In 1831, American inventor Cyrus Hall McCormick invented the first successful reaping machine, which marked a great advance in the field of agriculture. Keep learning on MSN Encarta.
This Week: Itchy, Scratchy What makes us itch? Bill Nye the Science Guy speculates on this head-scratching mystery. Take the body quiz If our skin is our largest organ, no wonder we're so itchy. Is Bigfoot ticklish? Since he's so shy, nobody's sure -- yet.