Page:EB1911 - Volume 20.djvu/263

NAVAL GUNS] astern to 30° before either beam in the case of the after turret. The secondary armament, consisting of twelve 6-in. guns, was also symmetrically disposed. Two guns on either side (four in the “Majestic” class) were mounted with arcs of fire of from 60° before to 60° abaft the beam, while two guns each side forward and two aft (one forward and one aft in the “Majestic” class) fired through similar arcs to the turret guns, but on their own sides only. Four of these 6-in. guns were mounted on either side of the main deck and two on either side of the upper deck, all being enclosed in casemates. EB1911 - Ordnance Fig 89.png

EB1911 - Ordnance Fig 90.png

In the armoured and large protected cruisers built contemporaneously with these classes of battleships, the 9·2-in. gun had been largely mounted, and it was the improvements brought about by practical experience in the rate and accuracy of fire of this gun that suggested its adoption in battleships to replace the whole or a part of the 6-in. armament. During the period in which the battleships referred to above were constructed, the idea of the functions of the respective divisions of the armament was that the 12-in. guns were to injure the enemy’s vitals by piercing his armour with armour-piercing shot or shell, while the business of the 6-in. guns was to cover him with a hail of shells of large

capacity which were to kill and demoralize his personnel, pierce his funnels, destroy any navigational or sighting appliances which were exposed, set his woodwork on fire and render extinction of the fires impossible, and by piercing or bursting on unarmoured portions of his side diminish his reserve of buoyancy and so impair his sea-going qualities.

These ideas were gradually losing favour; it was realized that the damage done by an armour-piercing shot, whether or not it hit and pierced armour, was limited to its own path, while that done by an armour-piercing shell striking an unarmoured portion of the ship’s side was inconsiderable as compared with that effected by a common shell of the same calibre. Further, the area of side, by piercing which an armour-piercing projectile would reach any portion of the propelling machinery or magazines of an enemy, was so small compared with the whole exposed area of his side and upper works that it was scarcely advantageous to fire at it projectiles, the effectiveness of which, if they struck another portion of the enemy, was small in comparison with that of other projectiles which might equally well be fired from the same gun. Again, the lessons of practical experience showed that ships might be and were defeated by shell fire alone, while their armour remained unpierced, and propelling machinery and magazines intact.

All these considerations led to the conclusion that it was to intensity of shell-fire, and especially to the fire of large capacity and high explosive shell, that attention should be directed. At the same time, while the rate of fire of the 6-in. guns, to which great attention had been paid, remained stationary or nearly so, the rate of fire of the 9·2 in. and 12-in. guns had considerably improved, and their ballistic powers rendered possible more accurate firing at long ranges than could be effected with the 6-in. guns. The explosive effect of a shell is said to vary as the square of the weight of its bursting charge. The bursting charge, with shell of the same type, bears a constant proportion to the weight of the shell. Now the weight of the 12-in. shell is 850 ℔, that of the 9·2-in. 380 ℔, that of the 6-in. 100 ℔. Hence it would require fourteen 6-in. shells to produce the same effect as one 9·2-in., and seventy-two to produce the same effect as one 12-in. shell, consequently the 6-in. gun to produce the same shell effect as the 12-in. or 9·2-in. gun must fire 72 times, or 14 times, respectively, faster. The rate of fire of guns in action depends upon a variety of conditions, an important one being that of smoke interference, which tends to reduce the maximum rate of fire of the smaller guns nearer to that practicable with the heavier guns, but the rate of fire of the three guns in question,