Jon looked the surprise he felt. This sudden responsibility was making Jak more practical than he had ever been before ... just the same as it was making him. After all, it was to be expected. Jon knew Jak had an excellent mind--the elder brother had just used it for what Jon had previously felt were unimportant things--not mechanics, math, or such practical interests. But the way Jak had taken care of Pop; the way he had figured out how to feed him, and the right medicines to use on the bruise on his head--that must have injured Pop inside--and had known how to set his leg--it was a danged good thing, after all, that Jak had spent so much time studying those other subjects. Maybe mechanics and such sciences were not the main things in life, after all. Other things had their uses, too. Now the two went back to the ship and around to the stern. There, while Jak stayed on the ground on guard, watching in all directions in turn for any possible dangers, Jon surveyed the great driving tubes. He climbed the metal rungs set into the ship for that purpose, so he could reach each of the tubes. With his glotorch he studied the lining of each tube, crawling partially inside each one in turn. Finally he backed out of the last one and down to the ground. "They're all in fine shape," he reported happily to his brother. "Can't find a single thin spot in any of them. That new alloy is really something." Although the older brother did not know too much about such things, he felt a sudden relief at this report, for he felt that Jon did know, and he had real confidence in him. He had long realized the differences in their temperaments, and for several years had known his brother was almost a genius in the mechanical field. He remembered mentioning this matter to their father one time, and how his eyes had shone with pride as he answered, "Jon's really remarkable. Some day, if he keeps on like this, he's going to be known all over the galaxy because of what he'll do in mechanics." Nor had Jak been jealous at this high praise of his younger brother. "Jon's just a kid," he had said, "and he's thoughtless rather than conceited. But sometimes he makes me so darned mad." His father laughed. "Yes, like all kids, he hates the thought of letting anyone get ahead of him. That's particularly true of younger brothers. They feel, within themselves, that they are just as good or better than the older members of the family, and sometimes can't help showing it." Jak grinned. "I'll bust him one yet, some day, though, if he doesn't watch out." But he knew, and so did his father, that he never would. For both knew the real love that existed between the two brothers. Jak realized that his swiftly growing brother--now several inches taller and many pounds heavier than he--had a terrific mind. So, as now, he generally respected Jon's ideas, and shrugged away any momentary angers when Jon was particularly "bossy."