[nolemmings]

Love the topic Scot. While I believe your connection of Sheffer to both the 1917 and 1921 sets is plausible, I believe Felix Mendelsohn is the sole "brains" behind the m101-4/5 issues.

Mendelsohn was not all that mysterious, but instead was a fairly prominent publisher in Chicago, with offices downtown in the People's Gas Bldg (where there is now a Bennigan's or similar Irish chain bar). He published "The Story of 100 operas"--multiple printings-which is still readily found today (check ebay), as well as a cookbook. He was probably proudest of some more coffee-table style books that discuss the movers and shakers in Chicago's history. He published soft-cover items including baseball-related "Facts for Fans" and I recall from my old research that he also was into selling arcade-type items through the Sporting News.

My suspicions have been that in 1917, when Mendelsohn learned of the E135 cards surfacing in Chicago (actually H8101-8 Boston Store), he scrapped his idea of what we know as m101-unc because it was too similar in size to E135 and went straight to m101-6s, which he endeavored to copyright. His photos in that set I believe to be the first of their kind, although many were copied in subsequent sets. I have wondered if after that set he was involved with the Exhibit Supply Co., which also operated out of Chicago and which coincidentally started issuing baseball player subjects in 1921-very shortly after the last release of m101-6. This company would likely have been a direct competitor of Sheffer. I've just been too lazy to dig into the origins and principals of ESCO-- maybe the Exhibits experts here would find that to be an interesting project.