In other respects these three ships show the lines along which progress was being made. In the turrets of the _Devastation_ the twin 35-ton guns had been loaded and worked by hand; but in the forward turret of the _Thunderer_ the new hydraulic system of Messrs. Armstrong was applied with success to two 38-ton 12-inch guns; and this system was adopted for both turrets of the _Dreadnought_. The guns were loaded externally, the turrets being revolved by steam, after firing, till the guns were on the requisite bearing; they were then depressed by hydraulic power, and the 700-pound projectiles were rammed into their muzzles by a telescopic hydraulic rammer. In 1879 an accident occurred in the _Thunderer_ which helped, it is said, to hasten the return to breech-loading guns. Simultaneous firing was being carried out; one of the guns missed fire without anyone either inside or outside the turret being aware of it. The guns were loaded again, and, on being discharged, one of them burst. Such double-loading, it was clearly seen, would not have obtained with breech-loading guns. The _Devastation_ had twin screws driven by independent engines, but these were non-compound engines of the trunk type working with a maximum steam pressure of 30 lbs. per square inch. In the _Dreadnought_ an advance had been made to compound the three-cylinder vertical engines, working with 60 lbs. per square inch in engine-rooms divided by a longitudinal watertight bulkhead. § The evolution of the battleship was being forced along at a hot pace by the evolution of artillery. No sooner had the mastless turret ship received the sanction of the Committee on Designs as the standard type for warfare of the immediate future, than a sudden increase in the power of guns necessitated the consideration of new principles and brought into being a new type. So far, defence had managed to compete fairly successfully with offence; the naval architect, by devoting as much as 25 per cent of the total of a ship’s weight to protective armour, had been able to keep level with the artillerist. But it was clear that he could not follow much further, by the existing methods. Armour could not be thickened indefinitely. Penetrable armour was no better than none; worse, in fact, since it was a superfluity, and in a ship a superfluity was doubly wasteful, implying a loss of strength in some other direction. Armour might have to go altogether? It seemed that, after all, the predictions of Sir Howard Douglas might well come true; that, just as gunpowder had forced the foot soldier, after burdening him with an ever-increasing weight, to dispense altogether with body-armour, so rifled artillery would render ship armour increasingly ineffectual and, eventually, an altogether useless encumbrance.