 Section 20 of the romance of modern mechanism. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by Tina Ding. The romance of modern mechanism by Arch Bald Williams. Chapter 17. Mechanical Transporters and Conveyors. Mechanical Conveyors, Rope Waste, Cable Waste, Talfridge, Coaling Worships at Sea. A man carrying a sack of coal over a plank laid from the wall to the ship's side, a bricklayer's laborer moving slowly up a ladder with his hat of motor, these illustrate the most primitive methods of shifting material from one spot to another. When the wheelbarrow is used in the one case and the rope and pulley in the other, an advance has been made, but the effort is still great in proportion to the work accomplished. And were such processes universal in the great industries connected with mining and manufacture, the labor bill would be ruinous. The development of methods of transportation has gone on simultaneously with the improvement of machinery of all kinds. To be successful, an industry must be conducted economically throughout, thus to follow the history of wheat from the time that it is selected for sowing till it forms a loaf, we see it mechanically placed in the ground, mechanically reaped, threshed and dressed, mechanically hauled to the elevator, mechanically transferred to the bins of the same, mechanically shot into trucks or a ship, mechanically raised into a flour mill where it is cleaned, ground, weighed, packed and trucked by machinery, mechanically mixed with yeast and baked and possibly distributed by mechanically operated vehicles. As a result, we get a two pound loaf for less than three pence. Anyone who thinks that the price is regulated merely by the amount of wheat grown is greatly mistaken for the cheapness of handling and transportation conduces at least equally to the cheapness of the finished article. The same may be said of the metal articles with which every house is furnished. A fender would be dearer than it is were not the iron ore cheaply transported from mine to rail, from rail to the smelting furnace, from the ground to the top of a furnace. In short, to whatever industry we look in which large quantities of raw or finished material have to be moved, stored and distributed, the mechanical conveyor has supplanted human labor to such an extent that in lack of such devices, we can scarcely conceive how the industry could be conducted without either proving ruinous to the people who controlled it or enhancing prices enormously. The types of elevators and conveyors now commonly used in all parts of the world are so numerous that in the following pages only some selected examples can be treated. Speaking broadly, the mechanical transporter can be classified under two main hats. One, those which handle materials continuously as in the case of belt conveyors, pneumatic grain dischargers, etc. And two, those which work intermittently such as the telfer which carries skips on an aerial ropeway. The first class are most useful for short distances, the latter for longer distances, or where the conditions are such that the material must be transported in large masses at a time by powerful grabs. Some transporters work only in a vertical direction, others only horizontally, while a third large section combine the two movements. Again, while some are mere conveyors of materials shut into or attached to them, others scoop up their loads as they move. The distinctions in detail are numerous and will be brought out in the chapters devoted to the various types. Mechanical conveyors, we have already noticed banned conveyors in connection with the transportation of grain. They are also used for handling coal, coke, diamond dirt, gold ore, and other minerals, and for moving filled sex. The belts are sometimes made of rubber or of belada faced with rubber on the upper surface, which has to stand most of the wear and tear, sometimes of metal plates joined together by hinges at the ends. A modification of the belt is the continuous trough with sloping or vertical sides. This is built of open ended sections joined so that they may pass round the terminal rollers. While traveling in a straight line, the sides of the sections touch, preventing any escape of the material carried, but at the rollers the ends open in a V shape. Another form of conveyor has a stationary trough through which the substance to be handled is pulled along by plates attached to cables or endless chains running on rollers. Or, the moving agency may be plates dragged backwards and forwards periodically, or plates hanging in one direction only like flat delfs so as to pass over the material during the backwards stroke and bite it during the forward stroke. The vibrating conveyor is a trough which moves bodily backwards and forwards on hinged supports, the oscillation gradually shaking its contents along. While no dragging or pushing plates are here needed, this form of conveyor is very suitable for materials which are liable to be injured by rough treatment. Rope weighs. A certain person on asking what was the distance from X to Y received the reply. It is 10 miles as the crow flies. The country being mountainous, the answer did not satisfy him. And he said, Oh, but you see, I'm not a crow. Engineers laying out a railway can sympathize with this gentleman for they know from sad experience that places only a few miles apart in a straight line often require a track many miles long to connect them if gradients are to be kept moderate. Now, a locomotive, a railway carriage or a goods truck is very heavy and must run on the firm bosom of Mother Earth. But for comparatively light bodies, a path may be made which much more nearly resembles the proverbial flight of the crow, or, as our American cousins will say, a beeline. If you have traveled in Norway and Switzerland, you probably have noticed here and there steel wire ropes spanning a torrent or hanging across a narrow valley. Over these ropes, the peasants shoot their hay crops or wood faggots from the mountainside to their homes, or to a point near a road where the material can be transferred to carts. Adventurers folk even dare to entrust their own bodies to the seemingly frail steel thread using a break to control the velocity of the descent. The history of the modern ropeway and cableway dates from the 30s when the invention of wire rope supplied a flexible carrying agent of great strength in proportion to its weight and a sufficient hardness to resist much wear and tear and too inelastic to stretch under repeated stresses. To prevent confusion, we may at once state that a ropeway is an aerial track used only for the conveyance of material, whereas a cableway hoists as well as conveys. A further distinction, though it does not hold good in all cases, may be seen in the fact that while cableways are off a single span, ropeways are carried for distances ranging up to 20 miles over towers or poles placed at convenient intervals. Ropeways fall into two main classes. First, those in which the rope supporting the weight of the thing carried moves. Secondly, those in which the carrier rope is stationary and the skips or tups et cetera are dragged along it by a second rope. The moving rope system is best adapted for light loads not exceeding 600 weight or so, but over the second class, bodies scaling 5 or 6 tons have often been moved. In both systems, the line may be single or double according to the amount of traffic which it has to accommodate. The chief advantage of the double ropeway is that it permits a continuous service and an economy of power since in cases where material has to be delivered at a lower level than the point at which it is shipped. The weight of the descending full trucks can be utilized to haul up ascending empty trucks. Spans of 2000 feet or two-fifths of a mile are not at all unusual in a very rough country where the spots on which supports can be erected are few and far between. But engineers naturally endeavor to make the span as short as possible in order to be able to use a small size of rope. Glancing at some interesting ropeways, we may first notice that used in the construction of the new beachy head lighthouse recently erected on the foreshore below the head on which the original structure stands. For the sake of convenience, the workshops, storage yards, etc., were placed on the cliffs 400 feet above the sea and some 800 feet in the direct line from the site of the new lighthouse. Between the cliff summit and a staging in the sea were stretched two huge steel ropes, the one six inches in circumference for the track over which the four ton blocks of granite used in the building, machinery, tools, etc., should be lowered. The other five and a half inches in circumference for the return of the carriers and trucks containing workmen. The ropes had a breaking strain of 120 and 100 tons respectively. That is to say, if put in a hydraulic testing machine, they would have withstood poles equal to those exerted by masses of these weights hung on them. Their top ends were anchored in solid rock, their lower ends to a mass of concrete built up in the chalk forming the sea bottom. When a granite block was attached to the carrier traveling on the rope, its weight was gradually transferred to the rope by lowering the truck on which it had arrived until the ladder was clear of the block. As soon as the stone started on its journey, the truck was lifted again to the level of the rails and trundled away. A breaksman stationed at a point when he could command the whole rope way had under his hand the brake wheels regulating the movements of the trailing ropes for lowering and hauling on the two tracks. Another interesting rope way is that at Hong Kong, which transports the workmen in a sugar factory on the low fever breeding levels to their homes in the hills where they may sleep secure from noxious microbes. The carriers accommodate six men at a time and move at the rate of eight miles an hour. The sensation of being hauled through mid-air must be an exhilarating one and some of us will not mind changing places with the workmen for a trip or two reassured by the fact that this rope way has been in operation for several years without any accident. In southern India, in the enamelized hills, a rope way is used for delivering sawn timber from the forest to a point one and a quarter miles below. Prior to the establishment of this rope way, the locks were sent down a securities mountain track on bullet carts. Its erection was a matter of great difficulty on the count of the steep gradients and the dense and unhealthy forest through which a path had to be cut, not to mention the dragging uphill of a cable which, with the reel on which it was wound, weighed four tons. For this last operation, the combined strength of nine elephants and a number of coollies had to be requisitioned since the friction of the rope dragging on the ground was enormous. However, the engineers soon had the cable stretched over its supports and the winding machinery in place at the top of the grade. The single rope serves for both up and down traffic, a central crossing station being provided at which the descending can pass the ascending carrier. Seven sleepers at a time are sent flying down the track at a rate of 20 miles an hour, a load departing every half hour. The saving of labor, time and expense is set to be very great and when the sawmills have a larger output, the economy of working will be still more remarkable. The longest passenger ropeway ever built is probably that over the Chilcout Pass in Alaska, which was constructed in 1897 and 1898 to transport miners from Daya to Crater Lake on their way to the Yukon Goldfields. From Crater Lake to the Klondike, the Yukon River serves as a natural road, but the climb to its headwaters was a matter of great difficulty, especially during the winter months and accompanied by much suffering. But when the trestles had been erected for the fixed ropes to a number, miners and their kits were hauled over the seven miles at little physical cost, though naturally the charges for transportation ruled higher than in less rugged regions. The opening of the White Pass Railway from Skagway has largely abolished the need for this cable track, which has nevertheless done very useful work. The Chilcout ropeway has at least two spans of over 1500 feet. As an engineering enterprise, it claims our consideration, since the conveyance of ropes, timber, engines, etc., into so inhospitable a region, and the piecing of them together demanded great persistence on the part of the engineers and their employees. Cableways. For removing the overburden of service mines and dumping it in suitable places, for excavating canals, for dredging, and for many other operations in which matter has to be moved comparatively short distances, the cableway is largely employed. We have already noticed that it differs from the ropeway in that it has to hoist and discharge its burdens as well as convey them. The cableway generally consists of a single span between two towers, which are either fixed or movable on rails according to the requirements of the work to be done. In addition to the main cable which bears the weight and the rope which moves the skips along it, the cableway has the fall rope which lowers the skip to the ground and raises it, the dumping rope which discharges it, and the button rope which pulls blocks off the horn of the skip truck at intervals as the ladder moves to support the fall rope from the main cable. If the fall rope sagged, its weight would, after a certain amount had been paid out, overcome the weight of the skip and render it impossible to lower the skip to the filling point. So a series of fall rope carriers are at the commencement of a journey from one end of the cableway, riding on an arm in front of the skip carriage. The button rope passing under a pulley on the top of the skip carriage is furnished at intervals with buttons of a size increasing towards the point at which the skip must be lowered. The holes in the carriers are similarly graduated so as to pass over any button, but the one intended to arrest them. If we watched a skip traveling to the lowering point, we should notice that the carriers were successively pulled off the skip carriage by the buttons and strung along over the main cable and under the fall rope. When the skip has been lowered and filled, the fall and hauling ropes are wound in. The skip rises to the main cable and begins to travel towards the dumping point. As long as the dumping rope is also hauled in at the same rate as the hauling rope, it has no effect on the skip. But when its rate of travel is increased by moving it onto a larger winding drum, the skip is tipped or opened as the case may be without being arrested. The skip may be filled by hand or made self-filling where circumstances permit. The cableway is so economical in its working that it has greatly advanced the process of open pit mining. Where ore lies near the surface, it is desirable to remove the useless overlying matter called overburton bodily and to convey it right away in preference to sinking shallow shafts with their attendant drawbacks of timbering and pumping. An inclined railway is handicapped by the fact that it must occupy some of the surface to be uncovered while liable to blockage by the debris of blasting operations. The suspended cableway neither obstructs anything nor can be obstructed and is profitably employed when a ton of ore is laid bare for every four tons of overburton removed. In the case of the Tilly Foster Mine, New York, where the removal of 300,000 tons of rock exposed 600,000 tons of ore from an excavation 450 feet long by 300 feet wide, the saving affected by the cableway was enormous. Again, referring to the Chicago drainage canal, the records show that while laborers sludging and filling into cars averaged only 7 to 8.5 cubic yards per man per day in filling into skips for the cableways, the laborers averaged from 12 to 17 cubic yards per day. The first cableway erected by the Ligerwood Manufacturing Company for the prosecution of this engineering work handled 10,821 cubic yards a month and proved so successful that 19 similar plants were added. The cableways are suspended in this instance from two towers moving on parallel tracks on each bank of the canal and the towers being heavily belasted on the outer sides of their bases to counteract the pull of the cable. From time to time, when a length had been cleared, the towers were moved forward by engines hauling on fixed anchors. The cableway is much used in the erection of masonry piers for bridges across rivers or valleys. Materials are conveyed by it rapidly and easily to points over the piers and lowered into position. Spans of over 1,500 feet have been exceeded for such purposes and if neat B spans of 2,000 feet could be made to carry loads of 25 tons at a rate of 20 miles an hour. Telforage. On most ropeways, the skips or other conveyances are moved along the fixed ropes by trailing ropes working round drums driven by steam and controlled by brakes. But the employment of electricity has provided a system called Telforage in which the vehicle carries its own motor fed by current from the rope on which it runs and from auxiliary cables suspended a short distance above the main rope. Telfor is a term derived from two Greek words signifying a far carrier since the motor so named will move any distance so long as a track and current is supplied to it. The carrier for ore, coal, earth, barrels, sacks, timber, etc. is suspended from the Telfor by the usual hook shaped support common to ropeways to enable the load to pass the arms of the post or trestles bearing the rope. The Telfor usually has two motors, one placed on each side of a two wheeled carriage so as to balance but sometimes only a single motor is employed. Just above the running cable is the trolley cable from which the Telfor picks up current through a hinged arm after the manner of an electric tram. The carriers are controlled on steep grades by an electric braking device which acts automatically its effect varying with the speed at which the Telfor runs. The carrier wheels driven by the motors adhere to the cable without slipping on grades as severe as three in ten even when the surface has been moistened by rain. In order to stop the Telfor at any desired point the trolley wire is divided into a number of sections each controlled by a switch conveniently located. By opening a switch the current is cut off from the corresponding section and the Telfor will stop when it reaches this point. It is again started by closing the switch. At curves a section of the trolley wire that is overhead cable for current is connected to the source of current through a resistance which lowers the voltage pressure of the current across the motors at this point. Thus upon approaching a curve the Telfor automatically slows down runs slowly around the curve until it passes the resistance section and is then automatically accelerated. The Telfor line is very useful for transporting material considerable distances in districts where it would not pay to construct a surface railway. On plantations it serves admirably to shift grain, fruits, tobacco and other agricultural products. Then again a wide field is open to it for transmitting light articles such as castings and parts of machinery from one part of the foundry or manufactory to another or from factory to vessel or truck for shipment. When coal has to be handled the buckets are dumped automatically into bins. The Telfor has much the same advantages over the steamworked ropeway that an electric tram has over one moved by an endless cable. Its control is easier, there is less friction and the speed is higher. And in common with ropeways it can claim independence of obstructions on the ground and the ability to cross ravines with ease which in the case of a railway will have to be bridged at great expense. Coaling warships at sea. The war between Russia and Japan has brought prominently before the public the necessity of being able to keep a war vessel well supplied with coal. A task by no means easy when coaling stations are few and far between. The voyage of Admiral Rozda Zvinsky from Russia to eastern waters was marked by occasions on which he entered neutral ports to draw supplies for his furnaces. Though we know that colliers sailed with the warships to replenish their exhausted bunkers. In the old days of sailing vessels their motive power even if fitful was inexhaustible. But now that steam reigns supreme as the mover of the world's floating forts the problem of keeping the sea has become in one way very much more complicated. The radius of a vessel's action is limited by the capacity of her coal bunkers. Her captain in wartime would be perpetually perplexed by the question of fuel since movement is essential to naval success. While any misjudged fast steaming in pursuit of the enemy might render his ship an inert mass incapable of motion because the coal supplies had given out or at least might compel him to return for supplies to the nearest port at a slow speed. Losing valuable time just as a competitor in the long distance race takes his nourishment without halting so should a battleship be able to coal on the wing. The task of transferring so many tons of the mineral from one ship's hole to that of another may seem easy enough to the inexperienced critic and under favorable conditions it might not be attended by great difficulty. Why, someone may say, you have only to bring the Collier alongside the warship, make her fast and heave out the coals. In a perfect calm this might be feasible but let the slightest swell arise and then how the sides of the two craft would bump together with dire results to the weaker party. Actual tests have shown this. At present, Brotsite Coaling is considered impracticable but the from bold to stern method has passed through its initial stages and after many failures has reached a point of considerable efficiency. The difficulties in transferring coal from a Collier to a warship by which she is being told will be apparent after very little reflection. In the first place, there is the danger of the cableway and its load dipping into the water. Should the distance between the two vessels be suddenly diminished and the corresponding danger of the cable snapping should the pitching of the vessels increase the distance between the terminals of the cableway. These difficulties have made it impossible to merely shoot coals down a rope attached high up a mast of the Collier and to the deck of the warship. What is evidently needed is some system which shall pay the cableway out or take it in automatically so as to counterbalance any lengthening or shortening movement of the vessels. The Ligger Wood Manufacturing Company of New York under the direction of Mr. Spencer Miller have brought out a cableway specially adapted for marine work. The two vessels concerned are attached by a stout tow line, the Collier of course being in the rear. To carry the load a single endless wire rope, three eighth inch in diameter and two thousand feet long is employed. It spans the distance between Collier and ship twice giving an inward track for full sacks and an outward track for their return to the Collier. On one vessel are two winches, the drums of which both turn in the same direction, but while one drum is rigidly attached to its axle, the other slips under a stress greater than that needed to keep the rope sufficiently taut. Since the rope passes round a pulley at the other terminal, pressure placed at any point on the rope will tend to tighten both tracks while a slackening at any point would similarly ease them. Supposing then that the ships suddenly approach, there will be a certain amount of slack at once wound in. If on the other hand the ships draw apart, the slipping drum will pay out rope sufficient to supply the need. The constant slipping of this drum sets up great heat which is dissipated by currents of air. As the sacks of coal arrive on the men of war, they are automatically detached from the cable and fall down a chute into the hole. In the temporally miller marine cableway, the load is carried on the main cable kept taut by a friction drum and the hauling is done by an endless rope which has its own separate winches. In actual tests made at sea in rough weather, 60 tons per hour have been transferred, the vessels moving at from 4 to 8 miles an hour. End of Section 20 Section 21 of The Romance of Modern Mechanism This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. The Romance of Modern Mechanism by Archibald Williams Chapter 18. Automatic Wayers Scarcely less important than the rapid transference of materials from one place to another is the quick and accurate weighing of the same. If a pneumatic grain elevator were used in conjunction with an ordinary set of scales such as are to be found at a corn dealers, there would be great delay and the advantage of the elevator would largely be lost. Similarly, a mechanical transporter of coal or ore should automatically register the tonnage of the material handled to prevent undue waste of time. There are in existence many types of automatic weighing machines, the general principles of which vary with the nature of the commodity to be weighed. Finally divided substances such as grain, seeds, and sugar are usually handled by hopper-wayers. The grain, etc., is passed into a bin from the bottom of which it flows into a large pan. When the proper unit of weight, a hundred weight, or a ton, has nearly been attained, the flow is automatically throttled so that it may be more exactly controlled, and as soon as the full amount has passed, the machine closes the hopper door and tips the pan over. The ladder delivers its contents and returns to its original position while the door above is simultaneously opened for the operation to be repeated. Accounting apparatus records the number of tips so that a glance suffices to learn how much material has passed through the weigher, which may be locked up and allowed to look after itself for hours to gather. The Kronos automatic grain scale is built in many sizes for charges of from twelve to three thousand three hundred pounds of grain and tips five times a minute. Avery's grain weigher takes up to five and a half tons at a time. For materials of a lumpy nature such as coal and ore, a different method is generally used. The hopper process would not be absolutely accurate since the rate of feed cannot be exactly controlled when dust and large lumps weighing half a hundred weight or more are all jumbled together. Therefore, instead of a pan which tips automatically as soon as it has received a fixed weight, we find a bin which, when a quantity roughly equal to the correct amount has been let in, sinks on to a weigher and has its contents registered by an automatic counter, which continuously adds up the total of a number of weighings and displays it on a dial. So that if there be ten pounds in excess of a ton at the first charge, the dial records one ton and keeps the ten pounds up its sleeve against the next weighing, to which the excess is added. Avery's mineral scale works, however, on much the same principle as that for grain already noticed, a special device being fitted to render the feed to the weighing pan as regular as possible. His weigher is used to feed mechanical furnace stokers. The quantity of coal used can thus be checked while an automatic apparatus prevents the stoker bunkers from being overfilled. Continuous weighers register the amount carried by a conveyor while in motion. The recording apparatus comes into action at fixed intervals. For example, as soon as the conveyor has moved ten feet. The weighing mechanism is practically part of the conveyor and takes the weight of ten feet. The steel yard is adjusted to exactly counterbalance the unloaded belt or skips of its length, but rises in proportion to the load. As soon as the conveyor has traveled ten feet, the weight on the machine is immediately recorded and the steel yard returns to zero. Intermittent weighers record the weight of trucks or tubs passing over a railway or the cables of aerial track, the weigher forming part of the track and coming into play as soon as the load is fully on it. Some machines not only weigh material, but also stow and pack it. We find a good instance in Timewell's sacking apparatus which weighs corn, chaff, flour, oatmeal, rice, coffee, etc., transfers it to sacks and sows the sack up automatically. The amount of time saved by such a machine must be very great. Note, the author desires to express his indebtedness to Mr. George F. Zimmers, the mechanical handling of material, for some of the information contained in the above chapter, and to the publishers, Messers A, Crosby, Lockwood, and Son, for permission to make use of the same. End of section 21. Section 22 of The Romance of Modern Mechanism. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by Betty B. The Romance of Modern Mechanism by Archibald Williams. Transporter Bridges When the writer was in Rouen in 1898, two lofty iron towers were being constructed by the Seine. The one on the quai du Havre, the other on the quai Capelier, which borders the river on the side of the suburb, Saint Severe. The towers rose so far towards the sky that one had to throw one's head very far back to watch the workmen perched on the summit of the framework. What were the towers for? They seemed much too slender for the peers of an ordinary suspension bridge fit to carry heavy traffic. An inquiry produced the information that they were the first installment of a trans-bordeur or transporter bridge. What is a bridge of this kind? Well, it may best be described as a very lofty suspension bridge, the girder of which is far above the water to allow the passage of masted ships. The suspended girder serves only as the runway for a truck from which a traveling car hangs by stout steel ropes, the bottom of the car being but a few feet above the water. The truck is carried across from tower to tower, either by electric motors or by cables operated by steam power. The transporter bridge in a primitive form has existed for some centuries, but its present design is a very modern growth. With the increase of population has come an increased need for uninterrupted communication. Where rivers intervene they must be bridged and we see a steady growth in the number of bridges in London, Paris, New York and other large towns. Unfortunately, a bridge while joining land to land separates water from water and the dislocation of river traffic might not be compensated by the convenience is given to land traffic. The fourth, Brooklyn, Saltash and other bridges have therefore been built of such a height as to leave sufficient headroom under the girders for the masts of the tallest ships. But what money they have cost? And even the tower bridge with its hinged bascules or leaves and bridges with centers revolving horizontally devour large sums. Wanted therefore an efficient means of transport across a river which though not costly to install shall offer a good service and not impede river traffic. Thirty years ago, Mr. Charles Smith, a Hartlepool engineer, designed a bridge at the transporter type for crossing the tees at Middlesbrough. The bridge was not built because people feared that the towers would not stand the buffets of the northeasterly gales. The idea promulgated by an Englishman was taken up by foreign engineers who have erected bridges in Spain, Tunis and France. So successful has this type of ferry bridge proved that it is now receiving recognition in the land of its birth and at the present time transporter bridges are nearing completion in Wales and on the Mersey. The first transborder built was that spanning the Nervion, a river flowing into the Bay of Biscay near Bilbao, a Spanish town famous for the great deposits of iron ore close by. A pair of towers rises on each bank to a height of 240 feet and carry a suspended trust girder 530 feet long at a level of 150 feet above high water mark. The car, giving accommodation for 200 passengers, it does not handle vehicles, hangs on the end of cables 130 feet long and is propelled by a steam engine situated in one of the towers. Motion is controlled by the car conductor who is connected electrically with the engine room. The lofty towers are supported on the landward side by stout steel ropes firmly anchored in the ground. These ropes are carried over the girder in the familiar curve of the suspension bridge and attached to it at regular intervals by vertical steel braces. The cost of the bridge, 32,000 pounds, compares favorably with that of any alternative non-traffic blocking scheme and the graceful airy lines of the erection are by no means a blot on the landscape. The second transborder is that of Rouen, already referred to. Its span is rather less, 467 feet, but the suspension girder lies higher by 14 feet. The car is 42 feet long by 36 broad and weighs with a full load 60 tons. A passage which occupies 55 seconds costs one penny first class, one half penny second class, while a vehicle and horses pay two and a half pence to four pence according to weight. The car is propelled by electricity under the control of a man in the conning tower perched on the roof. At Biserta, we find the third flying ferry, which connects that town with Tunis over a narrow channel between the Mediterranean Sea and two inland lakes. It replaced a steam ferry, which had done duty for about 10 years. The lakes being an anchorage for war vessels, it was imperative that any bridge over the straits should not interrupt free ingress and egress. This bridge has a span of 500 feet and like that at Bilbao is worked by steam. Light as the structure appears, it has withstood a cyclone which did great damage in the neighborhood. It is reported that the French government has decided to remove the bridge to some other port because its prominence would make it serve as a range finder for an enemy's cannon in time of war. Its place would be taken either by a floating bridge or by a submarine tunnel. The nought transporter over the Loire differs from its fellows in one respect, these that it is built on the cantilever or balanced principle. Instead of a single girder spanning the space between the towers, it has three girders, the two end ones being balanced on the towers and anchored at their landward extremities by vertical cables. That between them is bridged by a third girder of bow shape, which is stiff enough in itself to need no central support. The mode of power is electricity. All these structures will soon be eclipsed by two English bridges, the one over the Usk at Newport, Monmouthshire, the other over the Mersey and Manchester Ship Canal at Runcorn Gap, where the river narrows to 1,200 feet. The first of these has towers 250 feet high and 685 feet apart. The girders will give 170 feet headroom above high watermark. 500 passengers will be able to travel at one time on the car, besides a number of road vehicles, and as the passage is calculated to take only one minute, the average velocity will exceed 8 miles an hour. The cost has been set down at 65,000 pounds, or about one-thirtieth that of a suspension bridge, and one-third that of a bascule bridge. The bridge is being built by the French engineers responsible for the Rouen transporteur. Coming to the much more imposing Runcorn Bridge, we find even these figures exceeded. This span is 1,000 feet in length. The designer, Mr. John J. Webster, has already made a name with the Great Wheel, which at Earl's Court London has given many thousands of pleasure seekers an aerial trip above the roofs of the metropolis. The following account by Mr. W. G. Archer in the magazine of Commerce describes this mammoth of its kind in some detail. The two main towers carrying the cables and the stiffening girders are built, one on the south side of the ship canal, and the other on the foreshore on the north bank of the river. And the approaches consist of new roadways, nearly flat, built between stone and concrete retaining walls, as far as the water's edge, and a corrugated steel flooring upon which are laid the timber blocks on concrete, resting on steel, elliptical girders, and cast-iron columns. The roadway in front of the towers is widened out to 70 feet for marshalling the traffic and for providing space for waiting rooms, etc. The towers are constructed wholly of steel, rise 190 feet above high water level, and are bolted firmly to the cast-iron cylinders below. Each tower consists of four legs, spaced 30 feet apart at the base, and each pair of towers are 70 feet apart and are braced together with strong, horizontal, and diagonal frames. Each of the two main cables consists of 19 steel ropes bound together, each rope being built up of 127 wires, 0.16 inches in diameter. The ends of the cable backstays are anchored into the solid rock on each side of the river, about 30 feet from the rock surface. The weight of the main cables is about 243 tons, and from them are suspended two longitudinal stiffening girders, 18 feet deep, and placed 35 feet apart horizontally, the underside of the girders being 82 feet above the level of high water. Upon the lower flange of the stiffening girders are fixed the rails upon which runs the traveler, from which is suspended the car. The traveler is 77 feet long and is carried by 16 wheels on each rail. It is propelled by two electric motors of about 35 horsepower each. The car will be capable of holding at one time four large wagons and 300 passengers, the latter being protected from the weather by a glazed shelter. The time occupied by the car and crossing will be two and one quarter minutes. So, allowing for the time spent in loading and unloading, it will be capable of making nine or ten trips per hour. This bridge, when completed, will have the largest span of any bridge in the United Kingdom designed for carrying road traffic. The clear space over the Mersey and Ship Canal being 1,000 feet. The total cost of the structure, including parliamentary expenses, will be about 150,000 pounds. Mr. Archer adds that, in spite of prophecies of disastrous collisions between transporter cars and passing ships, there has up to date been no accident of any kind. To those in search of a new sensation, the experience of skimming swiftly a few feet above the water may be recommended. End of section 22. Section 23 of the Romance of Modern Mechanism. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. The Romance of Modern Mechanism by Archibald Williams. Chapter 20. Boat and Ship Raising Lifts. In modern locomotion, whether by land or water, it becomes increasingly necessary to keep the way unobstructed where traffic is confined to the narrow limits of a pair of rails, a road, or a canal channel. We widen our roads, we double and quadruple our rails. Canals are, as a rule, not alterable except at immense cost, and if, in the first instance, they were not built broad enough for the work that they are afterwards called upon to do, much of their business must pass to rival methods of transportation. Modern canals, such as the Manchester and Kiel canals, were given generous proportions to start with as their purpose was to pass ocean-going ships, and for many years it will not be necessary to enlarge them. The Suez Canal has been widened in recent years by means of dredgers, which easily scoop out the sandy soil through which it runs and deposit it on the banks. But the Corinth Canal, cut through solid rock, cannot be thus economically expanded, and as a result it has proved a commercial failure. Even if a canal be of full capacity in its channel way, there are points at which its traffic is throttled. However gently the country it traverses may slope, there must occur at intervals the necessity of making a lock for transferring vessels from one level to the other. Sometimes the ascent or descent is affected by a series of steps, or flight of locks, on account of the magnitude of the fall, and in such cases the loss of time becomes a serious addition to the cost of transport. In several instances engineers have got over the difficulty by ingenious hydraulic lifts, which in a few minutes pass a boat through a perpendicular distance of many feet. At Anderton, where the Trent and Mersey Canal meets the Weaver Navigation, barges up to 100 tons displacement are raised 50 feet. Two troughs, each weighing with their contents 240 tons, are carried by two cast iron rams placed under their centers, the cylinders of which are connected by piping. When both troughs are full the pressure on the rams is equal and no movement results, but if six inches of water be transferred from one to the other the heavier at once forces up the lighter. At Fontenet's, on the Nuffauts Canal in France, at La Louvier in Belgium and at Peterborough in Canada, similar installations are found, the last handling vessels of 400 tons through a rise of 65 feet. Fine engineering feats as these are, they do not equal the canal lift on the Dortmund-M's Canal, which puts Dortmund in direct water communication with the Elbe, and opens the coal and iron deposits of the Rhine and Upper Silesia to the busy manufacturing district lying between these two localities. About 10 miles from its eastern extremity, the main reach of the canal forks off at Heinrichenburg, from the northward branch running to Dortmund, its level being on the average some 49 feet lower than the branch. For the transference of boats and up and down line of four locks each would have been needed, and apart from the inevitable two hours delay for locking, this method would have entailed the loss of a great quantity of precious water. Mr. Archer Dau, a prominent engineer of Dusseldorf-Graphenburg, therefore suggested an hydraulic lift which should accommodate boats of 700 tons and pass them from one level to the other in five minutes. This scheme was approved and has recently been completed. The principle of the lift is as follows. A trough 233 feet long rests on five vertical supports, themselves carried by as many hollow cylindrical floats moving up and down in deep wells full of water. The buoyancy of the five floats is just equal to the combined weight of the trough and its load, so that a comparatively small force causes the ladder to rise or fall as required. By letting off water from the trough, which is of course furnished with doors to seal its ends, it would be made to ascend, while the addition of a few tons would cause a descent. But this would mean waste of water, and where the trough not otherwise governed, a serious accident might happen if a float sprang a leak. Motion is therefore imparted to the trough by four huge vertical screws, resting on solid masonry piers and turning in large collars attached to the trough near its corners. All the screws work in unison through gearing, as they are sufficiently stout to bear the whole load. Even where the floats removed, no tilting or sudden fall is possible. The screws are driven by an electric motor of 150 horsepower, perched on the girders joining the tops of four steel towers, which act as guides for the trough to move in, while they absorb all wind pressure. Under normal circumstances, the trough rises or sinks at a speed of four inches per second. The total mass in motion, trough, water, boat, and floats, is 3,100 tons. Our ideas of a float do not ordinarily rise above the small cork which we take with us when we go fishing, or at the most, above a buoy which bobs up and down to mark a fair way. These five floats, so called, belong to a very much larger class of creations, each is 30 feet across inside and 46 and a half feet high. Their wells, 138 feet deep, are lined with concrete nearly a yard thick to ensure absolute water tightness inside the stout iron casings which rise 82 feet above the bottom. In view of the immense weight which they have to carry, the piers under the screw spindles are extremely solid. At its base, each measures 14 feet by 12 feet 4 inches and tapers upwards for 36 feet, till these dimensions have contracted to 8 feet 10 inches by 6 feet 6 inches. The spindles, 80 feet long and 11 inches in diameter, must be four of the largest screws in existence. To make it absolutely certain that they contained no flaws, a 4 inch central hole was drilled through them logitunally, another considerable workshop feat. If shafts of such length were left unsupported when the trough was at its highest point, there would be danger of their bending and breaking. And they are, therefore, provided with four sliding collars each, connected each to its fellow by a rod. When the trough has risen a fifth of its travel, the first rod lifts the first collar, which moves in the guide pillars. This in turn raises the second, the second, the third, and so on, so that by the time the trough is fully raised, each spindle is kept in line by four intermediate supports. The trough, 233 feet long by 34 and a half feet wide, will receive a vessel 223 feet long between perpendiculars. It has a rectangular section and is built up of stout plates laid on strong cross girders, all carried by a single huge logitunal girder resting on the float columns. One of the most difficult problems inseparable from a structure of this kind is the provision of a watertight joint between the trough and the upper and lower reaches of the canal. At each end of the trough is a sliding door faced in its outer edges with India rubber, which the pressure of the water inside holds tightly against flanges when pressure on the outside is removed. The termination of the canal reaches have similar doors, but as it would be impossible to arrange things so accurately that the two sets of flanges should be watertight, a wedge shaped like a big U and faced on both sides with rubber is interposed. The wedge at the lower reach gate is thickest at the bottom, the upper wedge the reverse, so that the trough in both cases jams it tight as it comes to rest. The wedges can be raised or lowered in accordance with the fluctuations of the canals. After thus briefly outlining the main constructional features of the lift, let us watch a boat pass through from the lower to the upper level. It is a steamer of 600 tons burden, quite a formidable craft to meet so far inland. While some distance away it blows a warning whistle and the motor man at his post moves a lever which sets the screw in motion. The trough sinks until it has reached the proper level when the current is automatically broken and it sinks no further. Its travel is thus controllable to within three sixteenths of an inch. An interlocking arrangement makes it impossible to open the trough or reach gates until the trough has settled or risen to the level of the water outside. On the other hand, the motor driving the lifting screws cannot be started until the gates have been closed so that an accidental flooding of the countryside is amply provided against. A man now turns the crank of a winch on the canal bank and unlocks the canal gate. A second twist couples the gates between the canal and the trough together and starts the lifting motors overhead, which raise the 28 ton mass 23 feet clear of the water level. The boat enters. The doors are lowered and uncoupled. The reach gate is locked. The spindle motor now starts. Up she goes and the process of coupling and raising gates is repeated before she is released into the upper reach. From start to finish the transfer occupies about five minutes. If a boat is not self-propelled, electric capstons help it to enter and leave the trough. Such a vessel could not be passed through in less than twenty minutes. Putting on one side the shipped dry docks, which can raise a 15,000 ton vessel clear of the sea, the Dortmund hydraulic lift is the largest lift in the world, and the novelty of its design will, it is hoped, render the above account acceptable to the reader. Before leaving the subject, another canal lift may be noticed, that on the Grand Junction Canal at Foxton Lestershire, which has replaced a system of ten locks to raise barges through a height of 75 feet. The new method is the invention of Messers G and CBJ Thomas. In principle, it consists of an inclined railway having eight rails, four for the up and as many for the down traffic. On each set of four rails runs a tank mounted on eight wheels, which is connected with a similar tank on the other set by seven inch steel wire ropes passing round winding drums at the top of the incline. The tanks are thus balanced. At the foot of the incline, a barge which has to ascend is floated into whichever tank may be ready to receive it, and the end gate is closed. An engine is then started, and the laden tank slides broadside on up the 300 foot slope. The summit being reached, the tank gates are brought into register with those of the upper reach, and as soon as they have been opened, the boat floats out into the upper canal. Boats of 70 tons can be thus transferred in about 12 minutes at a cost of but a few pence each. On a busy day, 6,000 tons are handled. The rider has treated one form of lift for raising ships out of the water, the floating dry dock, elsewhere, so his remarks in this place will be confined to mechanism which, having its foundations on Mother Earth, heaves mighty vessels out of their proper element by the force of hydraulic pressure. Looking round for a good example of an hydraulic ship lift, we select that of the Union ironworks San Francisco. Some years ago the works were moved from the heart of the city to the edge of Mission Bay with the object of carrying on a large business in marine engineering and shipbuilding. For such a purpose, a dry dock, which in a short time will lift a vessel clear of the water for cleaning or repairs, is of great importance to both owners and workmen. By the courtesy of the proprietors of Cassier's magazine, we are allowed to append the following account of this interesting lift. The site available for a dock at the Union ironworks was a mud flat. The depth of soft mud, being from 80 to 90 feet, would render the working of a graving dock, i.e. one dug out of the ground and pumped dry when the entrance doors have been closed, very disagreeable. As such docks, where much mud is carried in with the water, require a long time to be cleaned and to dry out. Plans were therefore prepared by Mr. George W. Dickey for an hydraulic dock, including an automatic control, which the designer felt confident would meet all the requirements of the situation, and which, after careful consideration, the Union ironworks decided to build. Work was begun in January 1886, and the dock was opened for business on June 15, 1887, a very fine record. This dock consists of a platform built of cross and longitudinal steel girders, 62 feet wide and 440 feet long, having keel blocks and siding bilge blocks upon which the ship to be lifted rests. The lifting power is generated by a set of 4 steam driven, single acting horizontal plunger pumps, the diameter of the plungers being 3.5 inches, and the stroke 36 inches. 40 strokes per minute is the regular speed. There is a weighted accumulator or regulator connected with the pumps, the throttle valve of the engines being controlled by the accumulator. The load on the accumulator consists of a number of flat discs of metal, the first one about 14 inches thick, and the other is about 4 inches thick, the diameter being about 4 feet. The first disc gives a pressure of 300 pounds per square inch. This is sufficient to lift the dock platform without a ship, and is always kept on. In lifting a ship as she comes out of the water and gets heavier on the platform, additional discs are taken on by the accumulator ram as required. The discs are suspended by pins on the side, catching into links of a chain. The engineer, to take on another disc, unhooks the throttle from the accumulator rod, runs the engine a little above the normal speed, the accumulator rises and takes the weight of the disc to be added. The link carrying that disc is thus relieved and is withdrawn. The engineer again hooks the accumulator rod to the engine throttle and the hole is self-acting again until another weight is required. When all the discs are on the ram, the full pressure of 1,100 pounds per square inch is reached, which enables a ship of 4,000 tons weight to be raised. There are 18 hydraulic rams on each side of the dock. These rams are each 30 inches in diameter and have a stroke of 16 feet. And as the platform rises 2 feet for one foot movement of the rams, the total vertical movement of the platform is 32 feet. When lowered to the lowest limit, there are 22 feet of water over the keel blocks at high tide. The foundations consist of 72 cylinders of iron, which extend from the top girders to several feet below the mudline. These cylinders are driven full of piles, no pile being shorter than 90 feet. The cylinders are to protect the piles from the tornado, the timber-boring worm, which is very destructive in San Francisco harbor. A heavy cast-iron cap completes each of the foundation piers, and two heavy steel girders extend the full length of the dock on each side, resting on the foundation piers and uniting them all longitudinally. The hydraulic cylinders are carried by large castings resting on the girders, each having a central opening to receive a cylinder, which passes down between the piers. There are 36 foundation piers and 18 hydraulic cylinders on each side of the dock. On the top of each hydraulic ram is a heavy sheave or pulley 6 feet in diameter, over which pass 8 steel cables 2 inches in diameter, making in all 288 cables. One end of each cable is anchored in the bed plates supporting the hydraulic cylinders, while the other end is secured to the side girders of the platform. Each of the cables has been tested with a load of 80 tons, so that the total test load for the ropes has been 21,000 tons. In lifting a ship, the load is never evenly distributed on the platform. There is, in fact, often more than one ship on the platform at once. Some rams, therefore, may have a full load and others much less. Under these conditions, to keep the platform a true plane, irrespective of the irregular distribution of the load, Dr. Dickey designed a special valve gear to make the action of the dock perfectly automatic. Down each side of the dock, a shaft is carried, operated by a special engine in the powerhouse. At each hydraulic ram, this shaft carries a worm, gearing with a worm wheel on a vertical screw, extending the full height reached by the stroke of the ram. The screw works in a nut on the end of a lever, the other end of which is attached to the ram. Between the two points of support, a rod working the valves, also carried by the ram, engages with the lever. If at a given moment the screw end is raised, say six inches, the lever opens the valve. As the ram rises, the lever, having its other end similarly lifted by the rise, gradually assumes a horizontal position and the valve closes. To lift the dock, the engine working the valve shaft is started, and with it the operating screws. These, through the levers, open the inlet valves. The rams now begin to move up. If anyone has a light load, it will move up ahead of the other, but in doing so it lifts the other end of the lever and closes the valve. In fact, the screws are continually opening the valves while the motion of the rams is continually closing them, so that no ram can move ahead of its screw, and the speed of the screw determines the rate of movement of the lifting platform. To lower the dock, the engine operating the valve shaft is reversed, and the screws and levers then control the outlet valves as they controlled the inlet valves in raising. When the platform has reached the limit of its movement, a line of locks on top of the foundation girders, 36 on each side, are pushed under the platform by a hydraulic cylinder, and the platform is lowered onto them, where it rests until the work is done on the ship. Then the platform is again lifted, the locks are drawn back, and the platform with its load is lowered until the ship floats out. All the operations are automatic. Since the dock was opened, well over a thousand ships have been lifted on it without any accident whatever. The total register tonnage approaching two million. The great favor in which the dock is held by ship owners and captains is partly due to the fact already mentioned, that the ship is lifted above the level of tide water where the air can circulate freely under the bottom, thus quickly taking up all the moisture, and where the workmen can carry on operations with greater comfort. When extensive repairs have to be undertaken on iron or steel vessels, the fact that this dock forms part of an extensive ship-building plant and is located right in the yard enables such repairs to be executed with dispatch and economy. Several large steamships have had the underwater portions of their hulls practically rebuilt in this dock. The steamship Columbia, of the Oregon line, had practically a new bottom, including the whole of the keel, completed in twenty-six days. This is possible because every facility is alongside the dock and the bottom of the vessel is on a level with the yard. This being the only hydraulic dock controlled automatically in 1897, it has attracted a large amount of attention from engineering experts in this class of work. English, French, German, and Russian engineers have visited the Union ironworks to study its working, and their reports have done much to bring the facilities offered to shipping for repairs by the Union ironworks to the notice of ship owners all the world over. End of Section 23. Section 24 of the Romance of Modern Mechanism. This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org. Recording by Betty B. The Romance of Modern Mechanism by Archibald Williams. A self-moving staircase. At the American Exhibition held in the Crystal Palace in 1902, there was shown a staircase which, on payment of a penny, transported any sufficiently daring person from the ground floor to the gallery above. All that the experimenters had to do was to step boldly on, take hold of the balustrade, which moved at an equal pace with the stairs, and step off when the upper level was reached. The escalator, Latin Scali, flight of stairs, hails from the United States, where it is proving a serious rival to the elevator. In principle, it is a continuously working lift, the slow travel of which is more than compensated by the fact that it is always available. The ordinary elevator is very useful in a large business or commercial house, where it saves the legs of people who, if they had to tramp up flight after flight of stairs, would probably not spend so much money as they would be ready to part with if their vertical travel from one floor to another was entirely free of effort. But the ordinary lift is, like a railway, intermittent. We all know what it means to stand at the grill and watch the cage slide downwards on its journey of perhaps four floors when we want to go to a floor higher up. Rather than face the delay, we use our legs. Theoretically, therefore, a large imporium should contain at least two lifts. If the number be further increased, the would-be passenger will have a still better chance of getting off at once. Thus, at the station of the central London railway, we have to wait but a very few seconds before a grill is thrown back and an attendant invites us to hurry up there, please. Yet there is delay while the cage is being filled. The actual journey occupies but a small fraction of the time, which elapses between the moment when the first passenger enters the lift at the one end of the trip and the moment when the last person leaves it at the other end. In a building where the lift stops every 15 feet or so to take people on or put them off, the waste of time is still more accentuated. The escalator is always ready. You step on and are transported one stage. A second staircase takes you on at once if you desire it. There is no delay. Furthermore, the room occupied by a single escalator is much less than that occupied by the number of lifts required to give anything like an equally efficient service. In large American stores then, it is coming into favor and also on the Manhattan elevated railway of New York. When once the little nervousness accompanying the first use has worn off, it eclipses the lift. A writer in Cassier's magazine says, In one large retail store during the holiday season, more than 6,000 persons per hour have been carried upon the escalator for five hours of the day. And the aggregate for an entire day is believed to be 50,000. In the same store on an ordinary day, the passengers alighting at the second floor from the eight large lifts which run from the basement to the fifth floor were counted, likewise the number at the escalator. This ladder was found to be 859% of the number delivered by the eight lifts. In another establishment in a very busy hour, the number taken from the first floor by the escalator was four times the number taken from the first floor by the 14 lifts, which were running at their maximum capacity. To the merchant, this spells opportunity for business. The experience at the 23rd Street and 6th Avenue Station of the Manhattan Elevated Railway in New York during a recent shutdown of the escalator, which has been in service for some time, is interesting as showing the attitude of the public, of which many millions have been carried by the installation during the several years of its operation. The daily traffic receipts of the station bore a period beginning several weeks before the shutdown and extending as many after for the years 1903 and 1902 and receipts of the adjacent stations for the same period were carefully plotted. And the loss area during the period of shutdown was determined. The loss area was found to embrace 64,645 fares. It was, furthermore, daily a matter of observation that numbers of people finding that the escalator was not running and refused to climb the stairs and turned away from the station. In the case of a great store, the escalator may be constructed as one continuous machine with landings at each floor and so a range that steps which carry passengers up may perform a like service in carrying others down. Or separate machines may be installed in various locations affording the best opportunity for displaying merchandise to the customer who may be proceeding from the lower to the upper floor. In the case of a six-story building so equipped with escalator service in both directions or in all ten escalator flights, it is obvious that the facilities are equal to an impossible number of elevators. And as facility of access has a direct bearing upon opportunities for business, it may well be argued that the relative value measured by rent of the main and upper floors is greatly changed. Each step in a staircase has two parts, the tread or horizontal board on which the foot is placed and the vertical riser, which acts both as a support to the tread above and also prevents the foot from slipping under the tread. In the escalator, each tread is attached rigidly to its riser and the two together form an independent unit where the convenience of passengers in stepping on or off at the upper and lower landings, the treads in these places are all in the same horizontal plane. As they approach the incline, the risers gradually appear and the treads separate vertically. At the top of the incline, the process is gradually reversed, the risers disappearing until the treads once more form a horizontal belt. The means of affecting this change is most ingenious. Each tread and its riser is carried on a couple of vertical, triangular brackets, one at each side of the staircase. The base of the bracket is uppermost to engage with the tread and its apex has a hole through which passes a transverse bar, which in its central part forms a pin in the link chain by which power is transmitted to the escalator. Naturally, the step would tip over. This is prevented by a yoke attached to each end of the bar. At right angles to it and parallel to the tread, the yoke has at each extremity a small wheel running on its own rail. There being two rails for each side of the staircase. Since step brackets bar and yoke are all rigidly joined together, the step is unable to leave the horizontal, but its relation to the steps above and below is determined by the arrangement of the rails on which the yoke wheels run. When these are in the same plane, all the yokes and consequently the treads will also be in the same plane. But at the incline where the inner rail gradually sinks lower than its fellow, the front wheel of one tread is lower than the front wheel of the next and the risers appear. It may be added that going to the double track at each side of the staircase, the back wheel of one tread does not interfere with the front wheel of that below. And that on the level they come abreast without jostling as the yoke is bent. The chain of which the step bars form pins travels under the center of the staircase. It is made up of links 18 inches long, having in addition to the bars a number of steel cross pins, one and one half inches in diameter. They're axis three inches apart so that the chain as a whole has a three inch pitch. The hubs of the links are bushed with bronze and have a graphite inlay, which makes them self lubricating. Every joint is turned to within one one thousandth inch of absolute accuracy. The tracks are steel and hardwood insulated from the ironwork, which supports them by sheets of rubber. The wheels are so constructed as to be practically noiseless so that as a whole the escalator works very quietly. It has been observed, says the authority already quoted, that beginners take pains to step upon a single tread and that after a little experience no attention whatever is given to the footing, owing to the facility of adapting oneself to the situation. The upper landing is somewhat longer thereby affording an interval for stepping off at either side of sufficient duration to meet the requirements of the aged and infirm. The sole function of the traveling landing is to provide a time interval to meet the requirements of the slowest acting passenger and not of the alert. The terminal of the exit landing be at top or bottom for the escalator operates equally well for either ascent or descent is a barrier called the shunt, of which the lower member travels horizontally in a plane oblique to the direction of movement of the steps and at a speed proportionately greater thereby imparting a right angle resultant to the person or obstacle on the step which may come in contact with the shunt. By reason of this resultant motion, the person or obstacle is gently pushed off the end of the step upon the floor without shock or injury in the slightest degree. The motion of the escalator is so smooth and constant that it does not interpose the least obstacle to the free movement of the passenger who may walk in either direction or assume any attitude to the same degree as upon a stationary staircase. At Cleveland, USA there has been erected a rolling roadway consisting of an inclined endless belt and platform made of planks eight feet long placed transversely across the roadway. The timbers are fastened together in trucks of two planks each adjoining trucks being joined by heavy links to form a moving roadway which runs on 4,000 small wheels. At each end, the roadway which is continuous passes round enormous rollers. Its total length is 420 feet and the rise 65 feet. Four electric motors placed at regular intervals along its length and all controlled by one man at the head of the incline drive it at three miles an hour. You can accommodate six wagons at a time. End of Section 24 Section 25 of the Romance of Modern Mechanism This is a LibriVox recording. All LibriVox recordings are in the public domain. For more information or to volunteer, please visit LibriVox.org The Romance of Modern Mechanism by Archibald Williams Chapter 22 Pneumatic Mail Tubes You put your money on the counter. The shop assistant makes out a bill and you wonder what he will do with it next. These large stores know nothing of an open till. Yet there are no cashier's desks visible nor any overhead wires to whisk a carrier off to some corner where a young lady and thrown in a box controls all the pecuniary affairs of that department. While you are wondering, the assistant has wrapped the coin in the bill and put the two into a dumbbell shaped carrier which he drops into a hole. A few seconds later, flop and the carrier has returned into a basket under another opening. There's something so mysterious about the operation that you ask questions and it is explained to you that there are pneumatic tubes running from every counter in the building to a central pay desk on the first or second floor and that an engine somewhere in the basement is hard at work all day compressing air to shoot the carriers through their tubes. Certainly a great improvement on those croquet ball receptacles which progressed with a deliberation maddening to anyone in a hurry along a wooden suspended railway. Now imagine tubes of this sort only of a much larger diameter in some cases passing for miles under the streets and houses and you will have an idea of what the pneumatic mail dispatch means the cash in bill being replaced by letters, telegrams and possibly small parcels. Swift as the wind is a phrase often in our mouths when we wish to emphasize the salarity of an individual an animal or machine and getting from one spot of the earth's surface to another. Mercury, the messenger of uncertain tempered jove was pictured with wings on his feet to convey symbolically the same notion of speed. The modern human messenger is so poor counterpart of the god and his feet are so far from being winged that for certain purposes we have fallen back on elemental air currents not unrestrained like the breezes but confined to the narrow and certain paths of the metal tube. The pneumatic dispatch which at the present day is by no means universal has been tried in various forms for several decades. Its first public installation dates from 1853 when a tube three inches in diameter and 220 yards long was laid in London to connect the International Telegraph Company with the stock exchange. A vacuum was created artificially in front of the carrier which the ordinary pressure of the atmosphere forced through the tube. Soon after the post office authorities took the matter up as the pneumatic system promised to be useful for the transmission of letters but refused to face the initial expense of laying the tube lines. When in 1858 Mr. CF Varly introduced the high pressure method. Pneumatic dispatch received an impetus comparable to that given to the steam engine by the employment of high pressure steam. It was now possible to use a double line of tubes economically. The air compressed for sending the carriers through the one line being pumped out of a chamber which sucked them back through the other. Tubes for postal work were soon installed in many large towns in Great Britain, Europe and the United States including the 30 inch pneumatic railway between the Northwestern District Post Office and Eversholt Street and Euston Station which for some months of 1863 transported the mails between these two points. The air was exhausted in front of the carriage by a large fan. Encouraged by its success the company built a much larger tube nearly four and a half feet in diameter to Euston Station with the general post office. This carried 14 tons of post office matter from one end to the other in a quarter of an hour. There was an intermediate station in Holborn where the engines for exhausting had been installed. But owing to the difficulty of preventing air leakage around the carriages the undertaking proved a commercial failure and for years the very route of this pneumatic railway could not be found. So quickly our failures forgotten the more useful small tube grew more vigorously in America and France. In or about the year 1875 the Western Union Telegraph Company laid tubes in New York to dispatch telegrams from one part of the city to the other because they found it quicker to send them this way than over the wires. 18 years later 15 miles of tubes were installed in Chicago to connect the main offices of the same company to the labor offices in the town and with various important public buildings. Messages which formally took an hour or more in delivery are now flipped from end to end in a few seconds. The Philadelphia people meanwhile had been busy with a double line of six inch tubes 3,000 feet long laid by Mr. B. C. Bacheller between the borse and the general post office for the carriage of males. The first thing to pass through the Bible wrapped in the stars and stripes. A 30 horsepower engine has kept busy exhausting and compressing the air needed for the service which amounts to about 800 cubic feet per minute. Philadelphia can also boast an 8 inch service connecting the general post office with the Union Railway Station a mile away. One and a half minutes suffice for the transit of the large carriers packed tightly with letters and circulars nearly half a million of which are handled by these tubes daily. New York is equally well served. Tubes run from the general post office to the produce exchange to Brooklyn and to the Grand Central Station. The last is three and a half miles distant but seven minutes only are needed for a tube journey which formally occupied the mail vans for nearly three quarters of an hour. Paris is a city of petite blue so important an institution in the gay capital. Here a network of tubes connects every post office in the urban area with the central bureau acting the part of a telephone exchange. If you want to send an express message to a friend anywhere in Paris you buy a petite blue i.e. a very thin letter card not exceeding one fourth ounce in weight at the nearest post office and post it in a special box. It whirls away to the exchange and is delivered there if its destination be close at hand. Otherwise it makes a second journey to the office most conveniently situated for delivery. Everybody uses the Voya Numatique of Paris so much cheaper then and quite as expeditious as the telegraph with the additional advantage that all messages are transmitted in the sender zone handwriting. The system has been instituted for a quarter of a century and the Parisians would feel lost without it. The system means tubeless for it has over 40 miles of one and a half two and a fourth and three inch lines radiating from the postal nerve center of the metropolis of lengths ranging from 100 to 2,000 yards. The tubes are in all cases composed of lead and closed in a protecting iron piping. To make a joint great care must be exercised so as to avoid any irregularity of war. When a length of piping and a line a chain is first passed through it which has at the end a bright steel mandrel just a shade larger than the pipe's internal diameter. This is heated and pushed halfway into the pipe already laid and the new length is forced on to the other half till the ends touch. A plumber's joint having been made the mandrel is drawn by the chain through the new length obliterating any dents or malformations in the interior. The main lines are doubled and up into down track short branches have one tube only to work the inward and the outward dispatches. The carriers are made of gutta percha covered with felt. One end is closed by filth discs fitting the tube accurately to prevent the passage of air the other is open for the introduction of messages. As they fly through the tube the carriers work an automatic signaling apparatus which tells how far they have progressed and when it will be safe to dispatch the next carrier. The London Post Office System has worked by six large engines situated in the basement of the General Post Office. So useful has the pneumatic tube proved that a bill has been before Parliament for supplying London with a 12 inch network of tubes tumbling 100 miles of double line. In the letter published to The Times April 19, 1905 the promoters of the scheme give a succinct account of their needs and of the benefits which they expect to accrue from the scheme have brought to completion. The Bachelors System they write with which it is proposed to equip London is not a development of the miniature systems used for telegrams or single letters here in Paris Berlin and other cities. Such systems deal with the felt carrier weighing a few ounces which is stopped by being blown into a box. The Bachelors System deals with a loaded steel carrier weighing 70 pounds traveling with a very high momentum. The difference is fundamental in this sense pneumatic tubes are a recent invention and absolutely new to Europe. The Bachelors System is the response to a pressing need. Careful observations show that more than 30% of the street traffic is occupied with parcels and males. These form a distinct class differentiated from passengers on the one hand and from heavy goods on the other. The Bachelors System will do for parcels and males what the underground electric railways do for passengers. It has been in use for 12 years in America for mail purposes and where used has come to be regarded as indispensable. The plan for London provides for nearly 100 miles of double tubes with about twice that number of stations for receiving and delivery. The system will cover practically the County of London and no point within that area can be more than one quarter of a mile from a tube station. Beyond the County of London deliveries will be made by a carefully organized suburban motor cart service. 30 of the receiving stations are to be established in the large stores. The diameter of the tube is to be of a size that will accommodate 80% of the parcels as now wrapped with 80% with slight adaption. The remaining 10% furniture, pianos and other heavy goods are to be dealt with by a supplementary motor service. If the tubes were enlarged their object would be partially defeated for what the increased size would go increased cost great surplus of capacity less frequent dispatch and low efficiency generally. The unsuccessful Houston tunnel of 40 years ago practically an underground railway is an extreme illustration of this point. Though in that case there are grave mechanical defects as well. From a mechanical point of view the system has been brought to such perfection that it is no more experimental than a locomotive or an electric tram car. The unique value of tube service is due to immediate dispatch, high velocity of transit immunity from traffic interruption and economy. The greatest obstacle to rapid intercommunication is the delay resulting from accumulations due to time schedules. The function of tube service is to abolish time schedules and all consequent delays. The number of trade parcels annually delivered in London is estimated at more than 200 million. A careful canvas has been made of 1000 shops only, which represent only a very small fraction of the total number in the county. It has been a certain that these 1000 shops deliver no fewer than 60 million parcels yearly. A fact that seems to more than justify the foregoing estimate. On the other hand it is known from official data that the parcel post in London is represented by less than 25 million or 1 ninth of the total parcel traffic. With the tube system in operation every parcel instead of waiting for the next delivery would leave the shop immediately. After being dispatched by the tube it would be delivered at a tube station within a quarter of a mile at least of its destination and then by messenger. The entire time consumed for an ordinary parcel would be not over an hour and for a special parcel 15 to 20 minutes. They require from 3 to 6 hours or longer at present. The advantages of the tube system to the public would be manifold. Customers would find their purchases at home upon their return or if they preferred could do their shopping by telephone making their selections from goods sent on approval by tube. The shop man would find himself relieved from a vast amount of confusion and annoyance less of his shop space given up to delivery and his expenses reduced. Small shops would be able to draw upon wholesale houses for goods not in stock while the customer waited. Such delay and confusion as are frequently occasioned by fogs would be reduced to a minimum. While the success of the project is not dependent on post office support the post office should be one of the greatest gainers by it. The time of delivery of local letters would be reduced from an average of 3 hours and 6 minutes to 1 hour. Express letters would be delivered more quickly than telegrams. This has been demonstrated conclusively again and again in New York and other American cities where the tubes have been in operation for years. The latest time of posting country letters would be deferred from 1 half to 1 hour and incoming letters would be advanced by a similar period. The parcels post would gain in precisely the same way but to an even larger extent. If the post office choose to avail themselves of the opportunity every post office will become a tube station and every tube station a post office. Thus the same number of postmen covering but a tithe of the present distances could make deliveries without time schedules at intervals of a few minutes with a handful instead of a bag full of letters. The sorting of mails would be performed at every station instead of at a few. Incoming country mails would be taken from the bags in the railway termini and the same bags refilled with the outgoing country mails thus avoiding needless carriage to the post office and back. No bags at all would be used for the local mails. The steel carriers themselves answering that purpose. At every tube terminal a post office clerk would be stationed so that the mails would never for an instant be out of post office control. Its absolute security would be further insured by a system of locking so that the mails could only be opened by authorized persons at the station to which they were directed. These safeguards offer striking contrast to the present method that entrusts mail bags to the sole custody of van drivers and the employee of private contractors. If the mails were handled by tube businessmen would be able to communicate with each other and receive replies several times in one day and country and foreign letters could always be answered upon the day of receipt. The effect would be felt all over the empire. Would the laying of the tube seriously impede traffic? The promoters assures that the inconvenience would not be comparable to that caused by the laying of a gas, water, or telephone system. When one of those has been laid the annoyance the urge has only begun. The streets must be periodically reopened for the purpose of making thousands of house connections, extensions, and repairs. When a pneumatic tube is once down it is good for a generation at least. It is not subject to recurrent alterations incidental to house connections and repairs. In three American cities the tubes have been touched but three times in 12 years and in those cases the causes were bursting water main and faulty adjacent electric installations. The repairs were affected in a few hours. From the general consideration of the scheme we may now turn to some mechanical details. The pipes would be of a one foot internal diameter made in 12 foot lengths. Straight sections writes an engineering correspondent of the Times would be of cast iron, board, counter board and turn to a slight taper at one end to fit a recess at the other end of the next tube. To form the joints which could be cocked joints made in this way are estimated to permit a deflection of two inches from the straight and the laying and bedding need not be exact. Bent sections are to be of seamless brass. These are bored true before bending. The permissible curvature is determined upon the basis of a maximum bend of one foot radius for every one inch of diameter. The one foot diameter of the London tubes would consequently be allowed a maximum curvature of 12 foot radius. Measured at the enlarged end the overall diameter of each pipe is 17 inches and as two such pipes are to be laid side by side with 18 inches between centers the clear width will be 35 inches. The trenches are therefore to be cut 36 inches wide and in order to have a comparatively free run for the sections it is proposed to cut the trenches 6 feet deep. When the 100 miles of piping have been laid the entire system will be tested to a pressure of 25 pounds to the square inch or about two and a half times the working pressure. Engines of 10,000 HP will be required to feed the lines with air for the propulsion of the carriers each 3 feet 10 inches long and weighing 70 pounds. In order to ensure the delivery of a carrier at its proper destination whether a terminus or an intermediate station Mr. Bachelor has made a most ingenious provision. On the front of a carrier there is a metal plate of a certain diameter at each station two electric wires project into the tube and as soon as a plate of sufficient diameter to short circuit these wires arrives the current operates delivery mechanism and the carrier switched off into the station box. The dispatcher knowing the exact size of disk for each station can therefore make certain that the carrier shall not go astray and may occur to the reader that should a carrier accidentally stick anywhere in the tubes it would be a matter of great difficulty to locate it. Evidently one could not feel for it with a long rod and half a mile of tubing the distance between every two stations with much hope of finding it. But science has evolved a simple and at the same time quite reliable method of coping with the problem. M. Bontemps is the inventor. He locates trouble in Paris tubes by firing a pistol and exactly measuring the time which elapsed between the report and its echo. As the rate of sound travel is definitely known instruments of great delicacy enable the necessary calculations to be made with great accuracy. When a breakdown occurred on the Philadelphia tube line Mr. Bachelor employed this method with great success. For street excavation made on the strength of rough measurements with the timing apparatus came within a few feet of the actual break in the pipe caused by a subsidence while the carriers themselves were found almost exactly at the point where the workmen had been told to begin digging. There's no doubt that where such a system is that proposed established an enormous amount of time would be saved to the community. A letter from Charing Cross to Liverpool Street says the world's work occupies by post three hours by tube transit it would occupy 20 to 40 minutes or by an express system of tube transit 10 to 15 minutes. Express messages carried by the post office in London last year, 1903 numbered about a million and a half but the cost sometimes seems very heavy. To send a special message by hand from Hampstead to Fleet Street for example cost one S3D and takes about an hour it is claimed that it could be sent by pneumatic tube at a cost of 3D and from 15 to 20 minutes and that for local service the tube would be far quicker than the telegraph and many times cheaper. It has been calculated that from one sixth to one quarter of the wheeled traffic of London is occupied with the distributions of males and parcels and that the tubes relieve the streets to this extent. This fact alone would be a strong argument in their favor. It is impossible to believe that tube transmission on a gigantic scale will not come. Hitherto its development has been hindered by mechanical difficulties but these have been mostly removed. In the United States with the adage time is money is lived up to in a manner scarcely known on this side of the Atlantic. The device has been welcomed for public libraries warehouses, railway depots, factories and shortfall purposes where the employment of human messengers means delay and uncertainty. Twenty years ago Berlier proposed to connect London and Paris by tubes of a diameter equal to that of the pipes contemplated in the scheme now before Parliament. Our descendants may see the tubes laid for when once its system of transportation has been proved efficient on a large scale its development soon assumes huge proportions. And even the present generation may witness the tubes of our big cities lengthen their octopus arms till town and town are in direct communication. After all it is merely a question of will it pay? We have the means of uniting Edenburg and London by tubes as effectually as by telephone or telegraph and since the general trend of modern commerce is to bring the article to the customer rather than to give the customer the trouble of going to select the article in situ. This applies of course to small portable things only Shopping from a distance will come into greater favor and the pneumatic tube will be recognized as a valuable ally. You can imagine that Mrs. Robinson of say reading will be glad to be spared the fatigue of a journey to Regent Street when a short conversation over the telephone wires is sufficient to bring to her door within an hour a selection of silverware from which to choose a wedding present and her husband whose car has perhaps broken a rod at Newbury will be equally glad of the quick delivery of a duplicate part from the makers. These are only two possible instances which not claim to be typical or particularly striking. If you sit down and consider what an immense amount of time and expense could be saved to you in the course of a year by a lightning dispatch you will soon come to the conclusion that the pneumatic tube has a great future before it. End of section 25 section 26 of The Romance of Modern Mechanism this is a LibriVox recording all LibriVox recordings are in the public domain for more information or to volunteer please visit LibriVox.org recording by Avahi in January 2020 The Romance of Modern Mechanism by Archibald Williams Chapter 23 An Electric Postal System Far swifter than the movements of air are those of the electric current which travels many thousands of miles in a second of time. 30 miles an hour is the speed proposed for the pneumatic tube system mentioned in our last chapter An Italian Count Roberto Taigo Piskicelli has elaborated an electric post which if realized will make such a velocity as that seem very slow motion indeed. Cable railways for the transmission of minerals are in very common use all over the world at Hong Kong and elsewhere they do good service for the transport of human beings the car or truck is hauled along a stout steel cable supported at intervals on strong poles of wood or metal by an endless rope wound off and on to a steam driven drum at one end of the line or motion is imparted to it by a motor which picks up current as it goes from the cable itself or other wires with which contact is made Count Piskicelli's electric post is an adaptation of the electric cableway to the needs of parcel and letter distribution At present the mail service between towns is entirely dependent on the railway for considerable distances and on motors and horse vehicles in cases where only a comparatively few miles intervene London and Birmingham to take an instance are served by seven dispatches each way every 24 hours a letter sent from London in the morning would under the most favorable conditions not bring an answer the same day at least not during business hours so that urgent correspondence must be conducted over either the telephone or the telegraph wires Count Piskicelli proposes a network of light cableways four lines on a single set of supports between the great towns of Britain each line or rather track consists of four wires to above and to below each pair on the same level the upper pair form the runway for the two main wheels of the carrier the lower pair are for the trailing wheels three of the wires supply the three phase current which drives the carrier to fourth operates the automatic switches installed every three or four miles for transforming the high tension 5000 volt current into low tension 500 volt current in the section just being entered the carriers would be suitable for letters, book parcels and light packages the speed at which they would move 150 miles per hour to begin with would render possible a 10 minute service between say the towns already mentioned the inventor has hopes of increasing the speed to 250 miles per hour a velocity which would appear visionary had been not already before us in fact that an electric car weighing many tons has already been sent over the Berlin-Sossen railway at 131 and a half miles per hour at any rate the electric post can reasonably be expected to outstrip the ordinary express train should such speeds as Count Pesci Giedli confidently discusses says the world's work be attained they would undoubtedly immense benefits upon the mercantile and agricultural community upon the agricultural community because in this system is to be found that avenue of transmission to big centres of population of the products of la petite culture in which Mr Ryder Haggard for example in his invaluable book on rural England sees help for the farmer and for all connected with the cultivation of the soil Count Pesci Giedli proposes to obviate the delays at dispatching and receiving towns by an inter-urban postal system in which the principal offices of any city would be connected with the head office and with the principal railway termini from each of the sub offices would radiate further lines along which post-collecting pillars are erected and over which lighter motors and collecting boxes similar to the dispatch boxes travel the letter is put in through a slot and the stamp cancelled by an automatic apparatus with the name of the district, number of the post and time of posting the letter then falls into a box at the foot of the column on the approach of a collecting box the letter slot would be closed and by means of an electric motor the receptacle containing the letters lifted to the top of the column and its contents deposited in the collecting box which travels alone past other post-collecting poles taking from each its toll and so on to the district office here in a mercantile centre a first sorting takes place local letter is being retained for distribution by postmen and other boxes carry their respective loads to the different railway termini central office where such an order of things established there would be a good excuse for the old country woman who sat watching the telegraph wire for the passage of a pair of boots she was sending to her son in far away London end of section 26