THE CHANNEL TUNNEL SCARE

Globe, Volume XXIV, Issue 2502, 14 April 1882, Page 3

THE CHANNEL TUNNEL SCARE

The controversy as to whether the safety of the country would or would not be endangered by a tunnel between England and France is beginning to wax hot. Sir Garnet Wolseley having delivered himself of a very strong opinion on the one side, Sir John Adyo has taken occasion to express an equally decided opinion upon the other side. The Surveyor-General of Ordnance ridicules the notion of two or three thousand Frenchmen being able to seize the English end of the tunnel, and to hold it until sufficiently reinforced to conquer England. “If ever an enemy was so foolish as to attempt an invasion in that way, and even succeed in sending through a few thousand men, ho should bo quite ready to taka down some of the Kentish Volunteers and frighten them away.” Sir Andrew Clarke, another officer of wide experience and high scientific reputation, has expressed himself to similar effect. We hoar it is the intention of the Government to appoint another and larger committee to take evidenoe from distinguished military men and others in relation to the proposed Chancel Tunnel. The committee is to be appointed at an early day, and the whole subject will bo fully inquired into before Parliamentary powers are granted for the construction of the tunnel between this country and France. Availing themselves of the invitation of the South-Eastern Railway Company, some sixty gentlemen had an opportunity on February 21st of seeing how the subway is being driven which is to unite England and France. About a stone’s throw from the spot where the railway dives under the towering Shakespeare’s Cliff at Dover a shaft has bean sunk 160 feet deep, and at the base of that shaft begins the future Channel Tunnel, Fortune has favored the brave attempt eo far. Mr Brady, the South-Eastern Company’s engineer, bringing his own practical science to boar, and taking the advice of the most eminent geologists, experimented with the grey chalk, and the result has been most satisfactory. It proves to be a rock impervious to water, easy to work, little troubled with "faulte” intrusions of other and harder rocks—and there is good reason to believe that it extends the whole way across. In fact, as an engineer remarked—lf we hud mode a material for the purpose, nothing could have been designed to answer one’s object better.” “We do not,” said Sir Edward Watkin, “intend lining our tunnel with expensive fire bricks and things of that kind, but with the material we excavate, making it into ooment.” Such is the dryness of this rock, that Sir Edward observed, “We are not troubled with a single drop of water,” and such its workability that the headway is pushed forward at the rate of nearly 100 yards per week. At present the tunnel has been carried 1050 yards, some 500 yards being under the sea. The process of construction ie easier and simpler than could well be conceived, though it involves great engineering skill and mathematical precision. To begin with, the English and French excavators agree to work simultaneously, to pursue a certain direction, to follow given levels, and to meet and shake hands in the middle at ten and a half miles from shore. What careful measurements and exact workmanship this implies it is needless to indicate —especially remembering that the headings are driven where necessarily no bearings can be taken. The slightest divergence, horizontal or vortical, would give us two tunnels instead of one. Favored, however, by the character of the rock, the work goes on most smoothly. At the farthest point of tbe eubway ie a section of the grey chalk. Applied to it is a disk of iron 7ft. of diameter, which is connected with a compressed air engine, the invention of Colonel Beaumont. At a given signal the compressed air pumped from the surface starts the engine, whioh grinds powerfully against the chalk, cutting and carving it out very much as if it were simply so much clay. The machine delivers the material into buckets, and it is easily removed on an underground tramway, and thus a perfectly circular tunnel is being carved out night and day, at the rate of fifteen or sixteen yards every twenty-four hours. It may be added that the subway is lighted by Swan’s electric incandescent lamps, and that the air, although warm, is kept quite fresh and agreeable by the current produced by the air whioh drives the machinery.—“ Home News.”