for directing their fire. In the first place, the bore was considerably larger than the shot, to facilitate loading and the use of red-hot shot. This difference of diameter was called 'windage,' and varied from one-fifth to one-third of an inch. It allowed, therefore, a considerable portion of the gunpowder gas to escape past the projectile, and wasted so much energy. Then, for reasons which would require too technical an explanation for this work, the round shot was subject to special inaccuracies in its flight. These defects were not so manifest at close quarters in action, which officers in command usually sought to attain, and the charge of powder, however reduced in energy by windage, retained sufficient power to penetrate wooden ships. But for some years previous to the substitution of ironclads for the old types of ships the Admiralty of this country had been impressed with the advantages of having the armament of the navy of greatly increased power and weight. This view was confirmed by the introduction of the 68-pounder, which proved a powerful and effective weapon. But when it had been ascertained that this gun was powerless against 4½-in. plates, it was at once evident that some new system of gun construction must be devised. A long series of experiments proved that the old ordnance was exceedingly defective; that every gun, great or small, should be rifled, in order to give long range and precision to the projectile; and that to have the required strength guns must be made of wrought-iron or steel.
The object of a rifled gun is to give to a cylindrical
