Sam and Cable gave a matinee reading in Boston [Turner, MT & GWC 59].  I can find no reference to this show other than Fears' mention,

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.]"

First joint reading in a big city to “a very large audience”. (pg 17, Cardwell)

Touring with Cable and Huck provides reviews from three Boston papers; The Boston Globe, Post and Transcript.

From the Boston Herald, November 12, 1884, page 4:

NOTES

This listing is found in Chronology of Speeches but this date is given as Lowell, MA in Touring with Cable and Huck

This listing is found in Chronology of Speeches but is given as November 12 in Touring with Cable and Huck

The Lowell Daily Courier published a review of the show on November 12, 1884, thus establishing the date of the show as November 11.

a crowd so large that extra seats had to be moved into the hall (pg16 Cardwell)

In the afternoon the audience filled about two-thirds of the sittings. The hall was nearly filled by a select and cultured audience at the evening entertainment. (From Providence Daily Journal 1884: November 10)

Mark reported to Livy on a poor reading in Springfield on November 7. (pg 16, Cardwell [Love Letters, p 366. The program at Springfield was experimental])

  Cable reported that the performance was “against terrible odds—brass music & fire-works in front of the hall, vast crowds blocking the streets and cannon firing directly in the rear of the house”     

Springfield Republican, Nov. 8, 1884 page 4.

The Twain-Cable Evening

East Orange Gazette, November 13, 1884
Mark Twain and George W. Cable

Sam was in Hartford, CT during the day but the tour began in New Haven that evening, with Livy in attendance. "The trip's my last--forever & ever"  

The (New Haven) Morning Journal and Courier 1884: November 6 TWAIN AND CABLE.