Catherine's death entry in the Bible is a little hard to read but 15 Oct 1781 was in fact a Tuesday. However, the age calculation appears to be off. Her birth entry states clearly that she was born in September. Her death entry shows October. There are not 23 years and 11 months apart.
It would appear that Catherine's (and by extension William's) birth entries in both the William Little and William Patterson family Bible's were either copied from a common source or one was copied from the other since Catherine's entry only mentions the month and year of her birth but not the day.
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