. Annual report of the American Institute, of the City of New York. Science. PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 405. re-eiiforce would be the result, as shown in the diagram. As the heat expands the metal in the direction of the diameter also, its effect in this direction also must be considered. The expansion of length, however, is of most conse- quence in considering the probable direction of fracture. That the fracture almost always intesects the vent, has been heretofore referred to the weakness resulting from drilling away part of the metal; but on page 355, Major Wade's Reports
. Annual report of the American Institute, of the City of New York. Science. PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 405. re-eiiforce would be the result, as shown in the diagram. As the heat expands the metal in the direction of the diameter also, its effect in this direction also must be considered. The expansion of length, however, is of most conse- quence in considering the probable direction of fracture. That the fracture almost always intesects the vent, has been heretofore referred to the weakness resulting from drilling away part of the metal; but on page 355, Major Wade's Reports on Metals for Guns, we find that after a gun had been put to extreme proof, and exhibited signs of fracture, a hole was drilled one inch forward of the base ring, and four inches from the line of the vent, to a depth of four inches, and of the diameter of one and a quarter inches. The gun was then fired with double charges of power, and with a bore full of balls and wads, eleven times, to bursting. Although the piece burst into more then twelve fragments, one of the frac- tures intersecting the vent, it did not split through the large hole, showing that the gun had strength to resist the pressure of the powder, but burst, notwithstanding the drilling away of so large a part of the metal, from the communication of heat. The true cause, px-obably, of the intersection of the vent by the fracture, was the communication of heat to the surface of the vent, thereby expanding the column of metal about it; for it should be recollected that the passage of a large quantity of gases through the vent would communicate more heat to its surface than would be communicated if there was no current, but the capacity of the vent only filled; in that case not much heat would be supplied to the surface, because the quantity contained within the vent would be small. But in this example, as in all others, as is well known to ordnance inspectors, the fracture began to exhibit itself on the interior sur
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