BRIDGING THE CHANNEL.

Globe, Volume XXI, Issue 1805, 4 December 1879, Page 2

BRIDGING THE CHANNEL.

A recent project is the scheme for bridging the English Channel, put forth by M. Verard de Saint Anne, France. He maintains that his bridge scheme is preferable to the tunnel scheme, because its execution would not cost more than 300,000,000 francs, whereas the tunnel could not be constructed for less than 500,000,000 francs, M. De Sainte Anne, moreover, affirms that his viaduct could be constructed in a much shorter space of time than the tunnel. As described in the London “ Standard,” the proposed viaduct is to span the Channel from Cape Grisnez to Folkestone, According to the Admiralty soundings the greatest depth of water to be found on the passage is fifty-five meters, and this is only for a distance of some four kilometers about half way between the Varne Hook and the French coast, The Varne Bock and its neighbour, the Calbart Beef, play an important part in the scheme. The former, situated at four kilometers from Folkestone and twenty kilometers from Cape Grisnez, is some four kilometers broad, covered with no more than from two to fifteen meters of water. Being of solid rock, and in a direct line with the projected viaduct, it offers itself as a natural half-way resting place. This rock has, till now, constituted one of the greatest dangers to the navigation of the Channel. M. De Sainte Anne proposes not oniy to turn it to account by using It as the foundation for a portion of the viaduct, but also, in conjunction with the Calbart Beef, for the construction of a free port in which vessels of the greatest tonnage will be able to seek shelter from the storms so frequent in the strait which separates England from France. Both for the 'construction of this port and for reducing the depth of the water to twenty meters in those places where he will be obliged to construct his columns, M. De Sainte Anne proposes to adopt the method employed in the construction of the Cherbourg breakwater, which consists in dropping huge masses of rock into the sea, and in consolidating them by means of Roman cement. On the foundations thus established it is intended to raise solid masses of masonry to some forty meters above the level of the sea. This is, of course, a gigantic work, the immensity of which will be seen at a glance, when it is remembered that M. De Sainte Anne does not contemplate attempting in his viaduct any span exceeding two hundred meters. The distance from Folkestone to Cape Grisnez being thirty-five kilometers, it will, therefore, be necessary to construct at the very least 175 immense blocks of masonry on which to place the superstructure As to the superstructure itself he proposes to employ three symptoms. Ou the Varne Back and at the two extremities where the water is shallow and the exigencies of navigation permit, he proposes to construct solid stone arches which will have nothing to fear from the fiercest tempest. This massive masonry is to be followed by the girder bridge system, such as employed in the Charing Cross railway bridge. But to span the deep water he had recourse to the tubular bridge system as applied by Sir Robert Stephenson in the erection of the Menai bridge. With these three systems combined he believes that he is not only certain to succeed in crossing the Channel, but also in satisfying the demands of every government concerning the precautions to be taken to prevent the navigation of the English Channel being rendered even more dangerous than it is at present.