Hiya, I bought that book! That's where I found the country of origin/return was Halifax as the Ancestry.com listing only gave his name Cassaday, age 37 (b 1783). That is him. I found in the Boston Advertiser newspaper which I get via a subscription to American Ancestors (used to be NEGHS) where I matched up the name of the schooner Victory with the dates of arrivals in Boston. And even though the newspaper article was a bit mangled, it was clear it was him.
I also found him living in Boston for several years in directories at the address given in his son's obituary even though the street names had changed. There was a lot of info in that obit His son John S. Cassidy had gone out with Admiral Perry to Japan, so it has been interesting. See attached file if it uploads.
But no name of John Sr wife or his birthplace in NI. I do have a court record in Plymouth for nis naturalisation but it does not correctly mention his birthplace, just Antrim. That is through American Ancestors as well. I may just have to order the Plymouth court record of his petition and hope I get the handwritten one and it will give more info.
Thanks for replying. I am happy to look up things on American Ancestors or in that port of Boston arrivals book if anyone needs one.
EDIT: The attached obit was from family papers passed on to me. John Sr and his son moved to Plymouth abt 1926, but the census didn't pick the families up until 1850. Don't know where they were as the obit indicates the family were in Plymouth except for John S's wanderings!