Art commenced outlining painfully the essential parts of a cyclotron. He sketched two hollow half-cylinders, with their open sides facing each other, close together. "These are made of copper," he stated, "and each one is an electrode for a very high frequency, high voltage power source. It's actually a sort of short-wave radio transmitter—I'll leave it out of the sketch. Then you have an enormously powerful electromagnet with its field running through the opening between the dees, the half-cylinders, and vertical to them. The whole thing is inside a big vacuum chamber. You get a source of ions-"

"What sort of ions?"

"Well, maybe you put a little hydrogen in the vacuum chamber and kick it up with a hot filament at the center point of the two dees. Then you get hydrogen nuclei-protons."

"Go ahead."

"The protons have a positive charge, of course. The alternating current would keep them kicking back and forth between the two electrodes—the dees. But the magnetic field, since the protons are charged particles, tends to make them whirl around in circles. Between the two of them, the protons go whirling around in a spiral, gaining speed each revolution until they finally fly out a little thin, metal window in the vacuum chamber, going to beat the band."

"But why bother?"

"Well, if you aim this stream of high-speed protons at some material, say a piece of metal, things begin to happen. It can knock electrons off the atoms, or it can even get inside and stir up the nuclei and cause transmutations or make the target radioactive—things like that."

"Good enough," Cargraves agreed, and went on to ask him several more questions to bring out details. "Just one thing," he said afterwards. "You know the answers, but just between ourselves, that sketch smells a bit. It's sloppy."

"I never did have any artistic talent," Art said defensively. "I'd rather take a photograph any day."

"You've taken too many photographs, maybe. As for artistic talent, I haven't any either, but I learned to sketch. Look, Art- the rest of you guys get this, too -if you can't sketch, you can't see. If you really see what you're looking at, you can put it down on paper, accurately. If you really remember what you have looked at, you can sketch it accurately from memory."

"But the lines don't go where I intend them to."

"A pencil will go where you push it. It hasn't any life of its own. The answer is practice and more practice and thinking about what you are looking at. All of you lugs want to be scientists. Well, the ability to sketch accurately is as necessary to a scientist as his slipstick. More necessary, you can get along without a slide rule. Okay, Art. You're next, Ross. Gimme a quick tell on the protoactinium radioactive series."

Ross took a deep breath. "There are three families of radioactive isotopes: the uranium family, the thorium family, and the protoactinium family. The last one starts with isotope U-235 and-" They kept at it for considerably longer than an hour and a half, for Cargraves had the intention of letting them be as free as possible later, while still keeping to the letter and spirit of his contract with Ross's father.

At last he said, "I think we had better eat again. The drive will cut out before long. It's been cutting down all the time—notice how light you feel?"

"How about a K-ration?" inquired Morrie, in his second capacity as commissary steward.

"No, I don't think so," Cargraves answered slowly. "I think maybe we had better limit this meal to some amino acids and some gelatine." He raised his eyebrows.

"Umm—I see," Morrie agreed, glancing at the other two. "Maybe you are right." Morrie and Cargraves, being pilots, had experienced free fall in school. The stomachs of Ross and Art were still to be tried.

"What's the idea?" Art demanded.

Ross looked disgusted. "Oh, he thinks we'll toss our cookies. Why, we hardly weigh anything now. What do you take us for, Doc? Babies?"

"No," said Cargraves, "but I still think you might get dropsick. I did. I think predigested foods are a good idea."

"Oh, shucks. My stomach is strong. I've never been air sick."

"Ever been seasick?"

"I've never been to sea."

"Well, suit yourself," Cargraves told him. "But one thing I insist on. Wear a sack over your face. I don't want what you lose in the air-conditioner." He turned away and started preparing some gelatine for himself by simply pouring the powder into water, stirring, and drinking.

Ross made a face but he did not dig out a K-ration. Instead he switched on the hot plate, preparatory to heating milk for amino-acid concentrates.

A little later Joe the Robot awoke from his nap and switched off the jet completely.

They did not bounce up to the ceiling. The rocket did not spin wildly. None of the comic-strip things happened to them. They simply gradually ceased to weigh anything as the thrust died away. Almost as much they noticed the deafening new silence. Cargraves had previously made a personal inspection of the entire ship to be sure that everything was tied, clamped, or stored firmly so that the ship would not become cluttered ‘up with loosely floating bric-a-brac.

Cargraves lifted himself away from his seat with one hand, turned in the air like a swimmer, and floated gently down, rather across- up and down had ceased to exist -to where Ross and Art floated, loosely attached to their hammocks by a single belt as an added precaution. Cargraves checked his progress with one hand and steadied himself by grasping Art's hammock. "How's everybody?"

"All right, I guess," Art answered, gulping. "It feels like a falling elevator." He was slightly green.

"You, Ross?"

"I'll get by," Ross declared, and suddenly gagged. His color was gray rather than green.

Space sickness is not a joke, as every cadet rocket pilot knows. It is something like seasickness, like the terrible, wild retching that results from heavy pitching of a ship at sea -- except that the sensation of everything dropping out from under one does not stop!

But the longest free-flight portions of a commercial rocket flight from point to point on earth last only a few minutes, with the balance of the trip on thrust or in glide, whereas the course Cargraves had decided on called for many hours of free fall. He could have chosen, with the power at his disposal, to make the whole trip on the jet, but that would have prevented them from turning ship, which he proposed to do now, until the time came to invert and drive the jet toward the moon to break their fall.

Only by turning the ship would they be able to see the earth from space; Cargraves wanted to do so before the earth was too far away.

"Just stay where you are for a while," he cautioned them.. "I'm about to turn ship."

"I want to see it," Ross said stoutly. "I've been looking forward to it." He unbuckled his safety belt, then suddenly he was retching again. Saliva overflowed and drooled out curiously, not down his chin but in large droplets that seemed undecided where to go.

"Use your handkerchief," Cargraves advised him, feeling none too well himself. "Then come along if you feel like it." He turned to Art.

Art was already using his handkerchief.

Cargraves turned away and floated back to the pilot's chair. He was aware that there was nothing that he could do for them, and his own stomach was doing flip-flops and slow, banked turns. He wanted to strap his safety belt across it. Back in his seat, he noticed that Morrie was doubled up and holding his stomach, but he said nothing and gave his attention to turning the ship. Morrie would be all right.

Swinging the ship around was a very simple matter. Located at the center of gravity of the ship was a small, heavy, metal wheel. He had controls on the panel in front of him whereby he could turn this wheel to any axis, as it was mounted freely on gymbals, and then lock the gymbals. An electric motor enabled him to spin it rapidly in either direction and to stop it afterwards.