NAVY, UNITED STATES. 



017 



iron are first rolled to 12 inches broad by 1 

 thick and sheared to 30 inches length ; 5 of 

 these are piled and rolled down to a rough 

 slab ; two such slabs are then welded and roll- 

 ed down to a plate l inches thick, which is 

 sheared to 4 ft. square. Four such plates arc 

 then piled and rolled down to one of 2-j inches 

 thickness, and 8 feet by 4 ; and, lastly, 4 of 

 these plates are piled and rolled to form the 

 entire plate. There are thus welded together, 

 during their successive reduction in thickness, 

 160 thicknesses of plate. That blisters and 

 imperfection of welding and of cohesion should 

 occur in a plate so produced is inevitable, espe- 

 cially, on account of the difficulty of bringing 

 so large a mass to a perfect welding heat 

 throughout, during the final operation of roll- 

 ing into one the 4 large plates, each of 2| in. 

 thickness; and this want of perfect incorpora- 

 tion is held to be a source of weakness, by 

 reducing the thick plate, in some degree, to 

 the condition of laminated armor composed 

 of plates extremely thin. Some plates recent- 

 ly made in this way, however, and of 5 inches 

 thickness, have been proved, by experiments 

 upon them at Shoeburyness, to possess a very 

 satisfactory degree of tenacity and strength. 



The subject of the methods adopted in fast- 

 ening the armor to the wooden or iron sides 

 of the vessel, by means of bolts, screws, &c., 

 is one of too much detail to be interesting to 

 others than the ship-builder or artisan; and, 

 besides, it is probably not in all cases fully 

 made known. It is still a matter of much 

 difficulty to fasten any armor securely enough 

 to the actual hull of an iron ship through a 

 considerable thickness of wood backing ; and, 

 again, to fasten thick plates strongly to either 

 an iron or wooden hull without, at the same 

 time, weakening the plate by the number or 

 size of the bolt-holes. The attempts to ren- 

 der thick plates in effect continuous by tongu- 

 ing and grooving appear to has'e been aban- 

 doned on account of their expense, as well as 

 of the weakness of the union thus made. 

 Different patents have lately been taken out, 

 however, for modes of fastening, partially or 

 wholly, of the character here referred to, and 

 both in this country and in England ; as well 

 as others for providing the plates with flanges 

 within, through which only the bolts requisite 

 for fastening are to be passed. Plates may be 

 fastened, to some extent, by bolts made to pro- 

 trude only from the back, or by holding them 

 between angle-irons; and it is believed that 

 they may yet be strengthened at the joints by 

 welding, in the manner lately employed with 

 boiler. joints, by moving along the part light 

 furnaces, from which a jet of flame is blown 

 upon it, and following up closely with ham- 

 mers. In some of the target experiments, in 

 which the thick armor plates were fastened by 

 means of screw bolts, screwed up from the in- 

 side, the bolts broke off short at the nuts 

 whenever the target was struck by heavy shot. 

 This mode of fastening is to some extent 



adopted in the Monitor turrets, and for the 

 plates of the New Ironsides, in the former of 

 which some bolts have been broken, in tin- way 

 named. An easy remedy appears to offer it- 

 self in screwing up the bolts less tightly. 



The Aspects of the Armor Question n, tun- 

 while Changing. The aim of the preceding 

 part of this article has been to show the more 

 important steps by which the plan of armor- 

 ing ships became gradually matured, and to 

 present in brief the several modes of armoring 

 that have been actually and in rapid succession 

 resorted to up to the beginning of the year 

 1863. Still, the armor actually adopted con- 

 stitutes only one side of the question, and this, 

 in fact, the secondary one. For, so long as 

 the power of ordnance can be yet further in- 

 creased, the demand for increased capability 

 of resistance on the part of the armor of ships 

 grows in the same ratio ; and just so long the 

 issue between the two remains undecided. 

 The struggle is, on one side, for positively 

 irresistible artillery ; on the other for absolute- 

 ly invulnerable ships: will either of the two 

 finally and completely distance its antagonist ? 

 and if so, which one ? or will the two come 

 ultimately again to a tolerable balance of 

 chances, such as, some 50 years since, existed 

 between wooden ships and broadsides of the 

 largest round shot then in use ? and, if this 

 is to be the result, through what steps is it to 

 be reached? 



It is a well-known fact that while, for the 

 past two years, iron-armored vessels of all 

 dimensions, and in great numbers, have been 

 hurriedly building on both sides of the Atlan- 

 tic, during this very period, and also on both 

 sides, the caliber and firing charge of cannon 

 have been undergoing a marked increase, and 

 which, moreover, promises still to continue. 

 Already shot and shell are safely and regular- 

 ly thrown, which have powers of crushing 

 and of penetration such as were not at all 

 contemplated in the estimates of requisite 

 strength that dictated the armor of La Gloire, 

 the Warrior, the ordinary Monitors, the Iron- 

 sides, and their counterparts. The present 

 phase of the armor question cannot be under- 

 stood without a fair idea of the most recent 

 advance in the capacities of heavy ordnance, 

 and of the execution done by the projectiles 

 thrown by it. "While upon these points theo- 

 retical views must, still, to a certain extent, 

 be accepted, much information may be drawn 

 from the set experiments made in the way of 

 firing upon targets; and. for the latter source, 

 reliance must, as yet, chiefly be placed upon 

 the English experiments, as the only ones very 

 fully published. Some principles relating to 

 the subjects of ordnance and projectiles must, 

 of course, here be introduced as preliminaries. 



Destructive Power of Projectiles. The mo- 

 mentum, or quantity of motion, in a moving 

 projectile is proportional to the product of its 

 weight into its velocity; that is, momentum 

 varies as "W X V. This is the measure of the 



