74 AXX17AL OF SCIENTIFIC DISCOVERY. 



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extending twenty-five feet beyond the bull at each end. The sides 

 are five feet high, and when in fighting order the lower hull will be 

 entirely immersed and the upper one sunk three feet six inches, thus 

 leaving but eighteen inches both fore and abaft above water, the bat- 

 tery drawing ten feet of water. The sides of this upper hull are com- 

 posed of an inner guard of iron ; outside of this is a strongly fastened 

 wall of white oak, thirty inches thick, and covered with an iron armor 

 six inches in thickness. The bottom of this vessel is joined to the hull, 

 so that the interior is open to the bottom, as in a sloop. The deck 

 comes flush with the top of the upper hull, and is bomb proof. First 

 is a frame of oak beams, ten inches square and twenty-six inches apart, 

 covered with eight-inch plank, and protected with two layers of iron, 

 each an inch thick. There will be no railing or bulwark of any kind 

 above the deck. 



The ends of the upper vessel projecting over the hull, fore and 

 abaft, serve as a protection to the propeller, rudder, and anchor. The 

 propeller is of course at the stern, and the equipoise rudder behind 

 that, and they are so protected by the upper vessel that they cannot 

 be struck by a ball. The anchor is in front, and is short but very 

 heavy. It is hoisted by a chain running into the hold, up into a place 

 fitted for it, outside of the lower hull, but within the impregnable walls 

 of the upper hull. The inclination of the lower hull is such that a ball, 

 to strike it in any part, must pass through at least twenty-five feet of 

 water, and then strike an inclined iron surface, at an angle of about 

 ten degrees. It is, therefore, absolutely protected, yet so light as to 

 give great buoyancy. A ball striking the eighteen inches of exposed 

 upper hull, to do material damage, must pass through six inches of 

 iron, thirty inches of white oak, and then about half an inch more of 

 iron. 



Boarding the vessel, we find that only three tilings are exposed 

 above the deck, viz., a wheel or steering house, a turret or citadel in 

 the centre, containing the armament of the vessel, and possibly a box 

 around the smoke-escape. 



The Wheel-house. The battery will be steered from the front, and 

 the wheel-house will stand before the turret. It will be of iron, very 

 strong though durinsr action it is not intended that it should be ex- 



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posed. It can be lowered into the hold like a bale of dry-goods on one 

 of the ordinary sidewalk falls in use in our great cities. When low- 

 ered, the top, which is bomb-proof, is level with and forms part of the 

 deck. The joints are water-tight. The house will be pierced for 

 sharp-shooters. 



The Chimneys. The draft for the furnaces is a forced one, and in 

 action no chimney will be used, as the smoke will pass through bomb- 

 proof gratings in the deck. As the deck will be continually washed 

 by the sea, the accumulation of cinders, etc., will be of no consequence. 

 Probably a small guard will surround these gratings, to prevent heavy 

 seas breaking into them, and a contrivance is made to prevent what 

 water may dash over from going into the furnaces. 



The whole vessel thus described is but a bed to support the castle. 

 The turret, which is the important feature of the structure, is a round 

 cylinder, twenty feet in interior diameter and nine feet high. It is 

 built entirely of iron plates, one inch in thickness, eight of them se- 



