MECHANICS AND USEFUL AETS. 77 



vessel, if indeed so much. It remains only to see how far the effects 

 of shot may be neutralized," etc. 



The introduction of new and very powerful ordnance by the 

 United States Navy in 1854 undoubtedly led foreign powers to the 

 effort to obtain even more powerful pieces, and the rifled cannon are 

 now about to share a place with the smooth-bores, if they do not re- 

 place them entirely. It was natural that the defence should be de- 

 sired to proceed pari passu with the offence, and metallic armature 

 has been adopted. France proposed to build. thirty such ships, but 

 was content to begin with ten, in order to correct defects by ex- 

 perience. England is also rapidly endeavoring to meet this emer- 

 gency at a cost of two and a half millions per ship. The United 

 States must, of necessity, follow where she might have led. 



Whether it is best to follow the details adopted for iron-plated ves- 

 sels constructed in England and France, is by no means certain. 

 The character of their armature, which is the essential feature, con- 

 templates the exclusion of solid shot, which, though not attained in 

 all cases, is yet as nearly effected in the very great proportion of 

 instances as can be useful, while shells, if not entirely neutralized, 

 are rendered of little avail. Now the iron sheathing used on the 

 French vessel, La Gloire, for this purpose, amounts to about one 

 thousand tons. Of course the capacity of the vessel to carry ord- 

 nance, coals, etc., upon which depends the power of attack, and to 

 keep the sea for any length of time, are proportionally lessened. To 

 decrease this weight, and yet to retain the material defence of the 

 ship, becomes an object ; and it is the purpose of this paper to sug- 

 gest whether the propositions made by me in 1852 may not still con- 

 tribute to this end. 1st. Use an iron ribbing externally with such 

 stowage of coal ivitliin as the ship permits ; using also an interior ar- 

 rangement of thin plates, calculated to give a harmless direction to 

 projectiles, that is, from vital parts. 2d. These cannot prevent the 

 entrance of shot, but they can be made to nullify shells, either by 

 direct fracture, if round, or by glancing them, if from rifled cannon. 

 3d. Such armature need not exceed in weight one-half that of the 

 present ship, and thus add some five hundred tons to the capacity 

 for coal, thereby doubling that now carried. 



If there should arise any objection to the ribbing not now per- 

 ceived, then I would recommend that the plated armature be re- 

 duced one-half in thickness, which, I apprehend, would not leave 

 the hull open to a dangerous action from shells ; for, as I have al- 

 ready stated in " Shells and Shell Guns," the proportion of round 

 shot or shells that glance is very considerable, even on wooden sides, 

 while great force is lost from ricochet. Now, in long projectiles, 

 this is so vastly increased, that it is obviously their weakest point, 

 and can be used well for defence. A very little inclination serves 

 to divert them, and on metal this would be the rule, while the rico- 

 chet is so abrupt and so uncertain as to detract largely from their 

 action. This plan would extend the sphere of such ships materially. 

 Now, without sailing power, and relying wholly on steam, it is obvi- 

 ous that they cannot go but a few days from their depots of coal, 

 therefore can only be used in coast defence or cruising along shore. 



But these more lightly clad steamers, carrying more coal, and 

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