Something else conjectured by Newton in the Principia was that a plumb bob hung near a mountain would incline very slightly toward the mountain, affected by the mountain's gravitational mass as well as by the Earth's.

牛顿在《原理》中作的另一个推测是：一根挂在大山附近的铅锤线，会受到大山和地球引力质量的影响，稍稍向着大山倾斜。