Then he stepped out to the smooth stone slab on which the nearest of the guards was standing. Immediately it was as if a tremendous weight was flung upon him, bearing him down until his knees buckled beneath him. He was rooted to the spot by an enormous force which dragged at his vitals and weighted his limbs to leaden uselessness. With a mighty effort he raised his head to look up into the grinning yellow face of the guard, and his thick neck muscles were taut gnarled ridges under the strain.
"Damn your hide!" he howled. "It's a trick. I'll break you in two for this, you slob!"
His huge biceps tensed and his fists came up. But they came up slowly and ineffectually, ponderous things he could scarcely lift. A great roaring of rocket tubes was in his ears then, and the ethership screamed off through the red mists while he dabbed futilely at the leering yellow face. And vile curses rasped from between his set teeth at the laughter of the guards.
Luke Fenton never had taken the trouble to learn or he would have known something about this planet Vulcan on which he was a prisoner. As far back as 1859, by Earth chronology, its existence within the orbit of Mercury had been reported by one Lescarbault, a French physician. But other astronomers had failed to confirm, in fact had ridiculed his discovery, and it was not until some years after the establishing of interplanetary travel in the first decade of the twenty-first century that the body was definitely located.
Vulcan, the smallest and innermost of the planets, circles the sun with great rapidity at a mean distance of twenty million miles. Its periods of rotation and revolution are equal, so that it always presents the same face toward the solar system's great center of heat and light—for which reason one side is terrifically hot and the other, that facing into outer space, unbearably cold.
There is no life native to the body, and mankind has found it possible to exist only in the narrow belt immediately on the dark side of the terminator, the line of demarcation between night and day. Here there are the dense vapors, illuminated perpetually by refracted light from the daylight side and by the internal fires of the planet itself, fires which erupt at regular intervals through many fissures and craters. And it is only under greatest hardship that man can exist even here, what with the noxious gases and the extremes of heat and cold to which his body it subjected. There is no natural source of water or of food, so these essentials must of necessity be conveyed from Mars or Earth by ethership.
In spite of all this, man has persisted in establishing himself in the vapor belt of Vulcan for the sake of wresting from the rocky soil its vast deposits of rare ores, and a great number of mining operations are continually in progress. All of these are commercial projects and are worked by adventurous seekers of fortune, save only the penal colony known as Vulcan's Workshop: But no Terrestrial or Martian, however greedy for riches, would dare to remain longer than two lunar months, which is the average time limit of human endurance. Only the condemned remain, and these remain to die.
Though hardly more than two hundred miles in diameter, Vulcan is possessed of a surface gravity almost six times greater than that on Earth. This is due to the planet's core of neutronium, the densest known substance of the universe, a little understood concentration of matter whose atoms comprise only nuclei from which all negative electrons have been stripped by some stupendous cataclysm of nature.