502 The Channel Tunnel. [October, 
level. Whatever the level of the spring the water of course 
passes through all the superincumbent portions of the Chalk 
Marl. This very commonly impermeable character of the 
Chalk Marl has given rise to the hope that it might prove 
compact enough for a submarine tunnel under the Channel 
between Cape Blancnez and the South Foreland; but when 
it is considered that such a work would have to face the 
risks arising from the lateral passage of the inland springs 
and from the chance fissures socommon to calcareous rocks 
communicating with the sea, it is feared that the difficulties 
would prove to be of a very formidable nature. It is to 
be observed that in the Channel the chalk is frequently bare, 
besides being unprotected by any overlying strata.” 
The foregoing observations demand our full respect, but, 
on the other hand, the possibility of tunnelling beneath the 
sea without being exposed to an irruption of sea water is 
shown in the submarine galleries of some mines in Cornwall, 
Cumberland, and elsewhere. In a treatise on Mines and 
Mining by Mr. Price, published in 1778, he treats especially 
of mining under the sea, and refers particularly to the free- 
dom of water in such works. 
It is probable, and the engineers anticipate that at the 
shore end of the Channel Tunnel, especially in constructing 
the shaft through the upper strata, a considerable quantity 
of water will be met with, but not sufficient to prevent the 
execution of the work, where pumping power of any mag- 
nitude could, if necessary, be applied. It is believed, and 
there appear to be reasonable grounds for such belief, that 
as the work attains a greater depth in the chalk, and espe- 
cially after the lower or grey chalk is reached, the quantity 
of water will diminish, and that in mid-channel it will be 
less than at the sides. 
The geological features of this projeét having now been 
duly considered, it remains to give some particulars of the 
engineering nature of the work. The distance across the 
Channel at the point selected is about 22 miles, but as con- 
siderable approaches will be necessary on either shore, in 
order to reach the level of the tunnel entrance, the entire 
scheme will embrace about 31 miles of railway. In the 
first instance shafts will be sunk on each shore to the depth 
of 450 feet below high-water mark, and, from the bottom of 
these, driftways will be driven for the drainage of the works 
whilst in progress, and for its permanent drainage after 
completion. The tunnel, which will be very similar to an 
ordinary railway tunnel having two lines of rails, will com- 
mence 200 feet above this driftway, and will be driven at 
