This reference work describes the trial-and-error experiments, discoveries, and inventions of early humans who lived from before recorded history to the Middle Ages. Krebs travels through the ancient periods of Egypt, China, and Mesoamerica, to the classical Greek and Roman periods, and finally to the Christian era, providing students with the link between science and history, while revealing information about many cultures around the world. Each entry provides the who, when, and where of each discovery, invention, or experiment. Entries include calendars, gunpowder, anesthesia,...