As you can see, the writer mentions a synagogue established (in 1823) by his grandfather Nathan Henry (b. 1764). It seems that even prior to the establishment of this synagogue, he presided over a minyan for Jewish debtor prisoners.
I happen to think that it is pretty cool how a man writing in 1905 can recall his grandfather telling him all about events in 1780. Of course there are loads of people alive today who had grandparents who told them all about life in 1886, but still. "The gulf of time is bridged over," indeed.