into jaw-plates or forked ends, for the purpose of packing closely the various members connected by the pin, these jaw-plates or post extensions shall be considered as columns, the thickness of each of which shall be determined by the following formula:

where p is the greatest allowable intensity of working-stress (impact being considered); l is the unsupported length in inches, measuring from the centre of the pinhole to the centre of the first transverse line of rivets beyond the point at which the full section of the member begins; and t is the total thickness in inches of one jaw. The length l is always to be made as small as practicable; and, in cases of unavoidably long extensions, the plates are to be stiffened by an interior diaphragm composed of a web with four, or sometimes only two, angles.

It is always better, whenever practicable, to avoid cutting away the ends of channels; but, if they must be trimmed, the ends must be reinforced so that the strength of the member shall not be reduced by the trimming.

In riveted tension-members, the net section through any pinhole shall have an area fifty (50) per cent in excess of the net sectional area of the body of the member. The net section outside of the pinhole along the centre line of stress shall be at least sixty-five (65) per cent of the net section through the pinhole.

Pins are to be proportioned to resist the greatest shearing and bending produced in them by the bars or struts which they connect. No pin is to have a diameter less than eight tenths (8/10) of the depth of the deepest eye-bar coupled thereon. No truss-pin is to have a smaller diameter than three and a half (3 1/2) inches, and no lateral pin, if any such be used, a diameter less than two and a half (2 1/2) inches.

Lower chords are to be packed as closely as possible, and in such a manner as to produce the least bending moments on the pins;  but  adjacent  eye-bars in the same panel must never have