MECHANICS AND USEFUL ARTS. 77 



rior target, 156 pounds, moving at the rate of 1,700 feet per second, 

 the work done will be 



= 156 + i (1700)2 - 7,008,238 one foot high. 



Showing at once the immense power that this small body is able to 

 deliver on every resisting medium tending to arrest its course and 

 bring its particles to a state of rest. Or, in other words, it is equiva- 

 lent to raising upwards of 3,000 tons a foot high in the air. 



Application of Iron for Defensive Purposes. But let us next con- 

 sider in what form, and under what circumstances, iron can best be 

 applied for the security of vessels and forts. To the latter the an- 

 swer is, make the battery shields thick enough ; but a very different 

 solution is required for the navy, where the weight and thickness of 

 the plates is limited to the carrying powers of the ship. If our new 

 construction of ships are strong enough to carry armaments of 300- 

 pounder guns, which is assumed to be the case, our plating of six or 

 seven inches thick would be penetrated, and probably become more de- 

 structive to those on board than if left to make a free passage through 

 the ship. In this case we should be exactly in the same position as we 

 were in former days with the wooden walls ; but with this difference, 

 that if built of iron the ship would not take fire, and might be made 

 shell-proof. It is, however, very different with forts, where weight is 

 not a consideration, and those, I am persuaded, may be made suffi- 

 ciently strong to resist the heaviest ordnance that can be brought to 

 bear against them. In this statement I do not mean to say that ships 

 of war should not be protected, but we have yet to learn in what form 

 this .protection can be effected to resist the powerful pieces of ord- 

 nance, and others of still greater force which are looming in the dis- 

 tance, and are sure to follow. 



A great outcry has been raised about the inutility of forts ; and the 

 government, in compliance ' with the general wish, has suspended 

 those at Spithead ; I think improperly so, as the recent experiments 

 at Shoeburyness clearly demonstrate that no vessel, however well pro- 

 tected by armor-plates, could resist the effects of such powerful artil- 

 lery ; and instead of the contest between the Merrimac and Monitor, 

 and that of the 300-pounder gun, being against, the results are to ap- 

 pearance in favor of forts. Should this be correct, we are now to 

 consider how we are to meet and how resist the smashing force of 

 such powerful ordnance as was levelled against the Warrior target. 



During the whole of the experiments at Shoeburyness I have most 

 intently Vatched the effects of shot on iron plates. Every descrip- 

 tion of form and quality of iron has been tried, and the results are 

 still far from satisfactory; and this is the more apparent since the 

 introduction of the large three-hundred-pounder, just at a time when 

 our previous experiments were 'fairly on the balance with the forty, 

 sixty-eight, one-hundred, and one-and-twenty-six-pounders. They 

 now appear worthless, and nothing is left but to begin our labors 

 again de novo. 



It has been a question of great importance, after having deter- 

 mined the law of resistance and the requisite quality of the iron to 

 be used as armor-plates, how these plates should be supported and 



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