"That's about what it comes to, I suppose, but you must not think it was altogether vanity. You see the German Government has bought Count Zeppelin's air-ship or steerable balloon, as it ought to be called, always supposing that they can steer it in a wind, and of course their idea is to make a fighting machine of it. Now Germany is engaged to stand by us in this trouble that's coming, and by way of cementing the alliance I thought it was just as well to let the wily Teuton know that there's something flying the British flag which could make very small mincemeat of their gas-bags." "And what about Old Glory?" said Miss Zaidie. "The _Astronef_ was built with English money and English skill, but----" "She is the creature of American genius. Of course she is. In fact she is the first concrete symbol of the Anglo-American Alliance, and when the daughter of her creator has gone into partnership with the man who made her we'll have two flagstaff's, and the Jack and Old Glory will float side by side." "And meanwhile where are we going?" asked Zaidie, after a moment's interval. "Ah, there we are through the clouds again. What makes us rise? Is that the force that Pop told me he discovered?" "I'll answer the last question first," said Redgrave. "That was the greatest of your father's discoveries. He got at the secret of gravitation, and was able to analyse it into two separate forces just as Volta did with electricity--positive and negative, or, to put it better, attractive and repulsive. "Three out of the five sets of engines in the _Astronef_ develop the R. Force, as I call it for short. This wheel with the hundred degrees marked behind it regulates the development. The further I turn it this way to the right, the more the R. Force overcomes the attractive force of the earth or any other planet that we may visit. Turn it back, and gravitation asserts itself. If I put this arrow-head on the wheel opposite zero the weight of the _Astronef_ is about a hundred and fifty tons, and of course she would go down like a stone, and a very big one at that. At ten she weighs nothing; that is to say the R. Force exactly counteracts gravitation. At eleven she begins to rise. At a hundred she would be hurled away from the earth like a shell from a twelve-inch gun, or even faster. Now, watch." He took up the speaking-tube. "Is she all tight everywhere, Andrew?" "Yes, my Lord," came gurgling through the tube.