262 ON THE DEFENCES OF POET JACKSON, 



The possibility of disabling even ordinary steamers moving 

 at ordinary speed is not to be relied on with only a small number 

 of guns and men. Major Owen in his " Essay on the Motion of 

 Projectiles," says : "As a steam vessel can constantly change her 

 position and move very rapidly, it is often extremely difficult when 

 tiring from a land battery, even to hit her, except when she is 

 obliged to advance in a certain direction or has arrived within a 

 very short range." He remarks upon the difficulty of judging 

 distances for laying a gun upon an object at a long range, from 

 the difficulty of observing the effect of the fire and the disturbing 

 influence of the wind, and recommends that " the ranges over 

 the water in front of the battery should be known to the gunners 

 in the battery." 



General Taylor, Inspector of Artillery, and late Commandant 

 at Shoeburyness, has also remarked : " It holds to the common 

 sense opinion that permanent fortifications to be effective at the 

 proper moment must be held by men who know exactly where 

 every shot will fall." 



If it be assumed that one or two experimental shots fired at 

 a vessel will determine the range, can the argument be sustained 

 for Port Jackson where every shot will have to be experimental 

 as the range will vary every moment with the motion of the 

 steamer ? Besides, it is on record that floating targets at long 

 ranges and also at comparatively short ones are not often hit with 

 the shots of the best rifled guns, even by the most practiced gun- 

 ners at Shoeburyness. 



These few remarks shew the great importance of target 

 practice at every one of our batteries and the necessity of having 

 guns fit to do the required work accurately at long or short ranges. 



I subjoin an official table of the comparative amount of work 

 done at 1000 yards by the smooth bore GH-pounder gun (95 cwt.) 

 and by the 150-pounder rifled gun, where it is seen that the 

 150-pounder gun can do 5.24 times the same work as the 

 68-pounder with only 2| times the same charge of powder, and 

 2 times the weight of shot, or the former will do 2 \ times more 

 work at 1000 yards than the 68-pounder will do at 200 yards. 

 If the 150-pounder is made the same bore as the 68-pounder 

 (8 in.), it is also found that the rifled gun has greater accuracy 

 than the smooth bore with spherical projectiles. 



