With no road signs and few maps, they had to put their trust in directions passed by word of mouth and in secret signsnails driven into trees, for example-that conductors used to mark the route north.

• 没有路标，地图也很少，他们只好相信别人给他们所指路的方向以及自己辨认那些钉在树上的暗号：例如，通常过往的向导都会留下向北的路标暗号。