Bookplates have gone out of style but clearly in the 1800s and 1900s they were the rage and people sometimes created elaborate bookplates to designate ownership of volumes for their library. The first bookplate probably dates back to the 1500s in Germany. People had fun swapping their plates too, becoming collectors. Catalogues of plates also appeared.
Though Morris and Chesley Young never designed or used personal bookplates for the books they collected they did request "extras" from those designed and used for books they donated to the Library of Congress, University of Texas, Austin, and the University of California, Berkeley. So they had those to occasionally swap with magician collectors so they might have a few magician's bookplates in their home collection of ephemera.
Those designed and used by the Library of Congress and University bookplates have been posted earlier on this blog. Posted here is a letter from J.B. Findlay, a Scottish conjurer and one-time editor of The Thistle, the official journal of the Scottish Conjurers Association. He swapped bookplates with Morris and I will soon post the plates Findlay sent. One was of Findlay's own design for his personal library. That plate itself is unusual in that it measures only one inch by 2 inches (quite small for a bookplate) and imprinted on it in very very small print are drawings of various books on magic along with the titles and some with the name of the author...so keep following the blog to see this rarity. I promise it will be the next item to be posted. For now, here is Findlay's letter to my dad...