Thanks for directing me to those Assessment Books, JM, I had no idea that resource existed. The Lunacy Commission Report says Thomas Brown was owner of considerable property, so it makes sense for him to turn up so many times in the area.
I've been looking through the newspaper archives for Thomas Browns associated with the Sherriff's Office, and the 1840 date seems to match the beginning of articles about him. I'm not sure who this John Brown fellow is though, he seems to appear in the papers as early as 1834 (although with a name as common as that, the 1834 article could be about someone else entirely). Thomas Brown's son John would seem to be younger than this John Brown, I wonder if it might be a brother.
Very odd that the age of the John Brown in St Peters Cemetery is off. The newspaper article about the funeral says clearly it was taking place in that Cemetery, so either there were two John Browns buried there on the same day, or that record is incorrect. 17 and 47 can look rather similar with bad handwriting.
Thanks for pointing out those Government Gazettes, I'd had a quick look for them as they were mentioned in a few newspaper articles but forgot that the states have changed so much since then.
Cando, I didn't realize transcriptions were an option, that's very helpful.
I'll have to put John Brown on hold for a while, with Christmas coming up. I hadn't hoped to make nearly so much headway on the Browne family, so thanks very much to all of you for your help with this.