PROJECTS Remaking History
vacuum in a space, who could say otherwise?
In an earlier column of Remaking History,
we explored the Magdeburg hemispheres, a
famous vacuum-related demonstration built
by the German experimenter Otto von Guericke
(see page 83). Von Guericke is given credit for
inventing the very first vacuum pump, but his
pump was inefficient and nearly impossible to use
for any real scientific purpose.
In order to carry out the important experiments
that Boyle wanted to attempt, a better, faster,
and more dependable pump had to be invented.
Boyle had built for him a series of three different
pumps, each one able to generate deeper and
longer lasting vacuum conditions than the one
before it.
In this column, we will build a replica of Boyle’s
second pump, originally designed and built for
him by Christiaan Huygens (Figure
A
). If built
with care, it can pull a fairly deep vacuum, which
is useful for all sorts of fun and interesting
experiments. Just as importantly, you can get a
true appreciation for just how difficult it was for
scientists like Boyle, Huygens, von Guericke, and
other early experimenters to construct their own
scientific instruments.
BUILD YOUR OWN BOYLE AIR PUMP
During the course of this project, refer to
Figure
B
to understand how the components
are arranged.
1. BUILD A STURDY BASE
Manually pumping the air out of a bell jar is hard
work. The piston we’ll be using measures 2" in
diameter, so the amount of force required to move
the piston against near-atmospheric vacuum is
in the neighborhood of 45 pounds. That’s a lot of
force, so a sturdy base is a must.
Figure B shows one way to build a base. You
have a lot of latitude here; the important thing is
having a surface at least 24" long by 10" wide and
24" high, to hold the bell jar and provide adequate
room to operate the pump. I used two 2×6s for
the top and 2×4s for the legs and other support
pieces, connected with deck screws.
2. MAKE A PISTON
Boyle made his pump out of a brass cylinder and
a leather-covered wooden piston. But that was
before the O-ring was invented. Take it from me,
rubber O-rings are much better at stopping leaks
than leather covers.
80 makezine.com
A B
Vacuum gauge
Stopper
Vacuum port
Diverting valve
Bell jar
Handle
Crank
10"
24"
24"
PTC
PTC
fitting
Cylinder
Guide plate
Bell jar
plate
Boyle air pump built by
Christiaan Huygens.
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