While reading through Sci-fi pre-1985 children's(ish?) book series about a boy who lived next door to an old scientist, I was suddenly struck with a memory of having read a book within the last few years (I'll start trolling through my library history tonight after work) with a kind of similar premise. The inventor in question had some sort of pull or influence over the town such that they couldn't quite get rid of him. I want to say that he developed projects for the U.S. Military, although he was sort of a "gentleman inventor" who was doing it for the fun of it rather than someone who was truly trying to push the boundaries of human understanding. The two bits that stick out to me are
He frequently causes incidents that require the fire department to show up, and he's got his own siren or klaxon for when things go wrong.
I don't remember if it was fires or gasses that were what kept happening, and I have a vague memory that the post office guy often got caught in the middle of incidents, to the point where the inventor treated him as a bit of a guinea pig.
He eventually gains a young boy as an assistant.
