Giovanni Alfonso Borelli

Italian physicist and physiologist

• Born: January 28, 1608
• Birthplace: Naples, Kingdom of Naples (now in Italy)
• Died: December 31, 1679
• Place of death: Rome, Papal States (now in Italy)

Borelli, a scientist with wide-ranging accomplishments, founded the field of biophysics (iatrophysics) with his pioneering work on the mechanical basis of muscular motions, respiration, and circulation in animals. He made significant contributions to mathematics, astronomy, physics, mechanics, hydraulics, medicine, epidemiology, and physiology.

Early Life

Giovanni Alfonso Borelli (jyoh-VAHN-nee ahl-FON-soh buh-REHL-lee), named Giovanni Francesco Antonio Alonso at birth, was the son of a Spanish soldier in the garrison in Naples, whose political problems led Borelli to suppress connections to his father, including his own date and place of birth. He may have had early instruction from the Catholic Humanist and empiricist Tommaso Campanella when Campanella was a prisoner of the Spanish Inquisition at Castel Nuovo in Naples, where Borelli’s father was stationed. It is also thought by some scholars that Borelli attended the medical school at the University of Naples, but no records of this have been found.

In about 1628, Borelli went to Rome and became a student of one of Galileo’s disciples, Benedetto Castelli. Along with Borelli was another student, a promising young scientist named Evangelista Torricelli . Perhaps at the recommendation of Castelli, Borelli took a position in 1637 as a public lecturer in mathematics at the University of Messina in Sicily. His scientific work led the senate of Messina to send him on a mission in 1641 and 1642 to Italian centers of learning to enlist lecturers for the university. He continued teaching for another fourteen years at Messina, where he became professor of mathematics in 1649. He was asked by the senate of Messina in 1647 to study a fever epidemic in the region, leading to the publication in Rome of a pamphlet entitled Delle cagioni de le febbri maligna (1649; on the causes of malignant fevers), which suggested contagious causes and chemical cures of fevers rather than the then-accepted astrological or meteorological causes of fevers.

Life’s Work

While still at the University of Messina, Borelli began a compendium of the four surviving books of the Greek mathematician Apollonius on conic sections, although it was not published until 1679. He also wrote a concise version of Euclid’s works on geometry entitled Euclides restitus (1658; Euclid restored), which led to his appointment as professor of mathematics at the University of Pisa in 1656 at the invitation of the Medici family.

During a decade in Tuscany, Borelli was especially active in the Accademia del Cimento (academy for experiments) and the experimental programs organized by Prince Leopold de’ Medici. At the University of Pisa he became a friend and mentor of Marcello Malpighi, whose pioneering work with the microscope led him to discover the capillary veins, confirming William Harvey’s theory of the circulation of the blood. The younger Malpighi stimulated Borelli’s interest in applying physical laws to biology, and he conducted dissections that aided Borelli in his groundbreaking research on animal movements. He also worked on lagoons near Pisa for the grand duke of Tuscany, Ferdinand II de’ Medici, and edited books on hydraulics. In 1665, he published a letter under the pseudonym Pier Maria Mutoli, which contained the first suggestion that comets travel along a parabolic path under the influence of the sun.

While still at Pisa, Borelli established an observatory in 1665 at the fortress of San Miniato outside Florence, using instruments he had designed. His most important work during this time was his research on Jupiter’s moons, which helped to establish a physical framework for the Copernican system without drawing the opposition that Galileo had experienced by emphasizing Earth’s motion. He introduced the idea that the planets are held in their orbits by an attractive force toward the Sun, based on a similar concept for the Galilean moons held in orbit by attraction toward Jupiter. However, he thought that this force of attraction had to be balanced by an outward centrifugal force to keep the planets in orbital equilibrium, rather than the later idea of Isaac Newton that the force of attraction prevents inertial motion in a straight line and causes orbital motion. Borelli published his ideas in an influential book entitled Theoricae Mediceorum planetarum ex causis physicis deductae (1666; theory of the Medicean planets deduced from physical causes).

Borelli left Tuscany in 1667 to return to his professorship at Messina. The same year, he published an expanded version of his research in physics at the Accademia del Cimento under the title De vi percussionis (1667; on percussion forces). The violent, historic eruption of Mount Etna in 1669 gave Borelli the opportunity to apply the laws of fluid motion to volcanic action in a pioneering contribution to volcanology. After five years in Messina, Borelli was forced to leave Sicily because of suspicions about his involvement in an anti-Spanish rebellion that had occurred in Messina in 1670.

In 1672, Borelli moved to Calabria in southern Italy and then to Rome, where in 1675 he joined the Academia Reale, established by Queen Christina of Sweden after her abdication and conversion to Roman Catholicism. Christina provided some support for Borelli, who served as her physician, and she encouraged him in his work on the movement of animals, offering to pay for the work’s publication. Arrangements were being made to publish this work when all his belongings were stolen in 1677.

In financial distress, Borelli accepted the hospitality of the Clerks Regular of the Pious Schools in Rome, where he taught mathematics to novices of the order (the Piarists) during the last two years of his life (1677-1679). During this time, he completed writing his masterpiece, the two-volume De motu animalium (1680-1681; On the Movement of Animals, 1989), which was dedicated to Queen Christina and published after his death. This pioneering work used the methods of Galileo to analyze the action of muscles acting on lever arms formed by bones. The first volume examined external motions, and the second volume described the internal actions of muscles, the heart, blood circulation, and respiration.

Significance

Borelli, along with Torricelli, Galileo’s secretary in the last three months of his life, carried on the scientific tradition that Galileo had initiated in Italy in spite of opposition from the Roman Catholic Church. Borelli’s work on the moons of Jupiter was the first to suggest that the force on an orbiting moon or planet was an attractive force toward the center of motion rather than a tangential force in the direction of motion. This extended and clarified Galileo’s ideas about orbital motions and was a major step toward the work of Newton, which finally resolved the problem of planetary motion in a heliocentric system. This same idea led Borelli to offer the first explanation for the motion of comets.

Borelli’s work on the movement of animals was the first application of Galileo’s methods to biology and one of the first attempts to develop the view of French philosopher René Descartes that the body can be viewed as a machine subject to mechanical principles. It initiated the historical school of iatrophysics (medical physics) by demonstrating the mechanical basis of muscular contractions, blood circulation, and respiration. In this respect, Borelli can be viewed as the founder of the discipline of biophysics.

Bibliography

Boorstin, Daniel. The Discoverers: A History of Man’s Search to Know His World and Himself. New York: Random House, 1983. This engaging book has a brief description of the work of Borelli in relation to that of Marcello Malpighi, who discovered the capillary veins, including their mutual support and friendship, and their eventual estrangement.

Borelli, Giovanni Alfonso. On the Movement of Animals. Translated by P. Maquet. New York: Springer-Verlag, 1989. A translation of Borelli’s major work. Includes illustrations, a bibliography, and an index.

Hall, A. Ruppert. From Galileo to Newton. New York: Dover, 1981. Borelli’s work in physiology is discussed in chapter 7, which includes diagrams of his mechanical analysis of muscle action. His work in astronomy is discussed in chapter 10 in relation to Newton’s law of universal gravitation.

Koyré, Alexandre. The Astronomical Revolution: Copernicus, Kepler, Borelli. New York: Dover, 1992. Translated by R. E. W. Maddison. Paris: Hermann, 1961. This English translation includes excerpts and diagrams from the astronomical work of Borelli.

Rossi, Paoli. The Birth of Modern Science. Malden, Mass.: Blackwell, 2001. Translated by Cynthia de Nardi Ipsen. Rome: Gius, Laterza & Figli, 2000. This English translation includes a brief discussion of Borelli’s mechanical physiology in chapter 9.