Paper is manufactured, on the principle of felting, in thin sheets from fibre of linen and cotton rags, of straw, rice-straw, and of various woods and grasses. The fibre is variously prepared, and reduced to fluid pulp, which is run into trays in a sheet or film, pressed between rollers, and dried. Paper has very largely superseded as a material for writing purposes bark, papyrus (q.v.), parchment (q.v.), and vellum (q.v.).