Page:Encyclopædia Britannica, Ninth Edition, v. 4.djvu/876

Rh 792 CANAL filled from the Mediterranean iu April 1867, lias risen 12 centi metres, or about 4 inches, and that its waters are continually run ning at a slow rate into the Mediterranean ; certainly this statement agreed with what we ourselves remarked, for we always found a current running northward from Lake Timsah at the rate of from half a mile to a mile an hour. Limited, however, as these tidal ob servations were, they were taken with great care, and appear suffi cient to show that, except at the Suez end, the tides will not ma terially affect the passage of vessels ; at that end, therefore, large vessels must regulate their time of passing ; indeed, the greatest difficulty which will be experienced will be not from the tides, but from the prevailing north-east wind in the canal, which will make close steerage difficult in going from north to south.&quot; It thus appears that the tidal column of 5 feet range in the Red Sea is reduced to 2 feet at the distance of G miles, and is practically annihilated by the wide expanse of the Bitter Lukes. But it would be highly interesting to have this conclusion continued by further systematic tidal obser vations. In executing this strange work of the desert, and converting dry sands into navigable lakes, it is stated that there have been about eighty millions of cubic yards of material excavated, and at one time sixty dredging-machines and nearly 30,000 labourers were employed. For their use a supply of fresh water was conveyed from the Nile at Cairo, and distributed along the Avhole length of the canal, a work which of itself was one of no small magnitude. The cost of the whole undertaking, including the harbours, is stated to have been about 20,000,000. The terminal harbours are important adjuncts of this great work. That on the Mediterranean is Port Said, which is formed by two breakwaters constructed of concrete blocks, the western one G940 feet in length and the eastern 6020 feet, enclosing an area of about 450 acres, with an average depth of only 13 or 14 feet, excepting in the channel leading to the canal, where the depth is 25 to 28 feet. The entrance to the canal at Suez is also protected by a breakwater, and in connection with the harbour at this place there are two large basins and a dry dock. The canal may be regarded as a highway for steamers of 400 feet in length and 50 feet beam. A delay of three days is calculated on for the passage across from Port Said to Suez. It is satisfactory to learn from the report of Commander AVharton, of H.M.S. &quot; Shearwater,&quot; &quot;that the canal retains its depth of water. That report states that &quot; comparing generally the depth of the canal in 1873 and 1875 it seems that it is in about the same condition, with perhaps a slight balance in favour of increased depth now ; while its average minimum may be stated at 2G feet, there are yet consider able tracts where 25 feet and even as little as 24 feet will be passed over.&quot; The survey of Lieutenant Millard, also reported to the Admiralty in 1875, shows that at the entrance to Port Said harbour the 27, 30, and 33 feet contour lines were seaward of those obtained before, proving that some shallowing of the water at the entrance has taken place. The use made of the canal may be judged of from the following table of the traffic passing through since its com mencement 1 : iYcar. Xnmber of Vessels. Gross Tonnage. Receipts. 1870 4SG 654,915 206,373 1871 705 1,142,200 359,748 1872 1082 1,744,481 656,303 1873 1173 2,085,072 915,892 1874 1264 2,423,672 994,375 The tonnage has thus been quadrupled in five years ; and the best means of enlarging the canal to accommodate increas- 1 The History of the Suez Canal, by F. de Lesseps, translated by Sir IT. D. Wolff, 1870. ing trade must soon become an important question for its owners. Such works as the ship canals we have been describing entirely revolutionize ocean navigation, and consequently demand the zealous attention of all nations whose interests they seem to affect. Of this zealous watchfulness the interest taken by the Powers of Europe in the distribution of the property in the Suez Canal may be cited as an sample. But notwithstanding the difficulties, legal and political, which the execution of such works are almost sure to create by severing continents before united, and onnecting seas before separated by thousands of miles of exposed navigation, we may safely conclude that wherever the perils and delays of ocean sailing can be lessened by forming canals these valuable helps to navigation will at all hazards be carried out. Viewing then the subject 2^ ospcc- tively, we offer no apology for noticing two important short- sea passages which, though still unexecuted, will doubtless in some form be eventually carried out. One of these canals is designed to obviate the navigation Proposed of the dangerous strait between Ceylon and the mainland Paumben of India, which is shallow and narrow, and in some states ca of the wind has a violent current, so that it can only be navigated by vessels of 1 small draught. Ships of the larger class have to circumnavigate Ceylon in making their pas sages to the eastern section of Hindustan. The importance of avoiding this detour round Ceylon of 350 miles of exposed navigation in the direct Suez route to Calcutta and Madras will be readily acknowledged, and the execution of the work cannot long be delayed. The strait to which we allude is the Paumben passage leading from the Gulf of Manaar on the west to Palk Bay on the east, as shown in fig. 1 l,and many attempts have been made by blasting to clear away the rocky obstructions that at present render its navigation dangerous. But in order to provide a safe passage of the strait between Ceylon and India for the ships which now navigate the Suez Canal, nothing will suffice but a canal affording the same depth and width, though very much shorter in length than its great pioneer in shortening ocean sailing ; and accordingly surveys have been made and schemes have been proposed to effect this important improvement. Mr George Robertson, Civil Engineer, when inspecting the harbours of India, was asked by the British Government to visit the locality and report on these schemes ; and from his Report on Indian Harbours we find that the site lie selected as most suit able is through the island of. llamaseram, about a mile east from Paumben lighthouse. The distance across from sea to sea is about 2 miles, the ground being a flat sandy plain, raised on an average about 7 feet above high water, and from the borings that have been made it is not expected that much rock will be found in the course of the canal. In order to assimilate it to the Suez Canal the navigable depth should if possible be about 2G feet. On the north side the distance from high water mark to 30 feet at low water is, according to a chart by the Surveyor- General at Colombo, upwards of a mile ; on the south side the distance to the same depth is still greater, so that very considerable works of dredging will be necessary in forming and afterwards maintaining the entrances to the canal. The south end of the canal is under shelter of a coral reef, but the north end may perhaps require to be protected by break waters. The cost of cutting the canal has been named at 440,000. The other scheme to which we referred has a far higher Atlantic importance, its object being to separate the continents of and Pael North and South America, and to give a free navigation between the Atlantic and the Pacific Oceans, by overcoming the physical difficulties presented by the climate and the geological formation of the Isthmus that separates the two