Background

Marin Mersenne was born on September 8, 1588, in Oizé, Pays de la Loire, France to the family of a laborer who escaped the poverty of his birth by the education which may have been subsidized by the Jesuits.

Education

It appears that his family was of quite modest means, and it is likely that Mersenne received external financial support during the course of his studies. Mersenne studied at the College of Mans. He then was educated at the Jesuit college of La Flèche soon after its founding in 1604. He may have met there the young René Descartes, who entered La Flèche in 1606, although it is unlikely that their friendship started then, as Descartes was 8 years his junior but later they became lifelong friends. When he left the college, Mersenne completed his training in theology, Greek and Hebrew in Paris at the Collège Royal and at the Sorbonne where he was instructed by the Thomist theologians François Ysambert and Philippe de Gamache.

Mersenne left Paris in 1614 but returned in 1620 and settled at the convent of L'Annonciade. There he studied mathematics and music and met with other kindred spirits such as René Descartes, Étienne Pascal, Pierre Petit, Gilles de Roberval, Thomas Hobbes, and Nicolas-Claude Fabri de Peiresc. He corresponded with Giovanni Doni, Jacques Alexandre Le Tenneur, Constantijn Huygens, Galileo Galilei, and other scholars in Italy, England, and the Dutch Republic.

Career

Mersenne entered the Order of Minims on 16 July 1611 and was ordained a priest in Paris in July 1612 after a two and a half month probationary period in the monasteries at Nigeon and Meaux. His first posting was in 1614 to the monastery in Nevers where he taught philosophy and theology to the younger members of the community. In fact one of his students, Hilarion de Coste, later became his confidant and biographer. It was during this period of his life that he is thought to have discovered the cycloid - a geometric curve.

After two years teaching Mersenne was elected superior of the Minim Convent de I’Annonciade near Place Royale, now Place des Vosges in Paris where he remained, except for brief journeys, until his death in 1648. It is believed that the Church supported him for most of his life, although in later years a fellow monk, Jacques Hallé, helped out with money and granted him access to his library. From the beginning of his time in Paris, mathematical problems played an important role in his life. The Minims recognized that Mersenne could best serve their interests through an apostolate of the intellect.

Minimizing worldly concerns may have been a major concern of Mersenne's religious order, but it hardly kept him from contact with the larger world. His correspondence with the leading scientific and philosophical thinkers of his time quickly became legendary. Mersenne's letters spanned much of the known world and consisted not only of his own insights but also of exhortations to the recipients of his letters that they pursue certain fields of inquiry or investigation. Furthermore, Mersenne invariably introduced his own correspondents to others with whom they might pursue independent correspondence. Thus he established a network of communications that reinforced, enriched, and extended the body of knowledge.

Mersenne also devoted much effort to theories of the nature of prime numbers, particularly large prime numbers. Although some of his theories proved to be flawed, today a number of computer programs are devoted to searching for what is still called Mersenne Primes.

In 1623 he published his first two papers consisting of studies against atheism and skepticism in France; L'usage de la raison and L'analyse de la vie spirituelle. Continuing his theological writing he had then wanted to disprove magic, however, a fellow monk pointed out that it was not appropriate, leading to his publication of Quaestiones celeberrime in genesim that includes the disapproval of magicians in the Scriptures. This book contains 1900 columns of text from the Bible in its first six chapters. It was because of this publication that, in September 1624 when he returned to Paris, he met Gassendi who had been asked to comment on Mersenne's results, and later became his closest friend.

The period between 1627 and 1634 was a transitional period in Mersenne's life. During this time he traveled to Holland for several months between 1629 and 1630. His main reason was to seek a cure for an illness with the help of spa water but he used the opportunity to visit scholars in the surrounding areas. The greater maturity in his writing in the seven years since his last publication became apparent when Questions inouyes and Questions harmoniques were printed in 1634. In October 1644 Mersenne traveled to Provence and Italy where he learned of the barometer experiment from Torricelli. On his return to Paris, he reported this news to encourage French scholars to carry out the experiments too.

Galileo also has to be grateful to Mersenne for making his work known outside Italy. Mersenne insisted on publishing Galileo's work and without this Galileo's ideas might never have become as widely known. Continuing his travels into his old age, in 1646 Mersenne set off on a trip to Bordeaux. There he met Pierre Trichet whom he helped make his mark. The success of the scientific life over in Bordeaux and Guyenne, which later formed the Académie Royale des Sciences, was largely due to the advice and experience Mersenne was able to offer. He returned to Paris in 1647.

Mersenne fell ill after his visit to see Descartes in July 1648 and, unfortunately, his health never improved. He was advised to mix wine with his water to help him get better, however, Minims do not drink wine. He had an abscess on the lung but the surgeon was unable to find it. Mersenne himself pointed out that the incision, which he asked for, had been attempted too low. Gassendi was there for Mersenne throughout his illness and remained with him until his death on 1 September 1648 in Paris, just 8 days from his 60th birthday. He never gave up his life-long desire to advance science. He even asked, in his will, that his body be used for biological research.

After Mersenne's death, letters in his cell were found from 78 different correspondents including Fermat, Huygens, Pell, Galileo, and Torricelli. Also, several physics instruments were found in his cell and a lot of Mersenne's library was retrieved from which L'optique et la catoptrique was published in 1651. Inside this publication, one of Roberval's texts was inserted. Later all the letters he sent and received from other scholars were accumulated and published in several volumes. These letters read like an international review of mechanics in the early 17th century. Mersenne was aware of all the science that was going on, what all the scientists were doing, and only wanted for them all to work together in advancing science.

Mersenne studied the cycloid for several years quoting his research in Quaestiones in Genesim (1623), Synopsis mathematica (1626) and Questions inouyes (1634). He gave the definition of a cycloid as the locus of a point at distance h from the center of a circle of radius a, that rolls along a straight line. He stated the obvious properties including the length of the baseline equals the circumference of the rolling circle. We note that Mersenne referred to the cycloid as the 'roulette' but the term cycloid was adopted later. He attempted to find the area under the curve by integration but having failed, so he put the question to Roberval. In 1638 he announced that Roberval had indeed found the area under the cycloid.

Mersenne undertook experiments to test Galileo's law of motion for falling bodies. In 1634 he presented the results that he had obtained when measuring the acceleration of falling bodies from heights of 147, 108 and 48 feet. These confirmed the time-squared law that Galileo had published in his Dialogue on the two chief world systems of 1632 but they also raised questions about the numerical data. One problem he tried to solve was whether acceleration was continuous as Galileo maintained or discontinuous as Descartes believed. Mersenne thought Galileo's assumption that a falling body passes through infinite degrees of speed was incompatible with a genuinely mechanistic explanation of acceleration.

In some of his non-mathematical works Mersenne looks at permutations and combinations. He states practical rules for calculating the number of combinations or permutations, solving the problem of finding the number of permutations with or without repetitions and gives an example of the making of anagrams. His main reason to study combinatorial analysis was, however, to optimize musical composition as he explains in The book on the art of singing well which is Book Six of Harmonie universelle (1636). In an unpublished manuscript preserved in the Bibliothèque Nationale in Paris, he gave the 40320 permutations of 8 notes.

During the final four years of his life, Mersenne spent a lot of time investigating the barometer. Pascal had already proved that air was not weightless and it was Mersenne who found the density of air to be approximately 1/19th that of water. He was informed of the barometer experiment, consisting of a glass tube about 3 feet long sealed at one end and filled with pure mercury, through several letters from De Verdus but it was not until October 1644, when he visited Torricelli in Italy, that he saw the experiment carried out. Torricelli used the pressure of the air to explain why the mercury moved up the glass tube. Mersenne was doubtful that the air pressure actually supported the mercury and on his return attempted to re-do the experiment but did not have the necessary equipment. Mersenne explained the problem to Étienne Pascal, his son Blaise Pascal, Petit, Roberval, and others in Paris. There is some confusion as to who, in 1647, initially suggested the experiments with the Torricellian tube and the mountain, later to be called the Puy de Dome experiments. Certainly, Mersenne had briefed both Huygens and Le Tenneur but it was not until three weeks after Mersenne's death in 1648 that these experiments were carried out. They consisted of collecting results both at the foot of the Puy de Dome and at the summit. Tests were made as to whether the level of mercury in the column was lower when at the top of the mountain than it was at the bottom. If this had proved to be true, they realized that this would be due to the pressure of the air alone. Perier, who finally conducted the experiments, did indeed find that there was a significant difference in the level of the mercury hence drawing the correct conclusion that the air pressure was supporting it.

Achievements

• Throughout his lifetime Mersenne helped many potential scientists by steering them in the right direction and advising some on the next step to take. He became a role model for Huygens whom Mersenne took under his wing and through his encouraging letters inspired Huygens' Theory of Music. The success of the scientific life over in Bordeaux and Guyenne, which later formed the Académie Royale des Sciences, was largely due to the advice and experience Mersenne was able to offer.

Works

More photos

• book

  • Harmonie universelle: the books on instruments 1637
  • L'impiété des déistes 1624
  • L'usage de la raison 1623
  • Questions Inouyes: Ou Recreation Des Scavans 1634
  • Lettere (1619-1648). Testo francese e latino a fronte 2015
  • Novarum Observationum Physico-Mathematicarum F. Marini Mersenni, T III. 1646
  • La Perspective Curieuse Du R. P. Niceron, Minime 1652
  • Cogitata Physico-Mathematica, Certissimis Demonstrationibus Explicantur 1644
  • La Verite Des Sciences: Contre Les Sceptiques Ou Pyrrhoniens 1625
  • Vniuersae geometriae mixtaeque mathematicae synopsis et bini refractionum demonstratarum tractatus 1644
  • F. Marini Mersenni Harmonicorum Libri 1636
  • Universæ Geometriæ, Mixtæque Mathematicæ Synopsis, Et Bini Refractionum Demonstratarum Tractatus, Vol. 2: Studio Et Operâ 1644

Religion

In 1611 Mersenne joined the Minim Friars, an order that took its name from its commitment to reducing worldly involvement and focusing on prayer and contemplation, study and reflection.

Views

Mersenne was beginning to realize that alongside religion it was science that really interested him. Mathematics was the area he studied in greatest depth, believing that without it no science was possible. He always had a philosophical approach to mathematics and believed that the cause of the sciences is the cause of God. So, in La vérité des sciences he proved, via many great discoveries, the value of the human mind. It was around this time that Mersenne started to become a coordinator for all European scholars. From 1623 he began to make a careful selection of savants who met at his convent in Paris or corresponded with him from all across Europe and even from as far afield as Constantinople and Transylvania (present-day Hungary). His regular visitors, or correspondents, included Peiresc, Gassendi, Descartes, Roberval, Beeckman, J B van Helmont, Fermat, Hobbes, Étienne Pascal, and his son Blaise Pascal. He set up meetings of scholars from around Europe during which they would read and review scientific papers, both national and international, exchange contacts with other scholars and plan and discuss experiments and other work. This came to be known as the Académie Parisiensis and sometimes among friends as the Académie Mersenne. It was notably one of most resourceful centers of research at that time, meeting weekly at members' houses and later in Mersenne's cell due to his weakened health. The list of Mersenne's correspondents kept increasing and Mersenne himself did not hesitate to travel to meetings with scholars all around Europe.

Mersenne had a strong interest in music and spent a lot of time researching acoustics and the speed of sound. In 1627 he published one of his most famous works, L'harmonie universelle. In this work he was the first to publish the laws relating to the vibrating string: its frequency is proportional to the square root of the tension, and inversely proportional to the length, to the diameter and to the square root of the specific weight of the string, provided all other conditions remain the same when one of these quantities is altered. Mersenne had already started encouraging the talents of others and helped them to share their ideas and results with other scholars. When Roberval arrived in Paris, after joining Mersenne's circle of scholars, his talent was soon recognized by Mersenne who encouraged him to work on the cycloid.

Mersenne insisted on publishing Galileo's work and without this Galileo's ideas might never have become as widely known.

Membership

• Order of Minims

Personality

Quotes from others about the person

• "During the first half of the seventeenth century, the debate over the Copernican hypothesis had spread beyond the ranks of astronomers and had stirred up so much controversy that the Church decided to intervene. In 1616 a theological examining body concluded that the idea of the earth's motion was philosophically false and in conflict with the Scriptures, and it suspended Copernicus's book until corrected. Historians have generally assumed that this decision and the subsequent condemnation of Galileo had such a devastating effect that scientific progress in Catholic countries was greatly retarded. However, the attitude of Mersenne, who was both a faithful member of a religious order and a central figure in the development of French science, does not support such a conclusion. An examination of Mersenne's reaction to Copernicanism indicates that no matter how disturbing the Church's decision, it was still possible, at least in France, to study Copernican ideas and to find them useful, despite some reservations. Mersenne was affected by such decisions of the Church, but less so than one might suppose." - William L. Hine, historian of science

Interests

• music

• Philosophers & Thinkers

  Aristotel

Connections

Marin Mersenne was a Roman Catholic monk thus he wasn't married and had no children.

Friend:

Rene Descartes

Acquaintance:

Galileo Galilei

Friend:

Pierre Gassendi

References

• Dictionary of Scientific Biography: Volumes 9 & 10
  1981
• Mersenne and the Learning of the Schools
  1988
• Tres cartas a Marin Mersenne
  1630