The existence of atmospheric pressure was strongly proved by two copper hemispheres, which were pressed together by vacuum in the middle of the experiment.

Torricelli, an Italian scientist, measured the height of the mercury column supported by atmospheric pressure with a glass tube, that is, 76cm, which was later defined as 1 standard atmospheric pressure, and its specific value was1.013×105pa.

So, the answer is: the experiment in the hemisphere of Madeborg; Torricelli