To ascertain what area a post must have in order to prevent the post, loaded with a given weight, from crushing the surface against which it presses, we have -

Rule 11. - Divide the given weight in pounds by the value of P, Table I., and the quotient will be the area required in inches; or -

A = W/P. (2.)

Example. - A post standing on a Georgia-pine girder is loaded with 100,000 pounds: what must be its area? The weight, 100000, divided by 900, the value of P, Table I., set opposite Georgia pine, the quotient, 111.11, is the required area in inches. The post may be 10 by 11 1/9, or 10 by 11 inches; or if square each side will be 10.54 inches, or 11 9/10 inches diameter if round.