马德堡半球    

        1654年德国马德堡市市长、学者奥托·格里克将两个直径38厘米的空心半球贴在一起，中间夹着一个皮革作的密封圈，把球中的空气抽掉，用八对马也没有拉开，使在场的人大为震惊，这就是有名的 “马德堡半球” 实验。我们这里分别做了3个内径为8厘米、10厘米、12厘米的半球，你可用尽全力试试看，能否把它们拉开?具体操作如下:1. 将上半球沿导向柱向下推，使其与下半球合拢；2. 按下按钮。电磁阀被驱动，使下半球出口与真空系统相连球内被抽空（可观看真空表指针的指示）后，你用力拉上半球。为什么虽然球径不大，但你却拉不开呢？原来当把上下两个半球合拢，球内抽成真空后，球受外压作用，大气压作用在一个F10cm直径的球上的力,约有七、八十公斤，一个人是很难拉开的。马德堡半球实验显示了大气压的威力。[注：小球（内径为8厘米）是为儿童准备的。]

Magdeburg Hemispheres    

        Magdeburg hemisphere test: O. Ven, Gerike mayor of Magdeburg in Germany made a test: He exhausted air from two copper hollow hemispheres with 38cm diameter, combined in a whole sphere. Then, eight horses in every side pulled the hemispheres from two opposite directions to separate them, but couldn’t do it anyway. The test shows the great power of the pressure difference between atmosphere and vacuum.In this exhibit there are three pairs of holloe hemisphere with diameters 8,10 and 12 cm. After the air inside the hemisphere is exhausted, visitor can try to separate them. It needs about 70-80kg to separate the hemispheres with 10cm diameter.