The space visitors

by Edmond Hamilton

"We can construct those globes of the strongest and lightest material known—steelite. As you all know, steelite is the recently devised metal that has immensely greater strength than steel but the merest fraction of its weight. The tensile strength of a substance, its hardness and other qualities, depend directly upon the arrangement of its molecules. By the recent discoveries of Browning we know that when steelite is synthetically made the arrangement of the molecules is such that it forms an extremely strong and rigid substance. This gives the material unheard-of strength with unheard-of lightness.

"A forty-foot globe of steelite can be made, with a charge of explosives of terrific power attached to it that will detonate when the globe is touched. This done, all air is exhausted from the hollow globe by great pumps, until the vacuum inside it is almost complete. The enormous strength of the steelite shell prevents its being crushed by the atmosphere's pressure as an ordinary steel shell would be.

"Released, the vacuum globe with its deadly charge will shoot up through the atmosphere with terrific speed. Its lightness for its size will be such that it will not halt until it floats on the very surface of our atmosphere. We will make these globes in countless thousands, each with its charge, and release them. Each globe will have a device that will repel any other, so that they do not detonate each other. We will sow the surface of our atmosphere with these deadly air-mines! Sooner or later the ship or ships cruising to and fro on our atmosphere's surface will strike one and will be destroyed by its detonating charge. In this way, and only in this way, can we fight back against the beings from space who are releasing this horror on us!"

"But to make these globes or mines in such numbers will engross all the earth's industrial activities!" the British ambassador exclaimed.

"It will," Dr. Howard agreed quietly. "But what of it? Have you not yet realized that a world crisis is upon us? Have you not yet realized that in this case there is no question of countries or races, of profits or dividends, or expediencies, but that we, as men, are fighting for the existence of man? That we are fighting against beings who may be immeasurably more advanced in knowledge and power than ourselves?"

"Dr. Howard is right," said the President. "Gentlemen, this emergency must be clear to you all, and I think that it is equally clear that Dr. Howard's plan is the only one that affords any possibility of combatting this terror from above. I place all the resources of the United States of America at your command, Dr. Howard, and I know that when the representatives of the other nations here have reported to their governments they will do the same. The whole world's efforts must concentrate upon the prevention of these terrible disorders."

"There is but one thing earth's peoples can do," Dr. Howard said. "Make air-mines! Thousands, tens of thousands—they must be turned out in ceaseless floods and released. For it is only with them that we can repel the menace above us."

Make air-mines! It was the watchword of all earth's races within a few hours of that momentous meeting. For the President and the heads of the earth's other governments sent statements in which Dr. Howard's suggested method of combatting the danger was stressed as the world's one chance. Thousands of air-mines must be made at once and continue to be turned out until the menace was repelled—scientists agreed, as one man, that it was the one possible way of fighting these grim visitors from space who were hovering in their enigmatic vessels at the surface of our atmosphere.

Within a half day after the meeting Dr. Howard and I, aided by several masters of aeronautical, chemical, and physical sciences had drawn up the plans of the air-mines. Each was to be a hollow steelite globe forty-two feet in outside diameter. This would give the globes a gross lifting power of about five thousand pounds and net of about twenty-five hundred. Attached in a special chamber at the side of each was the charge, a load of the most modern explosives, small in bulk but terrific in power, while striking-pins on the globe's sides made it inevitable that the charge be exploded whenever the globe was struck.

Through the night of the 6th, hundreds of men were busy in Washington turning out copies of the simple plans of the air-mine, and scores of planes were flying throughout the world with copies for all nations. On the 7th the manufacture of the great engines had already been begun in a hundred cities.