LUPTON: CHANNEL TUNNEL. 
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the locomotive. Taking all the circumstances into consideration it 
will be difficult to find any much more economical power than 
compressed air ; and it has this advantage, that the air given off by 
the locomotive will be sufficient for the ventilation of the tunnel. 
The locomotive proposed it is thought will take a train weighing 
150 tons, gross, at the rate of 30 miles an hour. Whilst the 
exhaust air from the engines will very likely suffice for absolute 
needs, yet it will probably be advisable to have a regular current of 
air, about 50,000 cubic feet may be sufficient, and this can be 
obtained by means of a fan and engine, such as are used for venti- 
lating coal mines. 
At present Colonel Beaumont has a locomotive made ready for 
hauling the dirt out of the tunnel, which is now working on the surface. 
It is a small locomotive using air at a pressure of l,0001bs. which is 
heated by a very small coke fire, this facilitates expansion and pre- 
vents freezing in the ports, the air is expanded down to atmospheric 
pressure by compound engines of which the high pressure cylinders 
are 2 in. in diameter and the larger cylinders 7 in. in diameter. 
The tunnel, whilst it is being driven will be ventilated by the 
exhaust air from the excavating machinery. It is now lighted by 
the “ Swan Electric Lamp,” of which there is a series fixed along 
the side so that the whole length is illuminated. 
There is also no doubt that the traffic in the tunnel might be 
worked by electricity as a motive power. And before the tunnel is 
completed it is probable that great progress will have been made in 
the construction of large engines worked through the agencies of 
magnetism. 
It is quite possible to construct both the tunnels under the sea 
at the rate of £50 a yard each, or a £100 a yard for the two, which 
amounts to £176,000 a mile, and 25 miles at this rate will amount 
to £4,400,000 or with approaches, apparatus for air compressing, 
rolling stock, &c., &c., say £5,000,000 in all. The interest in this 
at 4 per cent, will be £200,000 a year. It is difficult to see how 
the tunnel can fail to be profitable. Suppose for a moment England 
and France to be connected by a narrow isthmus, can it be supposed 
that a railway to connect the two countries would not pay, and if so 
