7-2 



ANNUAL OF SCIENTIFIC DISCOVERY. 



with one revolving turret, capable of carrying two heavy guns, which 

 is believed to be impenetrable against any projectile hitherto experi- 

 mented with. The following are its dimensions. The diameter of the 

 inside turret is twenty-four feet. The turret itself being formed of six 

 thicknesses of inch-plate riveted together. Over and outside of this is 

 another turret forming a sleeve, consisting of seven thicknesses of inch- 

 plates riveted, while between the two are additional shields of iron 

 hoops or bars, having an aggregate of five inches ; so that the whole 

 forms one great revolving iron tower eighteen inches in thickness, 

 twenty-seven feet in diameter, and weighing about two hundred tons. 

 A companion vessel to the Dictator, named the Puritan is also in the 

 course of construction. 



The Dunderberg.- -This name has been given to a vessel now in the 

 course of construction, at New York, which combines the features of a 

 ram and an iron-clad monitor. Her length is 378 feet, width sixty- 

 eight feet, and depth of hold thirty-two feet. The model is peculiar ; 

 the floor is dead flat, at an angle with the sides, except at the forward 

 end, where it is nearly vertical. The hull is divided into water-tight 

 compartments. The sides below the main deck are 6-1 feet thick, and 

 on the casemates there are three feet of solid timber firmly bolted. 

 The iron plating is 4-1 inches thick on the sides and 3-1 inches on the 

 casemate. This vessel is 7000 tons burthen. Her deck is bomb- 

 proof, and she will be rigged half-mast with yards and sails, which will 

 enable her to cruise without the aid of her engines. 



The whole forward part of the vessel, for a distance of fifty feet, is 

 solid wood-work, covered on the sides and edge with the iron armor, 

 constituting the ram, which has the profile of an axe edge. Should 

 this ram be knocked away, which is improbable, the hull will still re- 

 main water-tight. The engines are of 6,000 horse-power. 



The Dunderberg is to be furnished with two revolving turrets, twen- 

 ty-one feet in diameter inside, and nine feet high, placed fore and aft. 

 The hull is pierced for three broadside guns on each side, as well as 

 one fore and one aft for bow and stern chasers. The draught of water 

 of the Dunderberg when loaded will be twenty-one feet. 



New Iron-Clads of the Monitor pattern. The iron-clad turreted 

 vessels, of the so-called Monitor* pattern, introduced by Ericsson, 

 having proved eminently efficient and suitable for harbor attack and 

 defence, the U. S. Navy Department has continued their construction, 

 and has already a large fleet of them afloat, or on the stocks. Al- 

 though in the chief points of their structure there is great similarity 

 between the new vessels and the original Monitor, there is neverthe- 

 less a considerable difference in their details, which, as showing a prog- 

 ress in this department of naval architecture, is worthy of notice. 

 The following table shows the peculiarities of the original Monitor ; 

 of the Passaic, one of a second series of nine built subsequently ; and 

 of the Tecumseh, one of a third series of nine, built during the past 

 year (1863.) 



Original Monitor. Passaic. Tecumseh. 



190 ft. 200 ft. 235 ft. 



Length 



Width 

 Depth of hold 



Draft of water 

 Armor of sides 

 Thickness of turret 



30 " 



9 " 



9 " 



4| in. 

 11 " 



40 " 

 91 " 



10 " 

 4 in. 



11 " 



4G " 

 14 " 

 14 " 

 9 in. 

 11 " 



