Page:1902 Encyclopædia Britannica - Volume 26 - AUS-CHI.pdf/602

 552

CANALS

AND

INLAND

show liow rapidly the increase has been growing. This applies equally to the cost of transit on inland waterways, and it is only by following the example set by other countries in improving their canals that manufacturers and traders will gain the benefit of low rates of carriage. (e. l. w.) Inland Navigation. Lord Bacon wrote : “ There be three things which make a nation great and prosperous, a fertile soil, busy workshops, and easy conveyance for men and commodities from one place to another.” Inland navigation certainly provides the most easy and the cheapest mode of conveyance for minerals and goods, and the last quarter of the 19th century saw great improvements in canals and navigable rivers, more particularly in France, Belgium, Germany, and Canada. But, generally speaking, England has been indifferent to this important question, and the railway companies have been allowed to purchase the canals, with the result that they now possess 1139 miles out of a total length of 3907 miles of navigations in that country. Some of these railway-owned canals are links in main lines of communications, and independent canals in the route are therefore blocked from carrying out improvements that would assist through traffic, by deepening their waterways and enlarging the locks so as to admit of increase in the size of boats, a work which on the continent of Europe has been found efficient in reducing the cost of carriage. The maintenance of the railway-owned navigations is often much neglected, and generally they are useless for the purpose of active competition. The Board of Trade returns of canals and navigations for the year 1898 show that while the traffic on the independent canals had increased five million tons in Great Britain since 1888, the traffic on the railway-owned canals had decreased two million tons in the same period. There may be agricultural districts where the traffic would not justify the cost of bringing the early canals up to the standard of the improved navigations of the present day, but main lines of canals from large manufacturing or mineral districts, capable of taking large barges in trains towed by steampower, would greatly benefit traders, who now undergo severe competition from other countries that have improved their waterways as being the most economical means of giving cheap carriage of minerals and goods. Mr Samuel Lloyd has proposed taking Birmingham, with its large manufacturing and coal and iron industries, as a centre, and joining it with the rivers Severn, Thames, Mersey, and Humber, by improved canals which, passing through other important districts, would convey exports and imports to and from the principal ports on the English coast and serve local trade. Canalized Rivers.—Before canals were introduced in Great Britain, locks and weirs were constructed in rivers to improve the navigation, and the increased depth thus obtained, together with the water-power gained at the weirs for mills, was of great advantage. Previously, in dry weather, it was difficult to navigate the rivers, even with diminished cargoes, while the long deep pounds between the locks on the improved navigation provide ample water for lockage-power and form natural reservoirs for dry seasons. The first Act for the improvement of a river was for the Thames in the year 1423, and since that date nearly forty Acts to itweirs haveappear been to passed. The Thames. ear qegtrelating iocks and have been made by the owners of adjoining lands, more with a view to obtain mill-power than to improve the navigation, and heavy charges were levied by the landowners for the use of the locks, which were of the rude type termed flash-locks.

NAVIGATION

[inland

In 1730 the river was placed in the hands of Commissioners, with power to levy tolls and construct new locks and weirs; it is now a good barge navigation, notwithstanding the abstraction of a large proportion of the summer flow by the London Water Companies. As it does not pass through any mineral or manufacturing district of importance, the trade on the upper river is not large. Below Richmond, sluices and a lock have been erected across the river to maintain deeper water in the reaches above; they are of the same type as those described in use on the Manchester Ship Canal, except that when raised they take a horizontal position instead of a vertical one. In 1783 an Act was passed authorizing the construction of a canal 40 miles long to unite the Thames and Severn, beginning at Lechlade in Oxfordshire and terminating at Frampton-on-Severn, Gloucestershire. The canal was worked successfully for many years, but had been allowed to fall into a state of disrepair. In 1895 a public trust was formed for the purpose of restoration, and the works have been extensive, including powerful steam-pumps for providing a better supply of water to the summit-level, which is 353 feet above the sea, about midway between Stroud and Cirencester. The river Severn is navigable from Shrewsbury to Gloucester. Acts relating to it were passed from 1503 to 1811, mainly to meet the cost of maintenance and other charges on the towing-paths, and it was not until the year 1842 that a body of Commissioners, representing the various interests on the river, were appointed to Severn raise money on the security of the tolls and improve the navigation. Locks and weirs were constructed between Stourport and Worcester, a distance of 12 miles, and thence to Gloucester (28 miles); dredging and embankments only were employed, because a permanent raising of the level of the river so as to give a navigable depth of 6 feet was objected to by the landowners, as floods often occurred in winter, sometimes rising 18 feet above summer level. It wras held by the promoters’ engineers that by the proposed plans, which showed long weirs placed obliquely to the current in widened portions of the river, with locks in cuts, the floods would be carried off as rapidly as before, owing to the enlarged width at the w7eirs and the increased velocity of the floods, which wTould first pass over a deep channel and an almost vertical weir, instead of a shallow bed with shoals. Eminent engineers gave evidence against this view when the Bill was before the Parliamentary Committee, and it was decided that no locks or weirs were to be built below Worcester. From Worcester to Gloucester the shoals were dredged out, a million tons of marl and gravel being removed, with the result that although only a narrow channel had been cut through the shoals, the removal of those natural weirs caused the summer water-level at Diglis locks, near Worcester, to fall 3 feet. After protracted struggles in Parliament, an Act was obtained in 1853 to construct a lock and weir at Tewkesbury, about half-way between Worcester and Gloucester, and in 1869 further powers were got to construct locks and weirs near Gloucester. These powers Avere obtained largely by the evidence of landowners above Worcester, who proved that instead of the erection of the weirs damaging the land, as was expected, floods, on the contrary, did not occur so frequently, and passed off the land more rapidly. The canalization of the river Avas then completed, and there is now a minimum depth of 10 feet of water at, all seasons from Gloucester to Worcester, enabling vessels of 300 to 400 tons to reach the latter city. The Severn navigation is an important link in the chain of navigation between the ports of the Bristol Channel and the Midland districts. It connects the Gloucester and Berkeley Ship Canal at Gloucester with