If the mass is displaced from its rest position and released, it will oscillate up and down. 质量如果离开它的静止位置后再释放，将作上下振荡。
When the galvanometer reads zero the circuit is in the null-balance position. 当检流计的读数为零时，电路处于零平衡位置。
The bar would naturally tend to fall down from the top vertical position, which is a position of unsteady equilibrium. 棒子会有自然的趋势从最高的竖直位置下落，那是一个不稳定的平衡位置。
