研究液体内部压强的实验，传统的做法是将压强计的金属盒浸没在烧杯的水中，改变金属盒上橡皮膜的方向是靠一个相当于皮带传动的装置进行的．这种方法有如下缺点：１）用手悬空提着传动装置进行调节时，难免会引起金属盒在水中抖动或晃动，压强计上的示数就不稳定，难以观察； Experiments to study the internal pressure of liquids have traditionally been done by immersing the piezometer metal box in the beaker's water and changing the direction of the rubber film on the metal box by means of an equivalent belt drive. This method has the following shortcomings: 1) when carrying the actuator with the hand suspended, it will inevitably cause the metal box to shake or shake in the water, the gauge on the pressure gauge will be unstable and hard to be observed;