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 gelatin.” 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.”