one of the electric lights and looked at it. The
sketch was a plan of the Jovian System. There were some signs written
along one side, which he did not understand, but he divined that they
were calculations. Still, there was no mistaking the diagram. There was
a circle representing the huge bulk of Jupiter; there were four smaller
circles at varying distances in a nearly straight line from it, and
between the nearest of these and the planet was the figure of the
_Astronef_, with an arrow pointing upwards.

"Ah, I see!" he said, forgetting for a moment that the other did not
understand him, "that was the miracle! The four satellites came into
line with us just as the pull of Jupiter was getting too much for our
engines, and their combined pull just turned the scale. Well, thank God
for that, sir, for in a few minutes more we should have been cinders!"

The astronomer smiled again as he took the paper back. Meanwhile the
_Astronef_ was rushing upward like a meteor through the clouds. In ten
minutes the limits of the Jovian atmosphere were passed. Stars and suns
and planets blazed out of the black vault of Space, and the great disc
of the World that Is to Be once more covered the floor of Space beneath
them--an ocean of cloud, covering continents of lava and seas of flame,
the scene of the natal throes of a world which some day will be.

They passed Io and Europa, which changed from new to full moons as they
sped by towards the Sun, and then the golden yellow crescent of Ganymede
also began to fill out to the half and full disc, and by the tenth hour
of Earth-time, after they had risen from its surface, the _Astronef_ was
once more lying beside the gate of the Crystal City.

At midnight on the second night after their return, the ringed shape of
Saturn, attended by his eight satellites, hung in the zenith
magnificently inviting. The _Astronef's_ engines had been replenished
after the exhaustion of their struggle with the might of Jupiter. They
said farewell to their friends of the dying world. The doors of the
air-chamber closed. The signal tinkled in the engine-room, and a few
moments later a blurr of white lights on the brown background of the
surrounding desert was all they could see of the Crystal City under
whose domes they had seen and learnt so much.

CHAPTER XVII

The relative position of the two giants of the Solar System at the
moment when the _Astronef_ left the surface of Ganymede, was such that
s