AX IRISH CHAXXEL RAILWAY 343 



heaviest ships now afloat have a draft of about 36 feet, a depth of 40 to 

 45 feet in anticipation of increased draft, should be provided, as is 

 vrisely made in the Panama Canal. The roadway level would then lie 

 about 60 feet below the surface, instead of down beneath Beaufort's 

 Dyke, and the approaches would be proportionately shorter. In a sub- 

 merged position they would not be subject to pressure from wind and 

 wave, but would lie in comparatively quiet water. The chief objection 

 to these tubes is their deterioration from rust, and the difficulty or 

 impossibility of repairing them under water. When the metal is cor- 

 roded through, the concrete or other lining would be the only remaining 

 material for resisting external pressures. Since the tubes would be 

 supported along their whole length, they would need a comparatively 

 small section for strength, and if lying on the surface, the tubes would 

 be proportioned like ships, to receive varying support, and to bridge 

 the waves from one crest to another. The weight of the submerged 

 tubes should be such as to nearly equal the weight of water displaced. 

 If slightly less than the weight of water, there would be an upward 

 pull on the anchors when empty, and a corresponding downward thrust 

 under moving load, to be resisted by surface floats. If so arranged 

 that the upward and downward pressures are equal, the forces under 

 normal conditions would be a minimum, and the cross section of the 

 tubes might be nearly or quite uniform throughout. The tubes would 

 be made in convenient lengths of 200 to 400 feet, with their ends tem- 

 porarily closed, and floated out into position and sunk to their desired 

 depth, where they would be connected. The temporary dams should 

 be 3 to 4 feet back from the ends, leaving space for the divers while 

 bolting the sections together. A submerged viaduct of this kind across 

 the Irish Channel could probably be built for $25,000,000 to $30,000,- 

 000, and the type is the most promising of all to put into execution. 



Whether or not a channel railway would be profitable as a financial 

 investment is uncertain, but it would accomplish a far greater purpose 

 than merely earning dividends, for it would increase commercial activity 

 in Ireland, and with government security for interest on the investment, 

 it might in the end be one of the easiest means of bettering conditions 

 there. 



A high-level bridge over water of such great depth would necessarily 

 be on floating piers, and its cost would be from $150,000,000 to $200,- 

 000,000 — so great indeed as to be prohibitive. 



The construction of a channel railway to Ireland, and a ship canal 

 from Galway Bay to Dublin, the cost of which would be about $40,000,- 

 000, are of the utmost importance to the prosperity of the island and 

 its people, for ocean ports would then be established on the west coast 

 of Ireland, and this long neglected part of Great Britain would partici- 

 pate to a greater extent in the general welfare. 



