THE DUQUESNE AND TOURVILLE. The above outlines represent the modern French frigate Duquesne, recently set afloat at the Rochefort dock-yard. A sister ship, the Tourrille, is fast approaching completion, under contract, at a yard near Toulon. Both ships are termed cruisers of the rapid type, and are designed for seventeen knots per hour at sea. The frames, bulkheads, beams, and all interior parts, also masts, are composed of steel; but the outside plating of the hulls is entirely of iron, and the bottoms are sheathed with two layers of teak planks, in all 7 inches thick, and coppered; put on in a similar manner to the system of the English, except that, to insulate the iron from the copper, thick layers of marine glue have been placed between the iron hulls and the teak planks, also between the teak and copper. The dimensions are as follows: Length between perpendiculars.. Breadth at load water-line Draught of water forward WEIGHTS. Weight of hull............... Weight of guns and ammunition Coal ARMAMENT. 2,650 tons 260 tons. 1,280 tons. 655 tons. This consists of twenty-seven guns; twenty of these have a caliber of 14 centimeters, and seven of 24 centimeters, about 54 and 94 inches, respectively. MOTIVE MACHINERY. The engines and boilers for the Tourville were both designed and Constructed at the extensive Forges et Chantiers de la Méditerranée, at Marseilles. The engines are of a horizontal compound type, and consist of two sets, of four cylinders to the set, making, in all, eight cylinders, having four piston-rods connected to one crank-shaft, to work a single screw; i. e., the four low pressure cylinders are laid horizontally on one side of the shaft, each having its high-pressure cylinder bolted to the outboard end, the steam being admitted directly from the high to the low pressure cylinders without passing through a receiver. boilers are of the old box type, braced to carry a pressure of 45 pounds per square inch, and built after the systematic style of the French. The The grate-surface is 950 square feet, and the heating-surface 24,500 square feet. The diameter of the screw-propeller is 20 feet 3 inches. The estimated number of revolutions per minute is 76. The estimated indicated horse-power is 7,500, and the speed at these figures 17 knots per hour. The space occupied by these engines is greater than that occupied by the engines of any single-screw ship I have knowledge of, and the numerous parts and multitudinous connections make the com plication great, and will cause serious difficulty with the operation of the machinery, if it does not result in other evils; besides which, the boilers are of the discarded type, and cannot be worked to the pressure necessary to obtain the economy resulting from the compound system; and as the Tourville has been built for high speed as the first require ment, it may be regretted that a more simple type of machinery has not been adopted. The French naval authorities, in building this, their first rapid cruiser, have, in many features of the hull, followed the system of the English, and have accepted the errors admitted by the British authorities to exist in their modern frigate the Shah. Besides the original great cost, large cost for maintenance, and unwieldy bulk to handle, the motive power is decidedly objectionable, and the coal supply is only 655 tons. The motive machinery for the Duquesne is from a different design. It is being manufactured at the Usine d'Indret. SMALLER VESSELS. The corvette Duguay Trouin, building at Cherbourg, is also designed as a rapid cruiser. She is to have 3,180 tons displacement, to make 16 knots per hour on the measured mile, and is intended to compete with the English Rover class. There is also a third class building, of which the Rigault de Genouilly is the type. They are to compete with the English Opal class. These vessels are 240 feet long, have 44 feet extreme beam, 14 feet 7 inches mean draught, and a displacement of 1,640 tons. The list appended below contains the names of the vessels building and proposed January 1, 1876. It will give a very good idea of the progress made at that time in reconstructing the French navy. |