[131] In constructing shafts, French engineers prefer to place them on one side, and not over the centre of the tunnel, partly because they consider it more convenient for purposes of construction, and partly because they think it safer for the line, which is thus less exposed to accident or ill-will, or to the annoyances experienced from wet or dripping shafts.
French engineers construct tunnels on curves more than has been the practice of English engineers. One tunnel, that of Vierzon, 208 metres long, is on a reversed curve, one radius being 1,093 yards, and the other 1,366 yards.
[132] For full particulars of this tunnel see reports of Mr. Storrow, and of Messrs. Laurie & Latrobe, embodied in the report of the Commissioners of the State of Massachusetts on the Troy and Grenfield Railroad, and the Hoosac Tunnel, dated the 12th March 1863.
[133] Drawings of the tunnel entrances, and a section of it, are given in Engineering for September 27, 1867.
[134] Under water between France and England is not going to have it all its own way. In 1864 there was a scheme for very large ferry-boats between Dover and Calais, the boats to come, at each harbour, into a groove or dock specially to be made for them. The plan, however, was abandoned at an early stage, mainly, it is believed, because the French Government declined incurring the very great outlay that would have been unavoidable at Calais. In fact, the plan would have rendered necessary the construction of a new and much enlarged harbour there, involving an expenditure of three or four millions sterling. The present year has brought out several ferry schemes, one of which only we purpose referring to—that of Mr. T. B. Daft, C. E. This gentleman proposes to run his vessels between Dieppe and Newhaven. He has not, however, quite decided whether each ship is to consist of one hull or of two. If the hull be single, his deck is to be 500 feet long and 150 wide. If double, each is to be 50 feet wide, the pair to be placed 30 feet apart, and to be connected together by iron beams covered over by a broad deckway, so that passengers might go from one ship to another at their convenience. But no vessels so united could hold together in a heavy cross sea. The beams would be smashed to atoms by its violent and irregular action, and the difference of elevation of waves only a few feet distant from one another.
Mr. Daft proposes four pairs of engines of the collective power of 2,400 horses for his boats, to receive which there are to be special floating harbours at Dieppe and at Newhaven, so arranged that the trains can at once be put on the deck of the vessels at the departure harbour, and landed at that of arrival without disturbing passengers or luggage. Mr. Daft makes up his figures as follows:—Expenditure on capital account £1,000,000; 600,000 passengers during the year at 5s. each, £150,000; 300,000 tons of merchandise at 8s. each, £120,000; gross probable receipts £270,000. Per contra, wages of crew, £4,680; coals, 15,200 tons for twelve voyages per week, £11,250; stores, light dues and pilotage, £920; interest at 5 per cent. on capital £50,000; insurance, repairs, and depreciation, £100,000, making a gross annual expenditure of £166,850, thus showing a divisible profit (besides the 5 per cent. interest on the million of capital) of £103,150. We sincerely hope that the shareholders may find it, if ever these vessels and harbours be constructed. The only objection we shall dare to offer to the plan is the possible inconvenience to which a gallant male passenger may be subjected when a lady, whom he had perhaps found a most charming conversational compagnionne de voyage on terra firma, may all of a sudden, in a rough sea, ask him to be so good as to hand her the basin!
[135] M. Metres.
[136] C. Centimetres.
[137] For the first Half of 1867 only.
[138] On the other hand, Captain Tyler, in his report to the Board of Trade of his inspection of the Mont Cenis Railway, dated the 4th September, 1867, states, that, by the favour of the Italian Government, he visited the tunnel works on the 24th of August, when “on going with Signor Copello, the chief engineer of the French side, into the Grand Tunnel on that side of the Alps, I found that a great improvement had been effected in its ventilation since my visit of last year. A wooden partition had been completed under the roof for a distance of 1,500 metres. Four cylinders had been constructed, each four metres in diameter, and with a stroke of two metres, for drawing out the foul air at a maximum rate of ten strokes per minute. The head of water for working these cylinders was 70 metres.