Mars, as I have said, was thirty-five millions of miles away from the earth when the _Annihilator_ was headed toward it. To reach the moon, however, but 252,972 miles, at the most, must be traversed--a little more than a quarter of a million miles. As the distance from the earth to the moon varies, being between the figures I have named, and 221,614 miles, with the average distance computed as being 238,840 miles, it can readily be seen that at no time was the voyage to be considered as comparing in distance with the one to Mars. But there were other matters to be taken into consideration, and our friends began to ponder on them in the days during which they made their preparations. CHAPTER IV AN ACCIDENT Washington White was kept busy getting together the food for the voyage, and he had about completed his task, while Andy Sudds announced one morning that his department was ready for inspection, and that he thought he would go hunting until the projectile was ready to start. "Well, if you see anything of that queer man who sent me the note, just ask him what he meant by it," suggested Mark, for inquiry from the boy who had brought the message, developed the fact that Dick did not know the man, nor had he ever seen him before. He was a stranger in the neighborhood. But, as nothing more resulted from it, the two lads gave the matter no further thought. "How soon before we will be ready to start?" asked Jack one day, while he and his chum, with the two professors, were working over the projectile, which was soon to be shot through space. "In about two weeks," replied Mr. Roumann. "I want to make a few changes in the Cardite plates, which will replace the ones used on the Etherium motor. Then I want to test them, and, if I find that they work all right, as I hope, we will seal ourselves up in the _Annihilator_, and start for the moon." "Are you going to try to go around it, and land on the side turned away from us?" asked Mark, who had been studying astronomy lately. "What do you mean by that?" asked Jack. "Doesn't the moon turn around?" "Not as the earth does," replied his chum; "or, rather, to be more exact, it rotates exactly as the earth does, on its axis; but, in doing this it occupies precisely the same time that it takes to make a revolution about our planet. So that, in the long run, to quote from my astronomy, it keeps the same side always toward the earth; and today, or, to be more correct, each night that the moon is visible, we see the same face and aspect that Galileo did when he first looked at it through his telescope, and, unless something happens, the same thing will continue for thousands of years." "Then we've never seen the other side of the moon?" asked Jack. "Never; and that's why I wondered if the professor was going to attempt to reach it. Perhaps there are people there, and air and water, for it is practically certain that there is neither moisture nor atmosphere on this side of Luna."