"'Mornin', sir!" he gasped, drawing himself up and touching the peak of his hat. "Fine weather, sir." "For monkey tricks, yes," laughed the Commander. "Well, lad, how do you like the vessel? Seen the aeroplane? Eh? Like a trip aboard her? I'm the coxswain." "Rather, sir," gasped Dick. "This is the finest thing I've had to do since I joined the Navy." "Indeed! You've been an officer a long while I take it," smiled his senior. "Quite one of the older ones, Dick, eh? Come; I'll stop quizzing. Let's get along to the engines; Joe Gresson has gone there. There's no keeping him away from them. Come; you'll see the height of simplicity combined with the uttermost efficiency that has yet been attained." Dick did indeed inspect a machine which, with its components, gave extraordinary power to the ship. To put the description with the utmost plainness, he found when he descended to the engine-room three sets of engines, of moderate size, and of the internal-combustion variety. There was nothing remarkable, perhaps, about the engines themselves, except that they were a modification of the Diesel. "You see, a Diesel uses extremely high compression," Joe Gresson explained, leaning one hand affectionately on an engine which happened not to be working. "That can be managed easily ashore, and in the air also. But compressors are required in addition to the engine, for the explosive charge, consisting of the crudest oil, must be injected into the cylinders by pneumatic power at a critical moment, and that power must be at higher pressure than the contents of the cylinder. To me the most important question was the one of fuel. I barred petrol." "Why?" Dick ventured to ask. "It's used on other airships." "And other ships suffer from explosions and from fire. Petrol is too inflammable, particularly upon a ship which is lifted by a huge volume of gas. So I chose crude paraffin oil, the sort of oil that you can obtain in any part of Europe, almost in any part of the world. To discover a carburettor which would vaporize this crude oil was difficult. But a friend came to my help, and here you see the result. Our engines run steadily and strongly."