Which William Barnes died?

You do not need the year; the age decides it. (It cannot be 1812, which is how it may look at first: the older William married in 1833.) The pencil says "8_ years," a man in his eighties. The son born in October 1838 would have been only 33 or 43 if he died in 1872 or 1882, and anyone born in early October who dies on July 17 is some years and 9 months old, never "years and 22 days." Exhibit C shows this family could work an age out to the day: August 7, 1840, plus 1 year, 10 months and 19 days is exactly June 26, 1842. Run the pencil age backward the same way and William was born on June 25 of a year between about 1783 and 1802, old enough to be the man who married in 1833. That last step is a deduction, so record it as one; a census or gravestone can confirm it.

• When two people share a name, use dates you can check. An age at death turned into a birth date often tells a father from a son even when no Sr. or Jr. is written.
• Do the age arithmetic: death date minus years, months and days gives a birth date. Test it first on an entry you can check, as with Mary Barnes.
• A hard-to-read figure does not always block you. Ask which answers survive every possible reading; here the son fails whatever the year is, because of both the age in the eighties and the odd count of 22 days.
• Notice ink and order. An entry out of sequence or in different ink was probably added later, so it may rest on memory rather than being written at the time.
• Family Bibles rarely name parents beside children. That William of 1838 was the son of William and Elisabeth is likely but unproven; confirm it with a census.