to be continued for a few seconds—seemed astonishingly easy, as the revolution of the machine cut the chalk away and delivered it into the waggon behind ready for removal. The experimental tunnel is bored in the strata which are supposed to represent the continuous earth surface—between what are now the coasts of France and England—in prehistoric times when the land, now these islands, formed part of the great European continent. Messieurs Lavalley, Larousse, Potier, and Lapparent, in their report to the French Channel Tunnel Company, presented in 1877, say: "Examination of the cliffs on each coast of the Straits shows that the geological strata are the same in the area which concerns us, and which includes especially the cretaceous formation. On both sides are the same strata, with the same characteristics, and, remarkable to say, with the same thickness. Hence the presumption—authorised indeed by other considerations—that in the prehistoric period, instead of an arm of the sea, separating two coasts, there stretched here a continuous, more or less undulating, plain, between the points at which have since been built Calais and Boulogne on the one side, Folkestone and Dover on the other. According to this hypothesis, the Straits would be due to the gradual erosion of a soil of slight consistency, such as the cretaceous formation in general, which yielded before the ceaseless repetition of blows from the waves of the Northern Sea, a sea so stormy during the rougher months of the year. From this we gather the hope that the strata encountered beneath the sea, through which the tunnel must be driven, will be free from serious dislocations, and will only present slight undulations to which it will generally be possible to conform the plan of the subterranean railway without any great difficulty.
