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PageGalileo Galilei (1564-1642) William Harvey (1578-1658)
Giovani Alfonso Borelli (1608-1679) Thomas Young (1773-1829)
Herrmann von Helmholtz (1821-1894)
Galileo Galilei was a student of medicine before he became famous
as a physicist. He discovered the constancy of the pediod of a
pendulum, and used the pendulum to measure the pulse rate of
people, expressing the results quantitatively in terms of the
lenght of a pendulum syncrnous to the heart.
Galielo's fame was so grea and his lectures in Padua so popular
that his influence on biomechanics went far beyond his personal
contribtions. According to Singer (History, p. 237), William
Harvey should be regarded a disciple of Galileo. Harvey studied
in Padua (1598-1601) while Galileo was active there. By 1615
Harvey had formed the concept of circulation of blood. He
published his demonstration in 1628. The essential part of his
demonstration is the result not of mere observation but of the
application of Galieleo's principle of measurement. He showed
first thatthe blood can only leave the ventricle of the heart in
one direction. Then he measured the capacity of the heart, and
found it to be about two ounces. The heart beats 72 times a
minute, so that in one hour it throws into the system 2x72x60
ounces =8640 ounces = 234 kg! Where can all this blood come from?
Where can it all go? He concludes that the existence of
circuation is a necessary condition for the function of the
heart. (p.3)
Giovanni Alfonso Borelli was an eminent Italian mathematician and
astronomer, and a friend of Galieleo. His On the Motion of
Animals (De Motu Animalum) 1680 is a classic. He was succesful in
clarifying muscular movement and body dynamics. He treated the
flight of birds and the swimming of fish, as well as the movement
of the heart and the intestines.
Thomas Young studied the formation of human voic, identified it
as vibrations, connected it with the elasticity of materials,
gave us the legacy of Young's modulus, then developed the wave
theory of light, and a theory of color vision, as well as the
solution to a practical problemof astigmatism of lenses.
"When I took a degree in physic (medicine) at Gottingen, it was necessary, besides publishing a medical dissertation, to deliver a lecture upon some subject connected with medical studies, and I choose for this the Formation of the Human Voice... When I began the outline essay of the human voice, I found myself at a loss for a perfect conception of what sound was, and during the three years that I passed at Emmanuel College, Cambridge, I collected all the information relating to it that I could procure from books, and I made a variety of original experiments on sounds of all kinds, and on the motions of fluids in general.
T. Young, Reply to the Edinburgh Reviewers, 1804, Works, ed.
Peacock Vol. I, pp. 192-215.
Singer CJ (1959) A Short History of scientific Ideas to 1900
Oxford University Press, New York.
To Herrmann von Helmholtz might go the title "Father of
Bioengineering". He was profesor of physiology and pathology
in Konigsberg, professor of anatomy and physiolgy at Bonn,
professor of physiology at Heidelberg, and finally professor of
physics in Berlin (1871). He wrote his paper "On the Law of
Conservation of Energy" while he was in military service
fresh out of medical school. Hiscontributions ranged dover
optics,acoustics, thermodynamics, electrodynamics, physiology and
medicine. He discovered the focusing mecanism of the eye and,
following Young, formulated the trichromatic theory of color
vision. He studied the mechanism ofn hearing. He was the first to
determine the velocity of nerve pulse, giving the rate 30 m/s,
and to show that the heat released by muscular contraction is an
important source of animal heat.
Source: Fung YC, Biomechanics: Mechanical Properties of
Living Tissues, Springer-Verlag, 1993.
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