The tensile strength of steel used for shafts having increased from 24 to 30 tons, and in some cases 31 tons, considering that this was 2 tons above that specified, and that we were approaching what may be termed _hard steel_, I proposed to the makers to test this material beyond the usual tests, viz., tensile, extension, and cold bending test. The latter, I considered, was much too easy for this fine material, as a piece of fair iron will bend cold to a radius of 11/2 times its diameter or thickness, without fracture; and I proposed a test more resembling the fatigue that a crank shaft has sometimes to stand, and more worthy of this material; and in the event of its standing this successfully, I would pass the material of 30 or 31 tons tensile strength. Specimens of steel used in the shafts were cut off different parts--crank pins and main bearings--(the shafts being built shafts) and roughly planed to 11/2 inches square, and about 12 inches long. They were laid on the block as shown, and a cast iron block, fitted with a hammer head 1/2 ton weight, let suddenly fall 12 inches, the block striking the bar with a blow of about 4 tons. The steel bar was then turned upside down, and the blow repeated, reversing the piece every time until fracture was observed, and the bar ultimately broken. The results were that this steel stood 58 blows before showing signs of fracture, and was only broken after 77 blows. It is noticeable how many blows it stood after fracture. A bar of good wrought iron, undressed, of same dimensions, was tried, and broke the first blow. A bar cut from a piece of iron to form a large chain, afterward forged down and only filed to same dimensions, broke at 25 blows. I was well satisfied with the results, and considered this material, though possessing a high tensile strength, was in every way suitable for the construction and endurance required in crank shafts. Sheet No. 1 shows you some particulars of these tests: Tensile Elong. Fractured Broke Fall Tons. in 5" Bend. Blows. Blows. In. A = 30.5 28 p. c. Good 61 78 12 In order to test the comparative value of steel of 243/4 up to 35 tons tensile strength, I had several specimens taken from shafts tested in the manner described, which may be called a _fatigue_ test. The results are shown on the same sheet: B = 241/2 Good 64 72 7 B -- -- -- 48 54 12 C = 27 25.9 p. c. Good 76 81 12 D = 29.6 28.4 p. c. Good 71 78 12 E = 30.5 28.9 p. c. Good 58 77 12 F = 35.5 20 p. c. Good 80 91 12