Section d is that between Tor Point and the Mull of Cantyre : 

 this is the shortest water course (n^ miles) between Ireland and 

 Scotland, and is the route suggested by Sir Edward Watkin's 

 advisers. So far as regards the shortness of the tunnel this 

 presents the most favourable route, but owing to the long and 

 circuitous connections to be constructed at both ends, it does not 

 appear that the advantage gained would be at all commensurate 

 with the enormous expense entailed. 



Section e shews the route of the pioposed English Channel 

 Tunnel, and is added here merely to illustrate the comparative 

 depths of channels. 



These sections which shew the relative depths of the 

 Channels are drawn to scale : horizontally 1 inch equals 27,000 

 feet, and vertically 1 inch equals 600 feet. 



The foregoing distances are the minimum subaqueous 

 lengths of tunnels, to which must be added 4 to 5 miles 

 to each route for subterraneous approach tunnels, even with 

 the very heaviest workable gradients. 



Subaqueous tunnelling is proverbially one of the most 

 uncertain undertakings in civil engineering. Unforseen mishaps 

 make even the most sanguine fear the results, and it is no 

 uncommon occurrence in subaqueous tunnelling to have to 

 abandon the work for a time, even in the most recent cases, such 

 as the St. Clair and Severn. 



The difficulties, doubts, and uncertainties seem to increase by 

 geometrical progression as the lengths and depths, in subaqueous 

 tunnelling. 



The late Mr. Thomas A. Walker, who succeeded, after 

 numerous attempts, in completing the Severn tunnel, said, 

 " One such experience as the Severn tunnel, with its ever 

 varying and strangely contorted strata and its dangers from 

 floods above and floods below, is sufficient for me. One sub- 

 aqueous tunnel is enough in a lifetime." These are the words 

 of one of the largest and most successful railway, canal, bridge 

 and tunnel contractors the world has ever seen, and who had 

 contracts to the amount of ^"9,000,000 on hand when he died, 



