[1] The census is taken every ten years, save in these three provinces, where it is taken every five. Their population in 1906 was:— Manitoba, 360,000; Saskatchewan, 257,000; Alberta, 184,000.
[2] The areas assigned to Prince Edward Island, Nova Scotia, New Brunswick and British Columbia are exclusive of the territorial seas, that to Quebec is exclusive of the Gulf of St Lawrence (though including the islands lying within it), and that to Ontario is exclusive of the Canadian portion of the Great Lakes. About 500,000 sq. m. belong to the Arctic region and 125,755 sq. m. are water.
[3] In Canada a city must have over 10,000 inhabitants, a town over 2000.
[4] The date of foundation is given in brackets.
CANAL (from Lat. canalis, “channel” and “kennel” being doublets of the word), an artificial water course used for the drainage of low lands, for irrigation (q.v.), or more especially for the purpose of navigation by boats, barges or ships. Probably the first canals were made for irrigation, but in very early times they came also to be used for navigation, as in Assyria and Egypt. The Romans constructed various works of the kind, and Charlemagne projected a system of waterways connecting the Main and the Rhine with the Danube, while in China the Grand Canal, joining the Pei-ho and Yang-tse-Kiang and constructed in the 13th century, formed an important artery of commerce, serving also for irrigation. But although it appears from Marco Polo that inclines were used on the Grand Canal, these early waterways suffered in general from the defect that no method being known of conveniently transferring boats from one level to another they were only practicable between points that lay on nearly the same level; and inland navigation could not become generally useful and applicable until this defect had been remedied by the employment of locks. Great doubts exist as to the person, and even the nation, that first introduced locks. Some writers attribute their invention to the Dutch, holding that nearly a century earlier than in Italy locks were used in Holland where canals are very numerous, owing to the favourable physical conditions. On the other hand, the contrivance has been claimed for engineers of the Italian school, and it is said that two brothers Domenico of Viterbo constructed a lock-chamber enclosed by a pair of gates in 1481, and that in 1487 Leonardo da Vinci completed six locks uniting the canals of Milan. Be that as it may, however, the introduction of locks in the 14th or 15th century gave a new character to inland navigation and laid the basis of its successful extension.
The Languedoc Canal (Canal du Midi) may be regarded as the pioneer of the canals of modern Europe. Joining the Bay of Biscay and the Mediterranean it is 148 m. long and rises 620 ft. above sea-level with 119 locks, its depth being about 6½ ft. It was designed by Baron Paul Riquet de Bonrepos (1604-1680) and was finished in 1681. With it and the still earlier Briare canal (1605-1642) France began that policy of canal construction which has provided her with over 3000 m. of canals, in addition to over 4600 m. of navigable rivers. In Russia Peter the Great undertook the construction of a system of canals about the beginning of the 18th century, and in Sweden a canal with locks, connecting Eskilstuna with Lake Malar, was finished in 1606. In England the oldest artificial canal is the Foss Dyke, a relic of the Roman occupation. It extends from Lincoln to the river Trent near Torksey (11 m.), and formed a continuation of the Caer Dyke, also of Roman origin but now filled up, which ran from Lincoln to Peterborough (40 m.). Camden in his Britannia says that the Foss Dyke was deepened and to some extent rendered navigable in 1121. Little, however, was done in making canals in Great Britain until the middle of the 18th century, though before that date some progress had been made in rendering some of the larger rivers navigable. In 1759 the duke of Bridgewater obtained powers to construct a canal between Manchester and his collieries at Worsley, and this work, of which James Brindley was the engineer, and which was opened for traffic in 1761, was followed by a period of great activity in canal construction, which, however, came to an end with the introduction of railways. According to evidence given before the royal commission on canals in 1906 the total mileage of existing canals in the United Kingdom was 3901. In the United States the first canal was made in 1792-1796 at South Hadley, Massachusetts, and the canal-system, though its expansion was checked by the growth of railways, has attained a length of 4200 m., most of the mileage being in New York, Ohio, and Pennsylvania. The splendid inland navigation system of Canada mainly consists of natural lakes and rivers, and the artificial waterways are largely “lateral” canals, cut in order to enable vessels to avoid rapids in the rivers. (See the articles on the various countries for accounts of the canal-systems they possess.)
The canals that were made in the early days of canal-construction were mostly of the class known as barge or boat canals, and owing to their limited depth and breadth were only available for vessels of small size. But with the growth of commerce the advantage was seen of cutting canals of such dimensions as to enable them to accommodate sea-going ships. Such ship-canals, which from an engineering point of view chiefly differ from barge-canals in the magnitude of the works they involve, have mostly been constructed either to shorten the voyage between two seas by cutting through an intervening isthmus, or to convert important inland places into seaports. An early example of the first class is afforded by the Caledonian Canal (q.v.), while among later ones may be mentioned the Suez Canal (q.v.), the Kaiser Wilhelm, Nord-Ostsee or Kiel Canal, connecting Brunsbüttel at the mouth of the Elbe with Kiel (q.v.) on the Baltic, and the various canals that have been proposed across the isthmus that joins North and South America (see [Panama Canal]). Examples of the second class are the Manchester Ship Canal and the canal that runs from Zeebrugge on the North Sea to Bruges (q.v.).
Construction.—In laying out a line of canal the engineer is more restricted than in forming the route of a road or a railway. Since water runs downhill, gradients are inadmissible, and the canal must either be made on one uniform level or must be adapted to the general rise or fall of the country through which it passes by being constructed in a series of level reaches at varying heights above a chosen datum line, each closed by a lock or some equivalent device to enable vessels to be transferred from one to another. To avoid unduly heavy earthwork, the reaches must closely follow the bases of hills and the windings of valleys, but from time to time it will become necessary to cross a sudden depression by the aid of an embankment or aqueduct, while a piece of rising ground or a hill may involve a cutting or a tunnel. Brindley took the Bridgewater canal over the Irwell at Barton by means of an aqueduct of three stone arches, the centre one having a span of 63 ft., and T. Telford arranged that the Ellesmere canal should cross the Dee valley at Pont-y-Cysyllte partly by embankment and partly by aqueduct. The embankment was continued till it was 75 ft. above the ground, when it was succeeded by an aqueduct, 1000 ft. long and 127 ft. above the river, consisting of a cast iron trough supported on iron arches with stone piers. Occasionally when a navigable stream has to be crossed, a swing viaduct is necessary to allow shipping to pass. The first was that built by Sir E. Leader Williams to replace Brindley’s aqueduct at Barton, which was only high enough to give room for barges (see [Manchester Ship Canal]). One of the earliest canal tunnels was made in 1766-1777 by Brindley at Harecastle on the Trent and Mersey canal; it is 2880 yds. long, 12 ft. high and 9 ft. wide, and has no tow-path, the boats being propelled by men lying on their backs and pushing with their feet against the tunnel walls (“leggers”). A second tunnel, parallel to this but 16 ft. high and 14 ft. wide, with a tow-path, was finished by Telford in 1827. Standedge tunnel, on the Huddersfield canal, is over 3 m. long, and is also worked by leggers.