The driving power was derived from a combination of petrol and pulverised smokeless coal, treated with liquid oxygen, which made combustion practically perfect. There was no boilers or furnaces, only combustion chambers, and this fact made the carrying of the great weight of armour under the waterline possible. The speed of the _Ithuriel_ was forty-five knots ahead when all four screws were driving and pulling, and thirty knots astern when they were reversed. Her total capacity was five thousand two hundred tons. Behind the three forward guns was a dome-shaped conning-tower of nine-inch steel, hardened like the rest of the armour by an improvement on the Harvey process. Above the conning-tower were two searchlight projectors, both capable of throwing a clear ray to a distance of four miles and controlled from within the conning-tower. "Well, I am afraid I have kept you waiting, Mr Lennard," said Erskine, as the platform brought him up again into the conning-tower, in much shorter time than was necessary to make this needful description of what was probably the most formidable craft in the British Navy. "We're off now. I've fitted up half a dozen shells with that diabolical invention of yours. If we run across a battleship or a cruiser, we'll try them. I think our friends the enemy will find them somewhat of a paralyser, and there's nothing like beginning pretty strong." "Nothing like hitting them hard at first, and I hope that those things of mine will be what I think they are, and unless all my theories are quite wrong, I fancy you'll find them all right." "They would be the first theories of yours that have gone wrong, Mr Lennard," replied Erskine, "but anyhow, we shall soon see. I have put three of your shells in the forward guns. We'll try them there first, and if they're all right we'll use the other three. I've got the after guns loaded with my own shell, so if we come across anything big, we shall be able to try them against each other. At present, my instructions are to deal with the lighter craft only: destroyers and that sort of thing, you know." "But don't you fire on them?" said Lennard. "What would happen if they got a torpedo under you?" "Well," said Erskine, "as a matter of fact I don't think destroyers are worth shooting at. Our guns are meant for bigger game. But it's no good trying to explain things now. You'll see, pretty soon, and you'll learn more in half an hour than I could tell you in four hours." They were clear of the harbour by this time and running out at about ten knots between the two old North and South Spithead forts on the top of each of which one of the new fourteen-inch thousand-pounders had been mounted on disappearing carriages. "Now," he continued, "if we're going to find them anywhere, we shall find them here, or hereabouts. My orders are to smash everything that I can get at." "Fairly comprehensive," said Lennard.