_The dotted line joining the Earth to Mars shows the course taken._ _The dotted Circles show the Orbits of the Planets. The thick arrows show the distances travelled by the respective planets during the period covered by the Voyage: the line at the back end of the Arrow being the planet's position on the 3rd August, and the points of the Arrows the position reached on the 24th September._ _The Orbits of Mercury, Venus, the Earth and Mars are drawn approximately to scale, but those of the outer planets are not. On the same scale, the radii of the Orbits of the outer Planets would, approximately, be as stated below. These figures will afford some idea of the enormous distances separating those planets._ _Jupiter_ _3_ _Inches_ _Saturn_ _5-3/8_ " _Uranus_ _10-7/8_ " _Neptune_ _17_ " _Drawn by M. Wicks_ Plate V] CHAPTER VIII JOHN INSISTS ON GOING BACK AGAIN--A STRANGE, BUT AMUSING INCIDENT OCCURS When we rose the next day the moon was a considerable distance away from us, but not so far off as might at first be imagined if one only considered the speed at which we were travelling; for, although moving at our full speed, the earth was following us up pretty closely, as the curve of its orbit would, for several days, run nearly in the same direction as we were going. Still, 2,000,000 miles a day was sufficient to make a diminution in the apparent sizes of the sun and Venus; and there was a gradual increase in the size of the planets, Mars and Saturn, towards which we were moving. As regards the fixed stars, however, there was no change in our surroundings, as they are such an immense distance away--the nearest being, at least, twenty billions of miles from the earth, that a few million miles more or less make no difference in their apparent size, or in their positions in regard to each other in the constellations as we know them in our maps. As we were now fairly on our way, and moving rapidly in the direction we wished to travel, I thought it quite time to put into operation a scheme which John and I had previously decided upon, so I told M'Allister that he must be prepared to take a little change of air. "Why, Professor," he exclaimed, "that sounds almost like a proposal for going to the seaside!" "We certainly are not going there," I replied, "for we are rapidly moving away from all seaside resorts, and you are not likely to visit any of those places for a very long time to come." "Well, mon, where are we going to get our change of air then?" he inquired; "you know there's no air at all outside of this vessel." "Quite true," I answered; "so we must get our change of air inside the vessel." "Yes," interposed John, "and, Kenneth M'Allister, you will have to make up your mind to have rather short commons of it; the same as we shall!"