reminded Professor Graut, a practical aspect of Terra Research which belonged solely to practical men. His absorbing interest—you could almost call it an obsession—lay with the abstract. In his classes at Solar University, before he had been specially applied for by Research, E.S.P. Seven, this unyielding attitude has earned him the class soubriquet of "Old Mind Stuff Walstab". He did not resent it. Rather, he took pride in rooting intelligent life in the soil of the mental, as opposed to the material, plane. One of his favorite illustrations was the irrefutable fact that before a thing could make its appearance on the physical plane, it had first to come into existence on the mental plane. All creation had its origins in preceding thought. Practical accomplishment could only have origin in the foetus of Mind.
So, now, he gave his attention more and more to the singular note intermingling with the familiar tension of the cosmar screen. It came in ever increasing systole and dyastoje; now and then, the whole fading to a mere murmur, but finding every minute a renewed vigor, and—Dr. Walstab recognized in astonishment—something very like purpose. There were, indeed, moments when he thought to recognize the pattern of the human voice. Utterly impossible, of course; yet he felt a crawling sensation at his spine. The visual turmoil was, he told himself, also gaining momentum. The glowing background was perceptibly darker. There was a ragged core of shadow at its center.
He dragged his mind back to reality.
"The problem immediately confronting the crew of D.S.S. Challenge Queen," Professor Graut was saying, "is to proceed by stages from Jupiter VIII, via Jupiter VII, Jupiter VI. Callisto, Ganymede, Europa and Io, to Jupiter V.—which finds them a mere 112,600 miles from the planet itself. Ace Vice-Marshall Benhurion, in command, has full instructions. He will, if possible, reach Jupiter V. and there establish a base. The region of the seven inner satellites being as yet quite unknown to us—I remind you that the video screens can be misleading as to practical details, very often—we are not hopeful that he will, in fact, get further in than, say, Callisto. Until we receive his next report, due midnight, Earth time, we cannot really assess the chances. Meantime, our present purpose is to plot in preparation for any and every eventuality."
"Where is Challenge Queen now, sir?" Ace Peters asked.
"Approximately in the same sector as Vibrant was, two years ago. You laid the base on Jupiter VIII, then, Jaguers."
"Yes, sir. That was after Chris was . . . was lost"
Dr. Walstab, deciding he ought to show more interest in the conver-
