PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 307 



base is 434 feet above that at Modane. From the middle, toward Modane, 

 the gradient will be I in 45^, and toward Rardonneche, 1 in 2,000, suffi- 

 cient to allow the water to escape. At Modane, the entrance to the tunnel 

 is 328 feet above the valley, and the walls of the tunnel are entirely of 

 stone. At Bardonneche, the side walls are of stone, and the remainder of 

 brick. 



The boring' machines are driven by compressed air, used at 75 inches 

 pressure per square inch, which is conveyed to the " forehead " of the 

 advanced gallery by a pipe"7| inches in diameter. Two machines are used 

 for compressing the air; one on the hydraulic ram principle, has an air ves- 

 sel 14 feet high, and 2 feet in diameter. Into tliis, water, from a column 

 85 feet high, is admitted; the air thus compressed is forced through a valve 

 into a reservoir. When this valve closes, the water is discharged, air 

 admitted into the air chamber, and the operation of compression is repeated. 

 The machine makes about five strokes in two minutes. The other machine 

 resembles a pump. On one side of the piston, the water presses, and on 

 the other side, the air is compressed. 



To complete the tunnel by hand labor it would require twenty-five years. 

 In June last the advance at Modane was at the rate of 47 meters per day. 

 M. Sommeiller expects by his system to advance the tunnel three meters 

 at each end per day. At this rate the work would be completed in the 

 year 1868. 



Vapor of Water with Fuel. 



The selected subject was the same as discussed at the last meeting. To 

 show that this combination was not of recent origin, a communication from 

 Mr. Joseph Dixon, of Jersey City, was read, from which it appeared that 

 as early as 1826, when anthracite coal was but little used, he put up, in a 

 woolen factory at Canton, Mass., a boiler and attachments for heating pur- 

 poses. Supposing a flame would be more effective for making steam, he 

 tapped the boiler head near the top and inserted one end of a pipe having 

 in it a regulating cock; the other end entered the ash pit, so that the steam 

 discharged would pass through the grate bars, be decomposed on contact 

 contact with anthracite and thus increase the flame; but the great incon- 

 venience from the sulphide of hydrogen which escaped into the factory 

 from a want of draft in the stack, caused it to be discontinued. Again in 

 1845 or 1846, he tried the burning of steam for melting- iron in a cupola 

 furnace, erected at the expense of I. Savary & Son, in Jersey City, at their 

 foundery, but the boiler being sixty feet from the cupola it was after the 

 first melting laid aside, until a boiler could be made expressly for the pur- 

 pose and placed near by; that was never done. The idea of the burning of 

 the vapor of water is a very old one, as will be seen on examining the fol- 

 lowing dates of patents granted in this country: The American water- 

 burner was patented by Capt. Samuel Morey, of Oxford, N. H., December 

 11, 1817. An improvement on More^'^'s water-burner was patented by L. 

 L. Sullivan, of Boston, Mass., December 10, 1818, and another by him De- 

 cember 19, 1818. 



Mr. Stetson remarked that in the presence of the vapor of water, during 

 combustion, there may be a catalytic action, by which a more perfect union 



