"But you'll need a tank for the helium, won't you?" Bud objected.
Tom shook his head. "Enough can be compressed into a small capsule to supply the wearer's needs. Remember, it can be used over and over again."
"Pretty neat," Bud commented.
By morning Tom felt thoroughly recovered. He insisted upon flying back to Enterprises to make the necessary changes in his hydrolung. Bud accompanied him, eager to get back on the job.
In a few hours Tom had added a small fitting to his power unit to provide for helium substitution. Then the two boys hopped back to Fearing for a second deep-water test. This time, Tom was delighted to find that he could operate comfortably at great depths, as well as rise or descend suddenly without ill effect.
Bud was aglow with enthusiasm. "Boy, we can really explore now!"
After the boys had returned to Enterprises, Tom phoned Arv Hanson and asked that a duplicate of the hydrolung be turned out in the shop as soon as possible. It was ready the following Monday morning, so Tom suggested to his father that the two visit the proposed underwater site and make some sample plantings.
"Great idea, son," Mr. Swift agreed. "I want to try out your new diving apparatus myself. If it's successful, we'll be able to tackle two problems at once—recover the Jupiter prober and start the 'sea farm.'"
They flew to Fearing, then went by boat to the farm site, about half a mile offshore. Each carried several of the valuable Far Eastern plants.
