vertical plates must bear properly from end to end upon the base. No base-plate, vertical plate, or connecting angle shall be less in thickness than three quarters (3/4) of an inch. The vertical plates shall be of sufficient height and must contain enough metal and rivets to distribute properly the loads over the bearings or rollers. The bases of all cast-steel pedestals shall be planed so as to bear properly on the masonry or rollers. All rollers and the faces of base-plates in contact therewith are to be planed smooth, so as to furnish perfect contact between rollers and plates throughout their entire length.

All pedestals whether built or cast must have one or more diaphragms between webs, carried up as high as the general detailing will permit, so as to transmit transverse horizontal thrust to the base without overstraining the webs by bending in their weakest direction.

Heads of eye-bars are to be made of such dimensions that when the bars are tested to destruction they shall break in the body and not in the eyes; and in case of loop-eyes, so that they shall not fail in the welds. Rods with bent eyes shall not be used. In loop-eyes, the distance from the inner point of the loop to the centre of the pinhole must not be less than two and one half (2 1/2) times the diameter of the pin, and the loop must fit closely to the pin throughout its entire semi-circumference.

DETAILS OF DESIGN FOR TRESTLES AND ELE-
VATED RAILROADS.

The sections of main members of trestles shall, generally, be as follows: Columns, two channels laced with flanges turned either out or in, two channels with I-beam web between, four Z bars with web-plate, four Z bars with a single line of lacing inside and occasional stay-plates outside, or four angles with a single line of lacing inside; diagonals in transverse and longitudinal bracing, and all bottom horizontal bracing struts, four angles with a single line of lacing; horizontal   transverse  bracing   struts  at  top  of  towers,  bracing