Barton Horvath (1912-2004) of New York was a championship competitive bodybuilder, instructor of physical culture, and author of texts and articles on body building. He appeared on the cover of the first ever edition of Joe Weider's magazine Your Physique in 1940 and continued to appear as a model and as a writer well into the 1960's. I have exactly six nude photos of Mr. Horvath, and none of them have a photographer attribution. The style and the fact that they were apparently made in New York around 1940 bring Al Urban, Lon of New York, and Edwin Townsend to mind as possibilities. Edited to add: Horvath probably took these himself! See Tom's comment below.