1882.] on the Making and WorMng of a Channel Tunnel. 135 



In the thickness of the metal of the vessel there would be several 

 grooves, each containing an elastic tube ; during the passage of the 

 vessel these would be empty, and would lie below the line of its outer 

 circumference, as shown on the detailed figure, but each tube would have 

 a separate pipe leading through the thickness of the metal of the vessel. 

 When the fissure was passed, water would be pumped along these pipes, 

 swelling out the tubes, so as to press hard against the surface of 

 the excavation. In this way a perfect joint would be ensui'ed, and 

 this being obtained, the water would be let out from the inside 

 of the vessel, it would be ascertained that all was tight, the man- 

 hole doors would then be removed, the block of chalk that was 

 in the vessel would be cut to pieces and carried out, and the 

 result would be that the fissure would be bridged by an iron 

 cylindrical vessel water-tight in the chalk at both ends. Then the 

 end of the vessel would be taken awav. and the trial heading would 

 be complete across the fissure. I need hardly say that before these 

 appliances were put to work in the heading there would be a thorough 

 rehearsal in some chalk cliff, or other suitable place, on the surface, 

 provision being made to give the full water-pressure. 



If it be objected that this, although a feasible operation with a 

 7-foot diameter hole, would not be a feasible one with 14 feet diameter, 

 the answer to it is that there is no increase in difficulty whatever ; 

 the area becomes four times as great, or, allowing the extra diameter 

 needed for the lining, not quite six times as great, and the pressure to 

 be resisted, instead of being about 400 tons, becomes 2400 tons ; but 

 such a pressure as this is, as I have said, perfectly under control. 



Assuming, however, the grey chalk to be continuous from side to 

 side, I believe I have been most unnecessarily occupying your time 

 by the details of an apparatus which will never be needed ; for 1 must 

 be allowed to repeat once more that I cannot conceive an open fissure 

 existing in a material where there can have been no flow of water, 

 either out, or in, through the fissure, to keep it open. 



I could say much more upon the construction of the tunnel did 

 time admit of it ; but I must close this first branch of my subject 

 now, and must ask you to consider with me the second branch — The 

 Working of a Channel Tunnel. 



Whatever may be the futui-e of the ordinary locomotive, whether 

 it be destined to be improved and to continue, or whether it be destined 

 to be superseded by electricity, or by some new motor utilising the 

 energy stored up in the fuel directly and without the intervention of 

 water, no one can doubt that those who at the present time are re- 

 sponsible for the working of railways would prefer to retain for use 

 in the Channel tunnel the ordinary well-known locomotive, if for no 

 -other reason than this — that the existing stock of the railway com- 

 panies on the two sides of the tunnel would suffice for the haulage of 

 the trains, and that no special preparation need be made. But in the 



