Alfred W. Crosby, Jr. is professor emeritus of American studies, history, and geography at the University of Texas, Austin. He is the author of Ecological Imperialism: The Biological Expansion of Europe, 900-1900 (1986), America's Forgotten Pandemic: The Influenza of 1918 (1989), The Measure of Reality: Quantification and Western Society, 1250-1600 (1997), and most recently Throwing Fire: Projectile Technology through History (2002).