THE CHANNEL TUNNEL. 411 



over two miles from Dover, it is, afc the minimum distance, required to 

 pass with a gradient of 1 in 80 from the mouth of the tunnel to the re- 

 quired depth below the shore-line, and thus we get the shortest possible 

 land tunnel. I think that, so far, it has been shown that everything is in 

 favour of the tunnel terminating in the Valley of the Dour, and passing 

 beneath the shore-line near Fan Hole. It remains to be seen how far 

 these advantages are outweighed by any geological conditions aiForded by 

 the Folkestone route. 



The only reason which has been given for taking the tunnel under the 

 shore-line to the west of Dover is, that by so doing it can be made wholly 

 in the lowest beds of chalk. It is asserted that no water, or very little, 

 will be found in these lower beds. Now what are the facts. We are told 

 that little water is found in the heading from Shakespeare Cliff ; that may 

 be so, as far as it has gone. In the headings driven at Sangatte, in the 

 corresponding beds in France, water is met with flowing from fissures at 

 the sides and bottom, and not confined to one place, but throughout the 

 headings. The quantity which I saw was not large — the largest spring, 

 perhaps, 30 gallons per minute — but it is enough to prove that those 

 beds are not impermeable ; and no one can assert that where small water- 

 bearing fissures exist, larger ones may not be met with. In the region 

 where a tunnel is possible, the only other evidence we have as to the 

 water-bearing qualities of these beds below sea-level, is that obtained from 

 small borings, few in number, and not of much value as compared with 

 the evidence derived from headings and shafts through the beds. Above 

 the level of the sea we can study the beds at many points. I do not 

 attach much value to deductions as to the probable condition of the beds 

 below the sea-level, made from their observed conditions above the sea- 

 level, for the constant movement of the land waters, from the highest 

 levels to the points where they are discharged into the sea, must produce 

 well-defined drainage-channels underground, which need not necessarily 

 exist at greater depths where there is no such rapid circulation. Still, as 

 much has been made, especially by the French engineers, of evidence 

 derived from observations on the zones from which water is discharged 

 on land, I will give a few facts relating to them. In France water may 

 be seen to flow in many places from the lower beds of chalk, where they 

 appear in the cliffs, between Escalles and St. Pot. I saw water flowing at 

 the very junction of the lowest beds and the green sand. There are some 

 large springs near Escalles, which, on the section accompanying the 

 French Report (1877), are shown at about 60 feet above the upper 

 green sand. The section shows Lydden Spout on the same horizon, but 

 that copious and well-known spring, on the coast between Folkestone and 

 Dover, issues, according to Mr. F. G. H. Price, who carefully measured the 

 cliff section near it, at the top of the so-called ' cast bed,' about 32 feet 

 above the upper green sand, or 46 feet above the gault. Therefore, if 

 this evidence is worth anything, it shows that, on the French side, water 

 might be met with largely, 60 feet above the green sand ; or, allowing 36 

 feet for the depth occupied by the tunnel and its masonry, 24 feet only 

 above the tunnel, supposing it to be di-iven continuously along the top of 

 the green sand. On the English side, as the water is found only 32 feet 

 above the green sand, the top of the tunnel would be in this water-bearing' 

 zone, on the same assumption. It is needless to say that no railway 

 tunnel could be driven along the top of one bed, following all its flexures. 

 Thus, if the evidence from the permeability of the strata on land proves 



