1388

THEORY AND PRACTICE OF ENGINEERING.

Book II.

at the two extremities of the principal timbers, and pass over an iron standard, placed overthe revolving point; in this arrangement there is considerable strength : at Honfleur the

HONFLEUR SWING BRIDGE.

swing bridge is suspended over a lofty standard of timber, round which it revolves :those at Helvoetsluys swing around a pole or iron standard, being counterpoised on the

Fig. 2300.

HELVOETSLUYS SWING

banks sufficiently to prevent any inclination from taking place when the bridge is in motion.Double turning bridges may be made upon either of the principles already described.

Fig. 2301.

DOUBLE TURNING BRIDGE.