Book excerpt: Squeezed between a vast ocean and the longest mountain range on earth, Chile is 2,600 miles long and never more than 110 miles wide--not a country that lends itself to maps, as Sara Wheeler discovered when she traveled alone from the top to the bottom, from the driest desert in the world to the sepulchral wastes of Antarctica. Eloquent, astute, nimble with history and deftly amusing, Travels in a Thin Country established Sara Wheeler as one of the very best travel writers in the world.