The chief novelty in the machine is the additional roll provided under the ordinary bottom rolls. This extra roll, which is used for straightening old plates and for bending small tubes, pipes, etc., is made of steel, and is 7 in. in diameter by 5 ft. long. It is provided with a swing frame at one end to allow of taking-off pipes when bent, etc., and it is altogether a very useful addition. The machine we illustrate weighs 11 tons, and is all self-contained, the standards being mounted on a strong bedplate, which also carries the bearings for the shaft with fast and loose pulleys, belt gear, etc. Thus no foundation is required.--_Engineering_. * * * * * MODERN ORDNANCE. [Footnote: A paper read Feb. 8, 1882, before the Society of Arts, London.] By COLONEL MAITLAND. A great change has lately been taking place throughout Europe in the matter of armaments. Artillery knowledge has been advancing "by leaps and bounds;" and all the chief nations are vying with each other in the perfection of their _matériel_ of war. As a readiness to fight is the best insurance for peace, it behooves us to see from time to time how we stand, and the present moment is a peculiarly suitable one for taking stock of our powers and capabilities. I propose, therefore, to give you, this evening, a brief sketch of the principles of manufacture of modern guns, at home and abroad, concluding with a few words on their employment and power. The introduction of rifled cannon into practical use, about twenty years ago, caused a complete revolution in the art of gun-making. Cast iron and bronze were found no longer suitable for the purpose. Cast iron was too brittle to sustain the pressure of the powder gas, when its duration was increased by the use of elongated projectiles; while the softness of bronze was ill adapted to retain the nicety of form required by accurate rifling. From among a cloud of proposals, experiments, and inventions, two great systems at length disentangled themselves. They were the English construction of built-up wrought iron coils, and the Prussian construction of solid steel castings.