The _Hercules_, begun in June 1866, and launched in February 1869, was one of the best specimens of the entirely iron-built, iron-armoured frigates the Navy possessed at that time. Her ram bow did not protrude so far as in former vessels and only weighed about five tons. The armour plating on the sides of the ship weighed 1145 tons. The total weight of metal worked into the ship was 4252 tons. The bulwarks were of wood, but below them the first two strakes were of plates 6 inches thick; next was a strake of 8-inch armour covering the lower portion of the main deck or central box battery; then two strakes of 6-inch armour, then a belt of 9-inch armour along the water-line, then a strake of 6-inch plates resting above the double skin of the hull itself. The 9-inch plates were backed by 10 inches of teak, inside of which was an iron skin 1¹⁄₂ in. thick, supported by vertical frames 10 inches deep and 2 feet apart, while further stiffening structures were also included. The engines worked up to over 7000 indicated horse-power. The vessel also afforded an illustration of the tendency to reduce the number of guns and increase their weight. To add to her steering capacities she had a balanced rudder which was itself jointed and hinged upon the line of pivot. [Illustration: H.M.S. “DREADNOUGHT.”] The carrying of such quantities of armour was against the maintenance of high speed at sea, and accordingly the unarmoured iron frigate _Inconstant_ was launched later in the same year. She carried sixteen guns and was faster than any other warship afloat. The Prussian ironclad _Koenig Wilhelm_, built by the Thames Iron Works and Shipbuilding Company, from designs by Mr. E. J. Reid, in 1869, was commenced for the Turkish Government, and was built on the longitudinal system, having a series of wrought-iron girders or frames extending from end to end of the ship. There was an inner skin on the inner sides of the frames and ribs, as though one ship was inside another. She was then the heaviest vessel ever docked in the Thames, as she weighed 8500 tons. Her armour was 8 inches thick amidships and tapered slightly towards the ends.