An interesting post on this subject is here. It’s a follow-up to a more general article on Roman libraries here, which has a nice bibliography in the footnotes. Apparently ‘Boyd 1915 “Public Libraries and Literary Culture in Ancient Rome”‘ contains the references to the primary data. With that publication date, it should be online. And so it is, here.
That’s very interesting, that they did pick and choose what they put in their libraries, whereas Alexandria just grabbed everything. You can see both philosophies at work today in libraries; and the folks working to a plan, or working to provide some level of quality control on a budget, are often accused of censorship just because they don’t think a book fits their collection. (Literally, when space is a concern!)
I sympathize with the Alexandrians. I would have grabbed everything too. But when it comes to reading for pleasure or researching, it’s often more helpful to start with a smaller number of really useful or really well written books, rather than having to sort through everything with no idea where to begin or who to believe. Neither position is wrong, and both have their place.
I want to read Boyd’s book. I don’t have a proper feel for what we actually know about Roman libraries. But he certainly seems to tabulate the data.