Page:Popular Science Monthly Volume 51.djvu/170

160 upon, which yields a high grade of steel; but in uniformity of composition and elasticity it can scarcely be equal to the more expensive crucible steel. This perhaps may at present be only a matter of opinion. On such a point no definite and final conclusion should be reached without a series of comparisons such as can not be accomplished in a day.

An unfortunate mishap which occurred at Watervliet in 1895 may have some bearing in this connection. In assembling the parts of a forty-caliber twelve-inch rifle, the tube was, as usual, rested vertically upon its breech end, and the heated, jacket was let down over it. The heating had been insufficient to secure all



the expansion needed, and as a result the cooling jacket gripped the tube before quite reaching the final position intended. An interesting problem was now presented, that of separating the tube and jacket after they had become thoroughly cool, and completing the process which had been so unexpectedly interrupted. The gun was provided with the inlet and outlet tubes such as Rodman employed to secure a continuous flow of water in hollow casting, and the exposed part of the tube below the edge of the jacket was inclosed in a bag of asbestos cloth through which a stream of cold air could be transmitted. The gun with its adherent jacket and these adjuncts was let down into a furnace so as to heat the jacket. Immediately a flow of cold water was started through the tubes, and of cold air through the bag, while the inclosing jacket was soon raised to a temperature estimated to be 1100° F., which was maintained for several hours. The experiment proved unsuccessful. It was subsequently repeated twice with slight modifications, but all in vain. To test the correctness of the theory thus applied, a "dummy" was constructed, its parts