348 
TOrULAIt SCIENCE REVIEW. 
with what has been already observed in other places, and with 
other rocks that have been exposed to similar action ; and thus 
the geologist is strengthened in his own conclusions, and satis- 
fied with the correctness of the conclusions drawn by others 
in this department of geology, by the additional light thrown 
on his pursuits by the study of the works carried on in this 
remarkable tunnel. 
While alluding to this part of the subject, it would not 
be fair to exclude mention of a supposed discovery of a 
rounded pebble, said to have been found in a narrow dry cleft 
or fissure, from four to six inches in width, near the middle of 
the tunnel. The cleft was very irregular, and was partly filled 
with crystalline quartz, and was said to be open above. The 
pebble was oval, and somewhat resembled the undular concre- 
tions of limestone or ironstone often met with in slags and 
shales. The enclosing rock was a talcose schist, with quartz of 
the ordinary kind. As there was a possibility that the speci- 
men might have belonged to the rock, it was carefully broken, 
in the presence and at the request of the writer ; but the struc- 
ture showed it to be gritstone rounded by water. The speci- 
men had been brought to the resident engineer by the foreman 
of the works, who had not before or since found any curiosities, 
and who claimed to have taken it himself from underground. 
The story is given as it was related. 
The condition of the interior of the earth with regard to 
water is a subject on which it maybe expected that great light 
will be thrown by the perforation of the Alps. A clean cut 
through seven miles of rock under a mass of 5,000 feet of over- 
lying material nearly of the same kind may be expected to 
afford information of great value in this respect. The antici- 
pations that might have been made, judging from experience 
in other tunnels, are, however, not altogether borne out by the 
reality, and the result is almost negative. The total quantity 
of water entering the tunnel has at no time been large, and, 
compared with its great length, must be regarded as wonder- 
fully small. The average quantity is stated not to exceed one 
litre per second from each end, or less than 40,000 gallons per 
day from the whole excavation as at present completed. This 
quantity lias been increased from time to time, when -certain 
open but very narrow fissures and small cavities have been 
reached. In these cases there has generally been a rush of 
water, evidently under pressure, but the total content of the 
water cavities, including all their communications, has at no 
time been very large, and they have each in succession been 
exhausted, a very few days being generally sufficient for this 
purpose. In the case of the largest of them a quarter of a 
million gallons of water would seem to represent the full con- 
