Whose experiment proved air has weight?

In 1643 Evangelista Torricelli, a student of Galileo, filled a tube with mercury and inverted it in a dish, showing that the weight of the atmosphere held up a column of mercury. This invention, the barometer, proved that air has weight and exerts pressure. A few years later Otto von Guericke staged a famous demonstration with two metal hemispheres pressed together with the air pumped out; teams of horses could not pull them apart because of the surrounding air pressure. These experiments overturned the old idea that nature abhors a vacuum. They laid the groundwork for the study of gases and the atmosphere.