God only knows what possessed Bill Bryson, a reluctant adventurer if ever there was one, to undertake a gruelling hike along the world's longest continuous footpath—The Appalachian Trail.The 2,000-plus-mile trail winds through 14 states, stretching along the east coast of the United States, from Georgia to Maine. It snakes through some of the wildest and most spectacular landscapes in North America, as well as through some of its most poverty-stricken and primitive backwoods