Here John interposed. "Yes, M'Allister, you can take it from me that it is just what our world does do. I think you are aware that, like the moon, our world simply reflects the light it receives from the sun, and does not shine by its own light. So one side is light and the other side is dark, according to its position in regard to the sun. From our present position we are only able to see a small portion of the lighted side, the remainder being dark except for the moonlight shining upon it, so it looks just like a large new moon. It really serves as a moon to our moon, but its phases follow each other in reverse order. Thus, when the moon is full, the earth's disc is all dark, and when the moon is in its first quarter the earth, as seen from there, would be in its third quarter, and so on through all its phases. Do you follow all that, M'Allister?" "Well, mon," replied M'Allister, with a sly grin, "I've just heard you say it; but"--and here he turned to me--"is it all correct, Professor?" "Yes, quite correct," I answered, greatly amused at his distrust of John's statements. "M'Allister, you're like the Apostle Thomas," commented John, evidently a little nettled; "so you really doubted my word after all!" "Heh, mon," he answered, "you're not the Professor, you know; and I thought maybe you were pulling my leg!" "Well," laughed John, "perhaps you _will_ get your leg pulled the next time I condescend to give you a lesson in astronomy!" After this little spar between my two colleagues we proceeded to the machine-room, which John and I carefully inspected, to make sure that all was working properly; and having satisfied ourselves on this point, we gave M'Allister his instructions for the 'night'; though of course there was no night now. Mounting the steps of the conning turret, we then had a look at the earth, from which we were so rapidly moving away. It appeared about fifteen degrees in angular diameter, showing that we had travelled some thirty thousand miles from it. The full moon, as seen from the earth, appears just about half a degree in diameter--sometimes a little more, sometimes rather less; so the earth was apparently about thirty times the diameter the moon usually appears to us. It was only a thin crescent where lighted by the sun, but well might M'Allister describe it as "enormous," for it appeared still larger to him when he saw it some thirty minutes earlier and mistook it for the new moon.