I will definitely try to be more brief than the narrator is during his description of Uncle Podger. The narrator begins chapter three with a long description of Uncle Podger. The narrator does this because he tells readers that Harris is exactly like his Uncle Podger, so instead of telling us about Harris, we get to read a long, comical section about his uncle.
That’s Harris all over—so ready to take the burden of everything himself, and put it on the backs of other people.
He always reminds me of my poor Uncle Podger.
Uncle Podger is the kind of person that considers himself a real handyman, and he wants everybody to know that he's working on a particular project.
“Oh, you leave that to me. Don’t you, any of you, worry yourselves about that. I’ll do all that.”
The project in this particular case is the simple act of hanging a picture on the wall. Instead of just getting the tape measure, level, hammer, and nail himself and hanging the picture within ten minutes, Uncle Podger recruits the entire family to help him with the job. He sends a person out to get a nail, a different person to get the hammer, a different person to do something else, etc.
“Now you go and get me my hammer, Will,” he would shout; “and you bring me the rule, Tom; and I shall want the step-ladder, and I had better have a kitchen-chair, too; and, Jim! you run round to Mr. Goggles, and tell him, ‘Pa’s kind regards, and hopes his leg’s better; and will he lend him his spirit-level?’ And don’t you go, Maria, because I shall want somebody to hold me the light; and when the girl comes back, she must go out again for a bit of picture-cord; and Tom! — where’s Tom?—Tom, you come here; I shall want you to hand me up the picture.”
He doesn't perform any task completely by himself, and when he does, he messes it up. In the narrator's example, Uncle Podger finally gets to the point of actually hitting the nail in the wall; however, he hits his finger instead of the nail. Then he puts the hammer through the wall because he hit the nail too hard. By the time the job is finished, hours have passed by, and the picture isn't even on the wall straight.
Then we had to find the rule and the string again, and a new hole was made; and, about midnight, the picture would be up—very crooked and insecure, the wall for yards round looking as if it had been smoothed down with a rake, and everybody dead beat and wretched—except Uncle Podger.
Basically, Uncle Podger is the kind of person that can't do simple tasks, but he thinks he can. Additionally, he's the kind of person that makes simple tasks more complex because of the number of people he recruits to help him do the simple task.
The narrator sees this trait in Harris, so when Harris says that he'll do a simple job and asks for the narrator's help, the narrator immediately puts a stop to what he believes will be an ensuing fiasco.
“Now, the first thing to settle is what to take with us. Now, you get a bit of paper and write down, J., and you get the grocery catalogue, George, and somebody give me a bit of pencil, and then I’ll make out a list.”
“No; you get the paper, and the pencil, and the catalogue, and George write down, and I’ll do the work.”