-----
Addendum :? Congratulations to Connor de Jong of the Water Street Atelier. You have it. It is John Singer Sargent (American, 1856-1925) for his "Splendid Mountain Watercolors" Sketchbook, 1870. Sheets :. 11 x 16
Link to the Met site, where, thanks to an intuitive interface picture, you can scroll the image and see amazing closeups of all his works in collection
Charley Parker blog called lines and colors :. "Probably the best major site art museum in the world. "
