MECHANICS AND USEFUL ARTS. 73 



Original Monitor. Tassaic. Tecumseh. 



Diameter of turret . 21 ft. . 21 ft. ... 21 ft. 



Number of turrets .1 . . 



Dimensions of cylinders 30 in. . 

 Armament . . 2 11-in.guns. 



Tonnage . . 800 



1 ... 1 



35 in. . . . 40 in. 

 11 and 15-in. guns. 2 13-in. guns. 

 . . 1,400 



It will be observed that the most important differences between the 

 power of the first Monitor and the Tecumseh consist in the armor and 

 armament the offensive and defensive attributes. Instead of four 

 and one-half inches we have nine inches of iron, and instead of one 

 eleven and one fifteen-inch guns, the Tecumseh will have two thir- 

 teen-inch guns, which, however, will be able to burn more powder 

 than the old fifteen-inch guns. It was impossible when adding more 

 weight of armor to the ship to make the draft of water as light as in 

 the "Monitor, if that were even desirable, which is a matter not decided 

 on. One of the peculiarities of the Tecumseh is this, that she has 

 sponsons which tighten the frame to the vessel, as it were. In the 

 original Monitor this sponson was left out, and the consequence was 

 that the overhang was said to have been the cause of the loss of that 

 celebrated little vessel. 



The accident that happened to one of the monitors during Dupont's 

 attack on Charleston, which resulted in the temporary crippling of 

 the turret, cannot happen to the Tecumseh, because an immense band 

 of iron, several inches thick, perfectly solid and massive, covers the 

 whole external base o-f the turret, rendering it absolutely impossible 

 for any shot or shell to pierce it. This will insure the freedom of the 

 turret, so far as its revolving powers are concerned. The propeller is 

 driven by two powerful engines, with cylinders of forty inches in di- 

 ameter and twenty-eight inch stroke of piston ; and it will be observed 

 that the speed of the Tecumseh w^ll, in the natural course of things, be 

 much greater than that of the original monitors, as the dimensions of 

 her cylinders are nearly ten inches greater than those of the other 

 ships. The monitors of the Passaic series have not realized the speed 

 expected of them, but it is hoped that the Tecumseh series will do " 

 better. 



In still less important matters there are some points of difference ; 

 in keeping the anchor, for instance, an arrangement is now made by 

 which two holes are placed on each side of the bow, while in the other 

 monitors it was directly in the centre. In fastening, the armor-rivets 

 are substituted for bolts, as the latter give way and fly about when 

 struck by heavy projectiles "in a severe engagement. In the arrange- 

 ment of the machinery, the air and circulating pumps and the surface- 

 condensers are independent of the main engines, and can thus be op- 

 erated when the main engines are standing still, maintaining constant- 

 ly a vacuum, and being able to keep up the condensation of steam, in- 

 stead of blowing it off into the atmosphere, which every naval officer 

 will appreciate, because it has been one of the most Intolerable nui- 

 sances of the introduction of steam in the navy that when orders are 

 given upon the deck the blowing of the steam rendered them inaudible, 

 and it could not be silenced without danger of boiler explosions. 



New pattern Monitors. - - Several vessels of the Monitor pattern, 

 buildino- in Boston, and intended for the defence of Massachusetts har- 



^^ 



bors, have some marked differences of construction from the monitors 



7 



