1. They felt the ground quake as the bomb exploded.
    炸弹爆炸时, 他们觉得地都震动了.

2. The ideal to be aimed at was to devise an instrument that could record with a pen on paper, the movements of the ground or of the table as the quake passed by.
    理想的目标是设计出这样一种仪器：当地震发生时，它能用笔在纸上记录下大地和桌子运动情况。

3. Perhaps most interesting, and most easily measured, is a chemical change in ground water before a quake.
    也许最有趣、也最容易测量的，是地震前地下水发生的化学变化。