Indeed, Harry Baker was the cover of that particular issue of Genii
(May 1939). There are literally dozens of references to him in past issues of The Linking Ring
and in M-U-M
. Two other possible sources: inasmuch as Baker was also past president of the local Washington, DC SAM Assembly #23, some infomation may reside there. Another resource, of course, is Al Cohen -- a cornerstone of the magic community in our nation's capital for some fifty years and whose Memoirs of a Magic Dealer column appears in Genii
. As noted in his columns, Al can be reached at email@example.com
. Hope this helps.