150 THE POPULAR SCIENCE MONTHLY. 



called, of "279 feet, Mas sufficient at the northern end, while at the 

 southern a fall of 531 feet was employed. 



The air-compressor used at the St. Gothard had been improved to 

 such an extent by Professor Colladon, of Geneva, that it is often 

 called the Colladon compressor. One of the devices employed was 

 this : The compression of air rapidly generates heat, and to reduce 

 the temperature of the compressing cylinder a circulation of water 

 was kept up all around it. The piston and piston-rod were hollow, 

 and water was introduced into them in like manner. In the shape, 

 finally, of fine spray, water was injected into the cylinder, and thus 

 brought into contact with the air itself. 



Not a little interest attaches to circumstances connected with the 

 invention of Sommeiller. This engineer had two associates, Grandis 

 and Grattoni. All were Italians, and all worked together in the evo- 

 lution of the problem. No statement has appeared designating the 

 part, or significance of the part, taken by each — a fact somewhat to 

 their credit. Of the three, Sommeiller, however, came to be the best 

 known ; a member of the Sardinian Parliament, he appeared in public, 

 as his associates did not. His name suggests a French, or, at least, 

 Savoyard origin, but the inventor was a Piedmontese, and in his 

 writings used the Italian tongue. 



The St. Gothard Tunnel is by some considered the most remarkable 

 engineering work extant.* Mr. W. W. Evans, ah-eady quoted, writing 

 in 1879 — and whatever he says upon this point refers to his fixed idea 

 that the proper route for an interoceanic canal was San Bias — says : 



Our weak-kneed i)eoi)le, who get frightened at the idea of a tunnel, slioiild 

 go to Europe, and study tunneling as done there. I found over two hundred 

 tunnels between Nice and Spezzia on the edge of the Mediterranean, cut and 

 used for a very limited railway travel. The line of the St. Gothard Railway is a 

 perfect marvel for tunnels. Nearly one fourth of the whole line is in tunnels. 

 The great or summit tunnel is nine and a half miles long; and in seven places 

 on the line — three on the Swiss side of the St. Gothard, and four on the Italian 

 side — they have tunneled into the sides of the mountain in great entire circles of 

 a thousand metres diameter, merely to get distance and keep the line to their 

 fixed maximum gradient of one in forty, or say one liundred and thirty-two feet 

 to the mile. And what is all this terrihle expenditure for? Why, merely to 

 rehabilitate the trade which the Suez Canal has opened, and which the people 

 of the Mediterranean enjoyed, and out of which they built their great cities.t 



Whether or not we consider the connection as immediate between 

 Suez and St. Gothard, as our author does, it is to be admitted that the 

 introduction of new processes in the case of these tunnels and con- 

 sequent acceleration of the work naturally encouraged those, like Mr. 

 Evans and Major Shelbourne, intent upon the cutting of a tunnel for 

 ships. Nor would the larger dimensions of such a work necessarily 



* Appletons' "Annual Cyclop.Tedia," 1881, p. 819. 



f "Journal of the American Geographical Society for 1879," p. 145. 



