His aim was to search out feasible routes and determine such primary controls as mountain passes or suitable river crossings and to locate major obstacles such as steep slopes or marshes.

• 其目的是找出可行的线路，确定诸如山口以及适当的河流渡口等主要标志，并且还要确定主要障碍，如:斜坡或沼泽的位置。