Kitabı oku: «Inventions in the Century», sayfa 26
The ideas of William Thomson as to pneumatic and cushioned tires are now, after a lapse of fifty years, generally adopted. Even sportsmen were glad to seize upon them, and wheels of sulkies, provided with the pneumatic tires, have enabled them to lower the record of trotting horses. Their use on many other vehicles has accomplished his objects, "of lessening the power required to draw carriages, rendering the motion easier, and diminishing the noise."
It is impossible to overlook the fact in connection with this subject that the processes and machinery especially invented to make the various parts of a bicycle are as wonderful as the wheel itself. Counting the spokes there are, it is estimated, more than 300 different parts in such a wheel. The best and latest inventions and discoveries in the making of metals, wood, rubber and leather have been drawn upon in supplying these useful carriers. And what a revolution they have produced in the making of good roads, the saving of time, the dispatch of business, and more than all else, in the increase of the pleasure, the health and the amusement of mankind!
It was quite natural that when the rubber cushion and pneumatic tires rounded the pleasure of easy and noiseless riding in vehicles that Motor vehicles should be revived and improved. So we have the Automobiles in great variety. Invention has been and is still being greatly exercised as to the best motive power, in the adaption of electric motors, oil and gasoline or vapour engines, springs and air pumps, in attempts to reduce the number of complicated parts, and to render less strenuous the mental and muscular strain of the operator.
Traction Engines.– The old road engines that antedated the locomotives are being revived, and new ideas springing from other arts are being incorporated in these useful machines to render them more available than in former generations. Many of the principles and features of motor vehicles, but on a heavier scale, are being introduced to adapt them to the drawing of far heavier loads. Late devices comprise a spring link between the power and the traction wheel to prevent too sudden a start, and permit a yielding motion; steering devices by which the power of the engine is used to steer the machine; and application of convenient and easily-worked brakes.
An example of a modern traction engine may be found attached to one or more heavy cars adapted for street work, and on which may be found apparatus for making the mixed materials of which the roadbed is to be constructed, and all of which is moved along as the road or street surface is completed. When these fine roads become the possession of a country light traction engines for passenger traffic will be found largely supplanting the horse and the steam railroad engines.
Brakes, railway and electric, have already been referred to in the proper chapters. In the latest system of railroading greater attention has been paid to the lives and limbs of those employed as workmen on the trains, especially to those of brakemen. And if corporations have been slow to adopt such merciful devices, legislatures have stepped in to help the matter. One great source of accidents in this respect has been due to the necessity of the brakemen entering between the cars while they are in motion to couple them by hand. This is now being abolished by automatic couplers, by which, when the locking means have been withdrawn from connection or thrown up, they will be so held until the cars meet again, when the locking parts on the respective cars will be automatically thrown and locked, as easily and on the same principle as the hand of one man may clasp the hand of another.
The comfort of passengers and the safety of freight have also been greatly increased by the invention of Buffers on railroad cars and trains to prevent sudden and violent concussion. Fluid pressure car buffers, in which a constant supply of fluid under pressure is provided by a pump or train pipe connected to the engine is one of a great variety.
Another notable improvement in this line is the splendid vestibule trains, in which the cars are connected to one another by enclosed passages and which at their meeting ends are provided with yieldingly supported door-like frames engaging one another by frictional contact, usually, whereby the shock and rocking of cars are prevented in starting and stopping, and their oscillation reduced to a minimum.
As collisions and accidents cannot always be prevented, car frames are now built in which the frames are trussed, and made of rolled steel plates, angles, and channels, whereby a car body of great resistance to telescoping or crushing is obtained.
CHAPTER XXIX.
SHIPS AND SHIP-BUILDING
"Far as the breeze can bear, the billows foam,
Survey our empire, and behold our home."
"Ships are but boards," soliloquised the crafty Shylock, and were this still true, yet this present period has seen wonderful changes in construction.
The high castellated bows and sterns and long prows of The Great Harry, of the seventeenth century, and its successors in the eighteenth, with some moderation of cumbersome matter, gave way to lighter, speedier forms, first appearing in the quick-gliding Yankee clippers, during the first decade of the nineteenth century.
Eminent naval architects have regarded the proportions of Noah's ark, 300 cubits long, 50 cubits broad and 30 cubits high, in which the length was six times the breadth, and the depth three-fifths of the breadth, as the best combination of the elements of strength, capacity and stability.
Even that most modern mercantile vessel known as the "whale-back" with its nearly flat bottom, vertical sides, arched top or deck, skegged or spoon-shaped at bow and stern, straight deck lines, the upper deck cabins and steering gear raised on hollow turrets, with machinery and cargo in the main hull, has not departed much from the safe rule of proportions of its ancient prototype.
But in other respects the ideas of Noah and of the Phœnicians, the best of ancient ship-builders, as well as the Northmen, the Dutch, the French, and the English, the best ship-builders of later centuries, were decidedly improved upon by the Americans, who, as above intimated, were revolutionizing the art and building the finest vessels in the early part of the century, and these rivalled in speed the steam vessels for some years after steamships were ploughing the rivers and the ocean.
Discarding the lofty decks fore and aft and ponderous topsides, the principal characteristics of the American "clippers" were their fine sharp lines, built long and low, broad of beam before the centre, sharp above the water, and deep aft. A typical vessel of this sort was the clipper ship Great Republic, built by Donald McKay of Boston during the first half of the century. She was 325 feet long, 53 feet wide, 37 feet deep, with a capacity of about 4000 tons. She had four masts, each provided with a lightning rod. A single suit of her sails consisted of 15,563 yards of canvas. Her keel rose for 60 feet forward, gradually curved into the arc of a circle as it blended with the stern. Vessels of her type ran seventeen and eighteen miles an hour at a time when steam vessels were making only twelve or fourteen miles an hour, the latter speed being one which it was predicted by naval engineers could not with safety be exceeded with ocean steamships.
These vessels directed the attention of ship-builders to two prominent features, the shape of the bow and the length of the vessel. For the old convex form of bow and stern, the principal of an elongated wedge was substituted, the wedge slightly hollowed on its face, by which the waters were more easily parted and thrown aside.
A departure was early made in the matter of strengthening the "ribs of oak" to better meet the strains from the rough seas. In 1810 Sir Robert Seppings, surveyor of the English navy, devised and introduced the system of diagonal bracing. This was an arrangement of timbers crossing the ribs on the inside of the ship at angles of about 45°, and braced by diagonals and struts.
Of course the great and leading event of the nineteenth century in the matter of inventions relating to ships was the introduction of steam as the motive power. Of this we have treated in the chapter on steam engineering. The giant, steam, demanded and received the obeisance of every art before devoting his inexhaustible strength to their service. Systems of wood-working and metal manufacture must be revolutionised to give him room to work, and to withstand the strokes of his mighty arm. Lord Dundas at the beginning of the century had an iron boat built for the Forth and Clyde Canal, which was propelled by steam.
But the departure from the adage that "ships are but boards" did not take place, however, until about 1829-30, when the substitution of iron for wood in the construction of vessels had passed beyond the experimental stage. In those years the firm of John Laird of Birkenhead began the building of practical iron vessels, and he was followed soon by Sir William Fairbairn at Manchester, and Randolph, Elder & Co., and the Fairfield Works on the Clyde.
The advantage of iron over wood in strength, and in power to withstand tremendous shocks, was early illustrated in the Great Britain built about 1844, the first large, successful, seagoing vessel constructed. Not long thereafter this same vessel lay helpless upon the coast of Ireland, driven there by a great storm, and beaten by the tremendous waves of the Atlantic with a force that would have in a few hours or days broken up and pulverised a "ship of boards," and yet the Great Britain lay there several weeks, was finally brought off, and again restored to successful service.
Wood and iron both have their peculiar advantages and disadvantages. Wood is not only lighter, but easily procured and worked, and cheaper, in many small and private ship-yards where an iron frame and parts would be difficult and expensive to produce. It is thought that as to the fouling of ships' bottoms a wooden hull covered with copper fouls less, and consequently impedes the speed less; that the damage done by shocks or the penetration of shot is not so great or difficult to repair, and that the danger of variation of the compass by reason of local attraction of the metal is less.
But the advantages of iron and steel far outnumber those of wood. Its strength, its adaptability for all sizes and forms and lines, its increased cheapness, its resistance to shot penetration, its durability, and now its easy procurement, constitute qualities which have established iron ship-building as a great new and modern art. In this modern revolution in iron-clad ships, their adaptation to naval warfare was due to the genius of John Ericsson, and dates practically from the celebrated battle between the iron-clads the Merrimac and the Monitor in Hampton Roads on the Virginia coast in the Civil war in America in April, 1862.
Although the tendency at first in building iron and steel vessels, especially for the navy, was towards an entire metal structure, later experience resulted in a more composite style, using wood in some parts, where found best adapted by its capacity of lightness, non-absorption of heat and less electrical conductivity, etc., and at the same time protecting such interior portions by an iron shell or frame-work.
One great improvement in ship-building, whether in wood or metal, thought of and practised to some extent in former times, but after all a child of this century, is the building of the hull and hold in compartments, water-tight, and sometimes fire-proof, so that in case of a leakage or a fire in one or more compartments, the fire or water may be confined there and the extension of the danger to the entire ship prevented.
In the matter of Marine Propulsion, when the steam engine was made a practical and useful servant by Watt, and men began to think of driving boats and ships with it, the problem was how to adapt it to use with propelling means already known. Paddle-wheels and other wheels to move boats in place of oars had been suggested, and to some extent used from time to time, since the days of the Romans; and they were among the first devices used in steam vessels. Their whirl may still be heard on many waters. Learned men saw no reason why the screw of Archimedes should not be used for the same purpose, and the idea was occasionally advocated by French and English philosophers from at least 1680, by Franklin and Watt less than a century later, and finally, in 1794, Lyttleton of England obtained a patent for his "aquatic propeller," consisting of threads formed on a cylinder and revolving in a frame at the head, stern, or side of a vessel.
Other means had been also suggested prior to 1800, and by the same set of philosophers, and experimentally used by practical builders, such as steam-pumps for receiving the water forward, or amidships, and forcing it out astern, thus creating a propulsive movement. The latter part of the eighteenth century teemed with these suggestions and experiments, but it remained for the nineteenth to see their embodiment and adaptation to successful commercial use.
The earliest, most successful demonstrations of screw propellers and paddle wheels in steam vessels in the century were the construction and use of a boat with twin screws by Col. John Stevens of Hoboken, N. J., in 1804 and the paddle-wheel steamboat trial of Fulton on the Hudson in 1807.
But it was left to John Ericsson, that great Swedish inventor, going to England in 1826 with his brain full of ideas as to steam and solar engines, to first perfect the screw-propeller. He there patented in 1836 his celebrated propeller, consisting of several blades or segments of a screw, and based on such correct principles of twist that they were at once adopted and applied to steam vessels.
In 1837-1839 the knowledge of his inventions had preceded him to America, where his propeller was at once introduced and used in the vessels Frances B. Ogden and the Robert E. Stockton (the latter built by the Lairds of Birkenhead and launched in 1837). In 1839 or 1840 Ericsson went to America, and in 1841 he was engaged in the construction of the U.S. ship of war Princeton, the first naval screw warship built having propelling machinery under the water line and out of reach of shot.
The idea that steamships could not be safely run at a greater speed than ten or twelve miles an hour was now abandoned.
Twice Ericsson revolutionised the naval construction of the world by his inventions in America: first by the introduction of his screw-propeller in the Princeton; and second, by building the iron-clad Monitor.
Since Ericsson's day other inventors have made themselves also famous by giving new twists to the tail of this famous fish and new forms to its iron-ribbed body.
Pneumatic Propellers operated by the expulsion of air or gas against the surrounding body of water, and chain-propellers, consisting of a revolving chain provided with paddles or floats, have also been invented and tested, with more or less successful results.
A great warship as she lies in some one of the vast modern ship-yards of the world, resting securely on her long steel backbone, from which great ribs of steel rise and curve on either side and far overhead, like a monstrous skeleton of some huge animal that the sea alone can produce, clothed with a skin, also of steel; her huge interior, lined at bottom with an armoured deck that stretches across the entire breadth of the vessel, and built upon this deck, capacious steel compartments enclosing the engines and boilers, the coal, the magazines, the electric plant for supplying power to various motors for lighting the ship and for furnishing the current to powerful search-lights; having compartments for the sick, the apothecary shop, and the surgeon's hospital, the men's and the officers' quarters; above these the conning tower and the armoured pilot-house, then the great guns interspersed among these various parts, looking like the sunken eyes, or protruding like the bony prominences of some awful sea monster, is a structure that gives one an idea of the immense departure which has occurred during the last half century, not only from the wooden walls of the navies of all the past, but from all its mechanical arts.
What a great ocean liner contains and what the contributions are to modern ship-building from other modern arts is set forth in the following extract from McClure's Magazine for September, 1900, in describing the Deutschland. "The Deutschland, for instance has a complete refrigerating plant, four hospitals, a safety deposit vault for the immense quantities of gold and silver which pass between the banks of Europe and America, eight kitchens, a complete post-office with German and American clerks, thirty electrical motors, thirty-six pumps, most of them of American and English make, no fewer than seventy-two steam engines, a complete drug store, a complete fire department, with pumps, hose and other fire-fighting machinery, a library, 2600 electric lights, two barber shops, room for an orchestra and brass band, a telegraph system, a telephone system, a complete printing establishment, a photographic dark room, a cigar store, an electric fire-alarm system, and a special refrigerator for flowers."
We have seen, in treating of safes and locks, how burglars keep pace with the latest inventions to protect property by the use of dynamite and nitro-glycerine explosions. The reverse of this practice prevails when those policemen of the seas, the torpedo boats, guard the treasures of the shore. It is there the defenders are armed with the irresistible explosives. These explosives are either planted in harbours and discharged by electricity from the shore, or carried by very swift armoured boats, or by boats capable of being submerged, directed, and propelled by mechanisms contained there and controlled from the shore, or from another vessel; or by boats containing all instrumentalities, crew, and commander, and capable of submerging and raising itself, and of attacking and exploding the torpedo when and where desired. The latter are now considered as the most formidable and efficient class of destroyers.
No matter how staunch, sound and grand in dimensions man may build his ships, old Neptune can still toss them. But Franklin, a century and a half ago, called attention to his experiments of oiling his locks when in a tempestuous mood, and thus rendering the temper of the Old Man of the Sea as placid as a summer pond. Ships that had become unmanageable were thus enabled, by spreading oil on the waves from the windward side, to be brought under control, and dangerous surfs subdued, so that boats could land. Franklin's idea of pouring oil on the troubled waters has been revived during the last quarter of the century and various means for doing it vigorously patented. The means have varied in many instances, but chiefly consist of bags and other receptacles to hold and distribute the oil upon the surrounding water with economy and uniformity.
At the close of the century the world was still waiting for the successful Air-ship.
A few successful experiments in balloon navigation by the aid of small engines of different forms have been made since 1855. Some believe that Count Zeppelin, an officer of the German army has solved the great problem, especially since the ascent of his ship made on July 2, 1900, at Lake Constance.
It has been asserted that no vessel has yet been made to successfully fly unless made on the balloon principle, and Count Zeppelin's boat is on that principle. According to the description of Eugen Wolf, an aeronaut who took part in the ascent referred to and who published an account of the same in the November number of McClure's, 1900, it is not composed of one balloon, but of a row of them, and these are not exposed when inflated to every breeze that blows, but enclosed and combined in an enormous cylindrical shell, 420 feet in length, about 38 feet in diameter, with a volume of 14,780 cubic yards and with ends pointed like a cigar. This shell is a framework made up of aluminium trellis work, and divided into seventeen compartments, each having its own gas bag. The frame is further strengthened and the balloons stayed by a network of aluminium wire, and the entire frame covered with a soft ramie fibre. Over this is placed a water-tight covering of pegamoid, and the lower part covered with light silk. An air space of two feet is left between the cover and the balloons. Beneath the balloons extends a walking bridge 226 feet long, and from this bridge is suspended two aluminium cars, at front and rear of the centre, adapted to hold all the operative machinery and the operator and other passengers.
The balloons, provided with proper valves, served to lift the structure; large four-winged screws, one on each side of the ship, their shafts mounted on a light framework extending from the body of the ship, and driven backward and forward by two light benzine engines, one on each car, constituted the propelling force. Dirigibility (steering) was provided for by an apparatus consisting of a double pair of rudders, one pair forward and one aft, reaching out like great fins, and controlled by light metal cords from the cars. A ballast of water was carried in a compartment under each car. To give the ship an upward or a downward movement the plane on which the ship rests was provided with a weight adapted to slip back and forth on a cable underneath the balloon shell. When the weight was far aft the tip of the ship was upward and the movement was upward, when at the forward end the movement was downward, and when at the centre the ship was poised and travelled in a horizontal plane. The trip was made over the lake on a quiet evening. A distance of three and three-quarter miles, at a height of 1300 feet, was made in seventeen minutes. Evolutions from a straight course were accomplished. The ship was lowered to the lake, on which it settled easily and rode smoothly.
The other great plan of air navigation receiving the attention of scientists and aeronauts is the aeroplane system. Although the cohesive force of the air is so exceedingly small that it cannot be relied upon as a sufficient resisting medium through which propulsion may be accomplished alone by a counter-resisting agent like propeller blades, yet it is known what weight the air has and it has been ascertained what expanse of a thin plane is necessary without other means to support the weight of a man in the air.
To this idea must be added the means of flight, of starting and maintaining a stable flight and of directing its course. Careful observation of the manner of the flight of large heavy birds, especially in starting, has led to some successful experiments. They do not rise at once, but require an initiative force for soaring which they obtain by running on the ground before spreading their wings. The action of the wings in folding and unfolding for maintaining the flight and controlling its direction, is then to be noted.
It is along these lines that inventions in this system are now working. An initiative mechanism to start the ship along the earth or water, to raise it at an angle, to spread planes of sufficient extent to support the weight of the machine and its operators on the body of the air column, light engines to give the wing-planes an opening and closing action, rudders to steer by, means for maintaining equilibrium, and means when landing to float upon the water or roll upon the land, these are the principal problems that navigators of the great seas above us are now at work upon.
