Evangelista
Torricelli created a barometer, used to
measure the current air pressure at a particular
location in inches of Mercury. It is a
simple machine that places a tube with a vacuum
into a plate of liquid mercury, where the air
pressure pushes down on the mercury thereby
pushing mercury into the tube. The height
of the column indicates the amount of air
pressure, hence the name of the unit "inches of
Mercury" [6]. This type of barometer is
shown in Figure 1. Recall that a reading
of 29.29 inches of Mercury is equivalent to 1
atm.
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Figure 1
Torricelli's Barometer [5]
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