leyden jar and the passage of a spark between the knobs of an electrical machine are familiar experiments of school-days. The bright spark and loud snap would lead us to suppose that the discharge was single and instantaneous; but this is not the case. It really consists of a series of discharges back and forth, executed so rapidly as to appear like one. The rapidity of these oscillations

* A new determination of this velocity made in 1890 agrees more exactly with the known velocity of light.

depends on the size of the jar and on one or two other considerations. By proper changes, the discharges may be made as slow as from 500 to 2,000 a second, giving rise to musical notes. Instead of a Leyden jar, Hertz uses what he calls a vibrator,—a circuit of wire with a break in it. Across this small break he sends alternate discharges of electricity, every spark giving rise as in the case of the Leyden jar, to a series of oscillations about 500,000,000 a second. These oscillations, rapid as they are, set the ether all around in vibration, forming, according to Maxwell's theory, electrical waves in it that travel from the point of discharge in every direction, just as the vibrations of a tuning fork set the air about it in motion sending forth waves of sound. If these electrical vibrations were much more rapid the break in the vibrator would become luminous and the waves would be light-waves. As, however, they are not rapid enough to affect the eye, Hertz most ingeniously adopted a second circuit called the receiver, similar to the first, to make them apparent. This receiver vibrates sympathetically with the vibrator and when it is at certain distances a microscopic spark appears across the break. Hertz measured the intervals and found them equal to the length of the wave, which varied in his experiments from several inches to several miles. measured the velocity of these waves and found it equal to the velocity of light.

He

By means of the receiver he showed they could be reflected and brought to a focus just like light. He sent waves through a large pitch prism whose face was over a yard square and found they were refracted just as light is when sent through a glass prism. In short he established conclusively that they were in all respects similar to light-waves except in the matter of wave-length. The undulatory theory of light thus receives a new and unexpected confirmation; and the labors of Faraday and Maxwell through half a century are crowned with a success that completes in our own time an important period in the history of electricity.

Several interesting developments depend more or less on Hertz's discovery:

It would hardly be supposed that the firefly and the glow-worm could give points to the electrician in the matter of illumination. The fitful light of the one and the modest glow of the other do not appear to excel in any respect the brilliancy of the arc-light or the

fessor Langley has shown, however, that our best sources of light are surpassed by nature in one very important respect: the production of light unaccompanied by heat. Of the energy supplied by gas and oil for lighting purposes much more than 99 per cent is given out as heat. That is, for every dollar expended for light in lamp or burner, ninety-nine cents goes for heat we do not want in order to get a penny's worth of light we do want. Even in the electric arc-light the waste is 90 per cent and in the incandescent lamp 94 per cent. The insect world is much more economical. The most careful measures made with the delicate bolometer * fail to show any sensible heat in the light of the firefly. There is no reason why nature should not be successfully imitated in this respect, and Professor Hertz hopes to make a practical application of his discovery in a method of obtaining better results than we now do from our present ordinary means in getting electrical vibrations similar in every respect to those of light but of greater wave-length. By mod ifying his original apparatus and making use of the rapidly alternating currents now available in later experiments he has some prospect of producing waves so much shorter that all of them will be luminous; in other words, of developing a new source of light without heat. The result if successful will be an entirely new method of illumination differing as widely from the electric lights as they do from gas light and lamp light, and sur

*The bolometer is an instrument devised by Professor Langley to measure small changes of temperature. It

will measure accurately to less than one ten-thousandth

of a degree Fahrenheit.

The diurnal and annual variations of the compass have been observed for many years. These minute changes in the pointings of the needle were supposed to be due to the mutual action of the sun and earth; but in what way nobody knew. Professor F. H. Bigelow, of Washington, has advanced the theory that they are due to electricity and magnetism induced in the earth by the sun. The theory is the more important becauses it embraces at the same time an explanation of the solar corona and the terrestrial aurora borealis, those companion mysteries of our planet and its luminary. Starting with Maxwell's principle, corroborated by Hertz's experiments, that light is electrical vibrations radiated from the sun along straight lines, Professor Bigelow supposes that the corona, too, sends along its streamers waves of magnetic energy, electrical messengers which ultimately find a home in the earth. They are drawn in by the earth, so to say, along the lines sometimes so beautifully indicated by the aurora when it is visible.

The result of these two radiations, the one direct, the other coming by curved lines, is to constitute a double field of magnetic force within which the earth revolves on its axis and swings around the sun. In other words the earth and sun together form a large dynamo machine in which the sun is the field magnet and the earth is the revolving armature. The currents of electricity thus set up varying in intensity at different points in the earth's orbit and according to the parts of the sun and earth brought face to face by their rotations, give rise to the periodic changes in the needle's position.

I

name of religion, a European sovereignty over Japan, that brought on the merciless persecution that terminated only with the utter destruction of the native church in the first half of the seventeenth century. It was to prevent the re-introduction of the hated Western religion that Japan, in 1640, excluded all European nations from her shores excepting only the Dutch, whom she confined to a little artificial island in Nagasaki Bay, for

bidding them to hold religious services, to have Bibles or other Christian books in their houses, to make public use of the Christian calendar, or to import coins, jewelry, or any thing that bore the figure of the cross or any written or pictorial reference to the forbidden faith.

This condition of things continued down to the opening of the country in 1853. During the interval of more than two centuries that had elapsed since the expulsion of Europeans, a few foreign priests had dared to venture to Japan, but they were, without a single exception, seized and either put to death or imprisoned for life, and their converts, if they had made any, were crucified or burned at the stake. It was only when coerced into doing so, that Japan again admitted the foreigner to her shores, and her chief objection to his coming was the fear that he would bring his religion with him. "Our country is now open to foreigners," said the governor of Nagasaki, in 1857, to the officers of the American man-of-war Powhatan, “and we shall be glad of whatever you may bring us with the exception of two things, opium and Christianity." Two years later three missionary societies had laborers in Japan. For the first ten years no progress was made.

The government looked upon the presence of the increasing missionary force with the utmost alarm and hostility. The old edict against the foreign religion, making conversion to its teachings a capital crime upon the part of a Japanese subject, was revived, and, in 1868, a new enactment was promulgated. It ran thus: "The evil sect called Christian is strictly prohibited. Suspected persons should be reported to the proper officers, and rewards will be given." A year later many hundreds of Roman Catholic Christians, descendants of the martyrs of the sixteenth and the seventeenth centuries, who had maintained a secret allegiance to the faith of their fathers, were discovered and torn from their homes near Nagasaki and were then closely confined in prisons in different parts of the empire.

It was at this juncture that Christianity be came an important factor in Japan's political relations with foreign powers. The ministers and consuls of Western nations united in a protest against this unmerited persecution of native Christians. The Japanese government was made to understand that so long as it cherished such bitter, unreasoning ani

mosity toward the religion of civilized nations, the people of those nations would regard Japan as a barbarous country whose inhabitants were no whit superior to the maneaters of Fiji or the bushmen of Africa. Such were the arguments with which the representatives of the several treaty powers backed their appeals to have the edict against Christianity revoked and the persecution of native Christians forbidden. For a time these remonstrances were treated with a show of contempt. The government held that these were matters of internal policy with which strangers had no right to interfere. The foreign ministers nevertheless persevered in their undertaking and finally triumphed. In a decree bearing the date of February 24, 1873, the edict against Christianity was ordered to be removed from the public notice-boards throughout the empire.

That this important step was the result of the continued efforts of the foreign ministers and consuls there can be no doubt. That the Japanese government was led by purely political considerations to make the desired revocation is equally clear. The Japanese had long before awakened to a knowledge of the fact that the foreign powers had taken advantage of their ignorance when the treaties were made to impose restrictions upon their government that must be removed before Japan could assert herself as an independent and sovereign state.

The extra-territoriality clause by which foreign residents were considered as being under the laws of their own respective governments was particularly offensive. Yet they fully realized that they were bound hand and foot. To appeal to arms against a score of powerful nations was not to be thought of. The only possible hope of redress was to convince foreigners of their fitness to receive more rights in the great family of nations and, by winning the good-will of Western people generally, thus to bring a pressure to bear upon the governments of the several countries that would lead to a revision of the treaties. But, if their attitude toward Christianity was calculated to make Europe and America regard them as barbarians, clearly it was incumbent upon them to take steps that would remove that impression. It took some time for this view to prevail, but prevail it finally did, with the result above noted.

The decree of February 24, 1873, brought liberty of conscience in religious matters; thenceforward the missionaries were virtually