I managed to obtain a copy of this letter and will see about adding a
description of the journey across the isthmus to my project.

On Sat, 2020-04-18 at 15:55 -0700, scott wrote:
> I found this reference while reading letters on the Mark Twain
> Project:
> Davis, Chester L. 1967. “Letter to Paine from John P. Vollmer.”
> Twainian 26 (March-April): 3–4.
> 
> This is said to contain a description of the trip from Aspinwall to
> Panama City, across the Isthmus of Panama.  I'm unable to find any
> copies of the journal cited and am hoping someone might be able to
> send
> me a copy of Vollmer's description of this trip.
> 
> Thanks...