Another novelty of the type was the introduction of a special armoured glacis around the engine hatches. This system had, of course, been used before in the Italian monster ships _Italia_ and _Lepanto_, but it was first introduced in the British Navy in the _Blakes_.[13] The ships were very successful steamers, for all that neither made her expected twenty-two knots on trial. Trial results:-- _Blake_: Eight hours’ natural draught, mean I.H.P.--14,525 = 19.4 knots. _Blenheim_: Eight hours’ natural draught, mean I.H.P.--14,925 = 20.4 knots. _Blake_: Four hours’ force draught, mean I.H.P.--19,579 = 21.5 knots. _Blenheim_: Four hours’ forced draught, mean I.H.P.--21,411 = 21.8 knots. The principal item of the Naval Defence Act was eight first-class and two second-class battleships. All these ships were designed by Sir William White, and may be described as battleship editions of the _Blake_ and _Blenheim_, so far as the disposition of their armament was concerned. For the rest they may be described as attempts to combine in one ship the best features of the Read and Barnaby ideals. In place of the low freeboard of the _Admiral_ class, seven of the _Royal Sovereigns_ were given high freeboard fore and aft, with the big guns about twenty-three feet above water. The eighth ship, the _Hood_, was modified to suit the ideals of Admiral Hood, and was to some extent an improved _Trafalgar_, her big guns being in turrets some seventeen feet above the water, in turrets instead of _en barbette_, with guns exposed as in the rest of the class. In them, among other special features, 18-inch torpedo tubes were first introduced instead of 14-inch, and a stern torpedo tube appeared. The original idea of end-on torpedo tubes was torpedo attack from the bow in place of the ram. The _Polyphemus_ was the first ship in which an end-on tube appeared (submerged). In cruisers of a later date the bow tube was found to injure speed, and there was always the danger of a ship over-running her own torpedo. On this account the bow-tube never secured in the British Navy that vogue which it obtained, and still has, in Germany. The stern-tube appears to owe its origin to an idea that a defeated or overpowered ship, running from an enemy, might save herself by it: dim ideas of “runaway tactics” had also begun to appear.