The Materials Department library works with a good system. It looks as if someone made an effort to sort things out into vague topics, metallurgy over there, composites here, etc. Then another person came along and made up a numerical classification completely unlike the one usually used for non-fiction in every library I've ever seen, but still went from one end to the other and included all the books that happened to be out of order that day, and put them on a computer catalogue. This has the effect that if you are looking for a particular book about bone you might consult the catalogue, walk around the library looking for the classmark, walk into the section about steel getting more and more worried, and eventually find the bone book between two completely unrelated things. It's very entertaining.