them, as well as for the bending stresses, in designing the sections for these girders. Where the clearance over the waterway will permit, metal can be saved by letting the top flange of the longitudinal girder form the bottom chord of the truss.

In any arrangement of girders over the drum, bearing-plates at least one (1) inch thick must be used between the top flange of the drum and the bottom flanges of the girders, in order to make the points of concentration well defined, and so as to transmit the load properly from girders to drum.

All girders bearing on the drum are to have stiffeners on both sides of their webs at all points of concentration; and in no case are the stiffeners to be crimped, but are to have fillers beneath. They must have close bearings at top and bottom flanges, and are to be proportioned in the same manner as previously specified for those on the drum.

The rollers, tracks, drum, and girders over drum shall be completely assembled in the shop before shipment, all holes being reamed to fit and the sections being match-marked. Every roller must have a true bearing on both the upper and the lower tracks during a complete revolution of the draw.

Before the assembling of the rollers is done there must be marked on both the upper and the lower track segments a circle of the same diameter, which circles will come a trifle inside of the exterior ends of all rollers; then, after the turntable is perfectly adjusted, each roller is to be marked where these circles touch it. After the turntable is disconnected each roller is to be set up properly in a lathe, and the exterior periphery is to be chamfered off exactly to the points marked, so that when the turntable is set up in the field, if the exterior of each roller is brought exactly to the circles on the two tracks, the rollers will all be in their proper positions. These lines on the tracks will serve also afterwards to line up the rollers whenever the turntable is to be adjusted.