He was able to estimate the annual increment of salt to the oceans.
他能够估算出海水中盐分的年增量。
2
They sighted each pole, reading off measurements that were then used to calculate the change in elevation over each increment.
他们瞄准了每个极点，读出测量值，然后用这些测量值来计算每个增量上的海拔变化。
3
Surveyors marched inland from the coast for thousands of miles, stopping at increments of as little as a few feet to measure their elevation, and marking each increment with two poles.