sheets an hour. 1863: Rotary web-fed letterpress invented by William Bullock. 1865: Web offset press can print on both sides of paper at once. 1886: Linotype composing machine invented by Ottmar Mergenthaler. 1870: Paper is now mass-manufactured from wood pulp. 1878: Photogravure printing invented by Karl Klic. 1890: Mimeograph machine introduced.