July 13 or 14, 1877:   Sam traveled to New York [MTLE 2: 94].  He returned to Elmira August 3rd.

August 7, 1877:  The Clemens family possibly went to Ithaca, New York for a two-day visit to Hjalmar H. Boyesen and family. They were back in Elmira by Aug. 11.

August 11–14 Tuesday – Sam went to New York, business unknown, and stayed at the St. James Hotel [MTLE 2: 133].  No mention of how long he was there but he was back in Elmira  on or around August 18th.