[299] Paper on ‘Recent Improvements in the port of Dublin,’ read in 1878 before Section G of the British Association.
[300] Mr. Kennedy, chief engineer of Montreal, in Engineering, September, 1881.
[301] Paper by Mr. G. R. Jebb on “The Maintenance of Canals,” &c., in the ‘Journal of the Society of Arts’ for 1888.
[302] On the Birmingham Canal, which has an average top width of 36 feet, and an average depth of 5 feet, this has to be done with a Priestman Grab Dredger, but it causes very little trouble.
[CHAPTER XXXIV.]
CANAL BOATS.
“Instructed ships shall sail to quick commerce, By which remotest regions are allied; Which makes one city of the universe, Where some may gain, and all may be supplied.” —Dryden.
One of the most important matters that the canal engineer and manager has to deal with, is the adoption of the form of boat best suited for the gauge of his canal and the character of the traffic to be dealt with. The majority of canals are of too limited dimensions to admit of the employment of boats of large size. Even on some of the largest rivers—such as the Thames, the Danube, and the Rhine—the size of vessels employed has to be kept down to a limit which would be deemed ridiculous for ocean-going steamers. This fact alone renders the cost of transport on inland waterways much greater than the cost of sea transport. There is also the great drawback to be met, that on many through lines of communication, as on the through canal routes from Birmingham to London, and from the same midland capital to the Severn, the break of canal gauge renders it necessary to employ the size of boat suited to the minimum gauge, and this is, of course, a great waste of power.
The modified French canals of 6½ feet depth admit barges of 300 tons; and a depth of 8½ feet, on the Canal du Centre, of Belgium, allows of the passage of 400-ton barges. The large traffic on the Erie Canal, between Lake Erie and the Hudson River, is conducted in barges of 250 tons; the canal has a depth of 7 feet, with a bottom width of 56 feet, and pitched side slopes of 1 to 1·5; and the locks are 110 feet long and 18 feet wide. The Welland and St. Lawrence Canals are on a larger scale, as they provide access to the coast for the large inland lakes of North America, with vessels of 1000 to 1500 tons, and therefore, like the Ghent-Terneuzen Canal, occupy a sort of intermediate position between inland and ship canals.