1859 (ed. 2) 101 A ream of writing paper..is required to contain 18 quires of 24 good sheets and 2 quires of 20 sheets of outsides,..472 sheets in all, good and bad—this is called a mill ream.
1960 G. A. Glaister 257/2 Mill ream, 472 sheets of hand-made or mould-made paper, good or retree.