206 REPOKT— 1869. 



question, which is one not without interest for the physicist and the meclianical 

 eno-ineer. 



There are several other subjects I should liave gladly mentioned were I not 

 afraid of encroaching undulj' upon our time ; some of these "will, however, be brought 

 before the Section in the form of distinct papers, and will, I trust, lead to inter- 

 esting discussions. 



Description of a proposed Cast-Iron Tuhe for carryinri a Railway aci'oss the 

 Channel between the Coasts of England and France. By John Frederic 

 Bateman, F.B.S., M.Inst.O.E., and Julian John Eevt, M.Inst.C.E., 

 Vienna. 



The advantages which would accrue from a continuous railway communication 

 between England and France are great beyond any possibility of estimate. 



From time to time various proposals for effecting this object have been before 

 the public — by a tunnel to be driven beneath the bed of the sea, through the chalk, 

 which is supposed to be continuous — by submerged roadways and tubes — by large 

 ferry-boats carrying trains on board — and by bridges to be carried on piers formed 

 on islands to be sunk in the Straits. To the latter proposition there are so many 

 obvious objections, that it is hardly necessary to discuss its practicability. 



A large ferry-boat, of great length and breadth, large enough to receive a whole 

 ordinary train on board, and driven at high speed by powerful engines, would 

 unquestionably be a material improvement upon the present miserable means of 

 conveyance. Such boats cannot, however, be employed, except \)j the construction 

 of special harbours on each coast, which would be works of difficulty and expense. 

 However successfully such a scheme might be worked out, the anno5'ance attending 

 a sea-passage in rough weather, althougli mitigated, would not be removed ; and 

 it would frequently occur in the course of the year that tlie traffic would be inter- 

 rupted by fogs and bad weather. Under any circumstances ferry-boats across the 

 channel would be very far from a complete and perfect railway communication. 



With reference to a tunnel, it has been proposed to drive one of ordinaiy size 

 for a double line of railway, which shall descend by a gradient of 1 in GO on each 

 side of the channel to a depth of about 270 feet below the bed of the sea. The 

 total length of the tunnel would be thirty miles, of which twenty-two would be 

 beneath the sea. 



The uncertainty of the strata in the bed of the channel, and the dangers to which 

 any tunnelling operations for some twenty miles under the sea would be subject in 

 the event of meeting Avith open stratification or dislocated material, are such as 

 would in all probability deter capitalists from entering on so hazardous an enter- 

 prise, and would baffle and overpower both engineering skill and all mechanical 

 appliances. Still the project of a tunnel is entertained and advocated by engineers 

 of great standing and reputation, and must only be discarded on a better system 

 being proved to be available. 



The distance to be crossed, and the cost to be incuiTcd, require that the mode to 

 be adopted shall be absolutely free from serious doubt and risk, and shall be as 

 evidently capable of accomplishment as the most ordinary mechanical operation. 

 Some degree of uncertainty must exist in every contri^'ance and speculation ; but, 

 unless a scheme can be proposed which will be free from all doubt and objection 

 so far as human knowledge and foresight can extend, it will hardly deserve, and 

 will probably not receive, the support of the public. 



Our object has been to devise a scheme bj' which all difficulties of operating ia 

 water should be avoided. We propose to lay a tube of cast-iron on the bottom of 

 the sea, between coast and coast, to be commenced on one side of the channel, and 

 to be built up within the inside of a horizontal cylinder, or bell, or chamber, which 

 shall be constantly pushed forward as the building up of the tube proceeds. The 

 bell or chamber within which the tube is to be constructed will be about 80 feet 

 in length, 18 feet internal diameter, and composed of cast-iron rings 8 inches 

 thick, securely bolted together. The interior of the bell will be bored out to a true 

 cylindrical surface like the inside of a steam cylinder. The tube to be constructed 



