Chapter IX: Introduction (7)

The road from Omaha to Ogden, near the Great Salt Lake—a distance of 1,032 miles—is owned by the Union Pacific Company, and the Central Pacific joins the former at Ogden and completes the communication to San Francisco, a further length of 889 miles—the whole distance from Omaha to San Francisco being 1,911 miles. The Union Pacific was commenced in November, 1865, and completed in May, 1869. There are at Omaha extensive workshops provided with all the appliances for constructing and repairing locomotives and carriages, and these works cover 30 acres of ground, and give employment to several thousand men. The population of Omaha rose during the making of the railway from under 3,000 in 1864 to more than 16,000 in 1870, and it is now a flourishing town. A little distance from Omaha the line approaches the Platte River, and the valley of this river and one of its tributaries is ascended to Cheyenne, 516 miles from Omaha, the line being nowhere very far from the river’s course. Cheyenne is 5,075 ft. higher above the sea than Omaha, the elevation of which is 966 ft. The Platte River is a broad but very shallow stream, with a channel continually shifting, owing to the vast quantity of sand which its muddy waters carry down. This portion of the line passing through a district where leagues upon leagues of fertile land await the hand of the tiller, has opened up vast tracts of land—hedgeless, gateless green fields, free to all, and capable of receiving and supporting millions of human inhabitants. Cheyenne, a town of 3,000 inhabitants, is entirely the creation of the railways, for southward from Cheyenne a railway passes to Denver, a distance of 106 miles, through rich farming and grazing districts. Seven miles beyond Cheyenne the line begins to ascend the Black Hills by steep gradients, and at Granite Canyon, for example, the rise in five miles is 574 ft., or about 121 ft. per mile. Many lime-kilns have been erected in this neighbourhood, where limestone is very abundant. A little beyond this point the road is in many places protected by snow-sheds, fences of timber, and rude stonework. At Sherman, 549 miles from Omaha, the line attains the summit of its track over the Black Hills, and the highest point on any railway in the world, being 8,242 ft. above the level of the sea. Wild and desolate scenery characterizes the district round Sherman, and the hills, in places covered with a dense growth of wood, will furnish an immense supply of timber for years to come. The timber-sheds erected over the line, and the fences beside it are not so much on account of the depth of snow that falls, but to prevent it from blocking the line by being drifted into the cuts by the high wind. A few miles beyond Dale Creek at Sherman is the largest bridge on the line. It is a trestle bridge, 650 ft. long and 126 ft. high, and has a very light appearance—indeed, to an English eye unaccustomed to these _impromptu_ timber structures, it looks unpleasantly light. From Sherman the line descends to Laramie, which is 7,123 ft. above the sea level and 24 miles from Sherman, and here the railway has a workshop, for good coal is found within a few miles. A fine tract of grazing land, 60 miles long and 20 miles broad, stretches around this station, and it is said that nowhere in the whole North American continent can cattle be reared and fattened more cheaply. The line, now descending the Black Hills, crosses for many miles a long stretch of rolling prairie, covered in great part with sage-bush, and forming a tableland lying between the western base of the Black Hills and the eastern base of the snowy range of the Rocky Mountains, which latter reach an elevation of from 10,000 to 17,000 ft. above the sea level and are perpetually covered with snow. Such tablelands are termed in America “parks.” Before the line reaches the summit of the pass by which it crosses the range of the snowy mountains, it traverses some rough country among the spurs of the hills—through deep cuts and under snow-sheds, across ravines and rivers, and through tunnels. At Percy, 669 miles, is a station named after Colonel Percy, who was killed here by the Indians when surveying for the line. He was surprised by a party of the red men, and retreated to a cabin, where he withstood the attack of his assailants for three days, killing several of them; but at length they set fire to the cabin, and the unfortunate Colonel rushing out, fell a victim to their ferocity. Near Creston, 737 miles from Omaha, the highest point of the chief range is reached, though at an elevation lower by 1,212 ft. than the summit of the pass where the line crosses the Black Hills, which are the advanced guard of the Rocky Mountains. Here is the water-shed of the continent, for all streams rising to the east of this flow ultimately into the Atlantic,—while these, having their sources in the west, fall into the Pacific. Before reaching Ogden the line passes through some grand gorges, which open a way for the iron horse through the very hearts of the mountains, as if Nature had foreseen railways and providently formed gigantic cuttings—such as the Echo and Weber Canyons, which enable the line to traverse the Wahsatch Mountains.

FIG. 52.—_Trestle Bridge._
]

Echo Canyon is a ravine 7 miles long, about half a mile broad, flanked by precipitous cliffs, from 300 to 800 ft. high, and presenting a succession of wild and grand scenery. In Weber Canyon the river foams and rushes along between the mountains, which rise in massive grandeur on either side, plunging and eddying among the huge masses of rock fallen from the cliffs above. Along a part of the chasm the railway is cut in the side of the steep mountain, descending directly to the bed of the stream. Where the road could not be carried round or over the spurs of the mountains it passes through tunnels, often cut through solid stone. A few miles farther the line reaches the city of Ogden, in the state of Utah, the territory of the Mormons. This territory contains upwards of 65,000 square miles, and though the land is not naturally productive, it has, by irrigation, been brought into a high state of cultivation, and it abounds in valuable minerals, so that it now supports a population of 80,000 persons.

FIG. 53.—_American Canyon._
]

We have now arrived at Ogden, where the western portion of the great railway line connecting the two oceans unites to the Union Pacific we have just described. This western portion is known as the Central Pacific Railroad, and it stretches from Ogden to San Francisco, a distance of 882 miles.

The portion of the line which unites Sacramento to Ogden, 743 miles, was commenced in 1863 and finished in 1869, but nearly half of the entire length was constructed in 1868, and about 50 miles west of Ogden, the remarkable engineering feat of laying 10 miles of railway in one day was performed. It was thus accomplished: when the waggon loaded with the rails arrived at the end of the track, the two outer rails were seized, hauled forward off the car, and laid upon the sleepers by four men, who attended to this duty only. The waggon was pushed forwards over these rails, and the process of putting down the rails was repeated, while behind the waggon came a little army of men, who drove in the spikes and screwed on the fish-plates, and, lastly, a large number of Chinese workmen, with pickaxes and spades, who ballasted the line. The average rate at which these operations proceeded was about 240 ft. of track in 77½ seconds, and in these 10 miles of railway there were 2,585,000 cross-ties, 3,520 iron rails, 55,000 spikes, 7,040 fish-plates, and 14,080 bolts with screws, the whole weighing 4,362,000 lbs.! Four thousand men and hundreds of waggons were required, but in the 10 miles all the rails were laid by the same eight men, each of whom is said to have that day walked 10 miles and lifted 1,000 tons of iron rails. Nothing but the practice acquired during the four previous years and the most excellent arrangement and discipline could have made the performance of such a feat possible as the laying of eight miles of the track in six hours, which was the victory achieved by these stalwart navvies before dinner.

The line crosses the great American desert, distinguished for its desolate aspect and barren soil, and so thickly strewn with alkaline dust that it appears almost like a snow-covered plain. The alkali is caustic, and where it abounds no vegetation can exist, most of the surface of this waste being fine, hard grey sand, mixed with the fragments of marine shells and beds of alkali.

The third great mountain range of the North American continent is crossed by this line, at an elevation of 7,043 ft. above the sea level. The Sierra Nevada, as the name implies, is a range of rugged wild broken mountain-tops, always covered with snow. The more exposed portions of the road are covered with snow-sheds, solidly constructed of pine wood posts, 16 in. or 20 in. across: the total length of snow-sheds on the Sierra Nevada may equal 50 miles. These sheds sometimes take fire; but the company have a locomotive at the Summit Station, ready to start at a moment’s notice with cars carrying tanks of water. The snow falls there sometimes to a depth of 20 ft. in one winter; and in spring, when it falls into the valleys in avalanches, sweeping down the mountain-sides, they pass harmlessly over the sloping roofs of the snow-sheds. Where the line passes along the steep flank of a mountain, the roofs of these snow-sheds abut against the mountain-side, so that the masses of snow, gliding down from its heights, continue their slide without injury to line, or sheds, or trains. Where, however, the line lies on level ground, or in a ridge, the snow-sheds are built with a strong roof of double slope, in order to support or throw off the snow. From Summit (7,017 ft.) the line descends continuously to Sacramento, which is only 30 ft. above the sea level, and 104 miles from Summit. About 36 miles from Summit, the great American Canyon, one of the wildest gorges in the Sierra Nevada range, is passed. Here the American River is confined for a length of two miles between precipitous walls of rock, 2,000 ft. in height, and so steep that no human foot has ever yet followed the stream through this tremendous gorge (Fig. 53). A few miles beyond this the line is carried, by a daring feat of engineering, along the side of a mountain, overhanging a stream 2,500 ft. below. This mountain is known as “Cape Horn,” and is a place to try the nerves of timid people. When this portion of the line was commenced, the workmen were lowered and held by ropes, until they had hewn out a standing-place on the shelving sides of the precipice, along whose dizzy height, where even the agile Indian was unable to plant his foot, the science of the white man thus made for his iron horse a secure and direct road. (Fig. 54.)

FIG. 54.—“_Cape Horn._”
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FIG. 55.—_Snow Plough._
]

These lines of railway, connecting Omaha with Sacramento, are remarkable evidences of the energy and spirit which characterize the Anglo-Saxon race in America. The men who conceived the design of the Central Pacific Railroad, and actually carried it into effect, were not persons experienced in railway construction; but five middle-aged traders of Sacramento, two of whom where drapers, one a wholesale grocer, and the others ironmongers, believing that such a railway should be made, and finding no one ready to undertake it, united together, projected the railway, got it completed, and now manage it. These gentlemen were associated with an engineer named Judah, who was a sanguine advocate of the scheme, and made the preliminary surveys, if he did not plan the line. The line is considered one of the best appointed and best managed in the States; yet the project was at first ridiculed and pronounced impracticable by engineers of high repute, opposed by capitalists, and denounced by politicians. An eminent banker, who personally regarded the scheme with hopefulness, would not venture, however, to take any stock, lest the credit of his bank should be shaken, were he known to be connected with so wild a scheme. And, indeed, the difficulties appeared great. Except wood, all the materials required, the iron rails, the pickaxes and spades, the waggons, the locomotives, and the machinery had to be sent by sea from New York, round Cape Horn, a long and perilous voyage of nine months duration, and transhipped at San Francisco for another voyage of 120 miles before they could reach Sacramento. Add to this that workmen were so scarce in California, and wages so high, that to carry on the work it was necessary to obtain men from New York; and during its progress 10,000 Chinamen were brought across the Pacific, to work as labourers. Subscriptions came in very slowly, and before 30 miles of the line had been constructed, the price of iron rose in a very short time to nearly three times its former amount. At this critical juncture, the five merchants decided to defray, out of their own private fortunes, the cost of keeping 800 men at work on the line for a whole year. We cannot but admire the unswerving confidence in their enterprise displayed by these five country merchants, unskilled in railway making, unaided by public support, and even discouraged in their project by their own friends. The financial and legal obstacles they successfully surmounted were not the only difficulties to be overcome. They had the engineering difficulties of carrying their line over the steep Sierra, a work of four years; long tunnels had to be bored; one spring when snow 60 ft. in depth covered the track, it had to be removed by the shovel for 7 miles along the road; saw-mills had to be erected in the mountains, to prepare the sleepers and other timber work; wood and water had to be carried 40 miles across alkali plains, and locomotives and rails dragged over the mountains by teams of oxen. The chief engineer, who organized the force of labourers, laid out the road, designed the necessary structures, and successfully grappled with the novel problem of running trains over such a line in all seasons, was Mr. S. S. Montague. The requirements of the traffic necessitate not only solidly constructed iron-covered snow-sheds, but massive snow-ploughs to throw off the track the deep snow which could in no other way be prevented from interrupting the working of the line. These snow-ploughs are sometimes urged forward with the united power of eight heavy locomotives. Fig. 55 represents one of these ploughs cleaning the line, by throwing off the snow on to the sides of the track. The cutting apparatus varies in its arrangements, some forms being designed to push the snow off on one side, some on the other, and to fling it down the precipices; and others, like the one represented, are intended merely to throw it off the track.

FIG. 56.—_The first Steam Railroad Train in America._
]

Sacramento is 1,775 miles from Omaha, and is connected with San Francisco by a line 139 miles long. At San Francisco, or rather at Oakland, 1,911 miles from Omaha and 3,212 miles from New York, is the terminus of the great system of lines connecting the opposite shores of the vast North American continent. San Francisco, situated on the western shore of a bay, is connected with Oakland by a ferry; but the railway company have recently constructed a pier, which carries the trains out into the bay for 2¼ miles. This pier is strongly built, and is provided with a double set of rails and a carriage-road, and with slips at which ships land and embark passengers, so that ships trading to China, Japan, and Australia can load and unload directly into the trains, which may pass without change from the shores of the Pacific to those of the Atlantic Ocean. San Francisco is a marvellous example of rapid increase, for the population now numbers 170,000, yet a quarter of a century ago 500 white settlers could not be found in as many miles around its site. The first house was erected in 1846, and in 1847 not a ship visited the bay, but now forty large steamships ply regularly, carrying mails to China, Japan, Panama, South America, Australia, &c., and there are, of course, hundreds of other steamers and ships.

The descriptions we have given of only two lines of railway may suffice to show that the modern engineer is deterred by no obstacles, but boldly drives his lines through places apparently the most impracticable. He shrinks from no operations however difficult, nor hesitates to undertake works the mere magnitude of which would have made our forefathers stand aghast. Not in England or America alone, but in almost every part of the world, the railways have extended with wonderful rapidity; the continent of Europe is embraced by a network of lines; the distant colonies of Australia and New Zealand have thousands of miles of lines laid down, and many more in progress; the map of India shows that peninsula traversed in all directions by the iron roads; and in the far distant East we hear of Japan having several lines in successful operation, and the design of laying down more. In connection with such works, at home and abroad, many constructions of great size and daring have been designed and erected; many navigable rivers have been bridged, and not seldom has an arm of the sea itself been spanned; hundreds of miles of embankments and viaducts have been raised; hills have been pierced with innumerable cuttings and tunnels, and all these great works have been accomplished within the experience of a single generation of men, and have sprung from one single successful achievement of Stephenson’s—the Liverpool and Manchester Railway, completed and opened in 1830. We in England should also have pride in remembering that the growth of the railways here is due to the enterprise, industry, and energy of private persons; for the State has furnished no funds, but individuals, by combining their own resources, have executed the works, and manage the lines for their common interest and the public good. It is said that the amount of money which has been spent on railways in Great Britain is not far short of 500 millions of pounds sterling. The greatest railway company in the United Kingdom is the London and North-Western, which draws in annual receipts about seven millions of pounds; and the total receipts of all the railway companies would nearly equal half the revenue of the State.

FIG. 57.—_Railway Embankment near Bath._
]

PLATE VI.

MOUNT WASHINGTON INCLINED TRACK.
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_INCLINED RAILWAYS._

The construction of railways over lofty ranges of mountains will be found illustrated by the brief notices in other pages of the Union Pacific line in the United States, and of the St. Gothard railway over the Alps. In such cases, the track has been to a great extent carried over the spurs or along the sides of the mountains, so that such inclines might be obtained as the ordinary locomotive was capable of ascending. The expensive operation of tunnelling was resorted to only where sinuous deviations from the more direct route involved a still greater expenditure of initial cost, or a continual waste of time and energy in the actual working of the line. Sometimes winding tracks, almost returning by snake-like loops on their own route, as projected on the map, were required in order that the ascent could be made with an incline practicable for the ordinary locomotive. In the earlier development of railways, there were to be met with cable inclines, where the traction of the locomotive had to be superseded or supplemented by that of a rope or chain wound round a drum actuated by a stationary steam-engine. The more powerful locomotives of the present day are able to mount grades of such inclination that the employment of cable traction is no longer requisite, except in but a few cases. Railways had carried passengers about in all parts of the world for many years before the engineer addressed himself to the problem of easily and quickly taking people up heights of steep and toilsome ascent, sought generally for the sake of the prospect, etc. Such, at least, has been the object of most of the inclined railways already constructed, but to this their utility is by no means limited, and as their safety and stability has been proved by many years of use, they may find wider applications than the gratification of the tourist and pleasure-seeker.

The toothed rail or rack which was formerly supposed necessary to obtain power of traction on rails has been already mentioned (p. 101), and as early as 1812 such a contrivance appears to have been in use in England, near Leeds, the invention of a Mr. Blenkinsop. This mode of traction received no development or improvement worthy of notice until Mr. S. Marsh constructed, in 1866, a railway ladder—for so it may be called—for the ascent of Mount Washington in the United States. In this case there was a centre rail formed of iron, angle iron laid between and parallel to the metals on which ran the wheels of the carriages. In this centre rail angle irons were connected by round bars of wrought iron, which the teeth of a pinion of the locomotive engaged, so that a climbing action, resembling somewhat that of a wheel entering on the successive rounds of a ladder, was produced, and in this way an ascensive power was obtained sufficient to overcome gravity, the gradient not much exceeding a rise of one foot in three at any point (12 vertical to 32 horizontal). This railway was completed in 1869, and for more than a quarter of a century it has carried thousands of tourists to the summit of Mount Washington without a single fatal accident. This system of ascending mountains was soon adopted in Europe with certain improvements, for in 1870 an inclined railway was constructed to the summit of the Rigi, in which a system of involute gearing was substituted for the ladder-like rounds of Mr. Marsh. A certain vibratory action, due to the successive engagements of the teeth in the central rack, which was somewhat disagreeable for passengers, was soon afterwards obviated in the Abt system, in which two racks are used, with the teeth of one opposite the spaces of the other, and a double pinion provided, so that greater uniformity in the acting power is obtained. With certain modifications in detail, such as horizontal instead of vertical pinions, this system has been largely adopted wherever cables have been dispensed with. In the inclined railway by which Mount Pilatus, near Lucerne, is now ascended, horizontal teeth project from both sides of a centre rail, and these are engaged by horizontal pinions. The incline here is very steep, being in places nearly 30 degrees; teeth perpendicular to the plane of the incline would have offered a less margin of safety than those on the plan actually adopted. In some places, as among the Alps, and more particularly in South America, there are railways in which the ordinary mode of traction and that with the rack are combined; that is, where the gradient exceeds the ordinary limit, a central rack-rail is laid down, on approaching which the engineer slackens his speed, and allows pinions, moved by the locomotive, to become engaged in the double rack, by which he slowly climbs the steep ascent until a level tract is reached which permits of the ordinary traction being resumed.

FIG. 57_a_.—_Train Ascending the Rigi._
]

Instead of climbing the inclines by rack-work rails, there is another system which offers great advantages for economy in working, and one generally resorted to where the incline can be made in one vertical plane. This is the balanced cable, in which the gravitation force of a descending car or train is utilised to draw up, or assist to draw up, the ascending car or train. These cars are attached to the ends of a cable which passes round a drum at the top of the incline, and means are provided, according to circumstances, so that the drum may be turned, or its revolutions controlled by brakes. When there is a water supply at the upper end of the incline, a simple and economical mode of working the cable is available; for all that is necessary is to provide each car with a water-tank capable of being rapidly filled and emptied. The upper car is made the heavier when required, by filling its tank with water, when it raises the lower car, and on itself arriving at the bottom, the water is discharged before the load to be taken up is received.

FIG. 57_b_.—_At the Summit of the Rigi._
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Many inclined railways are now in operation in various parts of the world, as at Mount Vesuvius, where two of the slopes have a combined length of 10,500 feet; at Mount Supurga and at Mount San Salvatore there are others. At Burgen-stock in Switzerland there is one having a slope 57 feet vertical to 100 feet horizontal. These are cable inclines; but a rack is also used with a pinion regulated by a friction-brake to avoid accident, in case of the cable parting. The largest inclined railway in America is at the Catskill Mountains, where an ascent of 1,600 feet is made in a horizontal distance of 6,780 feet. In this a novel plan has been adopted for compensating the varying weight that has to be moved, for it is obvious that at the commencement the load at the top of the incline has to raise not only that at the bottom, but the whole weight of the cable also, equal to 35,000 pounds of wire rope, and again after the middle point has been passed, the descending power is constantly increasing, while the load being raised is diminishing. Now, in order that the engine may work with more uniform effect, the engineer has not made the incline a straight line, but with the slope lightest at the bottom and gradually increased towards the top, so that the line is really a curve in the vertical plane, and has at every point just the inclination required for balancing the weight of the wire cable, as this shifts from the one track to the other. Instead of a rack pinion and brake to control a too rapid descent from any accident, the cars are provided with clutches, which are automatically thrown out on wooden guard-rails, when a safe speed is exceeded. Inclined railways have also been constructed to the summit of Snowdon, in North Wales, and to that of the Jungfrau, in Switzerland.

PLATE VII.

PIKE’S PEAK RAILWAY, ROCKY MOUNTAINS.
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FIG. 58.—_The Great Eastern at Anchor._
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STEAM NAVIGATION.

The first practically successful steamboat was constructed by Symington, and used on the Forth and Clyde Canal in 1802. A few years afterwards Fulton established steam navigation in American waters, where a number of steamboats plied regularly for some years before the invention had received a corresponding development in England, for it was not until 1814 that a steam-packet ran for hire in the Thames. From that time, however, the principle was quickly and extensively applied, and steamers made their appearance on the chief rivers of Great Britain, and soon began also to make regular passages from one sea-port to another, until at length, in 1819, a steamer made the voyage from New York to Liverpool. It does not appear, however, that such ocean steam voyages became at once common, for we read that in 1825 the captain of the first steam-ship which made the voyage to India was rewarded by a large sum of money. It was not until 1838 that regular steam communication with America was commenced by the dispatch of the _Great Western_ from Bristol. Other large steamers were soon built expressly for the passage of the Atlantic, and a new era in steam navigation was reached when, in 1845, the _Great Britain_ made her first voyage to New York in fourteen days. This ship was of immense size, compared with her predecessors, her length being 320 ft., and she was moreover made of iron, while instead of paddles, she was provided with a screw-propeller, both circumstances at that time novelties in passenger ships. Fulton appears to have made trial in America of various forms of mechanism for propelling ships through the water. Among other plans he tried the screw, but finally decided in favour of paddle-wheels, and for a long time these were universally adopted. Many ships of war were built with paddle-wheels, but the advantages of the screw-propeller were at length perceived. The paddle-wheels could easily be disabled by an enemy’s shot, and the large paddle-boxes encumbered the decks and obstructed the operations of naval warfare. Another circumstance perhaps had a greater share in the general adoption of the screw, which had long before been proposed as a means of applying steam power to the propulsion of vessels. This was the introduction of a new method of placing the screw, so that its powers were used to greater advantage. Mr. J. P. Smith obtained a patent in 1836 for placing the propeller in that part of the vessel technically called the _dead-wood_, which is above the keel and immediately in front of the rudder. When the means of propulsion in a ship of war is so placed, this vital part is secure from injury by hostile projectiles, and the decks are clear for training guns and other operations. Thus placed, the screw has been proved to possess many advantages over paddle-wheels, so that at the present time it has largely superseded paddle-wheels in vessels of every class, except perhaps in those intended to ply on rivers and lakes. Many fine paddle-wheel vessels are still afloat, but sea-going steamers are nearly always now built with screw-propellers. In the application of the steam engine to navigation the machine has received many modifications in the form and arrangement of the parts, but in principle the marine engine is identical with the condensing engine already described. The engines in steam-ships are often remarkable for the great diameter given to the cylinders, which may be 8 ft. or 9 ft. or more. Of course other parts of the machinery are of corresponding dimensions. Such large cylinders require the exercise of great skill in their construction, for they must be cast in one piece and without flaws. The engraving, Fig. 59, depicts the scene presented at the works of Messrs. Penn during the casting of one of these large cylinders, the weight of which may amount to perhaps 30 tons. Only the top of the mould is visible, and the molten iron is being poured in from huge ladles, moved by powerful cranes. In paddle vessels the great wrought iron shaft which carries the paddle-wheels crosses the vessel from side to side. This shaft has two cranks, placed at right angles to each, and each one is turned by an engine, which is very commonly of the kind known as the side-lever engine. In this engine, instead of a beam being placed above the cylinder, two beams are used, one being set on each side of the cylinder, as low down as possible. The top of the piston-rod is attached to a crosshead, from each end of which hangs a great rod, which is hinged to the end of the side-beam. The other ends of the two beams are united by a cross-bar, to which is attached the connecting-rod that gives motion to the crank. Another favourite form of engine for steam-ships is that with oscillating cylinders. The paddle-wheels are constructed with an iron framework, to which flat boards, or floats, are attached, placed usually in a radial direction. But when thus fixed, each float enters the water obliquely, and in fact its surface is perpendicular to the direction of the vessel’s course only at the instant the float is vertically under the axis of the wheel. In order to avoid the loss of power consequent upon this oblique movement of the floats, they are sometimes hung upon centres, and are so moved by suitable mechanism that they are always in a nearly vertical position when passing through the water. Paddle-wheels constructed in this manner are termed _feathering_ wheels. They do not appear, however, to possess any great advantage over those of the ordinary construction, except when the paddles are deeply immersed in the water, and this result may be better understood when we reflect that the actual path of the floats through the water is not circular, as it would be if the vessel itself did not move; for all points of the wheel describe peculiar curves called _cycloids_, which result from the combination of the circular with the onward movement.

PLATE VIII.

THE “CLERMONT,” FROM A CONTEMPORARY DRAWING.
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FIG. 59.—_Casting Cylinder of a Marine Steam Engine._
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The next figure, 60, exhibits a very common form of the screw propeller, and shows the position which it occupies in the ship. The reader may not at once understand how a comparatively small two-armed wheel revolving in a plane perpendicular to the direction of the vessel’s motion is able to propel the vessel forward. In order to understand the action of the propeller, he should recall to mind the manner in which a screw-nail in a piece of wood advances by a distance equal to its pitch at every turn. If he will conceive a gigantic screw-nail to be attached to the vessel extending along the keel,—and suppose for a moment that the water surrounding this screw is not able to flow away from it, but that the screw works through the water as the nail does in the wood,—he will have no difficulty in understanding that, under such circumstances, if the screw were made to revolve, it would advance and carry the vessel with it. The reader may now form an accurate notion of the actual propeller by supposing the imaginary screw-nail to have the thread so deeply cut that but little solid core is left in the centre, and supposing also that only a very short piece of the screw is used—say the length of one revolution—and that this is placed in the dead-wood. Such was the construction of the earlier screw-propellers, but now a still shorter portion of the screw is used; for instead of a complete turn of the thread, less than one-sixth is now the common construction. Such a strip or segment of the screw-thread forms a _blade_, and two, three, four, or more blades are attached radially to one common axis. The blades spring when there are two from opposite points in the axis, and in other cases from points on the same circle. The blades of the propeller are cut and carved into every variety of shape according to the ideas of the designer, but the fundamental principle is the same in all the forms. It need hardly be said that the particles of the water are by no means fixed like those of the wood in which a screw advances. But as the water is not put in motion by the screw without offering some resistance by reason of its inertia, this resistance reacting on the screw operates in the same manner, but not to the same extent, as the wood in the other case. When we know the pitch of the screw, we can calculate what distance the screw would be moved forward in a given number of revolutions if it were working through a solid. This distance is usually greater than the actual distance the ship is propelled, but in some cases the vessel is urged through the water with a greater velocity than if the screw were working in a solid nut. The shaft which carries the screw extends from the stem to the centre of the ship where the engines are placed, and it passes outward through a bearing lined with wood, of which _lignum vitæ_ is found to be the best kind, the lubricant for this bearing being not oil but water. The screw would not have met with the success it has attained but for this simple contrivance; for it was found that with brass bearings a violent thumping action was soon produced by the rapid rotation of the screw. The wearing action between the wood and the iron is very slight, whereas brass bearings in this position quickly wear and their adjustments become impaired. The screw-shaft is very massive and is made in several lengths, which are supported in appropriate bearings; there is also a special arrangement for receiving the thrust of the shaft, for it is by this thrust received from the screw that the vessel is propelled, and the strain must be distributed to some strong part of the ship’s frame. There is usually also an arrangement by which the screw-shaft can, when required, be disconnected from the engine, in order to allow the screw to turn freely by the action of the water when the vessel is under sail alone.

FIG. 60.—_Screw Propeller._
]

A screw-propeller has one important advantage over paddle-wheels in the following particular: whereas the paddle-wheels act with the best effect when the wheel is immersed in the water to the depth of the lowest float, the efficiency of the screw when properly placed is not practically altered by the depth of immersion. As the coals with which a steamer starts for a long voyage are consumed, the immersion is decreased—hence the paddle-wheels of such a steamer can never be immersed to the proper extent _throughout_ the voyage; they will be acting at a disadvantage during the greater part of the voyage. Again, even when the immersion of the vessel is such as to give the best advantage to the paddle-wheels, that advantage is lost whenever a side-wind inclines the ship to one side, or whenever by the action of the waves the immersion of the paddles is changed by excess or defect. From all such causes of inefficiency arising from the position of the vessel the screw-propeller is free. The reader will now understand why paddle-wheel steamers are at the present day constructed for inland waters only.

A great impulse was given to steam navigation, by the substitution of iron for wood in the construction of ships. The weight of an iron ship is only two-thirds that of a wooden ship of the same size. It must be remembered that, though iron is many times heavier than wood, bulk for bulk, the required strength is obtained by a much less quantity of the former. A young reader might, perhaps, think that a wooden ship must float better than an iron one; but the law of floating bodies is, that the part of the floating body which is below the level of the water, takes up the space of exactly so much water as would have the same weight as the floating body, or in fewer words, a floating body displaces its own _weight_ of water. Thus we see that an iron ship, being lighter than a wooden one, must have more buoyancy. The use of iron in ship-building was strenuously advocated by the late Sir W. Fairbairn, and his practical knowledge of the material gave great authority to his opinion. He pointed out that the strains to which ships are exposed are of such a nature, that vessels should be made on much the same principles as the built-up iron beams or girders of railway bridges. How successfully these principles have been applied will be noticed in the case of the _Great Eastern_. This ship, by far the largest vessel ever built, was designed by Mr. Brunel, and was intended to carry mails and passengers to India by the long sea route. The expectations of the promoters were disappointed in regard to the speed of the vessel, which did not exceed 15 miles an hour; and no sooner had she gone to sea than she met with a series of accidents, which appear, for a time, to have destroyed public confidence in the vessel as a sea-going passenger ship. Some damage and much consternation were produced on board by the explosion of a steam jacket a few days after the launch. Then the huge ship encountered a strong gale in Holyhead Harbour, and afterwards was disabled by a hurricane in the Atlantic, in which her rudder and paddles were so damaged, that she rolled about for several days at the mercy of the waves. At New York she ran upon a rock, and the outer iron plates were stripped off the bottom of the ship for a length of 80 ft. She was repaired and came home safely; but the companies which owned her found themselves in financial difficulties, and the big ship, which had cost half a million sterling, was sold for only £25,000, or only about one-third of her value as old materials.

The misfortunes of the _Great Eastern_, and its failure as a commercial speculation in the hands of its first proprietors, have been quoted as an illustration of the ill luck, if it might be so called, which seems to have attended several of the great works designed by the Brunels—for the Thames Tunnel was, commercially, a failure; the Great Western Railway, with its magnificent embankments, cuttings, and tunnels, has reverted to the narrow gauge, and therefore the extra expense of the large scale has been financially thrown away; the Box Tunnel, a more timid engineer would have avoided; and then there is the _Great Eastern_. It is, however, equally remarkable that all these have been glorious and successful achievements as engineering works, and the scientific merit of their designers remains unimpaired by the merely accidental circumstance of their not bringing large dividends to their shareholders. Nor is their value to the world diminished by this circumstance, for the Brunels showed mankind the way to accomplish designs which, perhaps, less gifted engineers would never have had the boldness to propose. The Box Tunnel led the way to other longer and longer tunnels, culminating in that of Mont Cenis; but for the Thames Tunnel—once ranked as the eighth wonder of the world—we should probably not have heard of the English Channel Tunnel—a scheme which appears less audacious now than the other did then; if no _Great Eastern_ had existed, we should not now have had an Atlantic Telegraph. Possibly this huge ship is but the precursor of others still larger, and it is undoubtedly true that since its construction the ideas of naval architects have been greatly enlarged, and the tendency is towards increased size and speed in our steam-ships, whether for peace or war.

FIG. 61.—_Section of Great Eastern Amidships._
]

FIG. 62.—_The Great Eastern in course of Construction._
]

The accidents which had happened to the ship had not, however, materially damaged either the hull or the machinery; and the _Great Eastern_ was refitted, and afterwards employed in a service for which she had not been designed, but which no other vessel could have attempted. This was the work of carrying and laying the whole length of the Atlantic Telegraph Cable of 1865, of which 2,600 miles were shipped on board in enormous tanks, that with the contents weighed upwards of 5,000 tons. The ship has since been constantly engaged in similar operations.[1] The _Great Eastern_ is six times the size of our largest line-of-battle ships, and about seven times as large as the splendid steamers of the Cunard line, which run between Liverpool and New York. She has three times the steam power of the largest of these Atlantic steamers, and could carry twenty times as many passengers, with coal for forty days’ consumption instead of fifteen. Her length is 692 ft.; width, 83 ft.; depth, 60 ft.; tonnage, 24,000 tons; draught of water when unloaded, 20 ft.; when loaded, 30 ft.; and a promenade round her decks would be a walk of more than a quarter of a mile. The vessel is built on the cellular plan to 3 ft. above the water-line; that is, there is an inner and an outer hull, each of iron plates ¾ in. thick, placed 2 ft. 10 in. apart, with ribs every 6 ft., and united by transverse plates, so that in place of the ribs of wooden ships, the hull is, as it were, built up of curved cellular beams of wrought iron. The ship is divided longitudinally by two vertical partitions or bulkheads of wrought iron, ½ in. thick. These are 350 ft. long and 60 ft. high, and are crossed at intervals by transverse bulkheads, in such a manner that the ship is divided into nineteen compartments, of which twelve are completely water-tight, and the rest nearly so. The diagram (Fig. 61) represents a transverse section, and shows the cellular construction below the water-line. The strength and safety of the vessel are thus amply provided for. The latter quality was proved in the accident to the ship at New York; and the former was shown at the launch, for when the vessel stuck, and for two months could not be moved, it was found that, although one-quarter of the ship’s length was unsupported, it exhibited no deflection, or rather the amount of deflection was imperceptible. Fig. 62 is from a photograph taken during the building of the ship, and Fig. 63 shows the hull when completed and nearly ready for launching, while the vignette at the head of the chapter exhibits the big ship at anchor when completely equipped. The paddle-wheels are 56 ft. in diameter, and are turned by four steam engines, each having a cylinder 6 ft. 2 in. in diameter, and 14 ft. in length. The vessel is also provided with a four-bladed screw-propeller of 24 ft. diameter, driven by another engine having four cylinders, six boilers, and seventy-two furnaces. The total actual power of the engines is more than that of 8,000 horses, and the vessel could carry coals enough to take her round the world—a capability which was the object of her enormous size. The vessel as originally constructed contained accommodation for 800 first-class passengers, 2,000 second class, and 1,200 third class—that is, for 4,000 passengers in all. The principal saloon was 100 ft. long, 36 ft. wide, and 13 ft. high. Each of her ten boilers weighs 50 tons, and when all are in action, 12 tons of coal are burnt every hour, and the total displacement of the vessel laden with coal is 22,500 tons.

Footnote 1:

She was broken up for old iron, 1889.

FIG. 63.—_The Great Eastern ready for Launching._
]

The use of steam power in navigation has increased at an amazing rate. Between 1850 and 1860 the tonnage of the steam shipping entering the port of London increased three-fold, and every reader knows that there are many fleets of fine steamers plying to ports of the United Kingdom. There are, for example, the splendid Atlantic steamers, some of which almost daily enter or leave Liverpool, and the well-appointed ships belonging to the Peninsular and Oriental Company. The steamers on the Holyhead and Kingston line may be taken as good examples of first-class passenger ships. These are paddle-wheel boats, and are constructed entirely of iron, with the exception of the deck and cabin fittings. Taking one of these as a type of the rest, we may note the following particulars: the vessel is 334 ft. long, the diameter of the paddle-wheels is 31 ft., and each has fourteen floats, which are 12 ft. long and 4 ft. 4 in. wide. The cylinders of the engines are 8 ft. 2 in. in diameter, and 6 ft. 6 in. long. The ship cost about £75,000. The average passage between the two ports—a distance of 65½ miles—occupies 3 hours 52 minutes, and at the measured mile the vessel attained the speed of 20·811 miles per hour. As an example of the magnificent vessels owned by the Cunard Company, we shall give now a few figures relating to one of their largest steam-ships, the _Persia_, launched in 1858, and built by Mr. N. Napier, of Glasgow, for the company, to carry mails and passengers between Liverpool and New York. Her length is 389 ft., and her breadth 45 ft. She is a paddle-wheel steamer, with engines of 850 horse-power, having cylinders 100 in. in diameter with a stroke of 10 ft. The paddle-wheels are 38 ft. 6 in. in diameter, and each has twenty-eight floats, 10 ft. 8 in. long and 2 ft. wide. The _Persia_ carries 1,200 tons of coal, and displaces about 5,400 tons of water.

FIG. 64.—_Comparative Sizes of Steamships._

1838, _Great Western_; 1844, _Great Britain_; 1856, _Persia_; 1858,
_Great Eastern_.

A, Section amidships of _Great Eastern_; B, The same of _Great
Western_. Both on the same scale, but on a larger one than their
profiles.
]

A velocity of twenty-six miles per hour appears to be about the highest yet attained by a steamer.[2] This is probably near the limit beyond which the speed cannot be increased to any useful purpose. The resistance offered by water to a vessel moving through it increases more rapidly than the velocity. Thus, if a vessel were made to move through the water by being pulled with a rope, there would be a certain strain upon the rope when the vessel was dragged, say, at the rate of five miles an hour. If we desired the vessel to move at double the speed, the strain on the rope must be increased four-fold. To increase the velocity to fifteen miles per hour, we should have to pull the vessel with nine times the original force. This is expressed by saying that the resistance varies as the square of the velocity. Hence, to double the speed, the impelling force must be quadrupled, and as that force is exerted through twice the distance in the same time, an engine would be required of eight times the power—or, in other words, the power of the engine must be increased in proportion to the _cube_ of the velocity; so that to propel a boat at the rate of 15 miles an hour would require engines twenty-seven times more powerful than those which would suffice to propel it at the rate of five miles an hour.

Footnote 2:

This has now (1895) been far surpassed.—_Vide infra._

The actual speed attained by steam-ships with engines of a given power and a given section amidships will depend greatly upon the shape of the vessel. When the bow is sharp, the water displaced is more gradually and slowly moved aside, and therefore does not offer nearly so much resistance as in the opposite case; but the greater part of the power required to urge the vessel forward is employed in overcoming a resistance which in some degree resembles friction between the bottom of the vessel and the water.

The wonderful progress which has, in a comparatively short time, taken place in the power and size of steam-vessels, cannot be better brought home to the reader than by a glance at Fig. 64, which gives the profiles of four steamships, drawn on one and the same scale, thus showing the relative lengths and depths of those vessels, each of which was the largest ship afloat at the date which is marked below it, and the whole period includes only the brief space of twenty years!—for this, surely, is a brief space in the history of such an art as navigation. All these ships have been named in the course of this article, but in the following table a few particulars concerning each are brought together for the sake of comparing the figures:

┌─────┬─────────────────┬─────────────────┬────────┬────────┐
│Date.│ Name. │ Propulsion. │Length. │Breadth.│
├─────┼─────────────────┼─────────────────┼────────┼────────┤
│1838 │_Great Western_ │Paddles │236 ft. │ 36 ft. │
│1844 │_Great Britain_ │Screw │322 ft. │ 51 ft. │
│1856 │_Persia_ │Paddles │390 ft. │ 45 ft. │
│1858 │_Great Eastern_ │Screw and paddles│690 ft. │ 83 ft. │
└─────┴─────────────────┴─────────────────┴────────┴────────┘

FIG. 65.—_The s.s. City of Rome._
]