2-blade fans were pretty common in the 1920's and early 30's, particularly on Ford Model T's and Model A's. Yours is most likely half of a 4-blade fan that was disassembled for some reason- - - - -maybe one blade segment was broken or bent and was discarded.
Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!