Prompted by a request to identify Mark Twain from a photograph (which 
proved to be false), I have found two sources, both from W. B. Northrup. 
His book "With Pen and Camera" has some very interesting photographs but 
except for descriptions of his cottage and tent is mostly cursory 
semi-biographical information from popular sources.  Reportedly Sam 
learned to be a riverboat pilot from Captain Bart Bowen.  The article 
published in the St. Louis Post-Dispatch is much better but the 
photograph included is a montage of the same photos used in Northrup's 
book.  Sam rented the cottage from June to September of 1901 but much of 
August was spent on the Kanawha with H. H. Rogers.

I have created a linked page to my entry for Saranac Lake that has the 
mapped locations of places mentioned in the Day By Day entries.  These 
entries can be access with the link "Saranac Lake: Day By Day.

https://twainsgeography.com/episode/saranac-lake

I must thank Leslie Myrick and Barbara Schmidt for these sources.

-- 
/Unaffiliated Geographer and Twain aficionado/