The weight of a cubic foot of any solid or liquid is found by multiplying its specific gravity by 62.425 lb. avoirdupois. The weight of a cubic foot of any gas at atmospheric pressure and at 32° F. is found by multiplying its specific gravity by .08073 lb. avoirdupois. WROUGHT-IRON CHAIN CABLES. The strength of a chain link is less than twice that of a straight bar of a sectional area equal to that of one side of the link. A weld exists at one end and a bend at the other, each requiring at least one heat, which produces a decrease in the strength. The report of the committee of the U. S. Testing Board, on tests of wrought-iron and chain cables, contains the following conclusions: "That beyond doubt, when made of American bar iron, with cast-iron studs, the studded link is inferior in strength to the unstudded one. "That, when proper care is exercised in the selection of material, a variation of 5% to 17% of the strongest may be expected in the resistance of cables. Without this care the variation may rise to 25%. "That with proper material and construction the ultimate resistance of the chain may be expected to vary from 155% to 170% of that of the bar used in making the links, and show an average of about 163%. "That the proof test of a chain cable should be about 50% of the ultimate resistance of the weakest link." From a great number of tests of bars and unfinished cables, the committee considered that the average ultimate resistance and proof tests of chain cables made of the bars, whose diameters are given, should be such as are shown in the accompanying table. ULTIMATE RESISTANCE AND PROOF TESTS OF CHAIN CABLES. In the above table, L represents the lead, and A the anti mony in the alloy. |