Destiny seemed to have sent us on this expedition into space for the purpose of clearing off mysteries that had long puzzled the minds of men. When on the moon we had unexpectedly to ourselves settled the question that had been debated from the beginning of astronomical history of the former habitability of that globe. Now, on Mars, we had put to rest no less mysterious questions relating to the past history of our own planet. Adelung, as the Heidelberg professor asserted, had named the Vale of Cashmere, as the probable site of the Garden of Eden, and the place of origin of the human race, but later investigators had taken issue with this opinion and the question where the Aryans originated on the earth had long been one of the most puzzling that science presented. This question seemed now to have been settled. Aina had said that Mars had completed 5,000 circuits about the sun since her people were brought to it as captives. One circuit of Mars occupies 687 days. More than 9000 years had therefore elapsed since the first invasion of the earth by the Martians. Another great mystery--that of the origin of those gigantic and inexplicable monuments, the great pyramids and the Sphinx, on the banks of the Nile, had also apparently been solved by us, although these Egyptian wonders had been the furthest things from our thoughts when we set out for the planet Mars. We had traveled more than thirty millions of miles in order to get answers to questions which could not be solved at home. But from these speculations and retrospects we were recalled by the commander of the expedition. "This is all very interesting and very romantic, gentlemen," he said, "but now let us get at the practical side of it. We have learned Aina's language and heard her story. Let us next ascertain whether she can not place in our hands some key which will place Mars at our mercy. Remember what we came here for, and remember that the earth expects every man of us to do his duty." This Nelson-like summons again changed the current of our thoughts, and we instantly set to work to learn from Aina if Mars, like Achilles, had not some vulnerable point where a blow would be mortal. CHAPTER FOURTEEN _THE FLOOD GATES OF MARS_ It was a curious scene when the momentous interview which was to determine our fate and that of Mars began. Aina had been warned of what was coming. We in the flagship had all learned to speak her language with more or less ease, but it was deemed best that the Heidelberg professor, assisted by one of his colleagues, should act as interpreter.