BY G. A. MOKELL, ESQ., C.E. 



263 



The greater point blank range of rifled guns over the smooth 

 bore is well known, and I have given only a few tables of ranges 

 and deviations of the heaviest guns up to 600 pounders. 



At sea, vessels will fight at the distance their guns will 

 cany ; but in our Defences we must use rifled guns, because we 

 must have power and accuracy in order to reach the enemy. 



I have calculated the strength of the iron walls of the forts 

 and batteries I proposed in my plan of defence, considering 

 weight and cost, to give the greatest resisting power obtainable 

 against racking or punching projectiles, whether ponderous shots 

 fired at a low velocity or rifled bolts fired with the highest 

 possible velocity, so as to distribute their effects over the whole 

 structure. The same calculations are made in designing iron-clad 

 vessels, so that our superiority over an enemy must depend 

 chiefly on the power of our guns to do the work required of them, 

 at from 1000 to 4000 yards. The short time vessels may be 

 exposed to the fire of our batteries renders it necessary to have 

 guns that will send their shot through armour plates, otherwise 

 we should require more guns and men than we can procure for 

 the purpose of racking vessels, and perhaps we should not have 

 the chance of shattering their sides with shells afterwards. 



Commander Scott, R.N., says in a paper he read before the 

 Royal United Service Institution, in June 1863, " The size of the 

 gun is of vast importance, more than is generally assigned to it, 

 and for this reason, 20 guns, each a one-pounder, are fired at a 

 target of Iron 1J in. thick, and produce no effect. One gun, a 

 20 pounder, is fired and smashes it. The velocity in both 

 lal, in both cases the same amount of metal is 



