arm loaded by a train and the other arm empty, there was no rising of the ends when the latter were properly supported. A late inspection showed that the timber cribs, which are used as a temporary support for the ends of the draw, had so shrunk vertically on account of the seasoning of the timber, that the end rollers barely touched their bearings, so the latter will have to be shimmed up. This condition of the ends afforded an excellent opportunity to observe the rise with one arm only loaded by an engine and enough cars to cover the said arm. The amount observed was three eighths of an inch. From this it may be concluded that with masonry piers and the completed superstructure, and with a hoist of one and a half inches by the lifting gear, there is no chance for the ends to rise from their bearings; for, to cause such a rise, it would take a live load just four times as large as the test load, which is more than could be placed on the double-track railway, wagonways, and footwalks. Had the bridge been built with shallow trusses and with eye-bars in a portion of the top chords between outer and inner hips, as was the similar bridge which was reported as giving trouble from rising ends, it is probable that similar difficulty would have been found in this structure.

Some engineers may think that, because each span of a draw is figured as an independent span for unbalanced live loads, on the assumption that the longitudinal tower rods are so small as to carry no vertical shear past the drum, there should be no tendency for the end of one arm to rise when the other arm is loaded; but such is not the case, as the tendency would exist if there were no longitudinal tower rods at all. The rising of one end is evidently due to the lowering of the inner hip of the other span and the consequent pull of the inclined top-chord eye-bars. Now imagine two cables attached to the top of the tower (which is still assumed to be without longitudinal rods), and running to drums on the shore. When these cables are strained sufficiently, the far end of the draw will rise;  and  under these conditions there will be no vertical shear whatsoever  in  the  tower  panel  of  the  truss.  As  far  as  vertical  shear  in  this  panel  is  concerned,   the   conditions   for  the