Chapter III: Part 3

The discovery of petroleum helped further to light the world and distinguish the century. It gave us gasolene, naphtha, gas oil, astral oil, and the very effective “mineral sperm,” which is almost universally used in lighthouses and as headlights for locomotives. With the addition of kerosene, a favorite light of the beginning of the century—the tallow dip of our grandmothers—began to fall into disuse. The homelike pictures of housewives at their annual candle-dippings, or in the manipulation of their moulds, became venerable antiques. Candle-light paled in the presence of the higher illuminants. Though still a convenient light under certain circumstances, it plays a gradually diminishing part amid its superiors.

One of the signal triumphs of the century has been the introduction of gas-lighting. Though illuminating gas made from coal was known as early as 1691, it did not come into use, except for experiments or in a very special way, until the beginning of the nineteenth century. In 1809, a few street lamps were lit with gas in London. An unsuccessful attempt was made to introduce gas into Baltimore in 1821. Between 1822 and 1827, the gas-light began to have a feeble foothold in Boston and New York. Other cities began to introduce it as an illuminant in streets and, eventually, in houses. But the process was very slow, owing to intense opposition on the part of both savants and common people, who saw in it a sure means of destruction by poison, explosion, or fire. It was not much before the middle of the century that prejudice against illuminating gas was sufficiently allayed to admit of its general use. But meanwhile many valuable experiments as to its production and adaptation were going on. The most productive source of illuminating gas was found to be bituminous coal. Though gas could be produced by distillation from other substances, such as shale, lignite, petroleum, water, turf, resins, oils, and fats, none could compete in quality, quantity, and economy with what is known as ordinary coal gas, at least, not until the time came, quite late in the century, when it was found that non-luminous gases, such as water gas, could be rendered luminous by impregnating them with hydrocarbon vapor. This became known commercially as water gas, and it is now largely used in place of coal gas, because it is cheaper and, for the most part, equally effective as a luminant.

Gas-lighting has, of course, its limitations. It is not adapted for use beyond the range of cities or towns whose populations are sufficient to warrant the large expenditures necessary for gas plants. It is a special rather than general light. Yet within its limited domain of use it has proved of wonderful utility,—a source of cheer for millions, a clean, safe, and economic light, a convenience far beyond the candle, the lamp, or any previous lighting appliance. In the street, it is a source of safety against thieves and way-layers. In the slums, it is both policeman and missionary, baffling the wrong-doer, exposing the secrecy that conduces to crime, laying bare the hotbeds of shame. It is as well a source of heat as light, and consequently convertible into power for light mechanical purposes. In the kitchen, it is more and more becoming a boon to the housewife, who by means of the gas range escapes, in cooking, much of the dust, smoke, worry, and even expense of the coal cook stove and range. In the parlor, library, or sick-room, it is a cheerful and effective substitute for the coal grate, and may be made to assume the cosy qualities and fantastic shapes of the old-fashioned wood fire. Coincident with the discovery of petroleum, its inseparable companion, natural gas, came into prominence as a source of both light and heat, or this became true, at least, after it was ascertained that natural gas regions existed which could be tapped by wells, and made to give forth their gaseous product independent of the oil that may have at one time existed near or in connection with it. This natural source of light and heat became as interesting to the geologist, explorer, and capitalist as the source of petroleum itself, and soon every likely section was prospected, with the hope of finding and tapping those mysterious caverns of earth in which the pent-up luminant abounded in paying quantities. It was found that workable natural gas regions were numerous in the United States, especially in proximity to petroleum or bituminous coal deposits, and little time was lost in their development. As if by magic, a new and profitable industry sprang into existence. The natural gas well became almost as common as the oil well, and at times far more awe-inspiring as it shot into space its volcanic blasts which, when ignited through carelessness, as sometimes happened, carried to the vicinage all the dangers and terrors of Vesuvius or Stromboli. Powerful as was the force with which natural gas sought its freedom, wonderful as was the phenomenon of its escape from the subterranean alembic in which it was distilled, human genius quickly harnessed it by appliances for conservation and carriage to places where it could be utilized. Sometimes great industries sprang up contiguous to the wells; at others, it was carried through pipes to cities many miles distant, where it became a light for street, home, and store, and a prodigious energy in factory, furnace, forge, and rolling-mill. In fact, no marvel of the century has been at once so weird and inscrutable in its origin as natural gas, or more potential as an agency within the areas to which its use is limited. The question is ever uppermost in connection with natural gas, will it last? The gas springs of the Caucasus Mountains have been burning for centuries. But that is where nature’s internal forces have their correlations and compensations. Where it is quite otherwise, that is, where the vents of natural gas reservoirs are abnormally numerous, or where those reservoirs are drained to the extreme for commercial purposes, not to say through sheer wastefulness, the geologist is ready to surmise that the natural gas supply cannot be a perpetual one.

But one of the most magnificent triumphs of the century in the matter of light came about through the agency of electricity. We have already seen the beginnings of electric lighting in the discovery of Sir Humphrey Davy, in 1809, that when the ends of two conducting wires, mounted with charcoal pieces, were brought close together, a brilliant light, in the shape of an arc or curve, leaped from one piece of charcoal to the other. Davy’s charcoal pieces or carbons were consumed by the fierce heat evolved; but the principle was established that an electric current, so interrupted, was a vivid light-producer, and might be made permanently so if a substance capable of resisting the heat could be substituted for his charcoal tips, and a generator of electricity of sufficient power and economy in use could be substituted for his voltaic batteries or cells.

Upon these two essentials hung the future of the electric light. The first essential, that of a substance at the ends of the wires or in the midst of the electric circuit which would resist the heat, was soon met by the use of specially prepared and hard graphite carbon tips, in the shape of candles. But the second essential, a generator of electricity cheaper and more powerful than the voltaic cell, was not met with till the dynamo machine reached an advanced stage of perfection; that is, about 1867.

The two grand essentials now being at command, invention of electric light appliances went on rapidly upon two lines, eventuating in two systems, which became known as arc lighting and incandescent lighting. By 1879–80, the arc light was sufficiently advanced to meet with favor as an illuminant for streets, railway stations, markets, and any large spaces, in which places it became a substitute for gas and other lights. The essential features of the arc light are: (1.) The dynamo machine, situated in some central place, for the generation of electricity. (2.) Conducting wires to carry the electricity throughout the areas or to the places to be lighted. (3.) The arc lamp, which may be suspended upon poles in the streets, or upon wires in stores and other covered places. Its mechanism consists of two pencils or candles of graphite carbon, very hard and incombustible, adjusted above and below each other so that their tips or ends are very close together, but not in contact. By means of a clockwork or simple gravity device these carbon tips are brought into contact at the moment the electric current is turned on, and then are slightly separated as soon as the current has heated them. The air between the heated tips, having also reached a high temperature, becomes a conductor, and the electricity leaps in the form of an arc or curve through it, rendering it brilliantly incandescent. Should the current be diminished in strength for any reason, the above-mentioned clockwork or gravity device brings the carbons a little closer together; and should the current be increased, the carbons are separated a little wider; thus the steadiness of the light is regulated. There are also various automatic devices for thus regulating the proximity of the carbons and maintaining the evenness of the glow. The power of an arc light is measured by candles. An ordinary arc light under two amperes of current gives a light equal to twenty-five candles, while under fifty amperes of current it gives a light equal to twenty thousand candles. In searchlights on board vessels, and where very large areas are to be lighted, both heavier currents and larger carbons are used than in the arc lamps for ordinary street purposes. No light surpasses the arc light in brilliancy, excepting the magnesium light. There are few cities in this country and Europe that do not employ the arc lamp as a means of street, station, and large-area lighting, owing to its superiority as an illuminant and the wonderful policing effect it has upon the slum sections.

The incandescent lamp, or electric lighting by incandescence, underwent a somewhat longer evolution at the hands of inventors than the arc lamp, owing to the difficulty of finding a substance suitable for the production of the necessary glow. The discovery of such substance may be accredited to Edison more fully than to any other. The incandescent or glow lamp is a glass bulb from which the air is exhausted. There passes into the bulb a filament of carbon, which, after a turn or two inside the bulb, passes out at the end through which it entered. When a current from a voltaic battery is sent through this carbon filament, it brings it, in the absence of oxygen within the bulb, to a high white heat without combustion. The portion of this high white heat which is radiated is the light-giving energy of the incandescent lamp. Metal filaments were at first tried in the bulb, but they quickly burned out. Carbon filaments were at length found to be the only ones capable of resisting the heat. They moreover had the advantage of cheapness, and of greater radiating energy than metals. Many substances, such as silk, cotton, hair, etc., were used in the preparation of the carbon filaments, but it was found that strips cut from the inside bark of the bamboo gave, when brought to a white heat by an electric current and then properly treated, the most tenacious and best conducting carbon filament.

The quality of light produced by an incandescent lamp is a gentler glow than that produced by the arc lamp, and in color more nearly resembles the light of gas or the oil lamp. The incandescent light speedily became for the home, hotel, hall, and limited covered area what the arc light became for the street and railway station, and, if anything, the former outstripped the latter in the extent and value of the industry it gave rise to.

In the arc lamp, the carbon pencils have to be renewed daily. In the incandescent lamp, the carbon filament, though very delicate, may last for quite a time, because incandescence takes place in the absence of oxygen. If the favor in which the electric light is held, and the great extent of its use, rested solely on the question of cheapness of production, such question would give rise to interesting debate. And, indeed, the debate would continue, if the question were the superior fitness of electric lighting for lighthouses and like service, where extreme brilliancy does not seem to penetrate a thick atmosphere as effectively as the more subdued glow of the oil lamp. But the debate ceases when the question is as to the beauty and efficiency of the electric light in the home, street, station, mine, on shipboard, and the thousand and one other places in which it has come to be deemed an essential equipment. In all such places the question of economy of production and use is subordinate to the higher question of utility and indispensability.

VII. ELECTRIC LOCOMOTION.

The dawn of the nineteenth century saw, as vehicles of locomotion, the saddled hackney, the clumsy wagon, the ostentatious stage-coach, the primitive dearborn, the lumbering carriage, the poetic “one-hoss shay.” The universal energy was the horse. A new energy came with the application of steam, and with it new vehicular locomotion,—easier, swifter, stronger, for the most part cheaper, rendering possible what was hitherto impossible as to time and distance.

This signal triumph of the century may not have been eclipsed by the introduction of subsequent locomotive changes, but it was to be supplemented by what, at the beginning, would have passed for the idle dream of a visionary. The horse-car came, had its brief day, and went out with all its inconveniences, cruelties, and horrors before, in part, the traction-car, and, in part, the rapidly revolutionizing energy of electricity.

The first conception of a railway to be operated by electricity dates from about 1835, when Thomas Davenport, of Brandon, Vt., contrived and moved a small car by means of a current from voltaic cells placed within it. In 1851, Professor Page, of the Smithsonian Institution, ran a car propelled by electricity upon the steam railway between Washington and Baltimore, but though he obtained a high rate of speed, the cost of supplying the current by means of batteries—the only means then known—prohibited the commercial use of his method.

With the invention of the dynamo as an economic and powerful generator of electricity, and also the invention of the motor as a means of turning electrical energy to mechanical account, the way was open, both in the United States and Europe, for more active investigation of the question of electric-car propulsion. Between 1872 and 1887, different inventors, at home and abroad, placed in operation several experimental electric railways. Few of them proved practical, though each furnished a fund of valuable experience. An underground electric street railway was operated in Denver as early as 1885; but the one upon the trolley plan, which proved sufficiently successful to warrant its being called the first operated in the United States, was built in Richmond, Va., in 1888. It gave such impetus to electric railway construction that, in five years’ time, enormous capital was embarked, and the new means of propulsion was generally accepted as convenient, safe, and profitable.

The essential features of the electric railway are: (1.) The track of two rails, similar to the steam railway, (2.) The cars, lightly yet strongly built. (3.) The power-house, containing the dynamos which generate the electricity. (4.) The feed-wire, usually of stout copper, running the length of the tracks of the system, and supported on poles or laid in conduits. (5.) The trolley-wire over the centre of the track, supported by insulated cross-wires passing from poles on opposite sides of the tracks, and connected at proper intervals with the feed-wire. (6.) The trolley-pole of metal jointed to the top of the car, and fitted with a spring which presses the wheel on the end of the pole up against the trolley-wire with a force of about fifteen pounds, and which also serves to conduct the electricity down through the car to the motor. (7.) The motor, which is suspended from the car truck, and passes its power to the car axle by means of a spur gearing. The power requisite for an ordinary trolley-car is about fifteen horse-power. The speed of trolley-cars is regulated in cities to from five to seven miles per hour, but they may be run, under favorable conditions, at a speed equal to, or in excess of, that of the steam-car.

As a means of city transit, and of rapid, convenient, and economic intercourse between suburban localities and rural towns and villages, the electric traction system ranks as one of the greatest wonders of the century. The speed with which it found favor, the enormous capital it provoked to activity, the stimulus it gave to further study and invention, the surprising number of passengers carried, go to make one of the most interesting chapters in electric annals. The end of the century sees thousands of these electric roads in existence; a comparatively new industry involving over $100,000,000; a passenger traffic running into the billions of people; a prospect that the trolley will succeed the steam-car for all utilizable purposes within the gradually extending influence of cities and towns upon their rural surroundings.

In speaking of the passing of the horse-car and its substitution by the trolley, a distinguished writer has well said: “Humanity in an electric-car differs widely from that in the horse-car, propelled at the expense of animal life. It is more cheerful, more confident, more awake to the energy at command, more imbued with the subtlety and majesty of the propelling force. The motor confirms the ethical fact that each introduction of a higher material force into the daily uses of humanity lifts it to a broader, brighter plane, gives its capabilities freer and more wholesome play, and opens fresh vistas for all possibilities. We applaud Franklin for seizing the lightning in the heavens, dragging it down to earth, and subjugating it to man. Let this pass as part of the poetry of physics. But when ethics comes to poetize, let it be said that electricity as an applied force lifts man up toward heaven, quickens all his appreciations of divine energy, draws him irresistibly toward the centre and source of nature’s forces. There is no dragging down and subjugation of a physical force. There is only a going out, or up, of genius to meet and to grasp it. Its universal application means the raising of mankind to its plane. If electricity be the principle of life, as some suppose, what wonder that we all feel better in an electric-car than any other? The motor becomes a sublime motive. God himself is tugging at the wheels, and we are riding with the Infinite.”

Enthusiasts say the trolley is only the beginning of electric locomotion, and that there is already in rapid evolution an electric system which will supersede steam even for trunk-line purposes. In vision, it presumes a speed of one hundred and twenty-five miles an hour instead of forty; greater safety, cleanliness, and comfort; and what is most momentous and startling, an economy in construction and operation which will warrant the sacrifice of the billions of dollars now invested in steam-railway properties. The proposition is not to sacrifice the steam-railway track, but to add to it a third rail, which is to carry the electric current. Then, by means of feed-conduits alongside of the track, and specially constructed electric locomotives and cars, the system is supposed to reach the practical perfection claimed for it. Experiments with such an electrical system, made upon branch lines of some of our trunk-line railways, as the Pennsylvania, New York Central, and New Haven & Hartford, give much encouragement to the hypothesis that it may become the next great step in the evolution of electrical science.

Another means of electric propulsion was provided by the investigations of Planté, which resulted in his invention of the “accumulator” or “storage battery,” in 1859. His battery consists of plates of lead immersed in dilute sulphuric acid. By the passage of an electric current through the acid, it is electrolytically decomposed. By continuing the current for a time, first in one direction and then in another, the lead plates become changed, the one at the point where the current leaves the cell taking on a deposit of spongy lead, and the one at the point where the current enters the cell taking on a coating of oxide of lead. When in this condition, the battery is said to be stored, and is capable of sending out an electric current in any circuit with which it may be connected. After exhausting itself, it can be re-stored or re-charged in the same way as at first. Faure greatly improved on Planté’s storage battery in 1880, by spreading the oxide of lead over the plates, thus greatly reducing the time in forming the plates. Subsequently, further improvements were made, till batteries came into existence capable of supplying a current of many hundred amperes for several hours. One of the first practical uses to which the storage battery was put was in the propulsion of street-cars; but its weight proved a drawback. It was found better adapted for the running of boats on rivers, and, in the business of water-freightage for short distances, has in many instances become a rival of steam. It found one of its most interesting applications in helping to solve the problem of the _automobile_, or “horseless carriage,” either for pleasure purposes or for street traffic. In this problem it has, at the end of the century, an active rival in compressed air; but as the “horseless carriage” is rapidly coming into demand, means may soon be found to utilize the strong and persistent energy of the storage battery, without the drawback found in its great weight.

VIII. THE X RAY.

An astounding electrical revelation came during the last years of the century through the discovery of the X, or unknown, or Roentgen ray. A hint of this discovery was given by Faraday during his investigation of the effect of electric discharges within rarefied gases. He also invented the terms _anode_ and _cathode_, both of which are in universal use in connection with instruments for producing the X rays; the anode being the positive pole or electrode of a galvanic battery, or, in general, the terminal of the conductor by which a current enters an electrolytic cell; and the cathode being the negative pole or electrode by which a current leaves said cell.

Geissler followed Faraday with an improved system of tubes for containing rarefied gases for experimentation. He partially exhausted his tubes of air, introduced into them permanent and sealed platinum electrodes, and produced those wonderful effects by the discharge obtained by connecting the electrodes with the terminals of an electric machine or induction coil, which from their novelty and beauty became known as Geissler effects, just as his tubes became known as Geissler tubes. In the attenuated atmosphere of the Geissler tube, the current does not pass directly from one platinum point or electrode to the other, but, instead, illuminates the entire atmospheric space. When other gases are introduced in rarefied form, they are similarly illuminated, but in colors corresponding to their composition. In his further experiments, Geissler noted that the gases in the tube behaved differently at the anode, or positive terminal, and the cathode, or negative terminal. A beautiful bluish light appeared at the cathode, while the anode assumed the same color as the illuminated space in the tube. It was also noted that after the electric discharge within the tube, there remained upon the inner surface of the glass a fluorescent or phosphorescent glow, which was attributed to the effect of the cathode.

This brought the study of the _cathode_ rays into prominence, and through the investigations of Professor William Crookes, in 1879 and afterwards, a conclusion was reached that a “Fourth State of Matter” really existed. He perfected tubes of very high vacuum, by means of which he showed that molecules of gas projected from the cathode moved freely and with great velocity among one another, and so bombarded the inner walls of the tube as to render it fluorescent.

Subsequently, Hertz showed that the cathodic rays would penetrate thin sheets of metal placed within the tube or bulb; and soon after, Paul Lenard (1894) demonstrated that the cathodic ray could be investigated as well outside of the tube or bulb as within it. He set an aluminum plate in the glass wall of the bulb opposite the cathode. Though ordinary light could not penetrate the aluminum plate, it was readily pierced by the cathodic rays, to a distance of three inches beyond its outside surface. With these rays, thus freed from their inclosure, he produced the same fluorescent effects as had been noted within the bulb, and even secured some photographic effects. These cathodic rays produced no effect on the eye, which proved their dissimilarity to light. Lenard showed further that the cathodic rays outside of the tube could be deflected from their straight course by a magnet, that they might pass through substances opaque to light, and that in so passing they might cast a shadow of objects less opaque, which shadow could be photographed. Now Professor Roentgen came upon the scene. He had been conducting his experiments in Germany, along the same lines as Lenard, and had reached practically the same results as to the penetrative, fluorescent, and photographic effects of the cathodic rays. But he had gone still further, and, in 1896, fairly set the scientific world aflame with the announcement that all the effects produced by Lenard in the limited space of a few inches could also be produced at long distances from the tube, and with sufficient intensity to depict solid substances within or behind other substances sufficiently solid to be impermeable by light. Professor Roentgen claims that his X ray is different from the cathodic ray of Lenard and others, because it cannot be deflected by a magnet. This claim has given rise to much controversy respecting the real nature of the X ray, a controversy not likely to end soon, yet one full of inspiration to further investigation.

By X Ray process.]

The essential features of the best approved apparatus designed to produce the X ray and to secure a photograph of an invisible object, are: (1.) A battery or light dynamo as a generator of the electric current, accompanied, of course, by the necessary induction coil, which should be so wound as to give a spark of at least two inches in length in the tube where a picture of a simple object, as a coin in a purse, is desired; a spark of four inches in length where pictures of the bones of the hands, feet, or arms are desired; and a spark of from eight to ten inches in length where inside views of the chest, thighs, or abdomen are desired. (2.) The second essential is the glass tube. The one in common use is the Crookes tube, usually pear-shaped, and resting upon a stand. Into it is inserted two aluminum electrodes or disks, the one through the smaller end of the tube being used as the cathode, and the one from below and near the large end being used as the anode. (3.) A fluoroscope with which to observe the conditions inside the tube necessary to the production of the X ray, to decide upon its proper intensity, and to establish the proper degree of fluorescence. The favorite fluoroscope for this purpose is the one invented by Edison. It is in the form of a stereopticon, in which is a dark chamber after the manner of a camera. In front are two openings, admitting of a view within of both eyes. At the opposite, and greatly enlarged, end is a screen which is rendered fluorescent by means of a new substance (tungstate of calcium) discovered by Mr. Edison after some eighteen hundred experiments. Such is the power of this fluoroscope that it may be used as an independent instrument in cases of minor surgery to locate bullets or other objects buried in the flesh, even before a photograph has been taken. (4.) The photographic plate, which is prepared with a sensitized film and mounted in a frame as in ordinary photography. Upon this film the object to be photographed is laid, say, for instance, the human hand, care being taken to have the film or plate at a proper distance from the Crookes tube. Current is now turned into the tube, the X ray is developed, the film is exposed to its effects, and the result is a negative showing the interior structure of the hand,—the bones or any foreign object therein. This negative is developed as in ordinary photography.

The discovery and application of the X ray has proved of immense value in medicine and surgery. By its means the physician is enabled to carry on far-reaching diagnoses, and to ascertain with certainty the whole internal structure of the human body. Fractures, dislocations, deformities, and diseases of the bones may be located and their character and treatment decided upon. In dentistry, the teeth may be photographed by means of the X ray, even before they come to the surface, and broken fangs and hidden fillings may be located. Foreign objects in the body, as bullets, needles, calculi in the bladder, etc., may be localized, and the surgery necessary for their safe removal greatly simplified. The beating of the heart, movement of the ribs in respiration, and outline of the liver may be exhibited to the eye. It has been boldly suggested that in the X ray will be found an agent capable of destroying the various bacilli which infest the human system, and become germs of such destructive diseases as cholera, yellow fever, typhoid fever, diphtheria, and consumption. Even if this be speculative as yet, there is still room for marvel at the actual results of the discovery of the X ray, and its future study opens a field full of the grandest possibilities.

IX. OTHER ELECTRICAL WONDERS.

The novel idea of keeping time by means of electricity originated quite early in the century, and culminated in two kinds of electric clocks, one moved directly by the electric current, the other moved by weights or springs, but regulated by electricity. The former have the advantage of running a very long time without attention, but as it is impossible to keep up an unvarying electric current, they are not so accurate as the latter in keeping time. Though the latter are popularly called electric clocks, they are really only clocks regulated by electricity, and in such regulation the electric current comes to be a most important agent, as is proved at all centres of astronomical and other observations, as at Greenwich and Washington. At such centres the astronomical time-keeper is set up so as to run as infallibly as possible. This central time-keeper, say at Washington, is electrically connected with other clocks, at observatories, signal-service stations, railway stations, clock-stores, city halls, etc., throughout the country. Should any of these clocks lose or gain the minutest fraction of time as compared with that of the central time-keeper, the electric current corrects such loss or gain, and so keeps all the clocks at a time uniform with one another and with the central one. Electrical devices are also often attached to individual clocks, as those upon city hall towers and in exposed places, for the purpose of meeting and correcting inequalities of time occasioned by weather exposure, expansion and contraction by heat and cold, etc.

The fatherhood of the very useful and elegant arts of electrotyping and electroplating is in dispute. Daniell, while perfecting his battery, noticed that a current of electricity would cause a deposit of copper. In 1831, Jacobi, of St. Petersburg, called attention to the fact that the copper deposited on his plates of copper by galvanic action could be removed in a perfect sheet, which presented in relief, and most accurately, every accidental indentation on the original plates. Following this up, he employed for his battery an engraved copper plate, caused the deposit to be formed upon it, removed the deposit, and found that the engraving was impressed on it in relief, and with sufficient firmness and sharpness to enable him to print from it. Jacobi called his discovery galvanoplasty in the publication of his observations in 1839. It was but a step from this discovery to the application of the electrotyping process to the art of printing. A mould of wax, plaster, or other suitable substance is made of an engraving or of a page of type. This mould is covered with powdered graphite (black lead) so as to make it a conductor of electricity. It is then inserted in a bath containing a solution of sulphate of copper. An electric current is passed through the bath, and the copper is deposited on the mould in sufficient quantity to give it a hard surface capable of offering greater resistance in printing than the types themselves, and also of producing a clearer impression. In electroplating, practically the same principle is employed. The bath is made to contain a solution of water, cyanide of potassium, and whatever metal—gold, silver, platinum, etc.—it is designed to precipitate on the article to be electroplated. The current is then passed through the bath, and the article—spoon, knife, fork, etc.—to be electroplated receives its coating of gold, silver, German silver, platinum, or whatever has been made the third agent in the bath.

The various modern submarine devices for the destruction of ships, known as torpedoes, submarine mines, etc., depend upon electricity for their efficiency. It is the lighting or firing agent, and is carried to the torpedo or mine by means of stout wires or cables from some safe shore-point of observation.

In railroading, electricity has become an indispensable agent for the operation of signal systems, opening and closing of switches, and limitation of safety sections. It moves the drill in the mine, sets off the blast, and supplies the light. It enables the dentist to manipulate his most delicate tools and do his cleanest and least painful work. In medicine it is a healing, soothing agent, boundless in variety of application and wondrous in results. It is a stimulus to the growth of certain plants, and has given rise to a new science called Electro-horticulture. It may be made a prolific source of heat for warming cars, and even for the welding of iron and steel. The electric fan cools our parlors and offices in summer, and the electric bell simplifies household service. In fact, it would appear that, in contrasting the electrical beginnings with the electrical endings of the nineteenth century, the space of a thousand rather than a hundred years had intervened, and that in measuring the agents which conduce to human comfort and convenience, electricity is easily the most potential.

X. ELECTRICAL LANGUAGE.

Out of the various discoveries and applications of electricity almost a new language has sprung. This is especially so of terms expressive of the measurements of electric energy, and of the laws governing the application of electric power. For a time, various nations measured and applied by means of terms chosen by themselves. This led to a jargon very confusing to writers and investigators. It became needful to have a language more in common, as in pharmacy, so that all nations could understand one another, could compute alike, and especially impart their meaning to those whose duty it became to apply discovered laws and actual calculations to practical electric operations. This was a difficult undertaking, owing to the tenacity with which nations clung to their own nomenclatures and terminologies. But the drift, though slow, finally ended at the Electrical Congress in Paris in 1881, in the adoption of a uniform system of measurements of electric force, and an agreement upon terms for laws and their application, which all could understand.

Three fundamental units of measurement were first agreed upon,—the _Centimetre_ (.394 in.) as a unit of length; the _Gramme_ (15.43 troy grains) as a unit of mass; the _Second_ (1/60 of a minute) as a unit of time. These three units became, when referred to together by their initial letters, the basis of the C. G. S. system of units. Now by these units of measurement something must be measured, as, for instance, the electric force; and when so measured, an absolute unit of force must be the result.

DYNE:—This is but a contraction of _dynam_, force. It was adopted as the name of the “Absolute Unit of Force,” or the C. G. S. unit of force, and is that force which, if it act for a second on one gramme of matter, gives to it a velocity of one centimetre per second.

AMPERE:—Electrical force produces electrical current. Current must be measured and an absolute unit of current strength agreed upon. The “Absolute Unit of Current” was settled as one of such strength as that when one centimetre length of its circuit is bent into an arc of one centimetre radius, the current in it exerts a force of one dyne on a unit magnet-pole placed at the centre. But the absolute unit of current as thus obtained was decided to be ten times too great for practical purposes. So a practical unit of current was fixed upon, which is just one tenth part of the above absolute unit of current. This practical unit of current was called the ampere, in honor of the celebrated French electrician, Ampère. It may be ascertained in other ways, as when a current is of sufficient strength to deposit in a copper electrolytic cell 1.174 grammes (18.116 grains) of copper in an hour, such current is said to be of one ampere strength; or a current of one ampere strength is such a one as would be given by an electro-motive force of one volt through a wire offering one ohm of resistance.

VOLT:—This was named from Volta, the celebrated Italian electrician, and was agreed upon as the unit of electro-motive force. It is that electro-motive force which would be generated by a conductor cutting across 100,000,000 C. G. S. lines in a field of force per second; or it is that electro-motive force which would carry one ampere of current against one ohm of resistance.

OHM:—So called from Ohm, a German electrician. It is the unit of resistance offered by a conductor to the passage of an electrical current. As an absolute unit of resistance, it is equal to 1,000,000,000 C. G. S. units of resistance. As a practical unit, and as agreed upon at the International Congress of Electricians (Chicago, 1893), it represents the resistance offered to an electric current at the temperature of melting ice by a column of mercury 14.451 grammes in mass, of a constant cross-sectional area, and 106.3 centimetres in length. This is called the international ohm. The resistance offered by 400 feet of ordinary telegraph wire is about an ohm.

These three units—ampere, volt, and ohm—are the factors in Ohm’s famous law that the current is directly proportional to the electro-motive force exerted in a circuit, and inversely proportional to the resistance of the circuit; that is,—

Current = Electro-motive force / Resistance

or,

Electro-motive force = Current × Resistance

or

Resistance = Electro-motive force / Current.

ERG:—From the Greek _ergon_, work, is the unit of work required to move a force of one dyne one centimetre. One foot-pound equals 13,560 ergs.

CALORIE:—Latin _calor_, heat, is the unit of heat; being the amount of heat required to raise the temperature of one kilogram of water one degree centigrade.

COULOMB:—In honor of C. A. de Coulomb, of France. It is the practical unit of quantity in measuring electricity, and is the amount conveyed by one ampere in one second.

FARAD:—From FARADAY, the physicist. It is the unit of electric capacity, and is the capacity of a condenser that retains one coulomb of charge with one volt difference of potential.

GAUSS:—From Carl F. Gauss (1785–1855). The C. G. S. unit of flux-density, or the unit by which the intensity of magnetic fields are measured. It equals one weber per normal square centimetre.

GILBERT:—The unit for measuring magneto-motive force, being produced by .7958 ampere-turn approximately.

HENRY:—From Joseph Henry, of the Smithsonian Institution, Washington, D. C. The practical unit for measuring the induction in a circuit when the electro-motive force induced is one international volt, while the inducing current varies at the rate of one ampere per second.

JOULE:—The C. G. S. unit of practical energy, being equivalent to the work done in keeping up for one second a current of one ampere against a resistance of one ohm. Named from J. P. Joule, of England.

OERSTED:—From Oersted, the electrician. It is the practical unit for measuring electrical reluctance.

WATT:—The practical electrical unit of the rate of working in a circuit, when the electro-motive force is one volt, and the intensity of current is one ampere. It is equal to 107 ergs per second, or .00134 horse-power per second. Named from James Watt, of Scotland.

WEBER:—The practical unit for measuring magnetic flux. Named from W. Weber, of Germany.

THE CENTURY’S NAVAL PROGRESS

BY REAR ADMIRAL GEORGE WALLACE MELVILLE, U. S. N.

I. INFLUENCE OF SEA POWER.

The share of navies in the great movements which have moulded human destiny and shaped the world’s progress, although long obscure and undervalued, has met in our time full recognition. Within a decade the influence of sea power upon history has become the frequent theme of historians and essayists who, in clear and striking form, have shown the cardinal importance, both in war and commerce, of the fleet—the nation’s right arm on the sea. It is fitting, therefore, that in the retrospect of a hundred years navies should have their place; that, in looking backward with history’s unclouded vision, we should mark, not only their growth and change, but, as well, their achievement in some of the most memorable conflicts of our race.

The century had but begun when, at Copenhagen, Nelson, with one titanic blow, shattered the naval strength of Denmark and the coalition of the Northern powers. His signal there, ever for “closer battle,” told in few words the life story of the Great Admiral, and foreshadowed his end. Four years later, at Trafalgar, the desire of his eager heart was satisfied, when he met in frank fight the fleets of France and Spain. Amid the thundering cannonade of that last victory his life-tide ebbed, bearing with it the power of France upon the seas and the broken fortunes of Napoleon. In the war of 1812, our disasters upon the land met compensation in victory afloat. The United States was then among the feeblest of maritime powers; and yet Macdonough and Perry on the lakes and our few frigates on the ocean opposed, with success, the swarming squadrons of a nation whose naval glory, as Hallam says, can be traced onward “in a continuous track of light” from the days of the Commonwealth. The oppression of the Sultan was ended for a time when, in 1827, the Turkish and Egyptian fleets were annihilated, in sudden fury, by the allied squadrons in that brief engagement which Wellington termed the “untoward event” of Navarino.

A generation later, the command of the sea enabled England and France to despatch, in unarmed transports, 63,000 men and 128 guns to the Crimea, and to land them, without opposition, for the red carnage of the Alma, Balaklava, Inkerman, and Sebastopol. Following closely upon the disease and death, the fatuity and the glory, of the Crimea, came the great war of modern times, in which the gun afloat played such a gallant part, as the blockade, with its constricting coils, slowly starved and strangled the Confederacy to death, and Farragut, on inland waters, split it in twain. Passing over the sea-fights of Lissa,—in which imperial Venice was the stake,—of South America and the Yalu, we note, lastly, the swift and fateful actions off Santiago and in Manila Bay, which destroyed once again the sea power of Spain, won distant territory for the United States, and opened up for us a noble pathway of commercial expansion to the uttermost island of the broad Pacific and the vast Asian littoral beyond. Who will say, in the retrospect of the century, that the fleets of the world have not had their full share in the making of its history?

II. THE CENTURY’S GROWTH IN NAVAL STRENGTH.

The United States fleet, in the year 1800, comprised 35 vessels, 10 of which were frigates mounting 32 guns or more. In 1812, America entered the lists against a navy of a thousand sail, with a fleet of but 20 ships, the largest of which was a 44-gun frigate. The operations of the Civil War were begun with but 82 vessels, 48 of which were sailing craft. Before the close of that gigantic struggle there were added, by construction or purchase, 674 steamers. In 1898, during the war with Spain, there were borne on the Naval Register, as building or in service, 13 battleships and 176 other vessels, including torpedo craft, with 123 converted merchantmen. The total naval force during hostilities was 22,832 men and 2382 officers, excluding the Marine Corps.

(Battle of Mobile Bay.)]

At London, in 1653, there was printed “A List of the Commonwealth of England’s Navy at Sea, in their expedition in May, 1653, under the command of the Right Honorable Colonel Richard Deane and Colonel George Monk, Esquires, Generals, and Admirals.” This quaint record of that early time gives the force afloat as 105 ships, 3840 guns, and 16,269 men. In Britain’s strife for that ocean empire, which is world empire, that fleet had grown, by the year 1800, to 757 vessels, built or building, with an aggregate tonnage of 629,211, and carrying 26,552 guns, 3653 officers, and 110,000 men. The stately three-decker, with its snowy canvas and maze of rigging, has vanished with the past; but, despite time and change, that mighty fleet still dominates the seas. Its strength, on February 1, 1898, was 615 vessels—61 of which were battleships,—carrying a total force of 110,050 officers and men.

Colbert, when the Grand Monarch was at the zenith of his power, found France with a few old and rotten vessels, and left her with a noble fleet of 40 ships of the line and 60 frigates, which, under D’Estrée, Jean Bart, Tourville, and Duquesne, carried her flag to every sea. A state paper of the time gives the force at the beginning of this century as 61 ships of the line, 42 corvettes, and a numerous, although unimportant, flotilla of small craft. With Aboukir and Trafalgar, the maritime power of France wasted away; and, by the year 1839, there were afloat but three effective sail of the line. In 1840, however, the revival began, and during the modern era the French fleet has, at times, been a formidable rival of that of England. It comprised, in 1898, 446 vessels, including torpedo craft, 26 of the total being battleships. The force afloat numbered 70,925, of all ranks and ratings.

Germany’s navy is of modern creation. It began, a little less than half a century ago, with one sailing corvette and two gunboats; and, in 1898, comprised 13 battleships and 179 other vessels of all types, carrying 23,302 officers and men. The fleet of united Italy had its inception, also, within the age of steam. It was on March 17, 1860, that Italian national life began with the ascension of the throne by Victor Emmanuel. From the beginning, the kingdom has been lavish with its fleet, its expenditures within the first six years reaching $60,000,000. In 1898 there were in the Italian navy 265 vessels of all types, 17 of which were battleships. The force afloat was 24,200, of all ranks and ratings.

The Crimean war found Russia but little advanced, either on the Black Sea or the Baltic, in the substitution of steam for sail. Since that time, however, she has re-created her battle fleet, which is now especially strong in torpedo craft and cruisers of great steaming radius. Her navy, in 1898, comprised 20 battleships and 263 other vessels, with a force of 32,477 officers and men. Japan began her fleet in 1866 with the purchase of an armor-clad from the United States. In 1898, she had a total of 145 vessels, built and building—8 of which were battleships—carrying 23,000 men of all ranks and ratings.

Of minor navies little need be said. Austria had, in 1898, a fleet of 115 vessels of all types, including 13 battleships and 79 torpedo craft. Holland’s force was 185 vessels, 3 being battleships and 93 torpedo craft. The fleets of Turkey, Greece, Spain, and Portugal are “paper-navies” mainly. Norway and Sweden have a combined strength of 171 vessels of all types. Denmark, which began the century with overwhelming naval disaster at Copenhagen, has now a force of 3000 men borne on 50 vessels, half of which are torpedo craft. Argentina, Brazil, and Chili have afloat 102 torpedo vessels and 49 of other types. The vast growth in naval armaments during the century may be measured from the fact that the personnel of the leading navies of Europe, with those of Japan and the United States, comprised, in the year 1898, 368,028 officers and men, with a total force of 2749 vessels of all types, including torpedo craft.

III. THE BATTLESHIP,—PAST AND PRESENT.

In tracing the evolution of the modern man-of-war, it will be instructive to compare with her the type of the sailing age. There are two ships of the old time which hold chief places in the memory of the Anglo-Saxon race,—the Victory, Nelson’s flagship at Trafalgar, and the Constitution, whose achievements under Hull, Bainbridge, and Stewart, rang around the world. There were, even before the days of steam, war-vessels twice as large and powerful as “Old Ironsides,” but over no sea, in any age, has there sailed a ship with a more gallant record. Plate I shows her as she was in her prime—before the wind, with all sail set. On Plate II there is given a side view of her hull, which is of historic interest, in that it is reproduced from the original drawing made in October, 1796.

When her power and dimensions are compared with those of the Oregon, our sea-fighter of to-day, one sees what time has wrought. The frigate carried 456 men, the armor-clad, 500; and yet, with this approximately equal force, the Oregon has a displacement 6½ times that of her famed predecessor; and although the number of the guns—44—is the same in each, she discharges a broadside 8.3 times heavier and in energy overwhelmingly superior. The speed of the battleship is one half greater than that of the Constitution, and she carries armor varying from 18 inches to 4 inches thick, which the frigate wholly lacked. The longitudinal section of the Oregon indicates the immense advance in other directions. Her hull is, for safety, minutely subdivided, and is provided with engines for propulsion, steering, lighting, drainage, and ventilation, numbering in all 84, with miles of piping and hundreds of valves. The time-honored frigate was but a sail-propelled gun-platform, whose wants were as few as her construction was simple; the steel-clad battleship is a mass of mechanism, a floating machine-plant, which for full efficiency must be manned by a personnel not only brave and daring as of old, but expert in many arts and sciences, which in the age of sail were but rudimentary or unknown.

IV. THE PROGRESS OF NAVAL ENGINEERING.

“_I have just read the project of Citizen Fulton, Engineer, which you have sent me much too late, since it is one which may change the face of the world._”

So, in the beginning of the century, wrote the first Napoleon from his Imperial camp at Boulogne. Wrapped in his day-dream of a descent upon the Thames, he saw, with prophetic vision, in the plans of the American engineer, the future of navigation, and he strove to grasp—but too late—the opportunity which might have made his armada victorious over wind and tide.