This self-portrait sketch was by famous Morro Bay artist Charles Hoxsey "Robby" Robinson (1862-145) who had studied from approximately mid 1890s to 1904 at the St. Louis School of Fine Arts at Washington University (same place where Paulus Roetter had taught).  His mentors there were John Hemming Fry (1852-1946), Carl Friedrich von Saltza (1858-1905), and Edmund Henry Wuerpel (1866-1958).  This postcard was dated 8 January 1938 and was sent to my grandfather-in-law, architect Alastair Simpson (1910-1992), who had apparently studied watercolor with him.
 
The poetic text below the sketch is as follows: "I'm resting, no jesting.  I'm telling U, I had the flu.  Three weeks, by jeeks!  Tough job, Uncle Rob.  Thanks dears for remembrances."  Click here for a reference photo of Robby Robinson from approx. 1945 while he was painting irises.