"With Martt beside me--we were both a little timid about it, naturally--I threw over the switch and started our growth." He paused for the length of a breath. "It was extraordinary--all our experience of the voyage from that moment was extraordinary. I hardly know how to begin telling you. . . ." III Dr. Gryce interrupted. "Just a minute, Brett--I want to make absolutely clear to Frank the principles involved in this change of size in relation to velocity." "May I ask a question first?" I hazarded. "All you like," said Brett. "I'm wondering why in your normal size you could attain no greater velocity than seven and one-half million miles an hour. Theoretically, you know, a freely falling body will accelerate to infinity. And with repulsion added--a body, not only falling, but being _pushed_ downward----" Frannie said, "Nogar found his approximate limit at five million----" "Our limitations were similar to his," Martt put in. "I know," I said. "I remember in the public newscasting they said----" "We found the same conditions," Brett put in. "Our vehicle--any vehicle traveling in outer Space--is not strictly a freely falling body. For low velocities--the general voyaging from here to Mercury, Venus or Mars--Space may almost be considered a vacuum. But it is not a vacuum, as we know. The imponderable, widely separated atoms of the ether--to use the ancient word--begin to be a factor at velocities over three million miles an hour. The drag became increasingly noticeable----" "And the heat of the friction warmed us up," Martt put in. "At six million miles an hour we were hot, let me tell you. Sweltering--even with the full refrigeration units going." "That friction held us to seven and one-half million as our limit," Brett added. "Anything else, Frank?" "Yes, I was wondering about our aural ray here. Could you still see it?" "Oh yes. Our sun of the Solar System had dwindled--small, but white and brilliant. With the naked eye the little star which was our earth showed very faint but distinguishable. With the aurometer--even using its spreading field of vision so that it embraced all that portion of the sky--we could see your beam sweeping slowly across the field as the earth rotated." "And the myrdoscope?" I suggested. "Hadn't you tried again to locate the image of that girl?" My heart thumped as I said it. He nodded. "Beyond Jupiter, when the long hours of inactivity hung on us, I spent many of them searching ahead of us with the myrdoscope. At last I picked up the image of the girl--held it for a few moments." "There was no change?" Dr. Gryce said eagerly. "No. The little distance we had traveled made no change--in fact, my smaller instrument, Father, showed it rather less clearly." "I mean no change in the girl's attitude," Dr. Gryce insisted. "No change in the attacking giant--or those grinning little dwarfs at the girl's ankle?"