It is pointed out,[70] on the other hand, and with some force, that in the case of a maritime war between France and England, the proposed Atlantic and Mediterranean Canal would allow of vessels reaching the former sea without passing Gibraltar. Brest and Toulon could also be brought into more rapid activity, and the concentration of troops could be more readily effected. A plan and profile of the proposed route appears at p. 101. _The Rhone Canals._—At the mouth of the Rhone artificial waterways of considerable importance have been provided for navigation purposes, the chief of which, the St. Louis Canal, has a draught of water of 19⅔ feet at low sea-level; its width is 100 feet at the bottom, and 207 feet at the surface of the water. The channel into the sea is 200 feet wide, at the bottom, from the shore out to the 4-metre (13 feet) line, and 656 feet wide from the 4-metre (13 feet) line to the 6-metre (20 feet) line. The canal is separated from the Rhone by a lock having a depth of water of 24½ feet, a depth of 72 feet, and an available length of 525 feet. Below the lock, at the commencement of the canal, a basin has been excavated, 30 acres in area, and with 20 feet depth of water. The works were begun in 1863, and finished in 1873. The St. Louis Canal is a work of far greater importance, as regards navigation, than the results anticipated from the improvement of the mouth of the Rhone, to vessels finding a sufficient depth to get up to Arles. This depth was restricted to 6½ feet at low-water level. The St. Louis Canal Works afford access to the Rhone for vessels up to 20 feet draught, and provide these vessels with a harbour, opening into a sheltered bay, in which they are able with ease to load and discharge their cargoes. The project of the St Louis Canal was from the first assailed by the partisans of the embankment works, as well as by those who considered that the proper expedient was to enlarge the canal from Arles to Bouc. It was urged that the canal would soon be silted up by deposits from the Rhone, both at the sea end and also at the lock. The canal from Arles to Bouc was constructed in 1802, but as it has only a depth of 6½ feet and a width of 26¼ feet on the locks, it has not been available for the craft usually navigating the Rhone since steam navigation was established. _General Features of French Canals._—The general characteristics of the principal canals of France will be understood from the following table, which gives the number of locks, the length of the locks, and their average width and depth on fifteen of the principal canals in the country, as recorded in the Government Reports on the French Waterways:— STATEMENT showing the number of Locks, with their length, width, and average depth, on the chief Canals in France.