Next morning Bob, in Yamaguchi’s company, made a round of the fighting admiral’s flagship. The youngest of four sister vessels, the _Mikasa_, launched at Barrow only four years previously, had a displacement of some 15,000 tons, a tremendous armament, and armour-casing varying from four inches to more than a foot in thickness. Forward and aft were two pairs of 12-inch breech-loading guns, mounted in barbettes encased in fourteen inches of armour. On the main-deck were ten 6-inch quick-firers, mounted on the "box-battery" system in an armoured citadel, the latest device of the naval architect to afford protection at once to the ship and to the crews fighting the guns. Bob already had some knowledge of armour-clad vessels, having more than once been sent by his firm to install range-finders in British ships, but never before had he enjoyed the opportunity of examining a vessel of the _Mikasa_ type, now being adopted in the British navy. For an hour or two he was busy on the navigating-officer’s bridge, examining the complicated apparatus of the range-finder. The difficulty of regulating this ingenious piece of mechanism is due to the unequal expansion of the metals of which it is made. Obviously it was impossible to test its accuracy until a shot could actually be fired at a given range, but Bob saw that all its adjustments were satisfactory, and had an interesting discussion with the navigating officer, whose duty it would be, when the vessel went into action, to call the ranges for the gunners below.