I was at the Rock County Register of Deeds office today and I looked up Thomas Welch in their book that included 1891. Here's the only Thomas Welch I found....
age at time of death: 64
Place of Birth: Ireland
Date of Birth:__________(according to his age at death he was born about 1830)
Date of Death: September 14, 1894
Cause of Death: Asthema and Bronchitis
Place of Death: Town of Rock, Wisconsin
Burial at Mt. Olivet, Janesville, Wisconsin
I know it's not real informative but I hope it helps. This was the only Thomas Welch that I could find in that particular date range.