An improvement in these projectiles was patented this week by Henry Bates, of New London, Conn., which consists in attaching to the butt end of a bomb, or other projectil; of similar character, a spiral spring or coil of wire, which, when the projectile is placed in the gun from which it is to be discharged, is compressed together, and lays close to the projectile, but when it is discharged is caused, either by reason of its own elasticity, or by the resistance of the atmosphere, to extend itself, in the form of a tail, some distance in the rear, where, by tho resistance it meets with, it serves to direct and steady the course of the bomb. He has also so improved the fuse tubes that they cannot be blown into the bomb on the discharge of the gun, and so set fire to the bomb before it has accomplished its flight.