Zimby lowered a nylon net and some pieces of fish to the two swimmers as they came alongside. With the food as bait they tried to lure the porpoise to the seacopter. But just as they thought they had it, the monster would scoot off. "It's just laughing at us!" Mel fumed. At last, after winning its confidence with several bits of fish, the boys succeeded in snaring the porpoise. Tom clambered onto the _Sea Hound_'s deck and helped Zimby haul their catch aboard. "Quacking" reproachfully, it was lowered through the hatch and placed in the tank, which was then pumped full of salt water. As soon as the _Sea Hound_ arrived at Fearing, Tom phoned Chow Winkler at Enterprises and asked him to fly out to the base. "Pardner, how'd you like to ride herd on this critter and gentle it down for me?" Tom asked, when he showed Chow the porpoise. It had been transferred to a huge, glass-paneled tank which had been set up just outside Tom's Fearing Island laboratory during his flight to the Florida Keys. "Reckon I kin try makin' friends with it," Chow declared. The porpoise stared morosely at Chow. The kindly old Texan's heart was touched by the odd creature. To his delight, it soon responded to his friendly overtures and quickly recovered its good nature. By the next morning the porpoise was playing catch with Chow, or else swimming over to have its back scratched. The cook named it Smiley. "She's kind of a sea cow," he told Tom, "and you got to talk to my Smiley like any cow!" Tom grinned and refrained from explaining to Chow that a real "sea cow" was a walrus. Meanwhile, the young inventor was busy with his own experiments. By means of a microphone placed in the tank, he made exact recordings of Smiley's "talk." Using Mel Flagler as a subject, Tom also tape-recorded the sound of a skin diver propelled through the water by ion drive. The next step was to compare the sound pattern of the tapes. Tom filtered out the difference in the two sounds with the correlation calculator unit of one of his quality analyzer sonars. "Uh-huh. So you got the difference betwixt Smiley's talk an' the noise Mel made," muttered Chow as he watched the jagged lines of light flashing on the pulse-check oscilloscope. "Now what're you fixin' to do with it?" "This will be fed into the diver's sonar along with his own noise output," Tom said, "to make him sound like a porpoise." Chow howled. "That I've got to hear!" The young inventor worked feverishly throughout the day and into the next, perfecting his new "porpoise sonar." Using microelectronic components, he was able to reduce all the units to amazingly small size. Next, Tom began tailoring himself a completely new skin-diving suit. Mask, ion-drive jet, and the various hydrolung units were molded into the plastic, with no loose wires or tubes showing.