"The clue! The clue 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?"

"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," said 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 defense 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 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 existance.

So we boldly quitted the little satellite with our entire squadron and once more rapidly approached the red planet of war. This time it was to be a death grapple and our chances of victory still seemed good.

As soon as we arrived so near the planet that there was danger of our being actually seen, we took pains to keep continually in the shadow of Mars, and the more surely to conceal our presence all lights upon the ships were extinguished. The precaution of the commander even went so far as to have the smooth metallic sides of the cars blackened over so that they should not reflect light, and thus become visible to the Martians as shining specks, moving suspiciously among the stars.

The precise location of the great power house on the sh.o.r.es of the Syrtis Major having been carefully ascertained, the squadron dropped down one night into the upper limits of the Martian atmosphere, directly over the gulf.

Then a consultation was called on the flagship and a plan of campaign was quickly devised.

It was deemed wise that the attempt should be made with a single electric ship, but that the others should be kept hovering near, ready to respond on the instant to any signal for aid which might come from below. It was thought that, notwithstanding the wonderful defences, which, according to Aina's account surrounded the building, a small party would have a better chance of success than a large one.

Mr. Edison was certain that the electrical network which was described as covering the power house would not prove a serious obstruction to us, because by carefully sweeping the s.p.a.ce where we intended to pa.s.s with the disintegrators before quitting the ship, the netting could be sufficiently cleared away to give us uninterrupted pa.s.sage.

At first the intention was to have twenty men, each armed with two disintegrators (that being the largest number one person could carry to advantage) descend from the electrical ship and make the venture. But, after further discussion, this number was reduced; first to a dozen, and finally, to only four. These four consisted of Mr. Edison, Colonel Smith, Mr. Sydney Phillips and myself.

Both by her own request and because we could not help feeling that her knowledge of the locality would be indispensable to us, Aina was also included in our party, but not, of course, as a fighting member of it.

It was about an hour after midnight when the ship in which we were to make the venture parted from the remainder of the squadron and dropped cautiously down. The blaze of electric lights running away in various directions indicated the lines of innumerable ca.n.a.ls with habitations crowded along their banks, which came to a focus at a point on the continent of Aeria, westward from the Syrtis Major.

We stopped the electrical ship at an elevation of perhaps three hundred feet above the vast roof of a structure which Aina a.s.sured us was the building of which we were in search.

Here we remained for a few minutes, cautiously reconnoitering. On that side of the power house which was opposite to the sh.o.r.e of the Syrtis Major there was a thick grove of trees, lighted beneath, as was apparent from the illumination which here and there streamed up through the cover of leaves, but, nevertheless, dark and gloomy above the tree tops.

"The electric network extends over the grove as well as over the building," said Aina.

This was lucky for us, because we wished to descend among the trees, and, by destroying part of the network over the tree tops, we could reach the shelter we desired and at the same time pa.s.s within the line of electric defenses.

With increased caution, and almost holding our breath lest we should make some noise that might reach the ears of the sentinels below, we caused the car to settle gently down until we caught sight of a metallic net stretched in the air between us and the trees.

After our first encounter with the Martians on the asteroid, where, as I have related, some metal which was included in their dress resisted the action of the disintegrators, Mr. Edison had readjusted the range of vibrations covered by the instruments, and since then we had found nothing that did not yield to them. Consequently, we had no fear that the metal of the network would not be destroyed.

There was danger, however, of arousing attention by shattering holes through the tree tops. This could be avoided by first carefully ascertaining how far away the network was and then with the adjustable mirrors attached to the disintegrators focusing the vibratory discharge at that distance.

So successful were we that we opened a considerable gap in the network without doing any perceptible damage to the trees beneath.

The ship was cautiously lowered through the opening and brought to rest among the upper branches of one of the tallest trees. Colonel Smith, Mr.

Phillips, Mr. Edison and myself at once clambered out upon a strong limb.

For a moment I feared our arrival had been betrayed on account of the altogether too noisy contest that arose between Colonel Smith and Mr.

Phillips as to which of them should a.s.sist Aina. To settle the dispute I took charge of her myself.

At length we were all safely in the tree.

Then followed the still more dangerous undertaking of descending from this great height to the ground. Fortunately, the branches were very close together and they extended down within a short distance of the soil. So the actual difficulties of the descent were not very great after all. The one thing that we had particularly to bear in mind was the absolute necessity of making no noise.

At length the descent was successfully accomplished, and we all five stood together in the shadow at the foot of the great tree. The grove was so thick around that while there was an abundance of electric lights among the trees, their illumination did not fall upon us where we stood.

Peering cautiously through the vistas in various directions, we ascertained our location with respect to the wall of the building. Like all the structures which we had seen on Mars, it was composed of polished red metal.

"Where is the entrance?" inquired Mr. Edison, in a whisper.

"Come softly this way, and look out for the sentinel," replied Aina.

Gripping our disintegrators firmly, and s.c.r.e.w.i.n.g up our courage, with noiseless steps we followed the girl among the shadows of the trees.

We had one-very great advantage. The Martians had evidently placed so much confidence in the electric network which surrounded the power house that they never dreamed of enemies being able to penetrate it--at least, without giving warning of their coming.

But the hole which we had blown in this network with the disintegrators had been made noiselessly, and Mr. Edison believed, since no enemies had appeared, that our operations had not been betrayed by any automatic signal to watchers inside the building.

Consequently, we had every reason to think that we now stood within the line of defense, in which they reposed the greatest confidence, without their having the least suspicion of our presence.

Aina a.s.sured us that on the occasion of her former visit to the power house there had been but two sentinels on guard at the entrance. At the inner end of a long pa.s.sage leading to the interior, she said, there were two more. Besides these there were three or four Martian engineers watching the machinery in the interior of the building. A number of airships were supposed to be on guard around the structure, but possibly their vigilance had been relaxed, because not long ago the Martians had sent an expedition against Ceres which had been so successful that the power of that planet to make any attack upon Mars had, for the present been destroyed.

Supposing us to have been annihilated in the recent battle among the clouds, they would have no fear or cause for vigilance on our account.

The entrance to the great structure was low--at least, when measured by the stature of the Martians. Evidently the intention was that only one person at a time should find room to pa.s.s through it.

Drawing cautiously near, we discerned the outlines of two gigantic forms, standing in the darkness, one on either side of the door. Colonel Smith whispered to me:

"If you will take the fellow on the right, I will attend to the other one."

Adjusting our aim as carefully as was possible in the gloom, Colonel Smith and I simultaneously discharged our disintegrators, sweeping them rapidly up and down in the manner which had become familiar to us when endeavoring to destroy one of the gigantic Martians with a single stroke. And so successful were we that the two sentinels disappeared as if they were ghosts of the night.

Instantly we all hurried forward and entered the door. Before us extended a long, straight pa.s.sage, brightly illuminated by a number of electric candles. Its polished sides gleamed with blood-red reflections, and the gallery terminated, at a distance of two or three hundred feet, with an opening into a large chamber beyond, on the further side of which we could see part of a gigantic and complicated ma.s.s of machinery.

Making as little noise as possible, we pushed ahead along the pa.s.sage, but when we had arrived within the distance of a dozen paces from the inner end, we stopped, and Colonel Smith, getting down upon his knees, crept forward, until he had reached the inner end of the pa.s.sage. There he peered cautiously around the edge into the chamber, and, turning his head a moment later, beckoned us to come forward. We crept to his side, and, looking out into the vast apartment, could perceive no enemies.

What had become of the sentinels supposed to stand at the inner end the pa.s.sage we could not imagine. At any rate, they were not at their posts.

The chamber was an immense square room at least a hundred feet in height and 400 feet on a side, and almost filling the wall opposite to us was an intricate display of machinery, wheels, levers, rods and polished plates. This we had no doubt was one end of the engine which opened and shut the great gates that could dam an ocean.

"There is no one in sight," said Colonel Smith.

"Then we must act quickly," said Mr. Edison.