Being the backmark looks to be rare and seems to be undocumented I considered that it may be from a more localized maker. I did find this notice from 1828 in the Gloucester Telegraph which I thought might be a possibility.
The business of John Mason & Son in Gloucester was operating through the 1830s.
Also included is an obituary when he died. It doesn't mention much about the mercantile operation he had but he is an interesting man - you can find his Cape Ann map online.