TUNNELS. 127 



The Nerthe tunnel, near Marseilles, is 15,153 feet long; has twenty-four shafts, whose aggre 

 gate length is 7,589 feet the deepest being 610 feet. It is in very hard limestone rock; is 29^ 

 feet high by 26^ feet wide. The shafts are lined with masonry ; a portion of the body of the 

 tunnel is lined with masonry, one, two, and three bricks thick ; another portion is not lined at all. 

 A semi-circular brick aqueduct, 4| inches in diameter, runs the whole length of the tunnel under 

 the floor. The time occupied in the construction is not stated. 



The cost of the Nerthe tunnel was as follows : 



For mining the body of the tunnel $705,982 20 



For mining the shafts $109,081 08 



Masonry for the shafts $49,069 31 



Lining for the body of the tunnel $423,711 1 8 



Cost of aqueduct , $10,607 10 



Total cost of the tunnel , $1,298,45087 



The average cost of excavating the shafts, which are nine feet ten inches in clear diameter, was 

 per yard down ; the average cost of the lining of the shafts was $19 40 per yard down. 

 The deepest shaft cost, on the average, $73 per yard down, completed. 



Cost of mining the body of the tunnel, $139 76| per running yard. 



On the German railways are ten tunnels. 



The great &quot; gallcrie d ecculemcnt &quot; of the Clansthal mines, through the Hartz mountains, is 6.5 

 miles long. It was commenced in 1777 and completed in 1800, (twenty-three years,) and cost 

 a little more than $350,000. Some authorities state this tunnel to be 7.5 miles long. Its dimen 

 sions are not given, but it is probably small. 



In Sardinia there is a tunnel two miles long, through Mt. Giovi, on the Genoa and Turin rail 

 way. On this road, in 25 miles through the Appenines, are nine tunnels. 



In Austria the Sommerung tunnel is one mile long. 



England has 48 canal tunnels of an aggregate length of 40 miles ; the largest being over three 

 miles, on the Huddersfield canal. She has also 79 railway tunnels ; 49 of which amount to 33 

 miles, the longest being three miles. 



The London and Birmingham railway has eight tunnels ; London and Dover, five ; Newcastle 

 and Dover, five. 



The Woodkea.d tunnel, between Manchester and Sheffield, is a little more than three miles long. 

 It has five shafts ten feet in diameter, which vary from 400 to 600 in depth. The character of the 

 rock is granitic, being &quot;mill-stone rock.&quot; The tunnel was about five years in construction, and 

 its whole cost was $1,026,705. 



Uppingham tunnel, 1,320 feet in length, cost $120 per lineal yard. 



Salt wood tunnel, in very wet sand, cost $524 43 per lineal yard. 



The United States has 67 tunnels on canals and railways, the longest of which is about one 

 mile. Details are difficult to obtain. Many of them are short, however. 



Baltimore and Ohio road has 16 tunnels; Parkersburg road, 17 ; Hempfield, seven. 



The old canal tunnels cost, on an average, about $17 77 per running yard. 



Those of ordinary size for railways cost from $83 per lineal yard, for those in soft sandstone not 

 requiring a lining of masonry, to $444 and $710 per yard, in very loose ground, such as quick 

 sand, &c., requiring a very tick lining. 



Ordinary brick lining costs from $8 to $9 per cubic yard, including centering. 



The shafts for the Blechingly tunnel, 10.5 feet in diameter, sunk in blue clay, and lined, cost 

 $68 44 per yard down. The longest shaft is 97 feet. 



Those of the Blaisy tunnel cost, lined, $139 11 per yard down. The soil was of clay, chalk, 

 and loose earth. Deepest shaft 646 feet, and few less than 328 feet. 



