The narrator makes this comparison in Chapter III of Three Men in a Boat. Harris seems to go overboard (so to speak) on wanting to list absolutely everything that must be taken along on the upcoming boat trip. This approach reminds the narrator of his own Uncle Podger:

That’s Harris all over – so ready to take the burden of everything himself, and put it on the backs of other people.

The narrator then relates a lengthy story about his Uncle Podger, who takes forever and goes through many tools and strategies to simply hang a picture on the wall. He makes the simplest acts more complex than they need to be. He’s stubborn enough to think that he knows quite well how to do many things. The reality is that he doesn’t know how to do these things at all. He does such a terrible job that eventually someone else must intervene in order for the task to get finished.

Later in Chapter XI, when Harris tries to make scrambled eggs, the outcome mirrors Uncle Podger’s difficulties in hanging the picture. Whatever can go wrong, does. And no one ends up with scrambled eggs for breakfast.

What similarities exist between Harris and J.'s Uncle Podger in the book?

Like J's Uncle Podger, Harris is a brash man who has an over-inflated sense of his own importance. He tends to assume a stance of pompous confidence when faced with challenges. Both Uncle Podger and Harris presume that their wisdom, analytical abilities, and powers of observation are equal to the difficulties before them. However, they are far less talented than they imagine themselves to be. Both men invariably end up needing the assistance of others.

In the story, Uncle Podger tries to hang up a picture frame for Aunt Podger. He assures her that she won't have to worry: after all, he's going to do it. Before long, however, Uncle Podger wrecks chaos on the whole household due to his short temper and even shorter attention span. He misplaces his hammer and his coat and makes the whole household responsible for locating them. His ineptness is further illustrated when he smashes his thumb with the hammer while driving a nail into the wall. Meanwhile, the women of the household complain about his poor attitude.

For his part, Uncle Podger steadfastly ignores their complaints. He pats himself on the back for a job well done and neglects to mention that he had assistance in completing the task. Harris behaves similarly in the Hampton Court maze fiasco. He portrays himself as the capable savior of those who are lost. Yet, he fails to lead the group out of the maze. Over and over again, Harris leads everyone in a circle. No one is able to get out until one of the old keepers comes to the group's assistance.

Later in the story, Harris tries to fix scrambled eggs for his friends. He proclaims his culinary prowess and assures everyone that he is a master at making the dish.

People who had once tasted his scrambled eggs, so we gathered from his conversation, never cared for any other food afterwards, but pined away and died when they could not get them.

However, Harris proves so inept at cooking up scrambled eggs that the party has to go without them for their breakfast. Due to his clumsiness and poor cooking skills, Harris is only able to produce a teaspoonful of very burnt eggs (he had originally cracked six eggs into the frying pan). So, we can see the similarities between Harris and Uncle Podger. Both are brash and prone to over-inflate their abilities. Neither is willing to admit that their individual rhetoric often fails to match reality.