1900 ] on the Great Alpine Tunnels. 433 



to centre of 55 feet 9 inches ; and one of the chief features is the 

 much lower altitude of the rails above sea level than any of the 

 other Alpine tunnels. This altitude is at its highest point 2314 feet, 

 being 1474 feet lower level than that of the St. Gothard, 1934 feet 

 lower than that of the Mont Cenis, and 1986 feet than that of the 

 Arlberg. This is a matter of great importance in the question of 

 haulage of all the traffic. 



The tunDel enters the mountain at the present level of the rail- 

 way at Brigue, so that no costly approaches are requisite on this 

 side ; but on the Iselle side, the connecting line with the existing 

 railway at Dorno d'Ossola necessitates heavy work with one helical 

 tunnel. The gradient on the northern portion of the tunnel will 

 only be that sufficient for drainage, viz. 1 in 500, but on the southern 

 portion the gradient will be 7 per 1000, or 1 in 142. 



Admirable arrangements have been made for the welfare of the 

 men, to avoid the heavy death-rate which occurred on the St. 

 Gothard, and it may be interesting to state what some of these are. 

 For every cubic foot of air sent into the latter tunnel, fifty times 

 as much will be delivered into the Simplon. Special arrangements 

 are made for cooling the air by means of fine jets of water and spray. 



The men on emerging from their work, wet through and fatigued, 

 are not allowed to go from the warm headings into the cold Alpine 

 air outside, but pass into a large building which is suitably warmed, 

 and where they change their mining clothes and are provided with 

 hot and cold douche baths. They put on warm dry clothes, and 

 can obtain excellent food at a moderate cost before returning to their 

 homes. Their wet and dirty mining clothes are taken charge of by 

 appointed custodians, who dry and clean them ready for the morrow's 

 work. These and other precautions are expected to reduce the death- 

 rate to a very great extent. 



With a view to the rapid advancement of the work, the late M. 

 Brandt, whose death is greatly to be deplored, devised after his long 

 experience on the St. Gothard, his now well-known drill. As details 

 of this have been published, and as they would be too technical for 

 this evening's discourse, it will only be necessary to refer to them 

 briefly. This drill is non-percussive, nor is it armed with diamond. 

 It is a rotatory drill 3 inches in diameter with a pressure on the 

 cutting points of 10 tons moving at slow speed, but capable of being 

 accelerated at pleasure, and of being rapidly withdrawn. It is armed 

 with a steel tool with 3 cutters, of which samples are on the table. 

 The carriage on which it is mounted enables it to work in any direc- 

 tion. The face of the tunnel is attacked by 10 to 12 holes in the 

 case of the hardest rock, those in the centre being 3 feet 3 inches in 

 depth, whilst those round the circumference are 4 feet 7 inches. The 

 drills are driven by hydraulic pressure of 100 atmospheres or 1470 lbs. 

 to the inch, and the cutter having a |-inch hole along its centre, all 

 the waste water is discharged right on to the cutting edges, thus 

 keeping them cool, and washing out the debris. 



