208 REPORT— 1869. 



coast. From an examination of the Admiralty Charts, and of snch information as 

 at present exists, the sea-bed on this line appears to be the most uniform in level, 

 and, while free from hard rocks and broken ground, to consist of coarse sand, gra'\'el, 

 and cla}'. The average depth of water is about 110 feet, the maximum about 

 200 feet. On the line suggested the water increases in depth on both sides of the 

 Channel more rapidly than elsewhere, although in no instance will the gradient be 

 more than about 1 in lOO. The tube, when completed, will occupy about 16 feet 

 in depth above the present bottom of the sea. Up to the point on each shore at 

 which the depth of water above the top of the tube would reach, say 30 feet at 

 low water, an open pier, or other protection, would have to be constructed for the 

 purpose of pointing out its position, and of preventing vessels striking against the 

 tube. These piers may be rendered subservient to harbour improvements. The 

 tube at each end would gradually emerge from the water, and on arriving above 

 the level of the sea would be connected with the existing railway systems, so that 

 the same carriage may travel all the way from London to Paris, or, if Captain 

 Tyler's anticipations be realized, all the way from John O'Groat's to Bombay. 



The distance across the Channel on the line chosen is about twenty-two miles. 

 The tube as proposed is large enough for the passage of carriages of the present 

 ordinary construction, and to avoid the objections to the use of locomotives in a 

 tube of so great a length, and the nuisance which Avould bo thereby created, and 

 taking advantage of the perfect circular form which the mechanical operation of 

 turning, facing, &c., will insure, it is proposed to work the traffic by pneumatic 

 pressure. The air will be exhausted on one side of the train and forced in on the 

 other, and so the required difference of pressure will be given for carrying the train 

 through at any determined speed. Powerful steam-engines, with the necessary 

 apparatus for exhausting and forcing the air into the tube, will he erected on shore 

 at each end ; and supposing one tube only to exist, the traffic will be worked alter- 

 nately in each direction. 



This system of working the traffic will secure a constant sup])ly of the purest air, 

 which will accompany every train ; and sitting in a train on its passage through 

 the tube, will be as pleasant and agreeable, in respect of ventilation, as sitting in 

 the open air on the sea-side or in tlie best ventilated drawing-room. 



By this system of working and by adopting the best description of materials and 

 rolling-stock, there would scarcely exist the chance of accident — no collision could 

 take place. There would never be foul air within the tube to anno_y the passengers 

 or to hinder the traffic by the necessity of removing the tainted air before another 

 train could pass tlirough. The pneumatic system, thougli hitherto tried on a small 

 scale only, is undoubtedly one which, by the proper choice of means, can be cer- 

 tainly and easily, as well as cheaply worked, and in so long a tunnel, we believe it 

 to be in every way preferable to locomotive power, although that also could be 

 adopted. 



It has been found by calculations, that, for moving a large amount of tonnage 

 and a great number of passengers, the most economical arrangement will be to send 

 combined goods and passenger trains through the tube at twenty miles an hour, 

 with occasional express trains at thirty miles an hour. Thus, an ordinary or slow 

 train would occupy about sixty-six minutes in the transit, and a quick or express 

 train about forty-five minutes. In this way the tube, if fully worked, would 

 permit the passage of sixteen ordinary slow trains (eight each way), and six express 

 trains (tliree each way), each conveying both goods and passengers — about 10,000 

 tons of goods per day, or upwards of 8,000,000 per ainium, and 5,000 passengers, 

 or nearly 2,000,000 per annum — might be taken through, or a less amount of goods 

 and a larger number of passengers, or rice icrsiJj if circumstances rendered other 

 proportions necessary or desirable. 



The horse-power required for working the traffic with the above number of 

 ordinary and express trains, will be, on the average, 1750 indicated, or about 

 400 nominal horse-power at each end. 



The journey from London to Paris may be easily performed in eight hours, or 

 less, without any break or change of carriage, and the annoyance, delay, and inter- 

 ruption attending a sea-passage would be altogether avoided. 



The estimated cost of the whole undertaking, including the statioua and approaches 



