, dear," she murmured, as though still half-dreaming.
"It is very glorious and wonderful; but what is it all--I mean, what is
the explanation of it?"

"The merely scientific explanation, dear, is very simple. I see it all
now. The force that was dragging us out of our course was the united
pull of two dead stars approaching each other in the same orbit. They
may have been doing that for millions of years. The shock of their
meeting has transformed their motion into light and heat. They have
united to form a single sun and a nebula, which will some day condense
into a system of planets like ours. To-night the astronomers on Earth
will discover a new star--a variable star as they'll call it--for it
will grow dimmer as it moves away from our system. It has often happened
before."

Then they turned back to the conning-tower.

The needle had swung to its old position. The new star, henceforth to be
known in the annals of astronomy as Lilla-Zaidie, had already set for
them to the right of the _Astronef_ and risen on the left, and, at a
distance of more than nine hundred million miles from the Earth, the
corner was turned, and the homeward voyage began.

CHAPTER XX

A week later they crossed the path of Jupiter, but the giant was
invisible, far away on the other side of the Sun. Redgrave laid his
course so as to avail himself to the utmost of the "pull" of the planets
without going near enough to them to be compelled to exert too much of
the priceless R. Force, which the indicators showed to be running
perilously low.

Between the orbits of Jupiter and Mars they made a most valuable economy
by landing on Ceres, one of the largest of the asteroids, and travelling
about fifty million miles on her towards the orbit of the Earth without
any expenditure of force whatever. They found that the tiny world
possessed a breathable atmosphere and a fluid resembling water, but
nearly as dense as mercury. A couple of flasks of it form the greatest
treasures of the British Museum and the National Museum at Washington.
The vegetable world was represented by coarse grass, lichens, and dwarf
shrubs, and the animal by different species of worms, lizards, flies,
and small burrowing animals of the rodent type.

As the orbit of Ceres, like that of the other asteroids, is considerably
inclined to that of the Earth, the _Astronef_ rose from its surface when
the plane of the Earth's revolution was reached, and the glittering
swarm of