U ; and before the ten- the chain shown, which is made fast at the forward the canal that boats can freely pass under them. side and is drawn around it, then passes over the pul- sion of the spring is taken up, the bridge starts from This class of bridges necessitates the building of an its… … such bridges have heretofore been exclusively used The chain is secured to the hollow weight, Q, and allowing it to pass through without breaking and is made in two parts for the purpose of enabling it to on canals in preference to flat drawbridges, which do wearing the swing. The center screw and…
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