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angle for a roadway, and at a span of 500feet has fixed the minimum angle at 2° 44'when iron is the material; supposing theallowance of three-fourths of the breakingstrength to compensate for the weight of theroadway and its contingent incumbrances;which, though the author is not so daringas to think a sufficient allowance, yet thereare others, who are of a less timid natureand of greater eminence than he can pre-tend to, who do.

In a chain-bridge, the greater the deflec-tion, or as the angle made with a perpen-dicular line diminishes to a certain limit,the greater the proportion of its strength toits stress; and, like small animals, it willcarry so much more than its own weight asthe deflection increases to that limit, andwill run faster, jump farther, and performany motion quicker when acted upon; thatis, its vibration will increase according to

t6 the 70 feet above high-water mark, would make theprops 170 feet above that level, besides their depth inthe water. (See Barlow, Strength and Stress of Timber,Append.)