Some other mixtures less expensive might be produced (lead and copper in certain proportions are very ductile), and at the same time sufficiently strong to resist all tendency to squash; as the softer metals would inevitably do. The more ductile metals are limited in their utility, by the same law which limits the use of pure lead: that is, to given weight, height of column, or velocity. Great doubt exists whether a bullet made of gun metal, and of the same proportionate dimensions and form as an Enfield bullet, but fitted for a ten-inch gun, would not, if fired with the proportionate charge of powder (namely, seventeen pounds), be as completely squashed, or driven in upon itself, as the Enfield bullet if fired with the old Brown Bess charge of four drachms and a half. Considerable time and experience will be required to ascertain the proportions of metallic mixture necessary to meet all contingencies; this, however, is a matter of detail, and must extend over so large an area, that it can be handled only by the government officials, with the necessary “sinews” of experiment. Nevertheless it must be undertaken; and the sooner it is done the better, for the prestige of that nation which would lead the van of improvement in gunnery, and increase its power of attack and defence beyond those of its rivals. Rifled cannon is a generic term of endless application, presenting to the mind modifications of projectiles in endless variety, ranging from the “_light firebrand_” to the twice deadly rocket: not rockets of that eccentric and erratic character by which Congreve made an undying name; but real _bonâ fide_ rifle rockets, which shall hit the dead-lights in the quarter-gallery of a frigate, carry away the halyards of your enemies’ ensign (making him drop his colours at the first shot) or dash the glass from the hand of the pilot. All such imaginary feats will yet be accomplished; though the reader may smile at the idea. My experience with rockets goes to justify me in asserting that rockets discharged from a gun, under certain circumstances, can be as effectually controlled, and kept to a direct course, as a bullet fired from a rifle. The rocket, however, may be fired a much greater distance than we have ever been able to project a bullet; because, in addition to the force which projects it from the gun, its flight is maintained by the self sustaining agency in the body of the rocket. Rockets require a much smaller charge of powder to project them than that which is used for a bullet; a rocket started by its own force, expends, in acquiring even an approximation to its highest velocity, at least one-third of the force with which it is charged; but when projected by a small charge of gunpowder this force is saved, and the flight of the rocket is afterwards sustained by the force with which it is charged.