I read these as a kid and loved them. All of my sons have read them multiple times. They are a lot of fun and very boy oriented.
The Great Brain is a series of children's books by American author John Dennis Fitzgerald (1906–1988). Set in the small town of Adenville, Utah, between 1896 and 1898, the stories are loosely based on Fitzgerald's childhood experiences. Chronicled by the first-person voice of John Dennis...
https://en.wikipedia.org/wiki/The_Great_Brain