They chose the Andes because they needed to measure near the equator, to determine if there really was a difference in sphericity there, and because they reasoned that mountains would give them good sightlines.

他们选择了安第斯山脉，因为他们需要测量靠近赤道的地方，以确定那里的圆度是否真有差异，还因为他们认为山区的视野比较开阔。