The probabilities of a general war in Europe invest the subject of the following paper with an unusual interest. It is worthy of notice that America has furnished so large a proportion of the improvements in war-engines of every description. Fulton's schemes are well known; we all remember something of the guns invented by Perkins; there is a gentleman now in daily conference with Mazzini and the revolutionary committees, in London, who proposes the noiseless discharge of twenty thousand missiles in a minute, by means of a machine invented in Ohio; and we find in the _Times_ an abstract of a paper read at the Institution of Civil Engineers, on the 25th of November, by our famous countryman Colonel Colt, "On the Application of Machinery to the Manufacture of Rotating Chambered-Breech Fire-Arms, and the Peculiarities of those Arms." The communication commenced with a historical account of such rotating chamber fire-arms as had been discovered by the author, in his researches after specimens of the early efforts of armorers for the construction of repeating weapons, the necessity for which appears to have been long ago admitted; and with the attention of such an intelligent class devoted to the subject, it is certainly remarkable that during so long a period so little was really effected towards the production of serviceable weapons of this sort. The collections in the Tower of London, the United Service Museum, the Rotunda at Woolwich, Warwick Castle, the Musee d'Artillerie, and the Hotel Cluny, at Paris, as well as some ancient Eastern arms brought from India by Lord William Bentinck, demonstrated the early efforts that had been made to produce arms capable of rapidly firing several times consecutively, without the delay of loading after each discharge. Drawings of these specimens were exhibited, comprising the match-lock, the pyrites wheel-lock, the flint-lock, down to the percussion-lock, as adapted by the author. Among the match-lock guns, some had as many as eight chambers, rotating by hand. Some of the pyrites wheel-lock guns had also as many as eight chambers, and rotated by hand; one of them, made in the seventeenth century, had the peculiarity of igniting the charge close behind the bullet, burning backwards towards the breech--an arrangement identical in principle with that of the modern Prussian "needle gun," for which great merit has been claimed. The flint-locks induced more determined efforts, but all were abortive, as the magazines for priming and the pan covers were continually blown off on the explosion of the charge. Indeed, from the earliest match-lock down to the present time, the premature explosion of several chambers, owing to the simultaneous ignition of the charges, from the spreading of the fire at their mouths, had been the great source of difficulty. In some of the most ancient specimens, orifices were provided in the butt of the barrel for the escape of the bullets in case of explosion, whilst others had