My original tumblr post was here. This image was researched by Bacchus at ErosBlog as part of the “Δ commission.” The research was originally published at Hedonix as “Δ 058 – The Floating Robot.” Here is what Bacchus found.

This image is signed H.W. McCauley (for Harold W. McCauley) and may be found on Flickr in downloadable sizes up to 2239×3000 pixels. It is the artwork that was used on the cover of Fantastic Adventures magazine in January of 1941:

The same robot appears in an interior illustration introducing the story The Floating Robot (by David Wright O’Brien):

Artist H.W. McCauley is the subject of a short profile here:

A Chicago native, Harold McCauley trained at the Art Institute of Chicago and at the American Academy of Art. From 1939 until 1942, he worked at Haddon Sundbloom’s busy Chicago art studio and posed for the original painting of the Quaker Oats Man. Starting in 1946, McCauley worked as a staff artist for the Ziff-Davis publishing house and painted over a hundred covers for magazines like Amazing, Fantastic Adventures, and Mammoth Detective. Duringthe early 1960s, he also painted several covers for Nightstand Library.

This fanzine article about McCauley offers a photograph of the artist, who does indeed somewhat resemble the famous Quaker Oats logo: