A HOLE WITHOUT FIGURES MEANS GEN! ADM! PERFORATION UP TO 3000 YARDS: MAXIMUM RANGES OF PERFORATION LESS THAN 3000 YARDS ARE MARKED IN FIGURES. SHADED GUNS ARE CORRECT IN GENERAL OUTLINE, DOTTED GUNS ONLY AS TO LENGTH. SCALE 20 FEET TO AN INCH. ALL BACKING IS 18 IN. OF WOOD WITH IN. SKIN. + A GUN OF 42 C.M.OF OLDER TYPE PATTERN 1875, WEIGHING 74'6 TONS IS SHOWN IN TABLE WITH MORE ENERGY THAN THE 37 C.M. GUN HERE DEPICTED, AND EQUAL PERFORATION SEE TABLE OF FRENCH NAVAL ORDNANCE PL.VII 7.9 ITALIAN. (DUILIO DAND (DANDOLO ITALIA LEPANTO AMADEO PALESTRO KONIG WILHELM KAISER PETER ST ROMA VENEZIA GEN! ADN! Pl. VIII were given by Captain Grenfell, R.N., in Engineering, and have been shown for some years past in the Austrian Marine Almanack as well as in the British Navy. To give to these diagrams a definite practical character, the following course has been followed. On the supposition that 3000 yards is the maximum range at which side armour will be systematically attacked, all projectiles perforating up to 3000 yards are shown with a clear blank hole. For every perforation effected only at shorter ranges, the limit of range is entered in or near the hole. Thus, any officer finding armour corresponding to that of his enemy with a blank hole opposite his gun on the diagram, may hope to perforate with a direct hit at least up to 3000 yards. Should he find a number less than 3000 yards entered, he must not expect to perforate beyond the range so entered. The armour is wrought-iron. It is only approximately representative. The types are chiefly French. The perforation includes backing and skin. General Maitland's diagram has been used for calculating loss of velocity at each range. On service each hit would have less power to perforate than is indicated on the diagrams, in proportion as it strikes more obliquely. value of The diagrams must be regarded as only approximate. They may Practical however be of practical value, for an officer may be able to see at a the glance that some ship's armour is well within the power of his guns or diagrams. quite beyond them, and behave accordingly. All armour-clad vessels built prior to 1876, and many subsequently, are iron-plated. To these the above directions apply. The question may naturally be asked, why ships clad in steel and compound armour are treated as if only sheathed in the same thickness of wrought-iron. The reply is that the object is to furnish a low limit for guns available for attack. In experimental firing, steel and compound plates have often been attacked and have suffered when projectiles have been employed just capable of perforating wroughtiron of the thickness of the steel in question. The yielding is more or less by fracture, and is a gradual process; still it would not be right to fix the limit higher, and to say that guns capable of such effects were useless for attack of such armour. Moreover, no other limit could be taken, seeing that some very soft steel armour exists approaching wrought-iron in quality, though how closely it is impossible to say. Thus it may be laid down that steel or steel-faced plates may be attacked by guns capable of perforating wrought-iron of the same |