"It's as safe as going to heaven in a rocking-chair," promptly answered the captain, like an oracle. "The fact is," he proceeded in a lower tone, "I have had the thing well tested. In the first place, I had it filled with air and coal gas, for the purpose of arranging the rigging, and then I took a little trip with it myself with proper hydrogen, and the petroleum motor hard at work, and it sailed aloft like a bird. In form, of course, it is similar to the balloon, `La France,' experimented with as long ago as 1834 by some French officers at Meudon--that is, it is shaped like a plaice--the front end being larger than the rear; while it is provided with a compensating ballonet, which is inflated with air by means of a fan controlled from the motor. The two cars, to hold three passengers each, like the motor, are supported by a pine framework, and are suspended at a distance of fifteen feet under the balloon. The propeller is an exceptionally large and strong one, and resembles a fish's tail, a mackerel's, for I contend we find all our true air affinities in the sea. It turns at the rate of two hundred and fifty revolutions a minute, and the whole apparatus is strong enough to let us take a fair amount of ballast; for the secret of my success in my invention does not turn on lightness, where so many flying-machine inventors have gone wrong of late, but on weight--weight to subdue the pressure of the wind, to conquer the dead force of the air, and to answer the power of the motor to get up anything approaching a decent speed." The enthusiast stopped. Some detail in the rigging as the great aerial monster rose higher and higher suddenly required his attention; and for the next few minutes none of us spoke at all, as the captain moved hither and thither, directing his subordinates, and getting everything into working order. Curiously enough, all his feverishness left him like magic directly there was any serious work to do. For that time he might have been quite alone in his workshop. He moved and spoke and acted as one who had perfect confidence in himself and in the issue of the daring experiment which he was about to undertake. CHAPTER SIXTEEN. ABOVE THE CLOUDS. At last everything seemed in readiness.