. Handbook of railroad construction; for the use of American engineers. Containing the necessary rules, tables, and formulæ for the location, construction, equipment, and management of railroads, as built in the United States .. . becomeseighteen feet, whence 10 to 18 as 7,500 to 13,500 lbs.; which would require only thirteen and one half inches forcompression, or a piece 4 X 3^. But is this enough forflexure ? On page 124 the load which may be safely borne, by arectangular post of wood, is shown by the formula WOODEN BRIDGES. 141 W= 2240 bd^ Substituting for b and d, the dimensions 4 X i? we
. Handbook of railroad construction; for the use of American engineers. Containing the necessary rules, tables, and formulæ for the location, construction, equipment, and management of railroads, as built in the United States .. . becomeseighteen feet, whence 10 to 18 as 7,500 to 13,500 lbs.; which would require only thirteen and one half inches forcompression, or a piece 4 X 3^. But is this enough forflexure ? On page 124 the load which may be safely borne, by arectangular post of wood, is shown by the formula WOODEN BRIDGES. 141 W= 2240 bd^ Substituting for b and d, the dimensions 4 X i? we have^ 2240X4X4^ 573,440 which is evidently too small. Placing 6 X 7, for 6 X d, we have 2240 X 6 X 7^W= ^1^- =14,227; exceeding by a small amount the requirement. 173. It is evidently immaterial whether we support thethe point D upon C, or suspend it as in fig. 62, providedwe prevent any Rg- 62. motion in thefeet of the in-clines A c B themagainst A B,throws a ten-sion against A B, found as follows: — Representing by cD, the applied weight,draw D E parallel toc B ; also E/ parallelto AB; E/ is thetension. The graphic construction gives results near enoughfor practice. Rigorously we have A c D, similar to E cf;. Fig. 63.
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectrailroadsdesignandco
