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Atmospheric system of South Devon
Atmospheric £kystem of South Devon.
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attached, and by placing thereon 260 tons of rails, pigs, bars, &c. In proving, the load was first put on two points at one end, then on the next two points, and so on, in order to produce, as nearly as possible, the same effect as the passage of a heavily loaded train. In the ease of one rib, the load was allowed to remain for several days, and then removed. After the lapse of a few days, the same load was replaced, and again allowed to remain some days. The results were very satisfactory. During the process of proving, observations were taken with a dumpy level, placed at a distance; and the sinking of the bearing plates in the ground was observed and noted. The bridges now being constructed, are intended to carry a double line of mils; and the test applied is, therefore, equal to two tons to each foot lineal of single line of rail. This test was fixed upon, in the belief that the greatest possible load which can, in working, be placed upon each line of rails, is about one ton per foot lineal; and that, to provide for the additional strain caused by the rapid motion, &e., of the practical load of trains passing, the proof-weight ought to be fixed at double the greatest possible load. In very large spans, (say 400 feet and upwards,) it would be necessary, on many accounts, to use four ribs instead of two, and to brace all the four ribs together overhead, so as to obtain additional transverse stiffness.--.Mining Journal. Lond. Mee. Mag., Sept. 1848.
The Don Bridge on the Northern Railway. The pile-driving at the Don bridge is completed, and the masonry work for the abutments commenced. We learn, from the Doncaster Chronicle, that the bridge will be constructed of wrought iron, on the principle of Fairbairn's patent hollow bridge, and will consist of two hollow iron girders, which will span the stream~ transverse girders for the rails to rest upon, and iron plate sides. The bridge will be 5 feet 6 inches high in the middle, 4 feet 8 inches at the ends, the side plates being only ~ t h s of an inch thick; the plates at the bottom of the bridge are ~ t h s of an inch thick. All these will be firmly riveted together, to form a rectangular beam. The brktge will be remarkable, chiefly, for its combination of lightness with strength and durability. The principle of construction is the same as that adopted at Conway, and which is now being very generally adopted for railway bridges. The span of the bridge will be 70 feet. Lond. Builder, Sept. 1848.
~qtmospheric System of South Devon. The atmospheric system on the South Devon fine has been abandoned, by the advice of Mr. Brunel, who had adopted it, it was alleged, at an expense to the Company of £343,535. The Directors, at their late meeting, avoided all discussion of this sore point from 'qegal considerations." They.have resolved, however, to allow the patentees and Mr. Samuda to experiment with the materials, "until the same shall be made efficient." Ibid.
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attached, and by placing thereon 260 tons of rails, pigs, bars, &c. In proving, the load was first put on two points at one end, then on the next two points, and so on, in order to produce, as nearly as possible, the same effect as the passage of a heavily loaded train. In the ease of one rib, the load was allowed to remain for several days, and then removed. After the lapse of a few days, the same load was replaced, and again allowed to remain some days. The results were very satisfactory. During the process of proving, observations were taken with a dumpy level, placed at a distance; and the sinking of the bearing plates in the ground was observed and noted. The bridges now being constructed, are intended to carry a double line of mils; and the test applied is, therefore, equal to two tons to each foot lineal of single line of rail. This test was fixed upon, in the belief that the greatest possible load which can, in working, be placed upon each line of rails, is about one ton per foot lineal; and that, to provide for the additional strain caused by the rapid motion, &e., of the practical load of trains passing, the proof-weight ought to be fixed at double the greatest possible load. In very large spans, (say 400 feet and upwards,) it would be necessary, on many accounts, to use four ribs instead of two, and to brace all the four ribs together overhead, so as to obtain additional transverse stiffness.--.Mining Journal. Lond. Mee. Mag., Sept. 1848.
The Don Bridge on the Northern Railway. The pile-driving at the Don bridge is completed, and the masonry work for the abutments commenced. We learn, from the Doncaster Chronicle, that the bridge will be constructed of wrought iron, on the principle of Fairbairn's patent hollow bridge, and will consist of two hollow iron girders, which will span the stream~ transverse girders for the rails to rest upon, and iron plate sides. The bridge will be 5 feet 6 inches high in the middle, 4 feet 8 inches at the ends, the side plates being only ~ t h s of an inch thick; the plates at the bottom of the bridge are ~ t h s of an inch thick. All these will be firmly riveted together, to form a rectangular beam. The brktge will be remarkable, chiefly, for its combination of lightness with strength and durability. The principle of construction is the same as that adopted at Conway, and which is now being very generally adopted for railway bridges. The span of the bridge will be 70 feet. Lond. Builder, Sept. 1848.
~qtmospheric System of South Devon. The atmospheric system on the South Devon fine has been abandoned, by the advice of Mr. Brunel, who had adopted it, it was alleged, at an expense to the Company of £343,535. The Directors, at their late meeting, avoided all discussion of this sore point from 'qegal considerations." They.have resolved, however, to allow the patentees and Mr. Samuda to experiment with the materials, "until the same shall be made efficient." Ibid.