820 



ST. GOTHARD RAILWAY AND TUNNEL. 



14,900 metres or nearly nine miles long, ex- 

 tending from Goeschenen, in the Canton Uri, 

 1,109 metres or 3,604 feet above the sea, on 

 the north, to Airolo, in the Canton Tessin, 

 1,145 metres or 3,721 feet above the sea, on 

 the south. The work has been eight years in 

 execution, and its progress has been attended 

 with some very skillful feats of engineering, and 

 the invention and application of important im- 

 provements in the machinery for carrying on 



extensive borings in rocks. The work was be- 

 gun under the direction of M. Louis Favre, engi- 

 neer, who died during its progress, on July 19, 

 1869, after having adopted the methods and 

 machinery the employment of which insured 

 its successful execution. The operations at St. 

 Gothard were begun under the advantage of 

 the possession of the experience, knowledge, 

 and skill that had been gained in constructing 

 the tunnel of Mont Cenis. 



PBOFILE ALOXO THE LENGTH OF THE TUNNEL. 



The preliminary surveys were attended by 

 difficulties which could be overcome only 

 through the application of rare scientific in- 

 genuity. The engineers of the tunnel of Mont 

 Cenis had a point at the highest part of the 

 ground from which they could see at once ob- 

 jects indicating the positions of both openings. 

 No such advantage existed at St. Gothard ; and 

 some of the summits in the way were so steep 

 and so high that it was impracticable to at- 

 tempt any direct tracing of the line of the tun- 

 nel over the mountain. The relative positions 

 of the two openings and the direction of the 

 tunnel had then to be calculated indirectly, 

 from triangulations. The directions and levels 

 were ascertained in this method ; and observa- 

 tories were then placed at the tunnel-mouths 

 to serve as direction-points for the miners. At 

 Goeschenen it was necessary, in order to get 

 a long enough line of sight, to make borings 

 of considerable length through two projecting 

 rocks. The surveys, originally made by M. 

 Gelpke, were verified by a second series of tri- 

 angulations made in 1874, by another engineer, 

 M. Koppe, on a different system. M. Gelpke 

 had based his surveys on summits in the neigh- 

 borhood, and had used triangles of only mod- 

 erate size. M. Koppe made his triangles as 

 large as possible, so that he might connect the 

 two openings of the tunnel by a minimum 

 number of intermediary stations. The two 

 triangulations gave results agreeing within two 

 seconds of direction with each other. M. Kop- 

 pe also verified his survey practically by project- 

 ing a line from the opening at Airolo toward a 

 mast which he set up at the highest attainable 

 point along the axis of the tunnel. Since he 

 was not able to go toward this point from Goe- 

 schenen, he went backward in the direction 

 of the continuation of the tunnel-axis, ascend- 

 ing the flanks of the monntain till he could 

 observe the mast. Then, having directed his 

 glass toward Goeschenen, he raised it verti- 

 cally to the level of the mast, when he saw 



the pole almost in the center of his field of 

 vision. The direction within the tunnel was 

 verified by means of field-glasses fixed within 

 the observatories, so far as they would answer, 

 then by means of lamps hung on the line of 

 the axis of the tunnel, and was verified from 

 the observatories two or three times a year. 



The drilling of the rocks was done with ma- 

 chines worked by compressed air, similar to 

 those which had been used at Mont Cenis, but 

 having many improvements over them. Sev- 

 eral kinds of machines moved by compressed air 

 have been invented, each of which bears the 

 name of its inventor. The one nsed in the 

 present work was that of M. Colladon. In 

 these machines the power is applied to work 

 a drill in the same manner as the hand-drill is 

 worked by miners, but with vastly more force, 

 and a speed of five or six hundred or more 

 blows a minute, instead of the fifty or sixty 

 blows a minute to which the capacity of the 

 hand-drill is limited. The drill is fixed upon 

 a piston which is driven by compressed air. It 

 strikes the rock, is drawn back, and strikes 

 again, having been turned a little in the inter- 

 val, so that its edge shall not strike exactly in 

 the mark made by the previous blow. A jet 

 of water may be thrown into the drill-hole to 

 remove the chips and prevent too great heat- 

 ing of the drill. Several drills may be mounted 

 upon the same supporting apparatus, and may 

 be directed, under inclinations varied accord- 

 ing to circumstances or the wish of the engi- 

 neer, against the same head of rock. 



A different perforator, and a more novel 

 one, called the Brandt machine, which was 

 worked by compressed water, was used in one 

 of the tunnels on the same line, though not in 

 the main tunnel. In this machine water, which 

 is given a pressure of a hundred atmospheres, 

 is employed instead of air, with the lighter 

 pressure of only one or two atmospheres, to 

 force a large hollow boring-tool, eight centi- 

 metres or nearly three and a half inches in 



