500 Mr, W. Fairhairn on the Properties of Iron, [May 9, 



target, 156 lbs., moving at the rate of 1700 feet per second, the work 



done will be — 



156 X (1700y 

 = g|7 -^ r= 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 equivalent to 

 raising upwards of 3000 tons a foot high in the air. 



The Application of Iron for Purposes of Defence. — Having exa- 

 mined in a very condensed and cursory manner the present state of our 

 knowledge in regard to iron, and its application to the purposes of 

 shipbuilding, let us now consider in what form and under what circum- 

 stances it can best be applied for the security of our vessels and forts. 

 To the latter the answer 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. 

 It has been observed with some truth that we have learnt a lesson from 

 the recent naval action on the American waters ; but it must be borne 

 in mind that neither of the vessels engaged nor the ordnance employed 

 were at all comparable to what have been used at Shoeburyness. 



To those who, like myself, have gone through the whole series of 

 experiments, the late engagement will appear instructive, but not cal- 

 culated to cause any great alarm, nor yet effect any other changes than 

 those primarily contemplated by the Government, and such as have 

 been deduced from our own experiments. It is, nevertheless, quite 

 evident that our future navy must be entirely of iron ; and judging 

 from the last experiment with the Armstrong smooth-bore gun, it would 

 almost appear as a problem yet to be solved, whether our ships of war 

 are not as safe without iron armour as with it. If our new construc- 

 tion of ships are strong enough to carry armaments of 300 -pounder 

 guns, which is assumed to be the case, our plating of 6 or 7 inches 

 thick would be penetrated, and probably become more destructive 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 sufficiently 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 last powerful ordnance, and others of still 

 greater force which are looming in the distance, 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 Shoe- 



