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.

by George L. Vose

d represents the depth in inches,

and L represents the length in inches,

and to reduce the load to one fourth of the breaking weight

W = 4sbd²
4L,

and finally, by substituting for 4s, 4 × 1,250, (1,250 of the table of woods,) we have

W = 5000bd²
4L.

Also, knowing the weight to be supported, and requiring the dimensions, we take out the values of d and b, and have

d = √(W × 4L
5000b) = the depth,

b = W × 4L
5000d² = the breadth.

As an example of the use of the formula, take the following:—