A million pounds of fatigue crashed down without warning on the back of Helmuth's neck, and he fell back into the reading chair with a gasp. The root of his beard ached, and Jupiters bloomed and wavered away before his closed eyes.

He struggled once, and fell asleep.

Instantly he was in the grip of the dream.

It started, as always, with commonplaces, almost realistic enough to be a documentary filmstrip--except for the appalling sense of pressure, and the distorted emotional significance with which the least word, the smallest movement was invested.

It was the sinking of the first caisson of the Bridge. The actual event had been bad enough. The job demanded enough exactness of placement to require that manned ships enter Jupiter's atmosphere itself; a squadron of twenty of the most powerful ships ever built, with the five million ton asteroid, trimmed and shaped in space, slung beneath them in an immense cat's cradle.

Four times that squadron had disappeared beneath the racing clouds; four times the tense voices of pilots and engineers had muttered in Helmuth's ears, and he had whispered back, trying to guide' them by what he could see of the conflicting tradeblasts from Jupiter V; four times there were shouts and futile orders and the snapping of cables and men screaming endlessly against the eternal howl of the Jovian sky.

It had cost, altogether, nine ships, and two hundred thirty-one men, to get one of five laboriously shaped asteroids planted in the shifting slush that was Jupiter's surface. Until that had been accomplished, the Bridge could never have been more than a dream. While the Great Red Spot had shown astronomers that some structures on Jupiter could last for long periods of time long enough, at least, to be seen by many generations of human beings it had been equally well known that nothing on Jupiter could be really permanent The planet did not even have a "surface" in the usual sense; instead, the bottom of the atmosphere 'merged more or less smoothly into a high-pressure sludge, which in turn thickened as it went deeper into solid pressure ice. At no point on the way down was there any interface between one layer and another, except in the rare areas where a part of the deeper, more "solid" medium had been thrust far up out of its normal level to form a continent which might last as long as two years or two hundred. It was on to one of these great ribs of bulging ice that the ships had tried to plant their asteroid and, after four tries, had succeeded.