Page:Encyclopædia Britannica, Ninth Edition, v. 4.djvu/870

Rh 788 CANAL Tlie district which discharges into the eastern outlet comprehends an area of about 700 square miles, chiefly of high mountainous country, intersected by streams and lakes, which discharge themselves into Loch Oich. Loch Ness, and Loch Doughfour, and thence are conveyed into the Moray Firth by the Kiver Ness. Loch Oich, the summit-level of the canal, has an area of about 2 square miles, and the present standard level of its surface is under stood to be 102 feet above the level of mean high water of neap tides in Beauly Firth. It receives the drainage of Loch Quoich and Loch Garry. The waters of Loch Oich are discharged through the River Oich into Loch Ness, which is about 24 miles in length, and has an area of about 30 square miles. Loch Ness receives the waters of the Tarff, the Foyers, and Glenmoriston, and the drainage of numerous other streams and lakes of less note. It discharges its waters through a comparatively narrow neck, called Bona Passage, into the small loch of Doughfour, whence they find an exit to the Beauly and Moray Firths by the River Ness, on which the town and harbour of Inverness are situated. The drainage of the western district of the country, including Loch Arkegg, finds its way into Loch Lochy, which is about 10 miles long, and thence by the River Lochy to the Western Sea at Loch Eil. The two locks in Loch Beauly at the northern entrance to the canal are each 170 feet long, 40 feet wide, and have a lift of about 8 feet. At Muirtowri, a little further on, are four locks of 170 feet in length and 40 feet in width, having a rise of 32 feet, raising the canal to the level of Loch Ness, which it enters at Bona. The works westward of Loch Ness are an artificial canal with seven looks com municating with Loch Oich. Between Lochs Oich and Lochy are two locks ; at the south end of Loch Lochy is a regulating lock, and the canal is carried from this point on the level of Loch Lochy to Banavie, where it descends 64 feet by eight connected locks, forming what is called in the country &quot; Neptune s Staircase ;&quot; finally at Corpach the canal descends by two locks to the level of Loch Eil. Of the whole distance, about 37^ miles are natural lake navigation, and the remaining 23 are artificial or canal navigation. The canals were made 120 feet in width at top-water level, 50 feet at bottom, and 20 feet in depth. In the course of inquiries as to the state of the canal, under a remit from the Admiralty, the author found that the shallows at Loch Oich and the cutting at the summit level originally contemplated had not been carried to the full depth, and an additional depth had been gained at that place by raising the level of Loch Oich ; but still he was led to the conclusion that the standard depth of the canal cannot be regarded as more than 18 feet, giving access to vessels of 160 feet in length, 38 feet beam, and 17 feet draught of water. 1 In carrying out this remarkable w^ork Telford had to deal with difficulties of no ordinary kind, in rendering available rugged Highland lakes, and surmounting the summit-level of the glen. The work, which cost about one million sterling, is a noble monument of his engineering skill. Canals of The canals of Holland are specimens of the second class North o f works to which reference has been made, and of these a nd. very remarkable one is the North Holland Canal, completed in 1825. It was designed by M. Blanksn, who, instead of the high rugged Highland glens of Scotland, had to deal with the proverbial lowness of the country, and to protect his works not from the assaults of mountain torrents but from encroachments of the waves, for there vessels are locked down from the sea into the canal. It extends from 1 Report on the Caledonian Canal to the Admiralty, 1849, by James Veitcli, RE., and David Stevenson, C.E. Amsterdam to the Holder, is 50 miles in length, and is formed of the cross-section shown in fig. 4. It enables vessels trading from Amsterdam to avoid the islands and sand-banks of the dangerous Zuider Zee, the passage through which in former times often occupied as many weeks as the transit through the canal now occupies hours. Fid. 4. Cross-section of North Holland Canal. But the North Holland Canal, which has long proved so Amstcr- useful to the commerce of the district, is destined soon to clam Canal be superseded by the new Amsterdam Canal, a work of great magnitude, which it is proposed to describe as an illustration of ship-canals of the second class, from details furnished by Mr J. C. Hawkshaw, C.E. The rapid increase in the trade of the ports to the south ward and eastward of the Holder, effected by the construc tion of railways throughout Europe, rendered it imperative for the merchants of Amsterdam to provide better com munication with the North Sea than that afforded by the North Holland ship canal already noticed, or suffer its trade to pass to other ports more favourably situated for over-sea traffic. In 1865 a company was formed for the purpose of con structing a canal from Amsterdam, in nearly a direct line, to the North Sea, through Lake Y and Wyker Meer, a dis tance of 16-o- miles. Sir John Hawkshaw and Mr Dirks were appointed the engineers to carry out the work, a plan and section of which are given in Plate XXXVI. The harbour in which the canal terminates in the North Sea is formed by two piers built of concrete blocks founded on a deposit of rough basalt. The piers are each 5069 feet in length, and enclose an area of about 260 acres. About 140 acres of this area are to be dredged to a depth of 26 feet, the remainder is to be left at the present depth for the accommodation of small craft and fishing-boats. From its commencement at the harbour the canal passes by a deep cutting through a broad belt of sand-hills which protect the whole of this part of the coast of Holland from the inroads of the sea. The cross-section of the canal at this place is shown in fig. 5. This cutting is about 3 miles - 89 FIG. 5. Cross-section of Amsterdam Canal. in length ; the greatest depth of cutting from the surface to the bottom of the canal is 78 feet, and the amount of earth work excavated is 6,21 3,000 cubic yards. On emerging from the sand-hills the canal passes by the village of Velsen, in the neighbourhood of which it is crossed by the railway from Haarlem to the Helder, and there enters the Wyker Meer, a large tract of tide-covered land. After traversing the Wyker Meer it passes by a cutting of 327,000 cubic yards through the promontory called Buitenhuizen, which sepa rates that Meer from Lake Y, another large tide-covered area. The rest of its course lies through Lake Y as far as Amsterdam. There are two sets of locks, one set at each end. The North Sea locks are at a distance of about three-quarters of a mile from the North Sea harbour. These locks, as shown in fig. 6, have three passages. The central or main one is 60 feet wide and 390 feet long, and will be furnished with two pairs of gates at each end, pointing in opposite direc-