IRON-CLAD SHIPS 383 of armored ships. The introduction of twin screws, and the necessity of having light- draught vessels for coast and harbor defence, have also led to further differences. When the first English ironclads were constructed, the most powerful guns used by their ships of war were 68-pdrs. or 8-inch smooth-bore guns. The Americans then used 9- and 10-inch guns, and 4J-inch armor plating was deemed sufficient when properly backed and supported. This thickness of armor backed in various ways forms the protection of a large number of the English and French ironclads. In the first iron ships, the Warrior, Black Prince, Achilles, Defence, Resistance, Hector, and Valiant, the 4J-inch armor was backed by 18 in. of teak fitted outside the hulls; and in the wooden ships the armor was bolted on the outside of the planking. In the Minotaur class the pla- ting was increased to 5| in., but the back- ing was reduced to 9 in., so that practically the sides of the latter class are of the same strength as those of the Warrior class. In the Belle- rophon the armor plating is 6 in. and the back- ing 10 in., but it is still further strengthened by having the skin plating 1 in. thick, or nearly an inch thicker than in the older iron- built vessels. The armor of sea-going broadside ships has, according to some English authorities, reached its greatest thickness in the Hercules, which has 9-inch armor at the water line, 8-inch on the most important parts of the broadside, and 6-inch on the remainder, with teak backing 10 and 12 in. thick outside the 14- inch skin plating. Below the lower deck, and down to the lower edge of the armor, the spaces known as the "wing passages" are filled in with solid teak backing, inside of which there is an iron skin in. thick, supported by vertical frames 7 in. deep. The total protec- tion in the region of the water line therefore consists of 11 J in. of iron, of which 9 in. are in one thickness, and 40 in. teak backing. The trial of a target at Shoeburyness, constructed to represent this part of the ship's side, proved that it was virtually impenetrable to the 600- pdr. rifle gun. But the maximum thickness of armor carried must not be considered to have been yet attained. Coast-defence vessels and rams have been built to carry 11- and 12-inch armor, and ships have been designed and will doubtless be built for sea-going purposes to carry 15, 18, and 20 in. of armor, either in tur- rets or broadsides. There can be little doubt that as improvements are made in the manu- facture and working of heavy guns, correspond- ing additions will be made to the thickness of armor. It is hardly possible to foresee in what ( way the competition between guns and ships will terminate. Grouping the iron-clad ships of the English navy according to the thickness of their armor and backing, without regard to the greater or less extent of the surface pro- tected, but dividing them into iron-built and wood-built, and remembering that turret armor is generally a little stronger than the side 438 VOL. ix. 25 armor, the preceding facts may be summarized as follows : IRON-BUILT. VESSELS. Armor. Bak- ing- Skin plating Pit-marks. Inches. } ,, ID. Incbeg , ( The weakest of Eng- r ** 9
lish ironclads. Viper ( But very slightly Vixen i m t stronger than the Waterwitch Warrior . .
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above. Black Prince Achilles n 1 , Valiant Prince Albert 5i 9 J Northumberland , Bellerophon I 6 6 10 10 1* ' J The greater thickness of skin plating in this and most of the following ships is ob- viously equivalent to an increase in the thickness of armor. Armor only 5 in. thick on some parts of the 1 broadside. Vanguard 6 10
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mor on the water- ( Triumph 1 .. ( The Captain had 8- Captain .. .
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12
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TT (On belt... c^rsr: Sul- j On sides tan j generally. TT * 1 On sides. . Si On b r st - v ( work (On sides . . pe*ter: Glatton 9 8 6 11 8 11 12 ) 10 10 12 12 12 12 12 j. H .
It H 1! H An additional protec- tion of about 30 in. of teak, backed by a f-inch iron skin, in the neighborhood of the water line. Thunderer Devastation H 18 it WOOD-BUILT. VESSELS. Armor. Thlcknm of ild>. IncUei. I.che.. 4i 29^ s ISM Pallas .. .. 22 41 26 19} 1M 51 86 6 29J 6 81 Lord Clyde* Lord Warden* . . . 4* 81J
- These two ships have an inner skin of 11-inch Iron, and a
strake of 51-Inch armor at the water line, and the frame la filled in solid behind the armor; so that In addition to the outer and inner armor, the whole thickness of the side Is available to resist penetration. In all the other wooden ships water can enter when the outside planking, which is only 8 or 10 in. thick, is penetrated.
