tight, but which will not retain water, and which are so designed that the sides can be readily removed for the purpose of cleaning. These boxes must be so designed as to permit of the free movement of the rollers in the longitudinal direction of span sufficient to take up the extreme variations in length due to temperature changes and deflection, and at the same time prevent any transverse motion of the end of span.

All shoe-plates, bed-plates, and roller-plates are to be so stiffened that the extreme fibre-stress under bending, when impact is included, shall not exceed sixteen thousand (16,000) pounds per square inch.

Pedestals shall be either of cast steel or built up of plates and shapes. In built pedestals, all bearing-surfaces of the base-plates and vertical bearing-plates must be planed. The vertical plates must be secured to the base by angles having at least two rows of rivets in the vertical legs; and the said vertical plates must bear properly from end to end upon said base. No base-plate, vertical plate, or connecting angle shall be less than five-eighths (5/8) of an inch in thickness. 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.

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 the 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 semi-circumference.