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there are, towards the middle and lower part, some sandy and 
calcareous hands which might yield water. But the upper part 
of the Clay is impervious ; and, taking all things into considera- 
tion, there is no formation below the Chalk which offers so 
many advantages. Another point of some consequence is that 
a tunnel through the Kimeridge Clay would pass under “ The 
Ridge ” — a shoal in mid-Channel ; and on this a shaft could be 
sunk, which would aid both in the first construction of the tunnel 
and in its permanent ventilation. 
The only serious objection to this proposal is perhaps a fatal 
one : a tunnel through the Kimeridge Clay might have to 
be nearly fifty miles long. In fig. 5 a section is shown from 
Fairlight to C. Grrisnez. The succession beneath Fairlight is 
inferred from what has been made known to us by the Sub- 
Wealden boring ; that at C. Grrisnez is sufficiently well known. 
The exact range under the Channel cannot be known until a 
boring has been made on the Ridge. It would be advisable to 
bore near Appledore, or at some other point nearer Hythe, in 
order to ascertain the thickness and character of the Kime- 
ridge Clay in that part. If the clay should continue in suffi- 
cient force as far as Hythe or Lympne, the tunnel could be 
carried under the Varne, on which a shaft could be sunk ; and 
the length of the tunnel would not greatly exceed that now 
proposed through the Chalk. 
It may be desirable here to point out that the whole of 
Romney Marsh must be left out of consideration in estimating 
the length of tunnels from coast to coast. We must regard 
that area as though it were sea, and reckon the shore to be the 
rising ground which bounds the marsh, from Winchelsea, past 
Rye, Appledore,' and Lympne, to Hythe. This line was once 
the shore, and Romney Marsh has been formed by the slow 
accumulation of sediment. It would be impossible to tunnel 
through this recent deposit, and any tunnel crossing in this 
direction must be carried well under the sea-level, in an 
impervious bed, before it reaches Romney Marsh. 
We will now turn to the Lower Chalk, in which the first 
attempt to tunnel will almost certainly be made. No formation 
is better known, and more tunnels have been carried through 
this than through any other bed which occurs in the south- 
east of England. It is certainly sufficiently thick, being 
nearly 400 feet on the English coast, and about 300 feet thick 
on the French coast. The Lower Chalk, as amass, is practically 
impervious, water only passing through it very slowly. The 
only way by which water in any quantity can occur is by means 
of fissures. These do exist, and yield water to wells, in the 
Upper Chalk, or the Chalk-with-flints ; but . they occur more 
rarely in the Lower Chalk. Moreover, as to the actual amount 
of water which these fissures yield ; well-sinkers are quite aware 
