500 The Channel Tunnel. [October, 
into the nature of the strata beneath the Channel, which 
confirmed the theories of the geologists, threw new light on 
the subject, and put the question of a submarine tunnel ina 
position to be seriously discussed and considered by the 
public. Before that time he had given the subje&t much 
consideration, but in that year he caused careful geological 
surveys and investigations to be made of the Channel, and 
afterwards, in conjunction with the late Mr. Brassey and 
Mr. George Wythes, had borings sunk on each coast. Sub- 
sequently, by means of apparatus contrived for the purpose, 
he examined the bottom of the Channel all across in a great 
number of places, and raised specimens of the sea bed for 
examination, by which it appears to have been satisfactorily 
established that the actual position of the chalk across the 
Channel is very nearly identical with that deduced from 
previous enquiries, and its unbroken continuity placed al- 
most beyond doubt. Its thickness, determined by deep 
borings on both sides, is proved to be above 500 feet below 
high-water mark, with an ample thickness of the lower or 
grey chalk between the bottom of the sea—which is nowhere 
more than 180 feet deep—and the crown of the tunnel, as 
well as between the bottom of the tunnel and the green 
sand or water-bearing strata underlying the grey chalk. 
The tunnel has been placed by the engineers at such a level 
that the depth of strata over it will nowhere be less than 
200 feet, and this depth, which is desirable for security, will 
permit the railway approaches to be formed with not un- 
favourable gradients. 
In the opinion of M. de Souch, Inspector-General of 
Mines in France, the line selected by the engineers of the 
Channel Tunnel Company is the only one which presents 
chances of success, and is the only rational one. The Com- 
mission appointed by the late Emperor of the French to 
examine this project reported that there was every reason 
to believe that the chalk formation extends under the Chan- 
nel between Dover and Calais and that ‘“‘the thickness of 
the grey chalk gives a certain latitude for the maintenance 
of the tunnel in the same direction, even where the level of 
the bed of the sea may be subject to some undulations ; and 
they believe that the existence of any great fracture in the 
chalk is very improbable.” 
On the other hand, we have the opinion of so high an 
authority as Mr. Joseph Prestwich, Vice-President of the 
Geological Society, who does not entertain such sanguine 
views as to the suitability of the chalk stratum for the con- 
struction of the proposed tunnel, as will be seen from the 
