The Hidden History of Mail-Art

As an occasional mail artist and a full-time collector of books and ephemera I came across this battered old copy of a Ripley's Believe It Or Not paperback. In it's yellowed pages was this account of the popularity of the brand.

Here is what the man himself, Robert Ripley had to say in regards to the scads of post he received as ringmaster of the sensational and the bizarre.

Wehman Bros.' New Book Of Fun, Magic & Mystery. 1905

This wonderful catalogue/sampler for Wehman Bros. of New York is chock full of excerpts and ads for many of their joke books and parlor games and such.
I was particularly struck by the illustrations gracing their myriad books featured on the back cover. They remind me of some the ink work from american underground comix of the 60s but, of course, they date from at least 1905.
I've separated individual illustrations for a better look.
& please don't shoot the messenger regarding the blatant racism depicted on some of the covers and their wording.
Dutch jokes ?