From December of 1936, and Detective Picture Stories #1, comes this tale of two famous detectives (one of whom is undoubtedly a great uncle of Duane Spurlock). It was uploaded to comicbookplus by stopper75, and story and art is credited to John A. Patterson. Another Spurlock and Watkins story (in black & white, alas) appeared in the next issue, and can be read HERE.
A third adventure (once again in color) will appear here too soon for some, not soon enough for others.