It still does not locate a copy of the book. "private circulation" means it was privately published, probably by a member of the family and would never have been on sale to the general public. Just occasionally such a publication does turn up on the market - I have such and it is just a best guess that someone who had had a copy (there were only ever 200) had died without issue and the book had been sent by whoever, executor?, to a genealogical bookshop. Which member of the "tribe" that was, or how it got into a bookshop at all is a complete mystery. I am not at all sure that a copy would even have been covered by copyright which meant it would have had to be deposited in one, or more, of the copyright libraries. I think the definition of copyright for that purpose meant it had to have been publicly published and available for sale - if it was for private circulation it could be that copyright deposit law did not apply.