60 ANNUAL OF SCIENTIFIC DISCOVERY. 



Simultaneously with these borings the bottom of the Cliannel 

 was c.'irerully examined, by means of a steamer provided with all 

 suitable apparatus. Tlie main useful results establislied by these 

 experiments appear to be, that on the English coast the depth of 

 chalk is 470 feet below iiigli Avater, of which 295 feet arc of the 

 gray formation, in wiiieh it is proposed to work; tliat on the 

 French coast, the deptli of chalk is 750 feet, 480 being gray ; and 

 tiiat there appears to bo no room to doubt tiie regularity of the 

 strata between the two shores along the line proposed. 



So, it would seem, first, that the chief condition is satisfacto- 

 rily insured, and the geological formation of the sea's bed is such 

 as to admit of the excavation of a tunnel through the lower gray 

 chalk ; and, secondly, that it is not necessary to go to a depth 

 unsuitable for railway trafTie. It is calculated that the approaches 

 to the tunnel can bo constructed at gradients not exceeding one 

 foot in 80. » 



The next point of paramount importance to the travelling pub- 

 lic is the question of the safety of the tunnel when made. The 

 dangers most carefully to be guarded against are two: any pos- 

 sible irruption of water from the sea, or from unexpected land- 

 springs; and any delicieney in ventilation. 



Engineers are of the opinion that these dangers can all be pro- 

 vided against. Recent borings on either side of the Channel 

 have prov(>d that there need be no fear of land water, and the 

 impermeability of chalk, and the depth below the bottom of the 

 sea, at which the tunnel will be placed, being in no case less than 

 100 feet, it is maintained that there would bf no danger from 

 incursions of the sea-water. The submarine excavations in the 

 Cornish mines are an existing demonstration of the safety of the 

 proposed tunnel. 



Ventilation will be secured by means of powerful steam en- 

 gines, and attempts to raise the necessary funds are wisely to bo 

 postponed until two small headings, or galleries, are driven from 

 each counlry, connected by transverse driltways. Ventilation 

 would thus be secured in the manner customary in coal mines 

 and works of a similar nature, and the feasibility or otherwise of 

 connecting England and France by a tunnel can be demonstrated. 



CANALS. 



The great ship canal which is to connect Amsterdam with the 

 North Sea is now once more in ])rogress, the government of the 

 Netheilands having relieved the contractors of certain dilHculties 

 which for a time hindered the work. The canal will be about 15 

 miles in length. The Zuyder Zee is to be shut out from Am- 

 sterdam, and the ram])us dam, by which this is to be elVected, is 

 ulreadv half fniished, and the locks and sluices connected with it 

 are in progress. 



A ship canal is to be constructed through Sehlcswig-Holstein to 

 connect the lialtic and tlu; North Seas. The i)reliminary sui'veys 

 have been completed. It is thought the Prussiau Government 

 will undertake the work of building. 



