422 Mr. Francis Fox [May 25, 



WEEKLY EVENING MEETING, 



Friday, May 25, 1900. 



His Grace the Duke of Northumberland, K.G. F.S.A., 

 President, in the Chair. 



Francis Fox, Esq., M. Inst. C.E. M.B.I. 



The Great Alpine Tunnels. 



The subject for this evening's discourse is that of the three great 

 tunnels through the Alps — viz., the Mont Cenis, the St. Gothard, and 

 that which is now in course of construction, the Sirnplon. 



But before dealing with the details of these particular works, it 

 will be desirable to consider what tunnelling is, and also some of the 

 more remarkable instances of it in bygone days. 



One great drawback in connection with the subject — so far as a 

 discourse is concerned — is its unsuitability for the photographic art. 

 Unlike a battleship, or a splendid bridge, or a grand block of build- 

 ings, which can be made into fine views and pictures, the work of the 

 mole is hardly adapted to the sensitive plate. I therefore propose 

 to make use of the " language of the pencil," and to make a few 

 rough sketches on the blackboard : by these means I trust I may 

 be able to explain some of the difficulties which have to be en- 

 countered, and also show how a tunnel is constructed. The child's 

 definition of drawing, " first you think, and then you draw a line 

 round your think," will come to our aid. 



The art of tunnelling dates back to very remote ages, and there 

 are records of such works which were constructed 500 to 600 years 

 before the Christian era. 



An interesting account is given by one of your most distinguished 

 members, in an article in the ' Encyclopaedia Britannica,' of the 

 tunnel under the river Euphrates at Babylon. This city, similar in 

 some respects to London, lay half on one side and half on the other 

 side of the river. High walls, penetrated by occasional gates, sur- 

 rounded the city, and lined each of the banks of the river. These 

 gates (of which a pair of the great hinges can be seen in the British 

 Museum) were closed at night and during war ; and a tunnel was 

 constructed below the bed of the river by means of what is techni- 

 cally known as the " cut-and-cover " system. In those days the 

 Greathead shield was unknown, and consequently the river had to be 

 diverted, so that the excavation could be made in the dry bed and 



