four o'clock
Tom said the device would be carried in a small case , hooked to the diver 's belt , with a single tuning-knob control . The `` throttle '' or speed control for the ion drive would be housed in the same unit . `` I ca n't wait to try out the new diving gear , '' Bud said excitedly . By four o'clock Tom had the apparatus perfected , and turned it over to Arv Hanson for fast duplication . `` We 'll give it a shakedown tomorrow morning , '' he told Bud . The duplicates of the ion drive and density control were ready and waiting when the boys arrived at the plant next day . They immediately flew to Fearing Island and embarked in a motor launch , with Zimby Cox again at the helm .