The Frenchman, as you may suppose, was greatly astonished, and to show how perfectly the machine worked Rob turned the indicator and rose a short distance above the tower, circling around it before he rejoined the professor on the roof.  Then he showed his food tablets, explaining how each was stored with sufficient nourishment for an entire day.
The scientist positively gasped for breath, so powerful was the excitement he experienced at witnessing these marvels.
"Eet is wonderful--grand--magnifique!" he exclaimed.
"But here is something of still greater interest," continued Rob, and taking the Automatic Record of Events from his pocket he allowed the professor to view the remarkable scenes that were being enacted throughout the civilized world.
The Frenchman was now trembling violently, and he implored Rob to tell him where he might obtain similar electrical machines.
"I can't do that," replied the boy, decidedly; "but, having seen these, you may be able to discover their construction for yourself. Now that you know such things to be possible and practical, the hint should be sufficient to enable a shrewd electrician to prepare duplicates of them."
The scientist glared at him with evident disappointment, and Rob continued:
"These are not all the wonders I can exhibit.  Here is another electrical device that is, perhaps, the most remarkable of any I possess."
He took the Character Marking spectacles from his pocket and fitted them to his eyes.  Then he gave a whistle of surprise and turned his back upon his new friend.  He had seen upon the Frenchman's forehead the letters "E" and "C."