What Verne might be saying about Harry if he has been "defeated" by the professor's scientific arguments is that Harry is not very intellectual
Explanation:
The expression defeated it is normally used in terms of fights or matches, any kind of competition as a general rule, the winner is the one that defeats, therefore The professor who was the winner had more knowledge and more concise arguments that Harry which demonstrates that he doesn't have as much intellectual knowledge as the professor does.
