Aerial navigation never presented any other problem than that of procuring power without weight. Once able to obtain the power of a ten-horse engine, with a weight, including machinery, of less than one ton, one might fly all over the world, and, by taking advantage of the air currents, a knowledge of which will soon be gained, fly at a speed of fifty or even one hundred miles an hour. The recent discovery of the immense power of a gas which it is possible to generate from benzine without the use of fuel, has made the air as available for the purposes of rapid transit by man as the ocean or the land. The great cost of locomotion by this means will doubtless prevent its use for the transportation of freight, or, indeed, of passengers, except for those who can afford the luxury, and for them it will supplant all other methods. The _Petrel_ was provided with the new patent condensed fuel, one pound of which for cooking and heating purposes is equal to ten pounds of coal. She was furnished with parachutes made of thin sheets of aluminum closely folded one above the other. These, when not in use, formed an awning or canopy over her deck, while, in case of accident, they could, by pulling a convenient lever, be instantly spread over an area large enough to insure her a gradual and safe descent, and should such descent be into the water, she was so constructed as to float as buoyantly as a cork upon its surface, while, by lessening the number of revolutions per minute of her aluminum propellers, they could be used as paddles for her propulsion through the water. The freight of the _Petrel_ consisted of two hundred shells of potentite, weighing one hundred pounds each, and the result to the Coronodo Islands of their falling upon it from a height of a mile or more, was predicted long in advance of the experiment. “If,” it was said, “fifty pounds of this explosive will destroy an ironclad, what will twenty thousand pounds of it do to an island of rock? What would a dozen _Petrels_ accomplish, hurling two hundred and forty thousand pounds of it upon an army, a city, or an enemy’s fortress?” They could level Gibraltar with the sea; they could extirpate an army of a million men; they could obliterate London or Berlin or New York from the face of the earth. A fleet of a hundred _Petrels_ could ascend from New York, cross the Atlantic in three days, destroy every city in the United Kingdom in six hours, and, leaving England a mass of ruins, with two-thirds of her people slain, return in three days to New York, with unused power enough to go to San Francisco and back without descending. England, or any other nation, could likewise destroy America, for neither aerial navigation nor the manufacture of potentite are secrets locked in any one man’s brain.