. Manual for railroad engineers and engineering students : containing the rules and tables needed for the location, construction, and equipment of railroads as built in the United States . <\ \ / , 2 4 S,\s r 3 H 3 N- - / ~~~ -— ^ — 1 ^- \ /// / I \ / i\ _ - 1 / / t „-* 1 ,-• * -* ~~~-- \ y fe^i 1 l^( ^\ ^ J^^ co __^-^~ Fig. 35- The line is straight, and the grade uniform, rising 1 in 38, or 139feet in a mile. The masonry is limestone, no bricks being heading was about ten feet square, and run forwards at thebottom ; but on account of the water which followed the descend-ing grade,
. Manual for railroad engineers and engineering students : containing the rules and tables needed for the location, construction, and equipment of railroads as built in the United States . <\ \ / , 2 4 S,\s r 3 H 3 N- - / ~~~ -— ^ — 1 ^- \ /// / I \ / i\ _ - 1 / / t „-* 1 ,-• * -* ~~~-- \ y fe^i 1 l^( ^\ ^ J^^ co __^-^~ Fig. 35- The line is straight, and the grade uniform, rising 1 in 38, or 139feet in a mile. The masonry is limestone, no bricks being heading was about ten feet square, and run forwards at thebottom ; but on account of the water which followed the descend-ing grade, it was not kept parallel with the intended roadbed, butwas run from the bottom ///, towards the roof, within the limitsof the section. From the heading, enlargements were made at AM) TUNNELLING. 97 different places, to get additional working faces. The progressof this work was as follows : Shaft No. i was sunk at an aver-age rate of 52 feet per month. Shaft No. 3 at an average of 41feet per month. The advance in the tunnel from shaft No. 1 was106 feet per month, at one face. From the south end the ratewas 109^ feet per month for 18 months, and feet per month. Fig. 36. for 23 months. From the north end the rate was feet permonth for 19 months, and feet per month for the last 10months. The advance was thus much less at the north end,where the water followed the grade, than at the south end, whereit could run off. The whole distance worked from the end faceswas 5720 feet in 41 months, or 70 feet a month at one face. The Mont Cenis Tunnel, which was completed in the summer of1871, is, without doubt, the largest work of this kind ever under-taken. It is 7 miles and 1044 yards long, and of the section7 98 MANUAL FOR RAILROAD ENGINEERS. shown in Fig. 37. The grade rises at the rate of feet permile, or feet in all, from the French end to the centre ;and falls, for the purpose of drainage, at the rate of feet permile, or ^ect
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Keywords: ., bookcentury1800, bookdecade1880, bookpublisherbosto, bookyear1883
