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

Also the lower chord resisting fifteen thousand pounds per square inch, must have

171875
12740 = 13.5 square inches

of area nearly.

If we make the tube at top of one fourth inch iron, and 8 × 10 inches; fastening the plates by one fourth inch angle iron, four inches on the side, the section becomes

One top plate	10 × ¼ =	2½	square inches.
One bottom plate	10 × ¼ =	2½	square inches.
Two side plates	8 × ¼ =	4	square inches.
Four angle irons	¼ × 8 =	8	square inches.
	In all,	17	square inches.

In the lower chord, if we bend the web plates (of ⅜ inch) so as to form a flange of eighteen inches in width, and to that rivet a bottom plate 18 × ¼, we shall have

In the flanges,	18 × ⅜ =	6¾
Bottom plate,	18 × ¼ =	4½
In all,		11¼

The web acting as both ties and braces, must be able to support the following load.

Whole weight of bridge and load is, in round numbers,	344,000 lbs.
One half,	172,000 lbs.
And upon each end of the truss,	86,000 lbs.

to resist which, at eleven thousand pounds per square inch, requires eight inches nearly, regarding the plate as a brace.