excess of strength in the details at all points thus spliced, as previously specified for fixed plate-girder spans.

Rigid bracing-frames are to be used between main girders of deck-spans at the points where the main girders bear on the drum; and heavy, rigid, plate cross-girders resting on the drum are to be used for half-through spans.

End lifts must be provided for draw-spans of Type No. 1, as hereinafter specified for truss-span drawbridges.

For spans of Type No. 2 the centre panel is to be made with pin connections, the bottom-chord pins resting in pedestals, which furnish proper bearings on the drum. The top-chord tension is to be taken up by eye-bars, which serve as toggles for raising the ends of span. These toggles are to be worked by a screw at centre of span.

The compression in bottom flanges of girders, due to dead load when the span is swung, is to be taken up by struts hinged on the bottom-chord pins.

The eye-bars of the top chords must have slotted eyes, so as to make sure that each half of the girder will act as a simple span when the live load is applied.

Proper shoes must be provided at ends of span, with grooves into which the sole-plates on ends of girders are lowered into place. These grooves should be deep enough to hold the ends of the girders securely, and the toggle at the centre must provide enough lift to clear the ends properly for turning.

All track-rails, guard-rails, and stringers must be discontinuous in the centre panel so that the toggle will be free to act.

The ends of each pair of girders over the drum must be thoroughly braced together.

The end lifting arrangement of these spans demands the most accurate shop-work; and in every case the whole span must be assembled in the shops, so that the lifting machinery call be thoroughly tested before being shipped.