He has a lot of other phonetic misspellings like "victoms", "darck", "epasode", "pencel", "paterned", "cruse", "coupples", "untill", "allready", "dissapeared", "rubed", "positivily", "ventalate", "silowets", "choaked", "extreamly", "posibly", "twich", "comitt", "descise", "saterical", "comidy", "butons", "considerbly", "promiced", "shure", "inthusiastic", "phraises", "nucenses", "truley", and mistakes like "to many" and "loose" for "lose".
It's possible there's a meaning to it, but I suspect the most boring explanation is the most likely one, there. He may have spent a lot more time speaking than reading/writing and perhaps might not have finished high school, or maybe just happens to not have been very good at memorizing spellings.
His misspellings sound a lot like phonetic misspellings I still regularly see online today, and like how people tended to write English more phonetically and less consistently a few centuries ago. We take it for granted, but English really is not at all an intuitive language when determining spelling from pronunciation or vice versa, compared to more consistent languages like German.
He does seem to have an interesting affinity for using the letter "c" almost any time a soft "c" or hard "c" could be called for, and sometimes eliding other letters. Like "twich", "darck", "promiced", and "paradice". I wonder if an automated analysis of basically every piece of writing you can find from around that time and area, taking some of those patterns into account, could uncover something. Like every single physical letter written to every newspaper about anything. It'd probably require way too much manual digitization labor to be feasible, though.