In 1846, two rifled cannon were invented, one by Major Cavalli, of the Sardinian Artillery; and the other by Baron Wahrendorff, a Swedish nobleman. Both of these were iron breech-loading guns, having two grooves in order to give the requisite rifle motion to their projectiles. ~Experiments to test.~ Experiments were carried on at Shoeburyness, in 1850, with these guns. The deviations were always in the direction of the rotation of the projectiles; but they were so variable in amount that no allowance could be made for them in laying the gun with respect to the object. The Cavalli gun became unserviceable after having fired four rounds, by the copper ring or bouche imbedded in the metal of the gun at the bottom of the bore being damaged. The Wahrendorff gun stood well, the wedge resisting more effectually the force of the discharge than that of the Cavalli gun. ~Lancaster’s rifle gun.~ Mr. Lancaster’s novel invention of applying the rifle principle to cannon, may be described as “a two-grooved rifle in disguise,” having a “gaining twist,” the bore being an ellipse. ~Defects of.~ The chief defect in the Lancaster gun is the liability of the projectile to jam in the bore, both in loading and firing, the former rendering the loading difficult, while the latter endangers the safety of the gun. In consequence of several of these guns bursting, and also from the anticipated large range with great precision not being obtained from them, the Lancaster guns were removed from the service after the Crimean war. ~Sir W. Armstrong.~ Sir W. Armstrong submitted a proposal for his breech-loading gun to the Duke of Newcastle, then Minister at War, towards the end of 1854; his proposal being accepted, and a gun accordingly constructed, it was submitted to numerous trials, both at Shoeburyness, and near Sir W. Armstrong’s private factory at Newcastle. This gun is now made entirely of wrought iron, although the original one had a steel bore. It is a built-up gun, that is to say, it is composed of separate pieces, each piece being of such moderate size as to admit of being forged without risk of flaw or failure. By this mode of construction, great strength, and consequently, great lightness, are secured. The shell used combines the principle of the shrapnel and percussion shell, i.e., it may be made to explode either as it approaches the object, or as it strikes it. Moreover, it may be made to explode at the instant of leaving the gun, in which case, the pieces spread out like a fan, and produce the usual effect of grape or canister. Armstrong’s guns are now (1860) being employed in China. ~Whitworth.~