From the 1820s through nearly the end of the 19th century the standard publication format for novels in England was three volumes, and these novels tended to be printed in short-run editions of under 1000 copies that were typically rented and not sold. The leading lending library was run by Charles Edward Mudie, from whom a typical invoice is illustrated here. Mudie's lending library business model was in direct contrast to the mass production, part-publication business models of publishers like Charles Knight, the Society for the Diffusion of Useful Knowledge, and Charles Dickens, who pioneered part-publication of his fiction.
"The standardized cost of a three volume novel was equivalent half the weekly income of a "modest, middle-class household. This cost was enough to deter even comparatively well-off members of the public from buying them. Instead, they were borrowed from commercial circulating libraries, the most well known being owned by Charles Edward Mudie. Mudie was able to buy novels for stock at round half the retail price - five shilling per volume.He charged his subscribers one guinea (21 shillings) a year for the right to borrow one volume at a time. A subscriber who wished to borrow three volumes, in order to read the complete novel without having to make two additional trips to the library, had to pay a higher annual fee.
Their high price meant both publisher and author could make a profit on the comparatively limited sales of such expensive books - three volume novels were typically printed in editions of under 1000 copies, which were often pre-sold to subscription libraries before the book was even published. It was very unusual for a three-volume novel to sell more than 1000 copies. The system encouraged publishers and authors to produce as many novels as possible, due to the almost-guaranteed, but limited, profits that would be made on each. (Wikipedia article on Three-volume novel, accessed 11-20-2018).