I'd call it as 1863.
Was there another, later Josiah who might have written the letter?
commented 10 minutes ago by Herbert Tardy
Maybe? The listing of the Massachusetts Anti-Slavey Society (MASS) shows Henshaw, Josiah, abolitionist, W. Brookfield, Massachusetts, Massachusetts Anti-Slavery Society, Vice-President, 1851-60-. (which argues that if he were VP from 1851 - 1860 (and ongoing?), that he was not dead in 1829).
Thanks, Melanie! But that means he was a steady-handed 111 year old when he wrote the letter.
I don't understand how an 1863 letter relates to this profile?
Nor do I. Different Josiah; must be.
See also (highlight mine):
May, Samuel, Jr., Leicester, Massachusetts, abolitionist. Executive Committee, 1849-1864, American Anti-Slavery Society. Vice President, 1840-1848, Counsellor, 1849-1860, Corresponding Secretary, 1854-1860, Massachusetts Anti-Slavery Society.
You're welcome, Melanie!
One final off-topic point, Ellie: Please spell out Massachusetts wherever it appears. Our international cousins are not always familiar with American abbreviations.
And welcome to G2G!
Found an orphaned profile Josiah https://www.wikitree.com/wiki/Henshaw-342 with lots of links that weren't working. Added birth (1791) and death (1871) sources from family search and linked him to Josiah and Sarah Phipps as parents. Could be this Josiah that the document refers to.