In 1643 Italian physicist Evangelista Torricelli filled a tube with mercury to the top, then capped the top with his finger, then positioned the sealed top into the bowl of mercury, then slipped out his finger, then inverted the tube vertically upside down, a vacuum then formed at the top of the tube; he then measured the height of the column of mercury to be 72 centimeters. The vacuum has since come to be known as a Torricellian vacuum. |