It must not be overlooked that before dynamo-magneto-electric machines were used practically in the production of the electric light for the purposes of illumination, the voltaic battery was used for the same purpose, but not economically.
The first private dwelling house ever lighted in America, or doubtless anywhere else, by electricity, was that of Moses G. Farmer, in Salem, Massachusetts, in the year 1859. A voltaic battery furnished the current to conducting wires which led to two electric lamps on the mantel-piece of the drawing-room, and in which strips of platinum constituted the resisting and lighting medium. A soft, mild, agreeable light was produced, which was more delightful to read or sew by than any artificial light ever before known. Either or both lamps could be lighted by turning a button, and they were maintained for several weeks, but were discontinued for the reason that the cost of maintaining them was much greater than of gas light.
It was in connection with the effective dynamo-electric apparatus of M. Gramme above referred to that the electric candle invented by M. Paul Jablochoff became soon thereafter extensively employed for electric lighting in Paris, and elsewhere in Europe. This invention, like the great majority of useful inventions, is noted for its simplicity. It consists of two carbon pencils placed side by side and insulated from each other by means of a thin plate of some refractory material which is a non-conductor at ordinary temperatures, but which becomes a conductor, and consequently a light, when fused by the action of a powerful current. Plaster of Paris was found to be the most suitable material for this purpose, and the light produced was soft, mellow, slightly rose-coloured, and quite agreeable to the eye.
It having been found that carbon was better adapted for lighting purposes than platinum or other metals, by reason of its greater radiating power for equal temperatures, and still greater infusibility at high temperatures, inventors turned their attention to the production of the best carbon lamp.
The two pointed pieces of hard conducting carbon used for the separated terminals constitute the voltaic arc light—a light only excelled in intense brilliancy by the sun itself. It is necessary in order to make such a light successful that it should be continuous. But as it is found that both carbons waste away under the consuming action of the intense heat engendered by their resistance to the electric current, and that one electrode, the positive, wastes away twice as fast as the opposite negative electrode, the distance between the points soon becomes too great for the current longer to leap over it, and the light is then extinguished. Many ingenious contrivances have been devised for correcting this trouble, and maintaining a continuously uniform distance between the carbons by giving to them a self-adjusting automatic action. Such an apparatus is called a regulator, and the variety of regulators is very great. The French were among the first to contrive such regulators,—Duboscq, Foucault, Serrin, Houdin, and Lontin invented most useful forms of such apparatus. Other early inventors were Hart of Scotland, Siemens of Germany, Thompson and Houston of England, and Farmer, Brush, Wallace, Maxim, and Weston and Westinghouse of America. Gramme made his armature of iron rods to prevent its destruction by heat. Weston in 1882 improved this method by making the armature of separate and insulated sheets of iron around which the coil is wound. The arc light is adapted for streets and great buildings, etc.; but for indoor illumination, when a milder, softer light is desirable, the incandescent light was invented, and this consists of a curved filament of carbon about the size of a coarse horsehair, seated in a bulb of glass from which the air has been exhausted. In exhausted air carbon rods or filaments are not consumed, and so great ingenuity was exercised on that line. Among the early noted inventors of incandescent carbon filament lamps were Edison and Maxim of New York, Swan, and Lane-Fox of England.
Another problem to be solved arose in the proposed use of arc lamps upon an extended scale, or in series, as in street lighting, wherein the current to all lamps was supplied by a single wire, and where it was found that owing to the unequal consumption of the carbons some were burning well, some poorly, and some going out. It was essential, therefore, to make each lamp independent of the resistance of the main circuit and of the action of the other lamps, and to have its regulating mechanism governed entirely by the resistance of its own arc. The solution of this difficult problem was the invention by Heffner von Alteneck of Germany, and his device came into use wherever throughout the world arc lamps were operated. Westinghouse also improved the direct alternating system of lighting by one wire by the introduction of two conducting wires parallel to each other, and passing an interrupted or alternating current through one, thereby inducing a similar and always an alternating current through the other. Brush adopted a three-wire system; and both obtained a uniform consumption of the carbons.
In a volume like this, room exists for mention only of those inventions which burn as beacon lights on the tallest hills—and so we must now pass on to others.
Just as Faraday was bringing his long series of experimental researches to a close in 1856-59, and introducing the fruits of his labours into the lighthouses of England, Cyrus W. Field of New York had commenced his trials in the great scheme of an ocean cable to “moor the new world alongside the old,” as John Bright expressed it. After crossing the ocean from New York to England fifty times, and baffled often by the ocean, which broke his cables, and by the incredulous public of both hemispheres, who laughed at him, and by electricity, which refused to do his bidding, he at last overcame all obstacles, and in 1866 the cable two thousand miles in length had been successfully stretched and communication perfected. To employ currents of great power, the cable insulation would have been disintegrated and finally destroyed by heat. Therefore only feeble currents could be used. But across that long distance these currents for many reasons grew still weaker. The inventor, Sir William Thomson, was at hand to provide the remedy. First, by his mirror galvanometer. A needle in the shape of a small magnet and connected to the current wires, is attached to the back of a small concave mirror having a hole in its centre; opposite the mirror is placed a graduated scale board, having slits through it, and a lighted lamp behind it. The light is thrown through the slits across to the hole at the center of the mirror and upon the needle. The feeblest imaginable current suffices to deflect the needle in one direction, which throws back the little beam of light upon it to the graduated front of the scale. When the current is reversed the needle and its shadow are deflected in the other direction, and so by a combination of right and left motions, and pauses, of the spots of light to represent letters, the message is spelled out. Second, a more expeditious instrument called the syphon recorder. In this the galvanometer needle is connected to a fine glass syphon tube conducting ink from a reservoir on to a strip of paper which is drawn under the point of the tube with a uniform motion. The irregular movements given the galvanometer needle by the varying current are clearly delineated on the paper. Or in writing very long cables the point of the syphon may not touch the paper, but the ink by electrical attraction from the paper is ejected from the syphon upon the paper in a succession of fine dots. The irregular lines of dots and dashes were translated into words in accordance with the principles of the Morse telegraph.
An instrument was exhibited at the Centennial International Exhibition at Philadelphia in 1876, which was considered by the judges “the greatest marvel hitherto achieved by the electric telegraph.” Such was the language used both by Prof. Joseph Henry and Sir Wm. Thomson, and concurred in by the other eminent judges from America, Germany, France, Austria and Switzerland. This instrument was the Telephone. It embodied, for the practical purpose of transmitting articulate speech to distances, the union of the two great forces,—sound and electricity. It consisted of a method and an apparatus. The apparatus or means consisted of an electric battery circuit, a transmitting cone placed at one end of the line into which speech and other vocal sounds were uttered, a diaphragm against which the sounds were projected, an armature secured to or forming a part of the diaphragm, an electro-magnet loosely connected to the armature, a wire connecting this magnet with another precisely similar arrangement of magnet, armature, diaphragm, and cone, at the receiving end. When speech was uttered in the transmitter the sound vibrations were received on the diaphragm, communicated to the electricised armature, from thence by induction to the magnet and the connecting wire current, which, undulating with precisely the same form of sound vibrations, carried them in exactly the same form to the receiving magnet. They were then carried through the receiving armature and reproduced on the receiving diaphragm, with all the same characteristics of pitch, loudness and quality.
The inventor was Alexander Graham Bell, by nativity a Scotchman, then a resident of Canada, and finally a citizen of the United States. His father was a teacher of vocal physiology at Edinburgh, and he himself became a teacher of deaf mutes. This occupation naturally led him to a thorough investigation of the laws of sound. He acknowledged the aid he received from the great work of Helmholtz on the Theory of Tone. His attention was called to sounds transmitted and reproduced by the electric current, especially by the ease with which telegraph operators read their messages by the duration of the “click” of their instruments. He knew of the old device of a tightly-stretched string or wire between two little boxes. He had read the publication of Prof. C. G. Page, of America, in 1837, on the Production of Galvanic Music, in which was described how musical notes were transmitted and reproduced by an interrupted magnetic circuit. He became acquainted with the experimental musical telephonic and acoustic researches of Reis, and others of Germany, and those of celebrated scientists in France, especially the phonautograph of Scott, a delicate instrument having a cone membrane and pointer, and used to reproduce on smoked glass the waves of sound. He commenced his experiments with magneto instruments in 1874, continued them in 1875, when he succeeded in reproducing speech, but poorly, owing to his imperfect instruments, and then made out his application, and obtained a patent in the United States in July, 1876.
Like all the other remarkable inventions recorded in these pages, this “marvel” did not spring forth as a sudden creation, but was a slow growth of a plant derived from old ideas, although it blossomed out suddenly one day when audible sounds were accidentally produced upon an apparatus with which he was experimenting.
It is impossible here to narrate the tremendous conflict that Bell now encountered to establish his title as first inventor, or to enumerate the multitude of improvements and changes made which go to make up the successful telephone of to-day.
The messages of the voice are carried on the wings of electricity wherever any messages are carried, except under the widest seas, and this difficulty inventors are now seeking to overcome.
The story of the marvellous inventions of the century in electricity is a fascinating one, but in length and details it is also marvellous, and we must hasten unwillingly to a close. Numerous applications of it will be mentioned in chapters relating to other arts.
In the generation of this mighty force improvements have been made, but those of greatest power still involve the principles discovered by Faraday and Henry seventy years ago. The ideas of Faraday of the “lines of force”—the magnetic power streaming from the poles of the magnet somewhat as the rays of heat issue on all sides from a hot body, forming the magnetic field—and that a magnet behaves like an electric current, producing an electric wave by its approach to or recession from a coil of wire, joined with Henry’s idea of increasing the magnetising effect by increasing the number of coils around the magnet, enter into all powerful dynamo electric machines of to-day. In them the lines of force must flow around the frame and across the path of the armature; and there must be a set of conductors to cut the lines of force twice in every revolution of the cylinder carrying the armature from which the current is taken.
When machines had been produced for generating with some economy powerful currents of electricity, their use for the world’s business purposes rapidly increased. Among such applications, and following closely the electric lighting, came the electric railway. A substitute for the slow animal, horse, and for the dangerous, noisy steam horse and its lumbering locomotive and train, was hailed with delight. Inventors came forward with adaptations of all the old systems they could think of for the purpose, and with many new ones. One plan was to adapt the storage battery—that silent chemical monster which carries its own power and its own machine—and place one on each car to actuate a motor connected to the driving wheels. Another plan was to conduct the current from the dynamo machine at its station along the rails on one side of the track to the motor on the car and the return current on the opposite track; another was to carry the current to the car on a third rail between the track, using both the other rails for the return; another to use an overhead wire for the current from the dynamo, and connect it with the car by a rod, one end of which had a little wheel or trolley running on the overhead wire, to take up the current, the other end being connected by a wire to the car motor; another plan to have a trench made leading from the central station underneath the track the whole length of the line, and put into this trench conducting wires from the dynamo, to one of which the car motor should be connected by a trolley rod or “brush,” extending down through a central slot between the rails of the track to carry the electric supply into the motor. In all these cases a lever was supplied to cut off communication between the conducting wire and the motor, and a brake lever to stop the car.
All of these plans have been tried, and some of them are still being tried with many improvements in detail, but not in principle.
The first electrical railway was constructed and operated at Berlin in 1879, by Messrs Siemens and Halske. It was two thousand seven hundred feet long and built on the third rail system. This was an experiment but a successful one. It was followed very soon by another line near Berlin for actual traffic; then still another in Saxony. At the Paris Exposition in 1881, Sir Wm. Siemens had in operation a road about one thousand six hundred feet in length, on which it is estimated ninety-five thousand passengers were conveyed in seven weeks. Then in the next year in London; and then in the following year one in the United States near New York, constructed by Edison. And thus they spread, until every important town and city in the world seems to have its electric plant, and its electric car system, and of course its lighting, telephone and telegraph systems.
In 1882 Prof. Fleeming Jenkin of England invented and has put to use a system called Telpherage, by which cars are suspended on an overhead wire which is both the track and electrical conductor. It has been found to be advantageous in the transportation of freight from mines and other places to central stations.
With the coming of the electric railway, the slow, much-abused horse, the puffing steam engine blowing off smoke and cinders through the streets, the great heavy cars, rails and roadbeds, the dangerous collisions and accidents, have disappeared.
The great problems to solve have related to generation, form, distribution and division of the electric current at the dynamos at the central stations for the purposes of running the distant motors and for furnishing independent supplies of light, heat, sound and power. These problems have received the attention of the keenest inventors and electrical engineers and have been solved.
The description of the inventions made by such electrical magicians as Thomas Edison and Nikola Tesla would fill volumes.
The original plan of sending but one message over a wire at a time has also been improved; and duplex, quadruplex and multiplex systems have been invented (by Stearns, Farmer, Edison and others) and applied, which have multiplied the capacity of the telegraphs, and by which even the alleged all-talk-at-the-same-time habit of certain members of the great human family can be carried on in opposite directions on the same wire at the same time between their gatherings in different cities and without a break.
To understand the manner of multiplying messages or signals on the same line, and using apparently the same electric current to perform different operations, the mind must revert to the theory already referred to, that a current of electricity does not consist of a stream of matter flowing like water through a conductor in one direction, but of particles of subtle ether, vibrating or oscillating in waves from and around the conductor which excites them; that the vibration of this line of waves proceeds at the rate of many thousand miles per second, almost with the velocity of waves of light, with which they are so closely related; that this wave current is susceptible of being varied in direction and in strength, according to the impulse given by the initial pressure of the transmitting and exciting instrument; and that some wave currents have power by reason of their form or strength to penetrate or pass others coming from an opposite direction. So that in the multiplex process, for instance, each transmission having a certain direction or strength and its own set of transmitting and receiving instruments, will have power to give its own peculiar and independent signal or message. Apparently there is but one continuous current, but in reality each transmission is separated from the others by an almost inconceivably short interval of time.
Among the inventions in the class of Telegraphy should also be mentioned the dial and the printing systems. Ever since the electric telegraph was invented, attempts have been made to use the electric influence to operate either a pointer to point out the letters of the message sent on a dial, or to print them on a moving strip of paper; and also to automatically reproduce on paper the handwriting of the sender or writer of the message. The earliest efforts were by Cooke and Prof. Wheatstone of London, in 1836-37; but it was not until 1839, after Prof. Henry had succeeded in perfecting the electromagnet, that dial and printing telegraphs were successfully produced. Dial telegraphs consist of the combination with magnets, armatures and printed dial plate of a clock-work and a pointer, means to set the pointer at the communicating end (which in some instances has been a piano keyboard) to any letter, the current operating automatically to indicate the same letters at the receiving end. These instruments have been modified and improved by Brequet and Froment of France, Dr. Siemens and Kramer, and Siemens and Halske of Germany, Prof. Wheatstone of England, Chester and Hamblet of America, and others. They have been used extensively upon private and municipal lines both in Europe and the United States.
The type-printing telegraph was coeval with the dial, and originated with Morse and Vail as early as 1837. The printing of the characters is effected in various ways; sometimes by clockwork mechanism and sometimes by the direct action of an electromagnet. Wheatstone exhibited one in 1841. House of Vermont invented in 1845-1846 the first printing telegraph that was brought into any extensive use in the United States. Then followed that of David E. Hughes of Kentucky in 1855, aided by his co-inventor George M. Phelps of Troy, New York, and which was subsequently adopted by the French government, by the United Kingdom Telegraph Co. of Great Britain, and by the American Telegraph Co in the United States. The system was subsequently greatly improved by Hughes and others. Alexander Bain of Edinburgh in 1845-46 originated the modern automatic chemical telegraph. In this system a kind of punch was used to perforate two rows of holes grouped to represent letters on a strip of paper conducted over a metal cylinder and arranged so as to permit spring levers to drop through the perforations and touch the cylinder, thus forming an electrical contact; and a recording apparatus consisting of a strip of paper carried through a chemical solution of an acid and potash and over a metal roller, and underneath one or two styles, or pens, which pens were connected by live wires with the poles of two batteries at the sending station. The operation is such that colored marks upon the paper were made by the pens corresponding precisely to the perforations in the strip at the sending station. Siemens, Wheatstone and others also improved this system; but none of these systems have as yet replaced or equalled in extensive use the Morse key and sounder system, and its great acoustic advantage of reading the messages by the click of the instrument. The type-printing system, however, has been recently greatly improved by the inventions of Howe, C. L. Buckingham, Fiske and others in the United States. Special contrivances and adaptations of the telegraph for printing stock reports and for transmitting fire alarm, police, and emergency calls, have been invented.
The erection of tall office and other buildings, some to the height of more than twenty stories, made practicable by the invention of the elevator system, has in turn brought out most ingenious devices for operating and controlling the elevators to insure safety and at the same time produce economy in the motive power.
The utility of the telephone has been greatly increased by the inventions of Hughes and Edison of the microphone. This consists, in one form, of pieces of carbon in loose contact placed in the circuit of a telephone. The very slightest vibrations communicated to the wood are heard distinctly in the telephone. By these inventions and certain improvements not only every sound and note of an opera or concert has been carried to distant places, but the slightest whispers, the minute movements of a watch, even the tread of a fly, and the pressure of a finger, have been rendered audible.
By the aid of the electric current certain rays of light directed upon the mineral selenium, and some other substances, have been discovered to emit musical sounds.
So wonderful and mysterious appear these communications along the electric wire that each and every force in the universe seems to have a voice awaiting utterance to man. The hope is indulged that by some such means we may indeed yet receive the “touch of a vanished hand and the sound of a voice that is still.”
In 1879 that eminent English scientist, Prof. Wm. Crookes, published his extensive researches in electrical discharges as manifested in glass tubes from which the air had been exhausted. These same tubes have already been referred to as Geissler tubes, from the name of a young artist of Bonn who invented them. In these tubes are inclosed various gases through which the sparks from an induction coil can be passed by means of platinum electrodes fused into the glass, and on the passage of the current a soft and delicately-tinted light is produced which streams through the tube from pole to pole.
In 1895, Wm. Konrad Roentgen, professor of Physics in the Royal University of Würzburg, while experimenting with these Crookes and Geissler tubes, discovered with one of them, which he had covered with a sort of black cardboard, that the rays emanating from the same and impinging on certain objects would render them self-luminous, or fluorescent; and on further investigation that such rays, unlike the rays of sunlight, were not deflected, refracted or condensed; but that they proceeded in straight lines from the point at which they were produced, and penetrated various articles, such as flesh, blood, and muscle, and thicknesses of paper, cloth and leather, and other substances which are opaque to ordinary light; and that thus while penetrating such objects and rendering them luminous, if a portion of the same were of a character too dense to admit of the penetration, the dark shadow of such obstacle would appear in the otherwise luminous mass.
Unable to explain the nature or cause of this wonderful revelation, Roentgen gave to the light an algebraic name for the unknown—the X rays.
This wonderful discovery, at first regarded as a figment of scientific magic, soon attracted profound attention. At first the experiments were confined to the gratification of curiosity—the interior of the hand was explored, and on one occasion the little mummified hand of an Egyptian princess folded in death three or four thousand years ago, was held up to this light, and the bones, dried blood, and muscle of the ancient Pharaohs exhibited to the startled eyes of the present generation. But soon surgery and medicine took advantage of the unknown rays for practical purposes. The location of previously unreachable bullets, and the condition of internal injuries, were determined; the cause of concealed disease was traced, the living brain explored, and the pulsations of the living heart were witnessed.
Retardation of the strength of the electric current by the inductive influence of neighboring wires and earth currents, together with the theory that the electric energy pervades all space and matter, gave rise to the idea that if the energy once established could be set in motion at such point above the ordinary surface of the earth as would free this upper current from all inductive disturbance, impulses of such power might be conveyed from one high point and communicated to another as to produce signals without the use of a conducting wire, retaining only the usual batteries and the earth connection. On July 30th, 1872, Mahlen Loomis of Washington, D. C., took out a patent for “the utilization of natural electricity from elevated points” for telegraphic purposes, based on the principle mentioned, and made successful experiments on the Blue Ridge mountains in Virginia near Washington, accounts of which were published in Washington papers at the time; but being poor and receiving no aid or encouragement he was compelled to give it up. Marconi of Italy has been more successful in this direction, and has sent electric messages and signals from high stations over the English Channel from the shores of France to England. So that now wireless telegraphy is an established fact.
It is certainly thrilling to realize that there is a mysterious, silent, invisible and powerful mechanical agent on every side of us, waiting to do our bidding, and to lend a hand in every field of human labour, and yet unable to be so used without excitement to action and direction in its course by some master, intermediate between itself and man. The principal masters for this purpose are steam and water power. A small portion of the power of the resistless Niagara has been taken, diverted to turn the machinery which excites electricity to action, and this energy in turn employed to operate a multitude of the most powerful motors and machines of many descriptions.
So great is the might of this willing agent that at a single turn of the hand of man it rushes forth to do work for him far exceeding in wonder and extent any labour of the gods of mythological renown.
CHAPTER X.
HOISTING, CONVEYING AND STORING.
Allusion has been made to the stupendous buildings and works of the ancients and of the middle ages; the immense multitude of workers and great extent of time and labour employed in their construction; and how the awful drudgery involved in such undertakings was relieved by the invention of modern engineering devices—the cranes, the derricks, and the steam giants to operate them, so that vast loads which required large numbers of men and beasts to move, and long periods of time in which to move them, can now be lifted with ease and carried to great heights and distances in a few minutes by the hands of one or of a few men.
But outside of the line of such undertakings there is an immense field of labor-saving appliances adapted for use in transportation of smaller loads from place to place, within and without buildings, and for carrying people and freight from the lower to the upper stories of tall structures. In fact the tall buildings which we see now in almost every great city towering cloudward from the ground to the height of fifteen, twenty and twenty-five stories, would have been extravagant and useless had not the invention of the modern elevator rendered their highest parts as easy of access as their lowest, and at the same time given to the air space above the city lot as great a commercial value in feet and inches as the stretch of earth itself.
Many of the “sky-scrapers” so called, are splendid monuments of the latest inventions of the century.
It is by means of the modern elevator that the business of a whole town may be transacted under a single roof.
In the multiplicity of modern human contrivances by which the sweat and drudgery of life are saved, and time economised for worthier objects, we are apt to overlook the painful and laborious steps by which they were reached, and to regard with impatience, or at least with indifference, the story of their evolution; and yet no correct or profound knowledge of the growth of humanity to its higher planes can be obtained without noting to what extent the minor inventions, as well as the startling ones, have aided the upward progress.
For instance, consider how few and comparatively awkward were the mechanical means before this century. The innumerable army of men when men were slaves, and when blood and muscle and brain were cheap, who, labouring with the beast, toiled upward for years on inclined ways to lay the stones of the stupendous pyramids, still had their counterpart centuries later in the stream of men carrying on their shoulders the loads of grain and other freight and burdens from the shore to the holds of vessels, from vessels to the shore, from the ground to high buildings and from one part of great warehouses to another. Now look at a vessel moved to a wharf, capable of holding fifty thousand or one hundred thousand bushels of grain and having that amount poured into it in three hours from the spouts of an elevator, to which the grain has been carried in a myriad buckets on a chain by steam power in about the same time; or to those arrangements of carriers, travelling on ropes, cords, wires, or cables, by which materials are quickly conveyed from one part of some structure or place to another, as hay and grain in barns or mows, ores from mines to cars, merchandise of all kinds from one part of a great store to another; or shot through pipes underground from one section of a city or town to their destination by a current of air.
True, as it has before been stated, the ancients and later generations had the wedge, the pulley, the inclined plane, the screw and the windlass, and by these powers, modified in form and increased in size as the occasion demanded, in the form of cranes, derricks, and operated by animal power, materials were lifted and transported; but down to the time of the practical and successful application of steam by Watt in the latter part of the 18th century, and until a much later period in most places in the world, these simple means actuated alone by men or animals were the best means employed for elevating and conveying loads, and even they were employed to a comparatively limited extent.
The century was well started before it was common to employ cups on elevator bands in mills, invented by Oliver Evans in 1780, to carry grain to the top of the mill, from whence it was to fall by gravity to the grinding and flouring apparatus below. It was not until 1795 that that powerful modern apparatus—the hydraulic, or hydrostatic, press was patented by Bramah in England. The model he then made is now in the museum of the Commissioner of Patents, London. In this a reservoir for water is provided, on which is placed a pump having a piston rod worked by a hand lever. The water is conveyed from the reservoir to a cylinder by a pipe, and this cylinder is provided with a piston carrying at its top a table, which rises between guides. The load to be carried is placed on this table, and as the machine was at first designed to compress materials the load is pressed by the rising table against an upper stationary plate. The elevation of the table is proportionate to the quantity of water injected, and the power proportionate to the receptive areas of the pump and the cylinder. The first great application of machines built on this principle was by Robert Stephenson in the elevation of the gigantic tubes for the tubular bridge across the Menai straits, already described in the chapter on Civil Engineering. The century was half through with before it was proposed to use water and steam for passenger elevators.
In 1852 J. T. Slade in England patented a device consisting of a drum to be actuated by steam, water, or compressed air, around which drum ropes were wound, and to which ropes were attached separate cages in separate wells, to counterbalance each other, the cages moving in guides, and provided with brakes and levers to stop and control the cages and the movement of the drum. Louis T. Van Elvean, also of England, in 1858 invented counterbalance weights for such lifts. Otis, an American, invented and patented in America and England in 1859 the first approach to the modern passenger elevator for hotels, warehouses, and other structures. The motive power was preferably a steam engine; and the elevating means was a large screw placed vertically and made to revolve by suitable gearing, and a cylinder to which the car was attached, having projections to work in the threads of the screw. Means were provided to start and to stop the car, and to retard its otherwise sudden fall and stoppage.
Elevators, which are now so largely used to raise passengers and freight from the lower to the upper stories of high edifices, have for their motive power steam, water, compressed air, and electricity. With steam a drum is rotated over which a hoisting wire-rope is wound, to which the elevator car is attached. The car for passengers may be a small but elegantly furnished room, which is carried on guide blocks, and the stationary guides are provided with ratchet teeth with which pawls on the car are adapted to engage should the hoisting rope give way. To the hoisting rope is attached a counterbalance weight to partly meet the weight of the car in order to prevent the car from sticking fast on its passage, and also to prevent a sudden dropping of the car should the rope become slack. A hand rope for the operator is provided, which at its lower end is connected with a starting lever controlling the valves of the cylinders into which steam is admitted to start the piston shaft, which in turn actuates the gear wheels, by which movement the ropes are wound around the drums.
In another form of steam elevator the drums are turned in opposite directions, by right and left worms driven by a belt.
In the hydraulic form of elevator, a motor worked by water is employed to lift the car, although steam power is also employed to raise the water. The car is connected to wire cables passing over large sheaves at the top of the well room to a counterbalancing bucket. This bucket fits closely in a water-tight upright tube, or stand-pipe, about two feet in diameter, extending from the basement to the upper story. Near this stand-pipe in the upper story is placed a water supply tank. A pipe discharges the water from the tank into the bucket, which moves up and down in the stand pipe. There is a valve in the tank which is opened by stepping on a treadle in the car, and this action admits to the bucket just enough weight of water to overbalance the load on the car. As soon as the bucket is heavier than the car it descends, and of course draws the car upward, thus using the minimum power required to raise each load, rather than, when steam is employed, the full power of the engine each and every time. The speed is controlled by means of brakes or clamps that firmly clasp wrought-iron slides secured to posts on each side of the well room, the operator having control of these brakes by a lever on the car. When the car has ascended as far as desired, the operator steps upon another treadle in the car connected with a valve in the bottom of the bucket and thus discharges the water into the receiving tank below until the car is heavier than the bucket, when it then of course descends. The water is thus taken from the upper tank into the bucket, discharged through the stand-pipe into the receiving tank under the floor of the basement and then pumped back again to the upper tank, so that it is used over and over again without loss.
Various modifications have been made in the hydraulic forms. In place of steam, electricity was introduced to control the hydraulic operation. Again, an electric motor has been invented to be placed on the car itself, with connected gearing engaging rack bars in the well.
Elevators have been contrived automatically controlled by switch mechanisms on the landings; and in connection with the electric motor safety devices are used to break the motor circuit and thus stop the car the moment the elevator door is opened; and there are devices to break the circuit and stop the car at once, should an obstruction, the foot for instance, be accidentally thrust out into the path of the car frame. Columns of water and of air have been so arranged that should the car fall the fall will be broken by the water or air cushion made to yield gradually to the pressure. So many safety devices have been invented that there is now no excuse for accidents. They result by a criminal neglect of builders or engineers to provide themselves with such devices, or by a most ignorant or careless management and operation of simple actuating mechanisms.
Between 1880 and 1890 there was great activity in the invention of what is known as store service conveyors. One of the earliest forms, and one which had been partly selected from other arts, was to suspend from a rigid frame work connected to the floor, roof, or side of the building, a long platform in the direction through the building it was desired the road to run, giving this platform a slight inclination. On this platform were placed tracks, and from the tracks were suspended trucks, baskets, or other merchandise receptacles, having wheels resting on and adapted to roll on the tracks. Double or single tracks could be provided as desired. The cars ran on these tracks by gravity, and considerable ingenuity was displayed in the feature alone of providing the out-going and returning inclined tracks; in hand straps and levers for raising and lowering the carriage, part or all of it, to or from the tracks, and in buffers to break the force of the blow of the carriages when arriving at their stopping places.
Then about 1882-83 it was found by some inventors if moderately fine wires were stretched level, and as tight as possible, they would afford such little friction and resistance to light and nicely balanced wheels, that no inclination of the tracks was necessary, and that the carriages mounted on such wheels and tracks would run the entire length of a long building and turn corners not too sharp by a single initial push of the hand. In other arrangements a carrier is self-propelled by means of a coiled spring on the carrier, which begins its operation as soon as the carrier is given a start; and to meet the exhausted strength of such spring, coiled springs at different points on the line are arranged to engage and give the carrier an additional push. Before the carrier is stopped its action is such as to automatically rewind its spring.
A system of pneumatic transmission was invented, by which a carrier is caused to travel through a tube by the agency of an air current, created therein by an air compressor, blower, or similar device. The device is so arranged that the air current is caused to take either direction through the tube; and in some instances gravity may be used to assist a vacuum formed behind the carrier. The tube is controlled at each end by one or more sliding gates or valves, and the carrier is made to actuate the gates, and close the one behind it, so that the carrier may be discharged without permitting the escape of the air and consequent reduction of pressure.
An interesting invention has been made by James M. Dodge of Philadelphia in the line of conveyors, whereby pea coal and other quite heavy materials introduced by a hopper into a trough are subjected to a powerful air blast which pushes the material forward; and as the trough is provided with a series of frequently occurring slots or perforations open to the outer air and inclined opposite the direction of travel, the powerful current from the blower in escaping through such outlets tends to lift or buoy the material and carry it forward in the air current, thereby greatly reducing frictional contact and increasing the impelling operation. The inventor claims that with such an apparatus many tons of material per hour may be conveyed with a comparatively small working air pressure.
In order that a conveyor carriage may be automatically switched off at a certain place or station on the line, one mode adopted was to arrange at a gate or station a sort of pin or projection or other deflector to engage some recess or corresponding feature on the carriage, so as to arrest and turn the carriage in its new direction at that point. Another mode was the adoption of electro-magnets, which would operate at a certain place to arrest or divert the carriage; and in either case the carriage was so constructed that its engaging features would operate automatically only in conjunction with certain features at a particular place on the line.
Signals have been also adopted, in some cases operated by an electric current, by which the operator can determine whether or not the controlling devices have operated to stop the carrier at the desired place. By electric or mechanical means it is also provided that one or more loop branches may be connected with or disconnected from the main circuit.
The “lazy tongs” principle has been introduced, by which a long lazy-tongs is shot forth through a tube or box to carry forward the carriage; and the same principle is employed in fire-escapes to throw up a cage to a great height to a window or other point, which cage is lowered gently and safely by the same means to the ground. Buffers of all kinds have been devised to effect the stoppage of the carrier without injury thereto under the different degrees of force with which it is moved upon its way, to prevent rebounding, and to enable the carrier to be discharged with facility at the end of its route.
Among the early mechanical means of transporting the carriage was an endless cable moved continuously by an engine, and this adoption of cable principle in store service was co-eval with its adoption for running street cars. Also the system of switching the cars from the main line to a branch, and in different parts of a city, at the same time that all lines are receiving their motive power from the main line, corresponds to the manner of conveying cash to all parts of a building at the same time from many points.
To the great department store or monstrous building wherein, as we have said, the whole business of a town may be transacted, the assemblage and conjoint use of elevators and conveyors seem to be actually necessary.
A very useful and important line of inventions consists in means for forming connections between rotary shafts and their pulleys and mechanisms to be operated thereby, by which such mechanism can be started or stopped at once, or their motion reversed or retarded; or by which an actuating shaft may be automatically stopped. These means are known as clutches.
They are designed often to afford a yielding connection between the shaft and a machine which shall prevent excessive strain and wear upon starting of the shaft. They are also often provided with a spring connection, which, in the rotation of the shaft in either direction, will operate to relieve the strain upon the shaft, or shafts, and its driving motor. Safety clutches are numerous, by which the machine is quickly and automatically stopped by the action of electro-magnets should a workman or other obstruction be caught in the machinery.
Electric auxiliary mechanism has also been devised to start or stop the main machine slowly, and thus prevent injury to small or delicate parts of complicated machines, like printing presses for instance. Clutches are arranged sometimes in the form of weights, resembling the action of the weights in steam governors, whereby centrifugal action is relied upon for swinging the weights outward to effect a clutching and coupling of the shaft, or other mechanism, so that two lines of shafting are coupled, or the machine started, or speeded, at a certain time during the operation. In order to avoid the great mischief arising sometimes from undue strain upon and the breaking of a shaft, a weak coupling composed of a link is sometimes employed between the shaft and the driven machine, whereby, should the force become suddenly too great, the link of weaker metal is broken, and the connection between the shaft thereby destroyed and the machine stopped.
To this class of inventions, as well as to many others, the phrase, “labour-saving”, is applied as a descriptive term, and as it is a correct one in most instances, since they save the labour of many human hands, they are regarded by many as detrimental to a great extent, as they result in throwing out of employment a large number of persons.
This derangement does sometimes occur, but the curtailment of the number of labourers is but temporary after all.
The increased production of materials, resulting from cheaper and better processes, and from the reduced cost of handling them, necessitates the employment of a larger number of persons to take care of, in many ways, the greater output caused by the increased demand; the new machinery demands the labour of additional numbers in its manufacture; the increase in the size and heights of buildings involves new modes of construction and a greater number of artisans in their erection; new forms of industry springing from every practical invention which produces a new product or results in a new mode of operation, complicates the systems of labour, and creates a demand for a large number of employers and employees in new fields. Hence, it is only necessary to resort to comparative, statistics (too extensive to cite here) to show that the number of unemployed people in proportion to the populations, is less in the present age than in any previous one. In this sense, therefore, inventions should be classed as labour-increasing devices.
CHAPTER XI.
HYDRAULICS.
The science of Hydraulics appears to be as old as the thirst of man.
When prehistoric men had only stone implements, with which to do their work, they built aqueducts, reservoirs and deep wells which rival in extent many great similar works that are the boast of their modern descendants. Modern inventors have also produced with a flourish nice instrumentalities for raising water, agencies which are covered with the moss of untold centuries in China.
It was more than an ancient observation that came down to Pliny’s time for record, that water would rise to a level with its source. The observation, however, was put into practical use in his time and long before without a knowledge of its philosophical cause.
Nothing in Egyptian sculpture portraying the arts in vogue around the cradle of the human race is older than the long lever rocking upon a cleft stick, one arm of the lever carrying a bracket and the other arm used to raise a bucket from a well. Forty centuries and more have not rendered this device obsolete.
Among other machines of the Egyptians, the Carthaginians, the Greeks, and the Romans for raising water was the tympanum, a drum-shape wheel divided into radial partitions, chambers, or pockets, which were open to a short depth on the periphery of the wheel, and inclined toward the axis, and which was driven by animal or manual power. These pockets scooped up the water from the stream or pond in which the wheel was located as the wheel revolved, and directed it toward the axis of the wheel, where it ran out into troughs, pipes, or gutters. The Noria, a chain of pots, and the screw of Archimedes were other forms of ancient pumps. The bucket pumps with some modifications are known in modern times as scoop wheels, and have been used extensively in the drainage of lands, especially by the Dutch, who at first drove them by windmills and later by steam.
The division of water-wheels into overshot, undershot and breast wheels is not a modern system.
In the Pneumatics of Hero, which compilation of inventions appeared in 225 B. C., seventy-nine illustrations are given and described of simple machines, between sixty and seventy of which are hydraulic devices. Among these, are siphon pumps, the force pump of Ctesibius, a “fire-pump,” having two cylinders, and two pistons, valves, and levers. We have in a previous chapter referred to Hero’s steam engine. The fact that a vacuum may be created in a pump into which water will rise by atmospheric pressure appears to have been availed of but not explained or understood.
The employment of the rope, pulley and windlass to raise water was known to Hero and his countrymen as well as by the Chinese before them. The chain pump and other pumps of simple form have only been improved since Hero’s day in matters of detail. The screw of Archimedes has been extended in application as a carrier of water, and converted into a conveyor of many other materials.
Thus, aqueducts, reservoirs, water-wheels (used for grinding grain), simple forms of pumps, fountains, hydraulic organs, and a few other hydraulic devices, were known to ancient peoples, but their limited knowledge of the laws of pneumatics and their little mechanical skill prevented much general progress or extensive general use of such inventions.
It is said that Frontinus, a Roman Consul, and inspector of public fountains and aqueducts in the reigns of Nerva and Trajan, and who wrote a book, De Aquaeductibus Urbis Romae Commentarius, describing the great aqueducts of Rome, was the first and the last of the ancients to attempt a scientific investigation of the motions of liquids.
In 1593 Serviere, a Frenchman, born in Lyons, invented the rotary pump. In this the pistons consisted of two cog wheels, their leaves intermeshing, and rotated in an elliptical shaped chamber. The water entered the chamber from a lower pipe, and the action of the wheels was such as to carry the water around the chamber and force it out through an opposite upper pipe. Subsequent changes involved the rotating of the cylinder instead of the wheels and many modifications in the form of the wheels. The same principle was subsequently adopted in rotary steam engines.
In 1586, a few years before this invention of Serviere, Stevinus, the great engineer of the dikes of Holland, wrote learnedly on the Principles of Statics and Hydrostatics, and Whewell states that his treatment of the subject embraces most of the elementary science of hydraulics and hydrostatics of the present day. This was followed by the investigations and treatises of Galileo, his pupil Torricelli, who discovered the law of air pressure, the great French genius, Pascal, and Sir Isaac Newton, in the 17th century; and Daniel Bernoulli, d’Alembert, Euler, the great German mathematician and inventor of the centrifugal pump, the Abbé Bossut, Venturi, Eylewein, and others in the 18th century.
It was not until the 17th and 18th centuries that mankind departed much from the practice of supplying their towns and cities with water from distant springs, rivers and lakes, by pipes and aqueducts, and resorted to water distribution systems from towers and elevated reservoirs. Certain cities in Germany and France were the first to do this, followed in the 18th century by England. This seems strange, as to England, as in 1582 one Peter Maurice, a Dutch engineer, erected at London, on the old arched bridge across the Thames, a series of forcing pumps worked by undershot wheels placed in the current of the river, by which he forced a supply of water to the uppermost rooms of lofty buildings adjacent to the bridge. Before the inventions of Newcomen and Watt in the latter part of the 18th century of steam pumps, the lift and force pumps were operated by wheels in currents, by horses, and sometimes by the force of currents of common sewers.
When the waters of rivers adjacent to towns and cities thus began to be pumped for drinking purposes, strainers and filters of various kinds were invented of necessity. The first ones of which there is any printed record made their appearance in 1776.
After the principles of hydraulics had thus been reviewed and discussed by the philosophers of the 17th and 18th centuries and applied, to the extent indicated, further application of them was made, and especially for the propelling of vessels. In 1718 La Hire revived and improved the double-acting pump of Ctesibius, but to what extent he put it into use does not appear. However, it was the double-acting pump having two chambers and two valves, and in which the piston acted to throw the water out at each stroke.
In 1730 Dr. John Allen of England designed a vessel having a tunnel or pipe open at the stern thereof through which water was to be pumped into the air or sea—the reaction thus occasioned driving the vessel forward. He put such a vessel at work in a canal, working the pumps by manual labor, and suggested the employment of a steam engine. A vessel of this kind was patented by David Ramsey of England in 1738. Rumsey of America in 1782 also invented a similar vessel, built one 50 feet long, and ran it experimentally on the Potomac river. Dr. Franklin also planned a boat of this kind in 1785 and illustrated the same by sketches. His plan has since been tried on the Scheldt, but two turbines were substituted for his simple force pump. Further mention will be made later on of a few more elaborate inventions of this kind.
It also having been discovered that the fall of a column of water in a tube would cause a portion of it to rise higher than its source by reason of the force of momentum, a machine was devised by which successive impulses of this force were used, in combination with atmospheric pressure, to raise a portion of the water at each impulse. This was the well-known ram, and the first inventor of such a machine was John Whitehurst of Cheapside, England, who constructed one in 1772. From a reservoir, spring, or cistern of water, the water was discharged downward into a long pipe of small diameter, and from thence into a shorter pipe governed by a stop-cock. On the opening of the stop-cock the water was given a quick momentum, and on closing the cock water was forced by the continuing momentum through another pipe into an air chamber. A valve in the latter-mentioned pipe opened into the air chamber. The air pressure served to overcome the momentum and to close the chamber and at the same time forced the water received into the air chamber up an adjacent pipe. Another impulse was obtained and another injection of water into the chamber by again opening the stop-cock, and thus by successive impulses water was forced into the chamber and pressed by the air up through the discharge pipe and thence through a building or other receptacle. But the fact that the stop-valve had to be opened and closed by hand to obtain the desired number of lifts rendered the machine ineffective.
In 1796 Montgolfier, a Frenchman and one of the inventors of the balloon, substituted for the stop-cock of the Whitehurst machine a loose impulse valve in the waste pipe, whereby the valve was raised by the rush of the water, made to set itself, check the outflow and turn the current into the air chamber. This simple alteration changed the character of the machine entirely, rendered it automatic in action and converted it into a highly successful water-raising machine. For this invention Montgolfier obtained a Gold Medal from the French Exposition of 1802. Where a head can be had from four to six feet, water can be raised to the height of 30 feet. Bodies of water greater in amount than is desired to be raised can thus be utilised, and this simple machine has come into very extensive use during the present century.
Allusion was made in the last chapter to the powerful hydraulic press of Joseph Bramah invented in 1795-1800, its practical introduction in this century and improvements therein of others. After the great improvements in the steam engine made by Watt, water, steam and air pressure joined their forces on the threshold of this century to lift and move the world, as it had never been moved before.
The strong hands of hydraulics are pumps. They are divided into classes by names indicating their purpose and mode of operation, such as single, double-acting, lift or force, reciprocating or rotary, etc.
Knight, in his celebrated Mechanical Dictionary, enumerates 100 differently constructed pumps connected with the various arts. In a broader enumeration, under the head of Hydraulic Engineering and Engineering Devices, he gives a list of over 600 species. The number has since increased. About nine-tenths of these contrivances have been invented during the 19th century, although the philosophical principles of the operation of most of them had been previously discovered.
The important epochs in the invention of pumps, ending with the 18th century, were thus the single-acting pump of Ctesibius, 225 B. C., the double-acting of La Hire in 1718, the hydraulic ram of Whitehurst, 1772, and the hydraulic press of Bramah of 1795-1802.
Bramah’s press illustrates how the theories of one age often lie dormant, but if true become the practices of a succeeding age. Pascal, 150 years before Bramah’s time, had written this seeming hydraulic paradox: “If a vessel closed on all sides has two openings, the one a hundred times as large as the other, and if each be supplied with a piston which fits it exactly, then a man pushing the small piston will equilibrate that of 100 men pushing the piston which is 100 times as large, and will overcome the other 99.” This is the law of the hydraulic press, that intensity of pressure is everywhere the same.
The next important epoch was the invention of Forneyron in 1823, of the water-wheel known as the Turbine and also as the Vortex Wheel. If we will return a moment to the little steam engine of the ancient Hero of Alexandria, called the Eolipile, it will be remembered that the steam admitted into a pivoted vessel and out of it through little opposite pipes, having bent exits turned in contrary directions, caused the vessel to rotate by reason of the reaction of the steam against the pipes. In what is called Barker’s mill, brought out in the 18th century, substantially the same form of engine is seen with water substituted for the steam.
A turbine is a wheel usually placed horizontally to the water. The wheel is provided with curved internal buckets against which the water is led by outer curved passages, the guides and the buckets both curved in such manner that the water shall enter the wheel as nearly as possible without shock, and leave it with the least possible velocity, thereby utilising the greatest possible amount of energy.
In the chapter on Electrical inventions reference is made to the mighty power of Niagara used to actuate a great number of electrical and other machines of vast power. This utilisation had long been the dream of engineers. Sir William Siemens had said that the power of all the coal raised in the world would barely represent the power of Niagara. The dream has been realised, and the turbine is the apparatus through which the power of the harnessed giant is transmitted. A canal is dug from the river a mile above the falls. It conducts water to a power house near the falls. At the power house the canal is furnished with a gate, and with cribs to keep back the obstructions, such as sticks. At the gate is placed a vertical iron tube called a penstock, 7½ feet in diameter and 160 feet deep. At the bottom of the penstock is placed a turbine wheel fixed on a shaft, and to which shaft is connected an electric generator or other power machine. On opening the gate a mass of water 7½ feet in diameter falls upon the turbine wheel 160 feet below. The water rushing through the wheel turns it and its shaft many hundred revolutions a minute. All the machinery is of enormous power and dimensions. One electric generator there is 11 feet 7 inches in diameter and spins around at the rate of 250 revolutions a minute. Means are provided by which the speed of each wheel is regulated automatically. Each turbine in a penstock represents the power of 5,000 horses, and there are now ten or more employed.
After the water has done its work on the wheels it falls into a tunnel and is carried back to the river below the falls. Not only are the manufactures of various kinds of a large town at the falls thus supplied with power, but electric power is transmitted to distant towns and cities.
Turbine pumps of the Forneyron type have an outward flow; but another form, invented also by a Frenchman, Jonval, has a downward discharge, and others are oblique, double, combined turbine, rotary, and centrifugal, embodying similar principles. The term rotary, broadly speaking, includes turbine and centrifugal pumps. The centrifugal pump, invented by Euler in 1754, was taken up in the nineteenth century and greatly improved.
In the centrifugal pump of the ordinary form the water is received at the centre of the wheel and diverted and carried out in an upward direction, but in most of its modern forms derived from the turbine, the principle is adopted of so shaping the vanes that the water, striking them in the curved direction, shall not have its line of curvature suddenly changed.
Among modern inventions of this class of pumps was the “Massachusetts” of 1818 and McCarty’s, in 1830, of America, that of some contemporary French engineers, and subsequently in France the Appold system, which latter was brought into prominent notice at the London Exposition of 1851. Improvements of great value were also made by Prof. James Thompson of England.
Centrifugal pumps have been used with great success in lifting large bodies of water to a moderate height, and for draining marshes and other low lands.
Holland, Germany, France, England and America have, through some of their ablest hydraulic engineers and inventors, produced most remarkable results in these various forms of pumps. We have noted what has been done at Niagara with the turbines; and the drainage of the marshes of Italy, the lowlands of Holland, the fens of England and the swamps of Florida bear evidence of the value of kindred inventions.
That modern form of pump known as the injector, has many uses in the arts and manufactures. One of its most useful functions is to automatically supply steam boilers with water, and regulate the supply. It was the invention of Giffard, patented in England in 1858, and consists of a steam pipe leading from the boiler and having its nozzle projecting into an annular space which communicates with a feed pipe from a water supply. A jet of steam is discharged with force into this space, producing a vacuum, into which the water from the feed pipe rushes, and the condensed steam and water are driven by the momentum of the jet into a pipe leading into the boiler. This exceedingly useful apparatus has been improved and universally used wherever steam boilers are found. This idea of injecting a stream of steam or water to create or increase the flow of another stream has been applied in intensifiers, to increase the pressure of water in hydraulic mains, pipes, and machines, by additional pressure energy. Thus the water from an ordinary main may be given such an increased pressure that a jet from a hydrant may be carried to the tops of high houses.
In connection with pumping it may be said that a great deal has been discovered and invented during this century concerning the force and utilisation of jets of water and the force of water flowing through orifices. In the art of mining, a new system called hydraulicising has been introduced, by which jets of water at high pressure have been directed against banks and hills, which have crumbled, been washed away, and made to reveal any precious ore they have concealed.
To assist this operation flexible nozzles have been invented which permit the stream to be easily turned in any desired direction.
Returning to the idea of raising weights by hydraulic pressure, mention must be made of the recent invention of the hydraulic jack, a portable machine for raising loads, and which has displaced the older and less efficient screw jack. As an example of the practical utility of the hydraulic jack, about a half century ago it required the aid of 480 men working at capstans to raise the Luxor Obelisk in Paris, whilst within 30 years thereafter Cleopatra’s Needle, a heavier monument, was raised to its present position on the Thames embankment by four men each working one hydraulic jack.
By the high pressures, or stresses given by the hydraulic press it was learned that cold metals have plasticity and can be moulded or stretched like other plastic bodies. Thus in one modification a machine is had for making lead pipes:—A “container” is filled with molten lead and then allowed to cool. The container is then forced by the pump against an elongated die of the size of the pipe required. A pressure from one to two tons per square inch is exerted, the lead is forced up through the die, and the pipe comes out completed. Wrought iron and cold steel can be forced like wax into different forms, and a rod of steel may be drawn through a die to form a piano wire.
By another modification of the hydraulic press pipes and cables are covered with a coating of lead to prevent deterioration from rust and other causes.
Not only are cotton and other bulky materials pressed into small compass by hydraulic machines, but very valuable oils are pressed from cotton seed and from other materials—the seed being first softened, then made into cakes, and the cakes pressed.
If it is desired to line tunnels or other channels with a metal lining, shield or casing, large segments of iron to compose the casing are put in position, and as fast as the tunnel is excavated the casing is pressed forward, and when the digging is done the cast-iron tunnel is complete.
If the iron hoops on great casks are to be tightened the cask is set on the plate of a hydraulic press, the hoops connected to a series of steel arms projecting from an overhanging support, and the cask is pressed upward until the proper degree of tightness is secured.
In the application of hydraulic power to machine tools great advances have been made. It has become a system, in which Tweddle of England was a pioneer. The great force of water pressure combined with comparatively slow motion constitutes the basis of the system. Sir William Fairbairn had done with steam what Tweddle and others accomplished with water. Thus the enormous force of men and the fearful clatter formerly displayed in these huge works where the riveting of boilers was carried on can now be dispensed with, and in place of the noisy hammer with its ceaseless blows has come the steam or the hydraulic riveting machine, which noiselessly drives the rivet through any thickness of metal, clinches the same, and smooths the jointed plate. The forging and the rolling of the plates are performed by the same means.
William George Armstrong of England, afterward Sir William, first a lawyer, but with the strongest bearing toward mechanical subjects, performed a great work in the advancement of hydraulic engineering. It is claimed that he did for hydraulic machinery, in the storage and transmission of power thereby, what Watt did for the steam engine and Bessemer did for steel. In 1838 he produced his first invention, an important improvement in the hydraulic engine. In 1840, in a letter to the Mechanics’ Magazine, he calls attention to the advantages of water as a mechanical agent and a reservoir of power, and showed how water pumped to an elevated reservoir by a steam engine might have the potential energy thus stored utilised in many advantageous ways. How, for instance, a small engine pumping continuously could thus supply many large engines working intermittently. In illustration of this idea he invented a crane, which was erected on Newcastle quay in 1846; another was constructed on the Albert dock at Liverpool, and others at other places. These cranes, adapted for the lifting and carrying of enormous loads, were worked by hydraulic pressure obtained from elevated tanks or reservoirs, as above indicated. But as a substitute for such tanks or reservoirs he invented the Accumulator. This consists of a large cast-iron cylinder fitted with a plunger, which is made to work water-tight therein by means of suitable packing. To this plunger is attached a weighted case filled with one or many tons of metal or other coarse material. Water is pumped into the cylinder until the plunger is raised to its full height within the cylinder, when the supply of water is cut off by the automatic operation of a valve. When the cranes or other apparatus to be worked thereby are in operation, water is passed from the cylinder through a small pipe which actuates the crane through hydraulic pressure. This pressure of course depends upon the weight of the plunger. Thus a pressure of from 500 to 1,000 pounds per square inch may be obtained. The descending plunger maintains a constant pressure upon the water, and the water is only pumped into the cylinder when it is required to be filled. With sensitive accumulators of this character hydraulic machinery is much used on board ships for steering them, and for loading, discharging and storing cargoes.