I got to learn more new things in this one: I learned what ambergris
is, I learned it's possible to get birds drunk by feeding them fermented berries (hah! hilarioius chapter!) and I learned that worm fiddling
is a real thing and was an actual sport-like event once upon a time. Oh, the obscure facts to be gained from children's books!
My favorite mysteries in this one are The Case of the Model Universe, The Case of the Flower Can and The Case of the Boy Boxers.