TUNNELS IN GENERAL AND THE ST. GO THAR D IN PARTICULAR. 663 



There they would enjoy a perpetual summer. The lecturer thought it also likely 

 that there might be some hardy Esquimaux who could manage to exist on the 

 planet Mars. As for the other planets, if they were inhabited at all, they were 

 inhabited by people of whom nothing was known, but who must necessarily be 

 adapted to the peculiar qualities of the various planets. — N. Y. Times. 



ENGINEERING. 



TUNNELS IN GENERAL, AND THE ST. GOTHARD IN 

 ^ PARTICULAR. 



Many curious things might be said about tunnels, old as well as new. For 

 instance, the stupendous work — whose history links modern with ancient engi- 

 neering — the object of which was to connect Lake Fucinus, now called Celano, 

 with the Liris, now the river Gariglino, was undertaken 42 A. D. It took near- 

 ly eleven years to complete, and 30,000 men are said to have been engaged upon 

 it. This subterranean canal was executed by order of the Emperor Claudius. 

 For nearly eighteen centuries it seemed to have been forgotten ; but on its dis- 

 covery, about sixty years ago, the Neapolitan Government resolved to clear it 

 out. This was accordingly done, but not until several years had been spent up- 

 on the task. The improved tunnel is four miles long; the original length was 

 three miles. Prince Torlonia of Rome gradually bought up the shares, and car- 

 ried on the operations at his expense until his death in 187 1. 



Modern tunneling — which by-the-way, is quite a distinct profession — is of 

 three classes : First, tunneling through soft ground, such as clay, loose rock, etc. 

 Second, rock-tunneling without machinery; Third, tunneling solid rock by the aid 

 of machinery. In piercing a hill or other mass of earth, a large quantity of timber 

 for temporary arching is required, until the brick or stone work has been provided. 

 In some methods of tunnel-making it is judged more secure to brick the timber in. 

 But this is very costly, especially when all the heavy timber has to be conveyed 

 down a shaft or slope. Where the ground is rather yielding, and much 

 water appears, an inverted arch is constructed across the bottom of the tunnel, 

 so as to resist the pressure from beneath. There are now, however, other meth- 

 ods of construction in use. A new system has been devised of employing iron 

 centers as a substitute for timber. Tunneling through loose rock, timbering, and 

 then arching, is a method mostly in use in England and America ; and where the 

 length is comparatively short, hand labor is found cheaper than the employment 

 of machinery. But at the present day, this kind of engineering is conducted on 

 a vast scale with steel and diamond-pointed drills, driven by compressed air (at 

 about forty pounds to the square inch), which latter serves for ventilation pur- 



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