Thank you very much for the quick response.  I was stepping on my own 
feet here as Twain's next lecture, in Brooklyn, is addressed on the next 
linked page.  I was still thinking that perhaps he returned to Boston 
before going to Brooklyn.  Thompsonville, CT is not so far afield in 
Twain's route as it is just a short jaunt to Hartford from Thompsonville 
and then on to Brooklyn.

On 6/21/21 1:09 PM, Munkittrick Associates wrote:
> According to T*he Springfield Daily Republican* (November 30, 1869) Twain
> was to lecture that evening in Thompsonville, Connecticut's North
> Congregational Church  on the "Curiosities of California" for the
> "Thompsonviille lecture association."
> Alain Munkittrick, Associate
> Architecture, Interior Design and Space Planning
> PO Box 167
> Cobalt, CT 06414