Ten thousand years ago the sun had grown too cool to supply heat enough for man; it was no longer possible to live on the frozen planets, and the two greatest of them had been hurled across the system to feed the dying fires. Jupiter and Saturn had been sacrificed. Neptune and Uranus had long since escaped from the weakened clutches of the vanishing sun, and now of the family of original wheeling planets, only four were left: Mars, Earth, Venus and Mercury. And now again the fires of the system were dying too low. One and a half million tons of matter must be destroyed every second in that titanic furnace to supply a comfortable amount of heat. In our day three million tons of matter vanish every second, to be poured out as a mighty flood of heat and light that sweeps across the depths of space to us. The inner planets had been drawn far closer to the parent body, but even these heroic measures were failing. Hal Jus worked at the controls of the electroscope for a moment and on one of the lambently glowing screens an image began to form, grayish at first, then quickly taking form and color. A great sphere swam on the screen; slowly as Hal Jus increased the power the body seemed to come nearer--it grew larger; it filled the screen, then rapidly there came a picture of low, age-old hills, worn low till they scarcely lifted their heads above the surrounding country. A mighty city of glistening metal buildings rising tier on tier a few miles north seemed to dwarf the hills into utter insignificance. Once a hill had lifted its proud head far into the blue of a two-hundred mile thick belt of atmosphere, but now the once mighty Mt. Everest alone remained as a relic of the high-flung mountains that old Earth had once known. High in the jet black sky, a scant hundred miles from the ground below, a mighty space-freighter was taking off for Venus. The thin belt of atmosphere permitted it to reach a high speed quickly. Already it was in full stride and heading at 1,000 miles a second for Venus. The scene on the screen blurred, grew gray, and faded out. Hal Jus was shifting the great electroscope tube. Again the screen glowed, and again an image appeared. It cleared quickly, then suddenly leaped into full life and color. The scene showed mighty machines working in a great pit of freshly tumbled soil. It was a land of intense shadow and where the dim red light of the distant sun did not touch, there was intense, utter blackness. There was no atmosphere here. And now, as a great freighter swung low, a machine on the ground below turned on a ray that stabbed out sharp and brilliant; a moment later the freighter tug lifted a half-million-ton piece of the planet on its attractor beams and rapidly gained headway as it shot off toward distant Venus.