Copyright stamp mystery

The IPKat's knowledge of all things connected with intellectual property is legendary, but it is probably based on the fact that, unlike most cats, the Kat has four brains and numerous degrees and qualifications. However, there are still many things of which the IPKat has to confess his woeful ignorance, and in such a circumstance he is very happy to draw on the combined knowledge and intelligence of his readers.

Recently the IPKat received an email from his friend Nadine Eriksson-Smith (Administrator, AHRC Research Centre for Studies in Intellectual Property and Technology Law, School of Law, University of Edinburgh). It reads, in relevant part:

"In the back of my World Classics edition of Stevenson's The Master of Ballantrae there is what appears to be some kind of copyright stamp. My collegues here are unsure of the function of this. The novel was first published in 1889 and the edition I have was published in 1936, after Stevenson's death in 1894. Any ideas as to what the stamp is for are most welcome".

The stamp is handsomely illustrated, above, right. The easy answer is to say that the stamp is there to raise money and it looks as though it may be something to do with author's royalties - but the IPKat feels that more explanation is needed and calls on his scholarly readers to help him answer Nadine's query. If you know anything about this stamp, can you please post the answer as a Comment below?

More on The Master of Ballantrae here
More on Robert Louis Stevenson here
More on Ballantrae here