for all cases where a lacing-bar would require a greater thickness than seven sixteenths (7/16) of an inch, angle lacing is to be used, the smallest section for same being 2" X 2 1/2" X 5/16", and the largest 2 1/2" X 3 1/2" X 3/8".

In general, the inclination of lacing-bars to axis of member shall be about sixty (60) degrees; but for members of minor importance the said inclination may be made slightly flatter.

Pin-plates shall be used at all pinholes in built members, for the double purpose of reinforcing for the metal cut away and reducing the intensity of pressure on pin and bearing to or below the specified limit. They shall be of such size as to distribute properly, through the rivets, the pressure carried by such plates to both flanges and web of each segment of the member, and shall extend at least six (6) inches within the tie-plates of said member, so as to provide for not less than two (2) transverse rows of rivets there.

When the pin ends of compression-members are cut away 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