April 21, 1870] 
NATORE 
633 
The general principle of the scheme, as invented and 
elaborated by Messrs. Bateman and Révy, may be easily 
understood by the ordinary reader. He can, however, 
have little idea how the practical difficulties attending the 
execution of such immense works have been overcome by 
these engineers. Take, for example, the first sentence or 
two we have quoted above. The general proposition is 
this: “ A tube of cast iron to be built up inside a 
horizontal cylinder or chamber.”—No doubt this may 
appear simple enough, but when we come to consider 
what the operation of duzl/ding means,—when we come 
to consider that no part of the tube to be so built up 
weighs in one piece less than fev ¢ons,—that those solid 
pieces of iron could not even be stirred by the power of 
scores of men, much less lifted or deposited in the right 
place—that this “ building up” is to take place in a 
comparatively small space, not exceeding 13 feet in 
diameter, the larger part of which is already occupied by 
the very plate weighing 10 tons ;—we may ina measure 
deposit these monster plates with the same ease, quick- 
ness, and certainty as a bricklayer would lay his brick in 
the construction of an arch, we venture to say the 
authors have made out their case. 
We believe it is the first time that any of the projectors 
or designers of Channel railways have paid serious atten- 
tion to the important question, how such a submerged 
railway or tunnel could be used and worked to advantage 
for the enormous traffic between England and France. 
Most of them seem to assume, as a matter of course, that 
such a tunnel of iron or brick would be worked as ordi- 
nary railways. It appears, however, from the investi- 
gations of Messrs. Bateman and Révy that there is but 
one way of working such a tunnel to advantage, and 
unless the arrangements and the construction of the 
works be kept in accordance with that mode of working 
the traffic, the tunnel, when completed, would be of no 
use for practical purposes. The authors find that the 
power for the propulsion of trains must be pneumatic 
SECTION OF THE TUBE. 
realise what the word “building” under these circum- 
stances signifies. 
But we have further to bear in mind, that it is not 
enough that we should be able somehow to “build up” 
the tube inside that chamber, but that it must be done 
quickly, without delay or a hitch, and that unless it could 
be so done the operation of “ building up” would take 
generations in crossing the Channel, and make the whole 
proposition, though practicable in every detail, yet a forlorn 
hope, because of the length of time. If thus we come to con- 
sider, that the authors have not contented themselves with 
saying that “their tube is to be built up in that chamber,” 
but have given us the precise designs and the exact mode 
of proceeding to be adopted ; that the designs and 
arrangements are so complete that they might be forth- 
with placed in the hands of a contractor ; that these 
mechanical arrangements would enable a boy of ordinary 
intelligence to take hold, lift, and place, and finally 
pressure ; not as applied in the old-fashioned style above 
ground, and known by the name of atmospheric railways, 
but a pressure of air applied by powerful pumps directly 
upon the train, which would form a kind of loose piston 
inside the tube. On the old plan, the train was outside a 
little tube ; on the new plan, the train is inside a large 
tube ; and with this simple alteration all the difficulties 
which led to the abandonment of the former, disappear 
on the latter plan. The difficulties of the old atmospheric 
railways were: (1) mechanical difficulty of connecting 
the piston of the little tube with the train outside 
it; (2) The high pressure required on the small 
area of the piston for the propulsion of the train, 
and consequent development of an excessive amount of 
heat within the pumps, leading to their rapid destruction 
and great loss of power by subsequent cooling of the air. 
By the new mode of atmospheric propulsion all these 
difficulties are done away with, for there is no connection 
