rial Aurora was playing about it,
illuminating the thin, yellow clouds with a bluish-violet light, which
made magnificent contrasts of colouring amongst them.

"Let us go down there and see what it's like," said Zaidie. "There must
be something nice under all those lovely colours."

Redgrave checked the R. Force and the _Astronef_ fell obliquely across
the pole towards the equator. As they approached the luminous clouds
Redgrave turned it on again, and they sank slowly through a glowing mist
of innumerable colours, until the surface of Ganymede came into plain
view about ten miles below them.

What they saw then was the strangest sight they had beheld since they
had left the Earth. As far as their eyes could reach the surface of the
Ganymede was covered with vast orderly patches, mostly rectangular, of
what they at first took for ice, but which they soon found to be a
something that was self-illuminating.

"Glorified hot-houses, as I'm alive," exclaimed Redgrave. "Whole cities
under glass, fields, too, and lit by electricity or something very like
it. Zaidie, we shall find human beings down there."

"Well, if we do I hope they won't be like the half-human things we found
on Mars! But isn't it all just lovely! Only there doesn't seem to be
anything outside the cities, at least nothing but bare, flat ground with
a few rugged mountains here and there. See, there's a nice level plain
there near the big glass city, or whatever it is. Suppose we go down
there."

Redgrave checked the after engine which was driving them obliquely over
the surface of the satellite, and the _Astronef_ fell vertically towards
a bare, flat plain of what looked like deep yellow sand, which spread
for miles alongside one of the glittering cities of glass.

"Oh, look, they've seen us!" exclaimed Zaidie. "I do hope they're going
to be as friendly as those dear people on Venus were."

"I hope so," replied Redgrave, "but if they're not we've got the guns
ready."

As he said this about twenty streams of an intense bluish light suddenly
shot up all round them, concentrating themselves upon the hull of the
_Astronef_, which was now about a mile and a half from the surface. The
light was so intense that the rays of the Sun were lost in it. They
looked at each other, and found that their faces looked almost perfectly
white in it. The plain and the city below had vanished.

To look downwards was like staring straight into the focus of a ten
thousan