174 ^^^ FOPULAB SCIENCE MONTHLY. 



12-inch, eight 8-inch, and ten 4-inch breecii-loading guns, be- 

 sides twenty machine guns and six tubes for discharging 18-inch 

 automobile torpedoes. It is one thing for a vessel to carry a large 

 battery capable of firing a tremendous weight of metal when all 

 the manipulating apparatus is in perfect order, but quite another 

 in these days of high explosives to have that battery and appa- 

 ratus securely protected from the guns of its antagonist, therefore 

 the 13-inch forty-four-ton guns of the Iowa are mounted in pairs 

 in turrets having walls of solid steel fifteen inches thick, and 

 protected from the water-line up by steel of the same thickness, 

 which effectually protects the loading, turning, and controlling 

 mechanisms. In order that these guns may be fought in heavy 

 weather the forward turret is placed on a forecastle deck with 

 the axis of the guns some twenty-five feet above the load line, 

 and has a train of three hundred degrees, or only sixty less than 

 a complete circle; the after 12-inch guns are mounted in the same 

 manner, but on a deck seven feet nearer the load line. Both for- 

 ward and after turrets are placed in the mid line of the vessel, in 

 order to have a great train and be as free as possible from the 

 motion due to rolling ; the turrets are revolved by steam power 

 at the rate of one revolution per minute. Some idea of the 

 power of these guns may be obtained from the following data : 

 The weight of one powder charge is four hundred and twenty- 

 five pounds ; that of the projectile, eight hundred and fifty 

 pounds ; its muzzle velocity, 2,100 feet, or four tenths of a mile 

 per second ; the muzzle energy, 25,085 foot tons, or capable of 

 raising that amount one foot in a minute, with a penetration in 

 wrought iron of 27'(; inches. The 8-inch guns are also mounted 

 in turrets, having great range, and are protected by armor vary- 

 ing from ten inches to seven inches and a half in thickness ; the 

 ten 4-inch guns, each discharging projectiles of thirty-six pounds 

 weight at the rate of ten rounds per minute, are protected by 

 fixed segmental shields four inches thick. 



While so much has been done to develop the battery and its 

 protection, the features of defense, stability, speed, and endurance 

 have received most careful attention ; the magazines, boilers, en- 

 gines, steering mechanism, etc., are all inclosed in a belt of steel, 

 covering about sixty-five per cent of the load-line area, of a maxi- 

 mum thickness of fourteen inches, and extending fr ir three feet 

 ^bove to five feet below the load line : at the upper edge of this 

 is worked from side to side of the vessel a horizontal deck 

 three inches thick (see Figs. 2 and ;3) ; above this, to protect the 

 stability, a steel belt four inches in thickness is worked to the 

 main deck, and at the unarmored ends double coffer dams six feet 

 wide, the outer one filled with obturating and the inner one with 

 wrater-excluding material, are provided as shown in Fig. 4. 



