INVENTIONS AT PANAMA. 149 



their tunnel about five times as fast as was the progress in the Mont Cenis Tun- 

 nel in 1863 by hand-drilling. Now, in the years 1878 and 1879, by the general 

 improvement of the whole administration in the St. Gothard Tunnel, they are 

 making a progress of more than eight to one, or about thirteen feet per day, 

 through granitic gneiss in a single heading. So that now, if they can excavate 

 and remove rock from a tunnel eight times faster than they could fifteen years 

 ago, you may readily see how much easier, how much more feasible, a tunnel 

 has become to-day on an isthmus-canal route than at the time, in 1870, when 

 the surveys of Selfridge were made. Indeed, these naval officers in their sphere 

 of action were ignorant of and had not conceived as possible these strides of 

 inventive and engineering skill.* 



A few weeks after the address of Major Shelbourne, a paper was 

 read before the American Society of Civil Engineers by Walton W. 

 Evans, in which he described the augnaented power of the Sommeiller 

 machine during the excavation of St. Gothard. He said : 



" I was shown at the St. Gothard Tunnel steam-drills that by slow motion 

 and high pressures would walk into granite as a knife would into cheese; there 

 was nothing used on the Mont Cenis Tunnel to approach them in efficiency. I 

 was shown air-compressors that kept their great reservoirs, night and day, un- 

 der pressures of 110 pounds to the square inch, and without difficulty ; it was 

 with difficulty and uncertainty that the air-compressors of the Mont Cenis Tunnel 

 could keep the pressure up to 60 pounds to the square inch." He adds: " We 

 are clearly a progressive race, and it would be a wise brain that could predict 

 with certainty what advance may be made by some live Yankee in tunneling 

 machinery when we come to cut a ship-tunnel." t 



Mr. Evans was, we may remember, like Major Shelbourne, in 

 favor of the San Bias route, and the tunnel which that route in- 

 volves. 



Certain details as to the machinery used in the Alps may be of in- 

 terest. After hand-drilling was given up, all the drills used were run 

 by compressed air, but the methods employed to compress it varied. 

 At Mont Cenis hydraulic power exclusively was used. Sommeiller 

 employed at first the fall of a column of water in the same way in 

 which it is applied in the case of the w^ater-ram. Afterward he sub- 

 stituted turbine-wheels. To compress the air at the St. Gothard, or- 

 dinary steam-power was at first used. J Afterward the improved 

 method of Sommeiller, the turbine-wheel, w^as substituted. It was 

 found that the amount of water available at the southern terminus 

 was not as large as at the northern ; in the former case, accordingly, 

 a higher fall of water was required. A useful or effective fall, as it is 



* "Journal of the American Geographical Society for 1879," p. 240. In the ex- 

 haustive report upon the canal problem submitted to the Navy Department in 1883 by 

 Lieutenant J. T. Sullivan, extracts occur from the address of Major Shelbourne. He is 

 our best authority as to the San Bias route. 



\ " Transactions of the American Society of Civil Engineers," 1880, p. 1.5. 



X Hence, perhaps, the somewhat ambiguous expression used by Mr. Evans, '' steam- 

 drills," though it is possible that " steam " is a misprint for " steel." (?) 



