626 THE GREAT ALPINE TUNNELS. 



fig-. 6.) The results are remarkable; the volumes of air thrown into 

 the tunnel per minute being as follows: 



Cubic feet. 



Direct from the fan 161 , 860 



Induced draft through open tunnel mouth 48, 140 



Total 210, 000 



or 100 cubic meters per second. 



The temperature of the tunnel air before the fan was started was 

 1<>7 F., with 97 per cent of moisture, whereas after the fan had been 

 running a few minutes the temperature was 81° F. , or a lowering of 

 26° F., and the tunnel was cool and free from smoke and vapor. 



One can travel through with both windows open and feel no incon- 

 venience, the only remark of the brakeman riding on the top of the 

 wagons and carriages being that he finds it almost too cold. 



This application is without doubt the solution of the difficult prob- 

 lem of tunnel ventilation under high mountains and elsewhere where 

 shafts are not available and where electric traction is not applicable. 



This system has within the last twelve months been brought into 

 operation on the St. Gothard, with the most satisfactory results. Care- 

 ful experiments are being made, but there is no doubt that the prob- 

 lem has been solved. 



In addition to these tunnels, the Saccardo system has been applied 

 to the Giovi Tunnel, near Genoa — 3,300 meters in length — and is being 

 installed on the Giovo Tunnel on the Genoa-Ronco Railway, 8,303 

 meters in length, besides on some seven other tunnels in Italy, and 

 plans are being prepared for the Mont Cenis. 



THE SIMPLON TUNNEL. 



This tunnel is now in rapid course of construction, the total length 

 of gallery driven up to end of April being as follows: 



Yards. 



On the north, or Brigue, side of the Alps 3, 228 



On the south, or Iselle, side of the Alps 2, 350 



or over 3 miles in little more than eighteen months, including the necessarily slow 

 progress at the commencement. 



The total distance between the two portals will be 21, 564 yards, or 

 12.26 miles. A gallery of direction has been driven at both ends until 

 the actual tunnels are reached, so as to form a directly straight line 

 for the accurate alignment of the work, from end to end. 



This great undertaking will consist of two single-line tunnels run- 

 ning parallel one to the other, at a distance apart from center to center 

 of 55 feet 9 inches; and one of the chief features is the much lower alti- 

 tude of the rails above sea level than any of the other Alpine tunnels. 

 This altitude is at its highest point 2,314 feet, being 1,474 feet lower 

 level than that of the St. Gothard, 1,934 feet lower than that of the 



