Ismaël Bullialdus

Ismaël Bullialdus

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Ismaël Bullialdus was a French
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...


Bullialdus was born Ismaël Boulliau in Loudun
Loudun is a commune in the Vienne department in the Poitou-Charentes region in western France.It is located south of the town of Chinon and 25 km to the east of the town Thouars...

, Vienne
Vienne is the northernmost département of the Poitou-Charentes region of France, named after the river Vienne.- Viennese history :Vienne is one of the original 83 departments, established on March 4, 1790 during the French Revolution. It was created from parts of the former provinces of Poitou,...

, France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

, the first surviving son to Calvinists
Calvinism is a Protestant theological system and an approach to the Christian life...

 Susanna Motet and Ismaël Boulliau, a notary
Civil law notary
Civil-law notaries, or Latin notaries, are lawyers of noncontentious private civil law who draft, take, and record legal instruments for private parties, provide legal advice and give attendance in person, and are vested as public officers with the authentication power of the State...

 by profession and amateur astronomer. At age twenty-one he converted to Catholicism
Catholicism is a broad term for the body of the Catholic faith, its theologies and doctrines, its liturgical, ethical, spiritual, and behavioral characteristics, as well as a religious people as a whole....

, and by twenty-six was ordained as a priest. In 1632 he moved to Paris
Paris is the capital and largest city in France, situated on the river Seine, in northern France, at the heart of the Île-de-France region...

, where he worked as a librarian for the Bibliothèque du Roi with brothers Pierre and Jacques Dupuy, traveling widely within Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

, Holland, and Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 to purchase books. In 1657 he became secretary to the French ambassador to Holland, then once again a librarian, and in 1666 moved to the Collège de Laon. During the final five years of his life, he returned to the priesthood at the Abbey St Victor in Paris, where he died.

Bullialdus was a friend of Pierre Gassendi
Pierre Gassendi
Pierre Gassendi was a French philosopher, priest, scientist, astronomer, and mathematician. With a church position in south-east France, he also spent much time in Paris, where he was a leader of a group of free-thinking intellectuals. He was also an active observational scientist, publishing the...

, Christiaan Huygens, Marin Mersenne
Marin Mersenne
Marin Mersenne, Marin Mersennus or le Père Mersenne was a French theologian, philosopher, mathematician and music theorist, often referred to as the "father of acoustics"...

, and Blaise Pascal
Blaise Pascal
Blaise Pascal , was a French mathematician, physicist, inventor, writer and Catholic philosopher. He was a child prodigy who was educated by his father, a tax collector in Rouen...

, and an active supporter of Galileo Galilei
Galileo Galilei
Galileo Galilei , was an Italian physicist, mathematician, astronomer, and philosopher who played a major role in the Scientific Revolution. His achievements include improvements to the telescope and consequent astronomical observations and support for Copernicanism...

 and Nicolaus Copernicus
Nicolaus Copernicus
Nicolaus Copernicus was a Renaissance astronomer and the first person to formulate a comprehensive heliocentric cosmology which displaced the Earth from the center of the universe....

. It is for his astronomical and mathematical works that he is best known. Chief among them is his Astronomia philolaica, (published 1645). In this work he strongly supported Kepler's hypothesis that the planets travel in elliptical orbits around the Sun, but argued against the physical theory the latter had proposed to explain them. In particular, he objected to Kepler's proposal that the strength of the force exerted on the planets by the Sun decreases in inverse proportion to their distance from it. He argued that if such a force existed it would instead have to follow an inverse-square law
Inverse-square law
In physics, an inverse-square law is any physical law stating that a specified physical quantity or strength is inversely proportional to the square of the distance from the source of that physical quantity....

As for the power by which the Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

 seizes or holds the planets, and which, being corporeal, functions in the manner of hands, it is emitted in straight lines throughout the whole extent of the world, and like the species of the Sun, it turns with the body of the Sun; now, seeing that it is corporeal, it becomes weaker and attenuated at a greater distance or interval, and the ratio of its decrease in strength is the same as in the case of light, namely, the duplicate proportion, but inversely, of the distances that is, 1/d².

However, Bullialdus did not believe that any such force did in fact exist. After writing the above-quoted passage, he then went on to write:
... I say that the Sun is moved by its own form around its axis, by which form it was ignited and made light, indeed I say that no kind of motion presses upon the remaining planets ... indeed [I say] that the individual planets are driven round by individual forms with which they were provided ...

In his Principia Mathematica
Philosophiae Naturalis Principia Mathematica
Philosophiæ Naturalis Principia Mathematica, Latin for "Mathematical Principles of Natural Philosophy", often referred to as simply the Principia, is a work in three books by Sir Isaac Newton, first published 5 July 1687. Newton also published two further editions, in 1713 and 1726...

of 1687, Isaac Newton
Isaac Newton
Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...

 acknowledged that Bullialdus's determination of the sizes of the planets' orbits ranked with Kepler's
Johannes Kepler
Johannes Kepler was a German mathematician, astronomer and astrologer. A key figure in the 17th century scientific revolution, he is best known for his eponymous laws of planetary motion, codified by later astronomers, based on his works Astronomia nova, Harmonices Mundi, and Epitome of Copernican...

 as the most accurate then available.

Bullialdus was one of the earliest members of the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...

, London, having been elected on April 4, 1667, seven years after its founding. The Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

's Bullialdus crater
Bullialdus (crater)
Bullialdus is a lunar impact crater located in the western part of the Mare Nubium. To the north by north-west is the broken-rimmed and lava-flooded crater Lubiniezky. South-west of Bullialdus lies the smaller crater König....

 is named in his honor.

Principal works

  • De natura lucis (1638)
  • Philolaus (1639)
  • Expositio rerum mathematicarum ad legendum Platonem utilium, translation of Theon of Smyrna
    Theon of Smyrna
    Theon of Smyrna was a Greek philosopher and mathematician, whose works were strongly influenced by the Pythagorean school of thought. His surviving On Mathematics Useful for the Understanding of Plato is an introductory survey of Greek mathematics.-Life:Little is known about the life of Theon of...

  • Astronomia philolaica (1645)
  • De lineis spiralibus (1657)
  • Opus novum ad arithmeticam infinitorum (1682)
  • Ad astronomos monita duo (1667)

Further reading

  • Nellen, H. J. M., Ismaël Boulliau (1605-1694), astronome, épistolier, nouvelliste et intermédiaire scientifique, Studies of the Pierre Bayle Institute Nijmegen (SIB), 24, APA-Holland University Press, 1994. ISBN 9030210346.

External links