256 ON THE DEFENCES OF PORT JACKSON, 



necessarily endure in actual engagement, and afford them security 

 when off duty. 



The formation of a corps of Volunteer Engineers, to act in 

 connection with the ISTaval Brigade and Volunteer Artillery, to 

 throw up earthworks at any place if required, as an additional 

 security against the landing of an enemy. 



The erection of a sunken barbette battery at Botany, for 

 one heavy gun, and two heavy field guns brought there when re- 

 quired. 



IV. 



The laws of attack and defence, although modified to meet 

 the requirements of improved artillery, remain nearly the same 

 for coast defences, for if we have long range guns and more pene- 

 trating projectiles, these will be opposed by vessels coated with 

 armour plates. 



The question is whether it is necessary for us to oppose iron- 

 coated forts to the artillery of an enemy ? 



The ordnance now carried by the vessels of foreign navies 

 (of which I shall speak presently) would justify such constructions 

 even if the superiority of iron forts to masonry had not been 

 admitted by every nation. 



Other considerations also induced me to propose the con- 

 struction of iron batteries. I rejected Earthworks on account of 

 the thickness of parapet that would be required to resist new 

 artillery. The firing through embrasures would be too limited, 

 and the accuracy of our opponents' rifled guns would render 

 these embrasures mere shell traps. If our guns were mounted 

 " en barbette," the direct or ricochetting fire of an enemy would 

 soon silence them. 



Sand batteries present nearly the same objections. We are 

 aware that the bomb-proof sand works of Fort Wagner, on Morris 

 Island, were captured after being breached by rifled artillery at 

 ranges of from 1300 yards to 2000 yards. 



Brickwork batteries and towers require too many guns on 

 account of the difficulty of obtaining a lateral range for them, 

 and the embrasures weaken the walls considerably. Thus Fort 

 Sumter, in South Carolina, a brickwork containing 135 guns, 

 succumbed to an attack of seven batteries of 8 in., 10 in., and 



