ClipArt ETC
"Girders (in cross-section). a to l, wrought-iron girders; m to z, cast-iron girders; aa, box-girder; bb, compound I-girder; cc, coumpound beam girder; dd, I-girder." -Whitney, 1911

Girder

"Girders (in cross-section). a to l, wrought-iron girders; m to z, cast-iron girders; aa, box-girder;…