The Russian guns which have been brought to this country present the same superabundance of metal at the muzzle, whilst at the breech there appears to be a deficiency; and when we take into consideration the extraordinary reports of their endurance, we must ascribe it to some other cause than the proper distribution of metal. Their endurance is no doubt owing in part to the goodness of the metal, in part also to the form of the breech, to the uniformity of thickness in the sides of the arch, and, lastly, to the absence of those protuberances called “reinforce rings.” These rings might with propriety be termed “rings of destruction;” for wherever irregularities exist in the substance of the metal, there the waves of vibration are interrupted, and the weak point then becomes fractured. The science of spring-making in all its varieties demonstrates the truth of this statement. Leave on a coach-spring an abutment of metal like a “reinforce ring,” and a few motions will be sufficient to break it, however well the spring may be constructed in every other part. The rigidity of this protuberance, by interrupting the waves of vibration, causes additional vibration in the adjacent and more yielding part, and thus produces fracture. The same thing occurs in all ill-constructed artillery: where the vibrations are checked, there is always a danger of some weaker part giving way. But the laws which regulate the distribution of vibrations in metal substances are not yet understood by artillerists, or cannon would be differently constructed. Those unscientific protuberances called “trunnions,” which are to be seen in almost every description of gun, prove the accuracy of my assertions. These protuberances, if scientifically considered, would soon be discarded, since they tend not only to the rapid destruction of the cannon, but also exert a most injurious influence on the direction of the projectile. The most wonderful shooting ever heard of (and which has been before alluded to) is partly to be attributed to the absence of trunnions. Trunnions act as the fulcrum of a scale-beam; they allow the breech and muzzle of the gun to oscillate, but in an opposite direction to a scale beam. Rifled cannon can never be correctly constructed whilst any weight impinges on the gun in front of the first starting point of the projectile; they must have the fulcrum behind the point of discharge, and the more nearly in a direct line the better. Rifled cannon will in some few years be perfectly constructed of cast steel; the projectile being made of gun metal, _i. e._, ninety-five parts of copper to five parts of tin, or of lead and its alloys, and at a probable cost of ten times that of a cast-iron projectile of equal weight.