thus restrained, the irrigating canals are kept full long enough
to mature the harvests."

"The clew! The clew at last!" exclaimed Mr. Edison. "That is the place
where we shall nip them. If we can close those gates now at the moment
of high tide we shall flood the country. Did you say," he continued,
turning to Aina, "that the movement of the gates was all controlled from
a single point?"

The Great Power House.

"Yes," said the girl. "There is a great building (power house) full of
tremendous machinery which I once entered when my father was taken there
by his master, and where I saw one Martian, by turning a little handle,
cause the great line of gates, stretching a hundred miles across the sea,
to slowly shut in, edge to edge, until the flow of the water toward the
north had been stopped."

"How is the building protected?"

"So completely," replied Aina, "that my only fear is that you may not be
able to reach it. On account of the danger from their enemies on Ceres,
the Martians have fortified it strongly on all sides, and have even
surrounded it and covered it overhead with a great electrical network,
to touch which would be instant death."

"Ah," said Mr. Edison, "they have got an electric shield, have they? Well,
I think we shall be able to manage that."

"Anyhow," he continued, "we have got to get into that power house, and we
have got to close those gates, and we must not lose much time in making
up our minds how it is to be done. Evidently this is our only chance. We
have not force enough to contend in open battle with the Martians, but
if we can flood them out, and thereby render the engines contained in
their fortifications useless, perhaps we shall be able to deal with the
airships, which will be all the means of defence that will then remain
to them."

This idea commended itself to all the leaders of the expedition. It was
determined to make a reconnaissance at once.

But it would not do for us to approach the planet too hastily, and we
certainly could not think of landing upon it in broad daylight. Still,
as long as we were yet at a considerable distance from Mars, we felt that
we should be safe from observation, because so much time had elapsed
while we were hidden behind Deimos that the Martians had undoubtedly
concluded that we were no longer in existence.

So we boldly quitted the little satellite with our entire squadron and
once more rapidly approached the red planet of war. This time i