Under the Sea.

Stratford Evening Post, Volume XXXIX, Issue 26, 22 May 1914, Page 5

Under the Sea.

THE CHANNEL TUNNEL. report of imperial defence COMMITTEE. JBt Eliotrio Telegraph—Copyhiqht [United Prebb Association London, May 21. Mr Asquith, questioned in the House of Commons, said the Imperial Defence Committee would shortly complete its report on the Channel tunnel. The revival of the Channel Tunnel scheme is a reminder now rapidly tunnel-making has progressed since Brunei built the Thames Tunnel, then one of the wonders of the world. By the help of compressed air, tunnels of any length can be bored with comparative ease. Both at Calais and at Dover shafts have been sunk, and about a mile and a half of tunnel bored. No special engineering difficulties are known to exist. Military considerations are not of a hienacing character, since the entrances could be held by a handful of men against an army, and arrangements could he made to instantly blow up and flood the tunnel in the event of necessity. The real objection seems to bo the cost, which has been estimate at about £16,000,00tL But the transit' of through carriages for passengers and goods, and the shortening of the time, would appeal to the community. The perennial project of the Channel Tunnel raises an engineering problem associated with the possible inflow of water. A problem of this kind has just been solved in the Astoria tunnel of New York constructed to carry gas mains. A portion of this, about 500 feet in length, passes through decomposed material of gneiss and limestone, with soft wet spaces in direct communication with the sea. This was rendered impervious to water by building walls of liquid concrete (grouting) forced into place under a pressure of from 200 pounds to 500 pounds per square inch, filling the seams, and keeping the water back until the grouting had hardened. In one working alone the water was pumped out in quantities of from 5000 to 6000 gallons per minute. This was done at about 270 feet below mean tide level, a case nearly parallel with that of. the proposed Channel Tunnel.