Cable wrote home:
"We had a great time last night. Twenty-two hundred people applauding, laughing & encoring, In Music Hall. This morning Clemens & I go out to make a call or two. Tonight we read in Brockton. Tomorrow afternoon & night in Chickering Hall. Our show is a great success. It isn’t easy to write as Mark Twain is singing “We shall walk through the Valley” [Turner, MT & GWC 59.]"
I don't currently have an image of the Brockton Opera House so I'm going to leave the image of the interior of the City Theater, which is interesting in it's own right. see City Theater
EMail correspondence from Barbara Schmidt Thu, 26 Feb 2015 : "As to Brockton, MA -- I did find a reference to a letter SLC wrote to Pond complaining that the Brockton venue had not been advertised sufficiently, and thus had a low turn out." I don't know if the Twain-Cable Tour visited City Theater or not but it does seem to be a good fit.
The Brockton Historical Society provided me with PDFs of some newspaper clips about this event. It took place in the Opera House to a "regrettably" small audience
"OPERA HOUSE.-- It is to be regretted that "Mark Twain" and Mr. George W. Cable were greeted by such a deplorably small audience at the Opera House last Friday. It was a reflection upon the literary taste of our people that so few were eager to come face to face with these popular American writers. Mr. Cable's readings were entirely from his latest novel, "Dr. Sevier," and were introduced with one of the wild, incoherent but musical Creole songs sung years ago in the Place Congo, New Orleans, by the African slaves. The readings introduced Narcisse, John and Mary Richling, Ristofalo and Mrs. Riley, those well remembered personages in his novel. Mr. Cable has a sympathetic voice and much dramatic spirit. His recitation of Mary's thrilling night ride through the forest, pursued by rebel scouts, was vividly portrayed. "Mark Twain"--who looks just like his published portrait, except that he has grown gray-haired with the weight of remorse for the things he has written--read several of his excruciatingly funny sketches. They gained added humor by the tone and manner in which the author read them, and set the audience in a gale of laughter. The only thing to regret about the whole evening was that there were so few there to enjoy the literary treat presented."
Brockton Enterprise, November 22, 1884 -- Thanks to the Brockton Historical Society
Old Colony Depot Image By Stark - James Henry Stark. Stranger's illustrated guide to Boston and its suburbs. Photo-Electrotype Co., 1883., Public Domain, https://commons.wikimedia.org/w/index.php?curid=10213525