This is all from memory so don't take it as read, but I seem to remember they first came out separately in 10 PARTS, paper copies, typical of the Victorian era, and it's conceivable that some people had these bound as was. When they started being published as books they were put into 5 volumes, and I have a vague recollection of even a 2 volume set.

I think the ESB did go into 2 editions. I never had a copy, making do with just a list of contents. It might well be online somewhere.