Regarding the origins of the elusive ‘Mystery Sculler’, here’s my hunch: the illustration may have been created/published by a type or graphic arts firm, as a ‘stock’ item from a sports collection of images that could be purchased individually or as a set. From my years in working in graphic arts and printing – and from coming from a family of three generations of printers – I’ve seen images such as the ‘Mystery Sculler’ in thick (as in three-to-four-inch-thick) catalogues that my ancestors acquired from type/font/graphics companies such as Mergenthaler Linotype, Monotype, Ludlow Typograph, et al. The products advertised in these catalogues were equivalent to today’s stock photography or Web graphics – off the shelf images ready for end-use by anyone for pretty much any purpose. I think the catalogues are often titled as ‘specimen’ books, and they demonstrated fonts, borders, lines, ding bats, all sorts of decorative ornaments. The books are generally quite heavy and of a large (e.g., 9×12 inches) format; perfect for pressing flowers or using as weights to set a sharp crease in something.
Try searching Google Images for “linotype specimen catalog 1920” or similar terms.
So far Raoul’s take on the ‘mystery sculler’.
As Tim Koch has noted, I found HTBS’s ‘mystery sculler’ in a 287-page book, Sports Pictures (1999), with a CD-Rom with high resolution images, published by Agile Rabbit Editions, a company based in Amsterdam. The book, see above, is filled with illustrations of all kind of sports, from archery to sailing. The sport of rowing has 29 images of old, all copyright-free.