Show of metals the question as to the fatigue of metals under long continued stress has been tested and it ia believed satia fac settled in the treatment of two similar suspension bridge links and the results obtained A square iron link 12 inches wide 1 inch thick and about 12 feet long was taken from a bridge at kieff russia then about forty years old and tested against a similar link which had lain unused in store ever since the building of the bridge under these circumstances the means of comparison were considered in the highest degree favorable and the result necessarily of a reliable character in determining whether or not iron actually loses and to what extent any of its strength in prolonged service the effect of the test showed for the old used link an ultimate tensile strength of tons per square inch an elastic i limit of tons per square inch an elongation of per cent and a contraction of 1735 per cent at the point of fracture in the case of the unused link the tensile strength was found to be tons per square inch with an elastic limit of tons and an elongation and contraction at fracture of 1842 per cent and 1875 per cent respectively from this it appears therefore that the two pieces of iron were of practically identical strength the small difference actually observed being well within the ordinary range of variability of similar pieces of such metal new york sua |