Chapter 1 Introduction to Fluid Power 23
the device was considered to be an interesting toy,
rather than a practical machine. His more practi-
cal and enduring contributions relate to basic con-
cepts of fluid flow and the study of the principles
of the siphon.
Leonardo da Vinci is a name commonly associ-
ated with the fine arts, but he also must be consid-
ered an equal genius in many other fields. During
the latter part of the fifteenth and early part of the
sixteenth centuries, he worked extensively in the
engineering and architectural fields in Italy and
France. He made many contributions in the fields
of mechanical design and fluid mechanics that
involved the flow of water, hydraulic machinery,
and principles that closely match the later work
of Pascal. As with many other early scientists, his
work was recorded as private notes, many of which
have been discovered only in recent years.
Blaise Pascal is usually credited with the basic
principle that is the foundation of the fluid power
industry, Figure 1-12. During his relatively short
life (1623–1662), he experimented extensively with
liquids and mechanical devices, including siphons,
syringes, and tubes. This work produced the proof
that many previous mathematicians and scientists
had sought:
In a fluid at rest, pressure
is equally transmitted in all
directions.
He is also credited with demonstrating and
clearly defining the principles involved in the
hydraulic press: multiplication of force, and piston
movement relationships.
The English scientist Robert Boyle (1627–1691)
was one of the first to work with the characteris-
tics of gases. He referred to this as the “springi-
ness of air.” By direct measurement, he was able
to establish:
If the temperature of a dry gas is
held constant, its volume inversely
varies with its pressure.
Today, this principle is referred to as Boyle’s law.
As in most other situations where new laws or
principles are under development, Boyle was not
the only person to do fundamental work in the
area of gases. Otto von Guericke (1602–1686) from
Germany was also involved in experimentation
with gases. He developed a vacuum pump in 1650.
He used this pump to demonstrate the pressure of
the atmosphere by pumping the air from a sphere
constructed of two equal parts. Once the air had
been removed, the pieces could not be pulled apart
by horses.
Figure 1-11. Archimedes is credited with the design
of the water screw, which has been used to move
and lift water since the third century BC. The basic
principles found in this device are still used in mod-
ern fl uid power components.
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and its licensors. All rights reserved.)
Figure 1-12. Blaise Pascal developed during the
1600s what is now called Pascal’s law. He is one
of a number of individuals who worked during the
fi fteenth through the eighteenth century identifying
and proving basic principles by using the scientifi c
method.
(©2007
Jupiterimages and its licensors.
All rights reserved.)