THE CHANNEL TUNNEL. 413 



its water, unless there is direct communication between two fissures, 

 operations at one do not generally affect the others. Now this property 

 of the chalk is of the greatest importance in carrying out engineering 

 works which require excavations to be made through the water-bearing 

 levels in it, for it enables the engineer to deal witli the water in detail. 

 Fissure after fissure may be cut through as long as the water flowing from 

 them leaves a sufficient margin of unused pumping power ; as soon as the 

 yield of water becomes so great as to diminish that margin unduly, some 

 of the fissures may be blocked up with temporary or permanent work. 

 Thus it will be seen that, in tunnelling through chalk, a very large 

 volume of water might be dealt with if it entered the work by separate 

 channels. A very large body of water entering at one point might give 

 trouble, and I shall accordingly select some facts from the very large 

 number available, to show tliat from no one area of chalk, even of con- 

 siderable extent, much less from one fissure, has a supply of water been 

 derived larger than could easily be dealt with, or which at all approaches 

 the volumes which have been dealt with on works completed or now in 

 progress. At Goldstone Bottom, one of the pumping stations of the 

 Brighton Waterworks, a greater quantity of water is obtained than at 

 any other locality known to me. Mr. Edward Easton, the best authority 

 on this subject, has kindly furnished me with some particulars respecting 

 these works. There are engines at Goldstone Bottom capable of raising 

 300,000 gallons an hour, or 5,000 gallons a minute, but it has been neces- 

 sary to make a length of 1,800 feet of tunnels to obtain the required sup- 

 ply. These are at right angles to the fissures, which here, as is so often 

 the case, are at right angles to the shore-line. At Lewes Road, another 

 of the Brighton pumping stations, there are engines capable of lifting 

 280,000 gallons an hour, or 4,666 gallons a minute, to supply which 

 2,400 feet of tunnels have been made. Mr. Easton tells me, and this is. 

 the important point, that the water in those tunnels is under complete 

 control, so that any one of them can be laid dry at any time of the 

 year. 



The work which has tested to the fullest our power to tunnel through 

 the wettest parts of the chalk is the Brighton intercepting sewer, for 

 which Sir John Hawkshaw was engineer. The main sewer is more than. 

 7 miles long. The outfall is placed on the coast, about 4 miles to the 

 east of Brighton ; and, throughout a distance of about 41 miles, a tunnel,, 

 from 9 to 10 feet in diameter, was excavated in the upper chalk, along the 

 base of the cliff, and close to the shore. Being below high- water level, it 

 cut through all the fissures which discharge the drainage of a large tract 

 of inland chalk country. Large fissures were cut through, which I had 

 frequent opportunities of inspecting, and, moreover, of seeing the perma- 

 nent work successfully carried across them. The greatest quantity of 

 water pumped at one time was 10,000 gallons a minute, or 600,000 an 

 hour; many other examples might be given, but none so striking as the 

 above. It may be urged that, by going below the levels reached by the 

 above works, more water would have been obtained, but that by no means 

 follows. The Brighton Sewer Works must have intercepted most of the. 

 land drainage ; by going deeper, some water, stored in cavities below sea- 

 level, might have been pumped. But the supply depends not on the 

 quantity stored, but upon the rate at which the fissures can deliver it. 

 Fissures there are, or, there have been, at all depths ; but, as the circula- 

 tion is not so rapid in the deeper ones, they are more liable to be choked 



