Discussion on the Proposed Channel Tunnel. 5 1 



full size of tunnel would be formed, and in this way a regular 

 system of construction at different stages at the same time 

 could be constantly gone on with, and the progress made would 

 be much more rapid than if carried out on the " Roof 

 Heading " system. The tunnel heading, when completed to 

 full size, would be substantially lined with masonry side walls 

 and brick arching, except where a sound rock formation is 

 met with. Proper ventilating and pumping culverts would be 

 provided, as well as a vertical bratticing of brickwork through- 

 out the entire length of the tunnel, to assist the ventilation and 

 regulation of the air currents. The tunnel during construction 

 and after completion would be kept clear of water by powerful 

 pumping machinery erected near the main shafts to be sunk 

 near the Scotch and Irish sides and to be connected with suitable 

 mains laid through the tunnel. Permanent flooding would be 

 prevented by means of specially constructed shields fixed at 

 short intervals, and these would be so designed as to be at all 

 times a place of safety for the workmen. The ventilation 

 would be maintained by powerful fans supplying fresh air into 

 specially laid mains in the tunnel, having branch air valves at 

 short intervals, from any one of which the fresh air could be drawn 

 into the tunnel when found necessary. The question of venti- 

 lation of the Irish Channel Tunnel would not be so difficult to 

 master as in the Alpine Tunnels, as the natural temperature in the 

 centre of the latter has been found to be about 118° Far. where- 

 as the natural temperature in the Whitehead and Portpatrick 

 tunnel would not be more than 68° or 70° Far. To have proper 

 ventilation in tunnels exceeding 10 miles in length, especially 

 when the traffic would come up to the average rate, the ordinary 

 steam locomotive must be abandoned, and electric or com- 

 pressed air engines used. 



The cost of the Whitehead and Portpatrick scheme has been 

 as carefully considered as the present prehminary state of 

 matters will permit. After making ample allowance for 

 everything, the cost of the earthwork and masonry work would 

 be;^2o6,844 per mile of tunnel, and allowing for cost of shafts, 



