What the nineteenth-century bookshops had in common was the name 'debitant' (retail trader) which later fell into disuse, and the diversity of bookshops should also be mentioned. As the bookshops detached themselves from the publishing houses and became an independent trade, the smaller booksellers began to look for supplementary income varying from the trade in butter to a shoemaker's shop or a commercial library in the back of the shop. But even then the threshold of the average bookshop was too high for the lesser educated. The man in the street bought his books from a door-to-door salesman, in the street or on the market. The bookstall and the street vendor were well-known phenomena. Schoolbooks were often bought from the school's principal. Less obvious was the distribution through postal officials who sold books to private individuals at lower prices, because they could arrange free mailing. Books were for many readers a considerable expenditure, which can explain the large variety of publishing formulas. Publishers granted discounts when the buyer subscribed in advance to an edition, and vast editions were offered in instalments in order to spread payments. Commercial libraries could buy inexpensive packages, which often consisted of titles that did not sell very well. At the beginning of the century, publishers sold their books via the bookshops on a commission basis, which made it easier for a bookseller to keep a well-stocked shop. After 1850, buying on account increased which made the booksellers more careful in ordering. On an international level, trade was conducted mainly with Germany. Transporting books was a time-consuming business, which usually took place by ship, but after the middle of the century also by train. Each bookshop was associated with a main correspondent in Amsterdam who collected parcels and circular letters and forwarded these to the bookshops in the provinces on a regular basis. Because of this working method a private person in the province sometimes had to wait as long as two months for his books. The 'Bestelhuis' (distribution office), now called the Centraal Boekhuis (Central Books House), was founded in 1874.