Suddenly a deep humming was heard. A moment later the sphere rose with gathering speed until it appeared to have reached a height of about half a mile. Then it shot abruptly off toward the south at great speed, disappearing rapidly over the horizon. While this was of great interest to Henry, it but served to increase his uneasiness. He could think of no good reason for the failure of the _Sphere_ to return from its trial trip but a fatal reoccurrence of the mechanical trouble suggested in the freighter’s report. * * * * * It was at this point in Henry’s gloomy reflections that a hearty laugh outside startled him. The professor! A moment later Robert and Professor Palmer entered. Both were in fine spirits. “Should have been along, Henry,” boomed the professor. “Missed the time of your young life.” “Been reading about it,” Henry replied, tapping the paper. “Were you really trying to drop into the lake, or couldn’t you help it?” “Fast work, Robert,” laughed the professor, as together they read over the article; “private trial trip in the afternoon--front page headlines next morning! Not so bad, eh?” “Just missed the freighter,” gasped Robert. “We didn’t have a chance to see her until we had checked our drop and drifted off astern. Phew!” “Never mind,” soothed the professor. “Can’t be helped now. Anyway, they will probably conclude that we were merely playing with them.” His mood would not be denied. He seemed more like a boy at that moment than a dignified professor of fifty-seven. “You folks seem to have had a dull trip,” remarked Henry, ironically. “Where were you last night?” “Must we tell you? Had you accepted our invitation, you’d know,” retorted the professor. “Man, don’t ask us so many questions. We’re as hungry as wolves.” They sat down before the appetizing, crisply fried bacon, and eggs that Jarvis, the peerless, smiling butler had brought in. “It was this way, Henry,” resumed the professor, after he had partly satisfied the inner man: “Robert and I didn’t expect to be gone long, and unfortunately failed to take any provisions along. Had it not been for a cake of chocolate in Robert’s pocket, which we shared, we should have had nothing to eat since we left.” “But you haven’t told me where you were last night,” persisted Henry. “Tell him, Robert.” “Well, after we ran out of power because the storage batteries had not been fully charged, and narrowly missed sinking that freighter, we had just enough current left to suspend the _Sphere_ in midair. Then we started the engines driving the dynamos, and soon had sufficient power to start back. But boy! It was a close shave.” Robert paused reminiscently. “We started back, but changed our minds and decided to see some more of the country first. You see, at five hundred or more miles an hour, it is quite a temptation to look around a bit.” Henry’s countenance registered a curious combination of astonishment and disbelief.