214 
LUPTON: CHANNEL TUNNEL. 
end only a few drops of water are to be seen in the tunnel, at the 
French end there is a good deal of water owing- to some faults. 
It is not likely that much water will be met with in driving the 
tunnel, as owing to the soft clayey nature of the grey chalk, it is 
hardly possible for it to contain any fissures, because the weight of 
ground and water above, would tend to consolidate the ground. But 
if water should be met with, even in large volumes, it can be tubbed 
out with cast iron cylinders, by a process well-known to the sinkers 
of coal shafts. Each feeder of water can be tubbed out as it is 
reached, so that the total volume of water to be dealt with at once, 
need never exceed a quantity that can be easily pumped up. 
After the 7ft. heading has been driven, it will be enlarged to a 
tunnel 14ft. wide inside the lining; the lining is to be made of 
cement concrete, the grey chalk excavated from the tunnel being 
used for this purpose. It is proposed to make two separate tunnels, 
one for each line of railway. This will be easier to make than one 
large tunnel, because the chalk is not strong enough to stand in a 
wide excavation ; and also, because if an accident should happen to 
one line, the other will not be blocked. And it will diminish the first 
cost of the tunnel, because one line can be completed and worked 
before the second line is made, and traffic developed. 
The cost of the tunnel need not apparently be very great, because 
there is no money to be paid for the land, and it would be impossible 
to find any ground more suitable for a tunnel than the grey chalk. 
The tunnel cannot be worked by steam engines, the products 
of combustion would be too dangerous and offensive ; but it may 
be worked either by compressed air or electrical engines. There is 
no reason why compressed air locomotives should not be used ; they 
are used now to a considerable extent in coal mines and elsewhere. 
The loss of power in using compressed air is very large, from 60 to 
80 per cent., but this is compensated for to a great extent by the 
greater economy of the stationary air compressor as compared with a 
locomotive; the boiler of the latter is expensive to repair, and it 
requires the best fuel ; a stationary air compressing engine need not 
use more than 2lbs. of cheap fuel per horse power per hour, and this 
will not mean more than lOlbs. of fuel per indicated horse power of 
