Torricelli showed that if you take a glass tube
closed on one end,
fill it with mercury, and invert it into a
cistern,
not all of the mercury leaves the tube,
leaving a gap at the closed end.
Water barometers had been made before
but no one before Torricelli realized
that the weight of the atmosphere
balanced the weight of the liquid in the tube.
The difficulty was that scientists believed
that air was weightless
and that a vacuum was an impossibility.
After all, if nothing was in the gap then what propagated
the light?
Pascal showed that the gap was a vacuum,
that the mechanical weight of the atmosphere
decreased as you ascended. If you hike high
enough,
you would reach the vacuum of space.
Perspective
From an airplane window
Canada looks flat. Mountains and valleys
are smashed into a plain of snow.
Perfectly good logic
Perfectly good logic
can begin with
foregone conclusions.
Perfectly good logic
convinced everyone
light couldn’t pass
through a vacuum.
But that was when
outer space was filled
with luminiferous aether
and air with phlogiston.
Torricelli was the first scientist to point out that wind is
caused by differences of atmospheric pressure.
Pascal’s law applies to liquids and gases. Pressure on
a fluid at any point is transmitted undiminished throughout the
fluid to all constraining points. Equal areas experience equal
pressure, so that the pressure transmitted to an area is
proportional to the size of the area.
Otto von Guericke invented the first vacuum pump and
conducted his famous Magdeburg hemispheres experiment to
demonstrate the force of atmospheric pressure.
Torricelli was the first scientist to point out that wind is caused by differences of atmospheric pressure.
Pascal’s law applies to liquids and gases. Pressure on a fluid at any point is transmitted undiminished throughout the fluid to all constraining points. Equal areas experience equal pressure, so that the pressure transmitted to an area is proportional to the size of the area.
Otto von Guericke invented the first vacuum pump and conducted his famous Magdeburg hemispheres experiment to demonstrate the force of atmospheric pressure.
See also in The book of science:
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