[TeX: $a = \frac{6 \times 10 \times 60 \times 12}{26 \times \frac{60
\times 12}{16}} = 37$]

and the area of the top flange will be,

37
-- = 6.16 inches--
6

[TeX: $\frac{37}{6} = 6.16$]

so that our dimensions will be as follows:

Length, 30 feet.
Depth, 45 inches.
Area Top Flange, 6.16 inches.
Area Bottom Flange, 37 inches.

[Illustration: Pl. 1.]

The thickness of web is usually a little greater at the bottom than
at the top, and varies from 1/14 to 1/24 of the depth of the girder.
The bottom rib is usually made from six to eight times as wide as it
is thick, and the top rib from three to six times as wide as thick, so
that, in the example above given, we could have as dimensions for the
parts

Top Flange, 4 1/4 x 1 1/2 inches nearly.
Bottom Flange, 6 x 2 1/2 inches nearly.