Giovanni Alfonso Borelli (28 January 1608 - 31 December 1679) was a Renaissance Italian physiologist, physicist, and mathematician. He contributed to the modern principle of scientific investigation by continuing Galileo's custom of testing hypotheses against observation. Trained in mathematics, Borelli also made extensive studies of Jupiter's moons, the mechanics of animal locomotion and, in microscopy, of the constituents of blood. He also used microscopy to investigate the stomatal movement of plants, and undertook studies in medicine and geology. During his career, he enjoyed the patronage of Queen Christina of Sweden. Biography Giovanni Borelli was born on 28 January 1608 in the district of Castel Nuovo, in Naples. He was the son of Spanish infantryman Miguel Alonso and a local woman named Laura Porello (alternately Porelli or Borelli.) Borelli eventually traveled to Rome where he studied under Benedetto Castelli,

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Borelli and Malpighi were both founder-members of the short-lived Accademia del Cimento, an Italian scientific academy founded in 1657. It was here that Borelli, piqued by Malpighi's own studies, began his first investigations into the science of animal movement, or biomechanics. This began an interest that would continue for the rest of his life, eventually earning him the title of the Father of Biomechanics. Borelli's involvement in the Accademia was temporary and the organization itself disbanded shortly after he left.

Borelli returned to Messina in 1668 but was quickly forced into exile for suspected involvement in political conspiracies. Here he first became acquainted with ex-Queen Christina of Sweden who had also been exiled to Rome for converting to Catholicism. Borelli lived the rest of his years in poverty, teaching basic mathematics at the school of the convent where he had been allowed to live. He never saw the publication of his masterwork, De Motu Animalium (On the Movement of Animals) as it was published posthumously, financed by Christina and his benefactors at the convent.
Sociopolitical climate

In 1542, the Congregation of the Holy Office (now known as the Congregation for the Doctrine of the Faith) was created by Pope Paul III to facilitate in the inquisition of heresy. This institution had influence in philosophy, mathematics, and science. The Holy Office was designed to protect the Catholic faith from ideas that were viewed as damaging to the Church. Its effects continued through the time of Borelli and on to modern times. The office was a well-structured, localized system that targeted new ideas considered to be dangerous by the Church. In addition to containing these ideas, the Holy Office could also punish the offending parties who brought the ideas into the public domain. This institution was one of many ways in which the Catholic Church responded to the Protestant Reformation of the sixteenth century.

Although Borelli lived and worked within this climate, the Holy Office did not hinder his work, perhaps because the Church did not find his work to be damaging to the faith. His work, and the work of many others, however, may still have been influenced by the Holy Office’s treatment of his contemporary Galileo Galilei. His work resembled that of many of his contemporaries in that he started to adhere to the rules of scientific exploration that are used in modern times, that is, building hypotheses and theories based on observations in the natural world, and then testing them.

Scientific achievements

Borelli’s major scientific achievements are focused around his investigation into biomechanics. This work originated with his studies of animals. His publications, De Motu Animalium I and De Motu Animalium II, borrowing their title from the Aristotelian treatise, relate animals to machines and utilize mathematics to prove his theories. The anatomists of the 17th century were the first to suggest the contractile movement of muscles. Borelli, however, first suggested that ‘muscles do not exercise vital movement otherwise than by contracting.’ He was also the first to deny corpuscular influence on the movements of muscles. This was proven through his scientific experiments demonstrating that living muscle did not release corpuscles into water when cut. Borelli also recognized that forward motion entailed movement of a body’s center of gravity forward, which was then followed by the swinging of its limbs in order to maintain balance. His studies also extended beyond muscle and locomotion. In particular he likened the action of the heart to that of a piston. For this to work properly he derived the idea that the arteries have to be elastic. For these discoveries, Borelli is labeled as the father of modern biomechanics and the American Society of Biomechanics uses the Borelli Award as its highest honour for research in the area.

Along with his work on biomechanics, Borelli also had interests in physics, specifically the orbits of the planets. Borelli believed that the planets were revolving as a result of three forces. The first force involved the planets' desire to approach the sun. The second force dictated that the planets were propelled to the side by impulses from sunlight, which is corporeal. Finally, the third force impelled the planets outward due to the sun’s revolution. The result of these forces is similar to a stone’s orbit when tied on a string. Borelli's measurements of the orbits of satellites of Jupiter are mentioned in Volume 3 of Newton's Principia.

Borelli is also considered to be the first man to consider a self-contained underwater breathing apparatus along with his early submarine design. The exhaled gas was cooled by sea water after passing through copper tubing. The helmet was brass with a glass window and 0.6 m (2 ft) in diameter. The apparatus was never likely to be used or tested.

. Submarine, by Giovanni Alfonso Borelli, in De Motu Animalium, 1680

Borelli also wrote:

    Della cagioni delle febbri maligne (Pisa, 1658)
    Euclides Restitutus (Pisa, 1658)
    Apollonii Pergaei Conicorum libri v., vi. et vii (Florence, 1661)
    Theoricae Mediceorum planetarum ex causis physicis deductae (Florence, 1666)
    De vi percussionis (Bologna, 1667)
    Meteorologia Aetnea (Reggio, 1669)
    De motionibus naturalibus a gravitate pendentibus (Bologna, 1670)