Discoveries and Inventions of the Nineteenth Century

The project of constructing a ship canal to connect Manchester with the sea appears to have been started just before the railway era, but it was then abandoned, as the opening of the Liverpool and Manchester Canal brought about an immediate reduction in the rates of carriage. Perhaps it was the success of the Suez Canal which caused the revival of this scheme, in 1880, combined with the depression of the cotton trade at that period, when the Liverpool dock dues and the comparatively high railway rates proved a heavier tax than usual on the great Lancashire industry. The first definite steps were taken two years afterwards, when two plans were submitted for the selection of a committee. One scheme proposed to construct the canal without any locks; but, as Manchester is 60 feet above the sea level, there would, it was felt, be certain inconveniences in loading or unloading ships in a deep depression. The other plan was submitted by Mr. Leader Williams, a well known canal engineer, who proposed to take the canal from Runcorn, a distance of 20 miles, and making use of locks. When Parliament was applied to for powers authorizing the prosecution of the enterprise, there was, of course, much opposition offered by the various interests involved, and the inquires before the Committees of each House of Parliament were unusually protracted, for they extended in all to 175 days, and the cost to the promoters is said to have amounted to £150,000. Then, when the Bill had passed, it was found that the capital (£8,000,000) could not be raised owing to the financial depression, and partly also to some want of confidence in 264the soundness of the undertaking on the part of the Lancashire capitalists. But the promoters submitted the whole scheme to a representative committee, who should consider any possible objections. This committee reported (after sitting almost daily for five weeks) upon every point, and were unanimous in pronouncing the undertaking to be perfectly practicable and commercially sound. After this there was no difficulty in raising the required capital, which was subscribed by corporate bodies as well as private persons. The contract was let for £5,750,000, and the work was commenced in November, 1887, the contractor undertaking to have the canal completed and ready for traffic by January 1st, 1892. Fig. 133.—Western Portion. Fig. 134.—Eastern Portion.Figs. 133 and 134.—Map of the Manchester Ship Canal. The Manchester Docks of this canal will cover an area of nearly 200 acres at the south-western suburb of that city, and from there the canal traverses the Valley of the Irwell, following, indeed, the general course of the river, but not its windings, so that the bed of the river is, in the distance of eight miles, or down to its junction with the Mersey, repeatedly crossed by the line of the canal. From the confluence of the rivers, the canal traverses the Valley of the Mersey, for this is the name retained by the combined streams. The course of the river, in its progress towards the sea, now makes wider bends, but the canal proceeds, by a slight and nearly uniform curve, to Latchford, near Warrington, passing to the south of which last named place it follows a straight line to Runcorn, which is at a distance of 23 miles from Manchester. Here it reaches what is now the estuary of the Mersey, but the embankments are continued along the southern shore to Eastham, where the terminal locks are placed. In this part of the canal, the engineer had difficulties to overcome of a different nature from those encountered in the upper part, where it was chiefly a matter of cutting across the ground intervening between the bends of the river, so as to form for its waters a new and direct channel everywhere of the requisite breadth and depth. But when Runcorn has been passed, and Weston Point rounded, there is the mouth of the River Weaver to be crossed, and this is marked by a great expanse of loose and shifting mud. Other affluents of the Mersey are dealt with by means of sluices, and in one instance the waters of a river are actually carried beneath the course of the canal by conduits of 12 feet in diameter. The total length of the canal from Manchester to the tidal locks at Eastham is 35 miles. Fig. 135.—A Cutting for the Manchester Ship Canal. Fig. 136.—Blasting Rocks for the Manchester Ship Canal. The minimum width of the canal at the bottom is 120 feet, its depth 26 feet. But for several miles below Manchester this width will be increased, so that ships may be moored along the sides, and yet sufficient space left for the up and down lines of traffic in the middle. In this way, works and manufactories on the banks will be able to load and unload their cargoes at their own doors, and it may be expected that the advantages so offered will cause the banks of the canal to be much in request for the sites of works of all kinds. At the several places where the locks are placed there will be a smaller and a larger one, side by side, so that water shall not be needlessly used in passing a moderate sized vessel through the greater locks. As these last are 550 feet long and 60 feet wide, they are capable of receiving the largest ships, whilst the smaller locks are 300 feet long and 40 feet wide. Again, both the larger and the smaller are provided with gates in the middle, so that only half their length may be used when that is found sufficient. Coming down the canal from Manchester, the first set of locks will be at Barton, about three miles distance, just below the place where the Bridgewater Canal is carried across the Irwell, which 266is now to become the ship canal, by means of the aqueduct of 1760, by which Brindley became so famous. There is a story told about Brindley being desirous of satisfying the duke about the practicability of his plan, and requesting the confirmatory opinion of another engineer. When, however, this gentleman was taken to the place where it was proposed to construct the aqueduct, he shook his head, and said that he had often heard of castles in the air, but had never before been shown where any of them were to be erected. This aqueduct is about 600 feet long, and the central one of its three arches spans the river at a height of nearly 40 feet above the water. But the Manchester Ship Canal requires a clear headway of 75 feet, and Mr. Williams is going to replace the fixed stone structure by a swinging aqueduct, or trough of iron, which can be turned round, so as to give a clear passage for ships in his canal. This trough, or great iron box, will have gates at each end, and gates will be provided in the aqueduct at each side, so that no water will be lost when the water bridge is turned aside. But more than this; hydraulic lifts have been designed, so that, in a few minutes, vessels can be lowered from the Bridgewater Canal into the Manchester Canal, or raised from the latter into the former while still floating in water. The supply of water for the canal will be ample, as it has the rivers Irwell, Mersey and Bollin, with their tributary streams, to draw from. It should be mentioned that the terminal locks at Eastham will be of somewhat larger dimensions than those already referred to, and will be three in number. The largest, 267which is on the south or landward side, will be 600 feet by 80 feet, the middle one 350 feet by 50 feet, and the smallest one 150 feet by 30 feet. These three locks will be separated by concrete piers 30 feet wide, on which will be placed the hydraulic machinery for opening and closing the gates. Besides the ordinary gates, there will be provided for each lock at Eastham an outer pair of storm-gates that will be closed only in rough weather. These gates will shut from the outside against the lock sills, and, by resisting the force of wind and waves, will protect the ordinary tidal gates from being forced open. The lock gates throughout will be made of a wood obtained from British Guiana, and known as greenheart. This timber is the product of a large tree (Nectandra Rodiœi) belonging to the laurel family. It is a very heavy and close grained wood, the strength and endurance of which have been proved many years ago by its use in ship-building, etc., and some of the logs imported for the canal are remarkably fine specimens, being 22 inches square and 60 feet long. A pair of the largest gates weigh about 500 tons. The gates of the tidal locks at Eastham will all be open for half the time of each tide, when there will be a depth of water, above the sills, greater by 11 feet than that of any dock in Liverpool or Birkenhead. Fig. 137.—Manchester Ship Canal Works, Runcorn. The way in which the difficulty is overcome of crossing the several busy lines of railway that intersect the course of the new canal, so that their traffic shall not be impeded, is one of special interest in this bold scheme. The London and North Western Railway crosses the Mersey 268at Runcorn by a bridge that leaves a clear headway of 75 feet at high water, and it was determined that this headway should be maintained in the bridges over the canal. The use of swing bridges on lines of railway over which trains are constantly passing being out of the question, it is necessary that the railways be carried over the canal at the required height. It is accordingly laid down in the Act of Parliament that before the Canal Company can cut the existing lines of railway it shall construct permanent bridges, and carry over them lines rising by gradients not exceeding 1 in 135, and not only so, but these deviation lines must be previously given up to the several railway companies for six months to be tried experimentally in that period for goods traffic. The cost of constructing these deviation lines, which, in all, will not be far short of 12 miles of new railway, will not be much less than £500,000. The traffic of the canal will probably have great feeders at certain points in the other canals and the railway lines that reach it. For instance, the Bridgewater Canal, now incorporated with the greater undertaking, will bring traffic from the Staffordshire potteries, the river Weaver brings salt laden barges from Cheshire, and at other points the railways will bring the produce of the excellent coal fields of South Yorkshire and South Lancashire, which will be automatically transferred from the waggons into ocean going steamships. Fig. 137a.—The French Steam Navvy. Fig. 137b.—The English Steam Navvy. Though the general notion of the construction of the canal as a deep, wide trench, or cutting following the course shown on the map, is sufficiently simple, the operation of carrying this into practice involves the exercise of great skill and ingenuity in dealing with mechanical 269obstacles. Man’s operations in the world consist but in changing the position of masses of matter; and the properties of matter—its inertia, cohesion, gravitation, etc., are the forces that oppose his efforts. The quantity of matter to be shifted in excavating this trench of thirty-five miles long across the country was no less than sixty millions of tons. The number of “navvies” employed at one time has been 15,000; but even this army of workmen would have made but slow progress with a cutting of this magnitude, had not the “strong shouldered steam” been also called into operation for scooping out the soil. The illustrations (Figs. 137a and #137b:fig137b) will show the arrangement of two forms of “steam navvies” that were much used on the works. One (Fig. 137a) is similar to the dredgers used for clearing mud out of rivers and canals: it consists of a series of scoops, or buckets, mounted on