The story of the reaper is told in: Herbert N. Casson, "Cyrus Hall McCormick; His Life and Work" (1909), and "The Romance of the Reaper" (1908), and Merritt F. Miller, "Evolution of Reaping Machines" (1902), U. S. Experiment Stations Office, Bulletin 103. Other farm inventions are covered in: William Macdonald, "Makers of Modern Agriculture" (1913); Emile Guarini, "The Use of Electric Power in Plowing" in The "Electrical Review", vol. XLIII; A. P. Yerkes, "The Gas Tractor in Eastern Farming" (1918), U. S. Department of Agriculture, Farmer's Bulletin 1004; and Herbert N. Casson and others, "Horse, Truck and Tractor; the Coming of Cheaper Power for City and Farm" (1913). CHAPTER VI An account of an early "agent of communication" is given by W. F. Bailey, article on the "Pony Express" in "The Century Magazine", vol. XXXIV (1898). For the story of the telegraph and its inventors, see: S. I. Prime, "Life of Samuel F. B. Morse" (1875); S. F. B. Morse, "The Electro-Magnetic Telegraph" (1858) and "Examination of the Telegraphic Apparatus and the Process in Telegraphy" (1869); Guglielmo Marconi, "The Progress of Wireless Telegraphy" (1912) in the "Transactions of the New York Electrical Society", no. 15; and Ray Stannard Baker, "Marconi's Achievement" in McClure's Magazine, vol. XVIII (1902). On the telephone, see Herbert N. Casson, "History of the Telephone" (1910); and Alexander Graham Bell, "The Telephone" (1878). On the cable: Charles Bright, "The Story of the Atlantic Cable" (1903). For facts in the history of printing and descriptions of printing machines, see: Edmund G. Gress, "American Handbook of Printing" (1907); Robert Hoe, "A Short History of the Printing Press and of the Improvements in Printing Machinery" (1902); and Otto Schoenrich, "Biography of Ottmar Mergenthaler and History of the Linotype" (1898), written under Mr. Mergenthaler's direction. On the best-known New York newspapers, see: H. Hapgood and A. B. Maurice, "The Great Newspapers of the United States; the New York Newspapers," in "The Bookman", vols. XIV and XV (1902). On the typewriter, see Charles Edward Weller, "The Early History of the Typewriter" (1918). On the camera, Paul Lewis Anderson, "The Story of Photography" (1918) in "The Mentor", vol. vi, no. 19.; and on the motion picture, Colin N. Bennett, "The Handbook of Kinematography"; "The History, Theory and Practice of Motion Photography and Projection", London: "Kinematograph Weekly" (1911). CHAPTER VII