Pierre Bouguer
Encyclopedia
Pierre Bouguer was a French
mathematician
, geophysicist, geodesist, and astronomer
. He is also known as "the father of naval architecture
".
His father, Jean Bouguer, one of the best hydrographers of his time, was regius professor of hydrography
at Croisic in lower Brittany
, and author of a treatise on navigation
. In 1713 Pierre was appointed to succeed his father as professor of hydrography. In 1727 he gained the prize given by the French Academy of Sciences
for his paper On the masting of ships, beating Leonhard Euler
; and two other prizes, one for his dissertation On the best method of observing the altitude of stars at sea, the other for his paper On the best method of observing the variation of the compass at sea. These were published in the Prix de l’Academie des Sciences.
In 1729 he published Essai d'optique sur la gradation de la lumière, the object of which is to define the quantity of light lost by passing through a given extent of the atmosphere
, and became the first known discoverer of what is now more commonly known as the Beer-Lambert law
. He found the light of the sun
to be 300 times more intense than that of the moon
, and thus made some of the earliest measurements in photometry
. In 1730 he was made professor of hydrography at Havre
, and succeeded Pierre Louis Maupertuis
as associate geometer of the Academy of Sciences. He also invented a heliometer
, afterwards perfected by Joseph von Fraunhofer
. He was afterwards promoted in the Academy to the place of Maupertuis, and went to reside in Paris
.
In 1735 Bouguer sailed with Charles Marie de La Condamine
on a scientific mission
to Peru
, in order to measure a degree of the meridian arc
near the equator
. Ten years were spent in this operation, a full account of which was published by Bouguer in 1749, La figure de la terre: déterminée par les observations de messieurs. In 1746 he published the first treatise of naval architecture,Traité du navire, which among other achievements first explained the use of the metacenter
as a measure of ships' stability. His later writings were nearly all upon the theory of navigation and naval architecture.
In January, 1750 he was elected a Fellow of the Royal Society. A crater
on Mars
was named in his honor. A lunar crater
was also named after him.
His name is also recalled as the meteorological term Bouguer's halo (also known as Ulloa's halo, after Antonio de Ulloa
, a Spanish
member of his South American expedition) which an observer may see infrequently in fog when sun breaks through (for example, on a mountain) and looks down-sun—effectively a "Fog bow
" (as opposed to a "rain-bow"). An infrequently observed meteorological phenomenon; a faint white, circular arc or complete ring of light that has a radius of 39 degrees and is centered on the antisolar point. When observed, it is usually in the form of a separate outer ring around an anticorona. Reference: Tricker, R. A. R., 1970: An Introduction to Meteorological Optics, pages 192–193.
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...
mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....
, geophysicist, geodesist, and astronomer
Astronomer
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...
. He is also known as "the father of naval architecture
Naval architecture
Naval architecture is an engineering discipline dealing with the design, construction, maintenance and operation of marine vessels and structures. Naval architecture involves basic and applied research, design, development, design evaluation and calculations during all stages of the life of a...
".
His father, Jean Bouguer, one of the best hydrographers of his time, was regius professor of hydrography
Hydrography
Hydrography is the measurement of the depths, the tides and currents of a body of water and establishment of the sea, river or lake bed topography and morphology. Normally and historically for the purpose of charting a body of water for the safe navigation of shipping...
at Croisic in lower Brittany
Brittany
Brittany is a cultural and administrative region in the north-west of France. Previously a kingdom and then a duchy, Brittany was united to the Kingdom of France in 1532 as a province. Brittany has also been referred to as Less, Lesser or Little Britain...
, and author of a treatise on navigation
Navigation
Navigation is the process of monitoring and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks...
. In 1713 Pierre was appointed to succeed his father as professor of hydrography. In 1727 he gained the prize given by the French Academy of Sciences
French Academy of Sciences
The French Academy of Sciences is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research...
for his paper On the masting of ships, beating Leonhard Euler
Leonhard Euler
Leonhard Euler was a pioneering Swiss mathematician and physicist. He made important discoveries in fields as diverse as infinitesimal calculus and graph theory. He also introduced much of the modern mathematical terminology and notation, particularly for mathematical analysis, such as the notion...
; and two other prizes, one for his dissertation On the best method of observing the altitude of stars at sea, the other for his paper On the best method of observing the variation of the compass at sea. These were published in the Prix de l’Academie des Sciences.
In 1729 he published Essai d'optique sur la gradation de la lumière, the object of which is to define the quantity of light lost by passing through a given extent of the atmosphere
Earth's atmosphere
The atmosphere of Earth is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
, and became the first known discoverer of what is now more commonly known as the Beer-Lambert law
Beer-Lambert law
In optics, the Beer–Lambert law, also known as Beer's law or the Lambert–Beer law or the Beer–Lambert–Bouguer law relates the absorption of light to the properties of the material through which the light is travelling.-Equations:The law states that there is a logarithmic dependence between the...
. He found the light of the sun
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...
to be 300 times more intense than that of the moon
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...
, and thus made some of the earliest measurements in photometry
Photometry (optics)
Photometry is the science of the measurement of light, in terms of its perceived brightness to the human eye. It is distinct from radiometry, which is the science of measurement of radiant energy in terms of absolute power; rather, in photometry, the radiant power at each wavelength is weighted by...
. In 1730 he was made professor of hydrography at Havre
Le Havre
Le Havre is a city in the Seine-Maritime department of the Haute-Normandie region in France. It is situated in north-western France, on the right bank of the mouth of the river Seine on the English Channel. Le Havre is the most populous commune in the Haute-Normandie region, although the total...
, and succeeded Pierre Louis Maupertuis
Pierre Louis Maupertuis
Pierre-Louis Moreau de Maupertuis was a French mathematician, philosopher and man of letters. He became the Director of the Académie des Sciences, and the first President of the Berlin Academy of Science, at the invitation of Frederick the Great....
as associate geometer of the Academy of Sciences. He also invented a heliometer
Heliometer
Heliometer is an instrument originally designed for measuring the variation of the sun's diameter at different seasons of the year, but applied now to the modern form of the instrument which is capable of much wider use....
, afterwards perfected by Joseph von Fraunhofer
Joseph von Fraunhofer
Joseph von Fraunhofer was a German optician. He is known for the discovery of the dark absorption lines known as Fraunhofer lines in the Sun's spectrum, and for making excellent optical glass and achromatic telescope objectives.-Biography:Fraunhofer was born in Straubing, Bavaria...
. He was afterwards promoted in the Academy to the place of Maupertuis, and went to reside in Paris
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...
.
In 1735 Bouguer sailed with Charles Marie de La Condamine
Charles Marie de La Condamine
Charles Marie de La Condamine was a French explorer, geographer, and mathematician. He spent ten years in present-day Ecuador measuring the length of a degree latitude at the equator and preparing the first map of the Amazon region based on astronomical observations.-Biography:Charles Marie de La...
on a scientific mission
French Geodesic Mission
The French Geodesic Mission was an 18th-century expedition to what is now Ecuador carried out for the purpose of measuring the roundness of the Earth and measuring the length of a degree of longitude at the Equator...
to Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
, in order to measure a degree of the meridian arc
Meridian arc
In geodesy, a meridian arc measurement is a highly accurate determination of the distance between two points with the same longitude. Two or more such determinations at different locations then specify the shape of the reference ellipsoid which best approximates the shape of the geoid. This...
near the equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
. Ten years were spent in this operation, a full account of which was published by Bouguer in 1749, La figure de la terre: déterminée par les observations de messieurs. In 1746 he published the first treatise of naval architecture,Traité du navire, which among other achievements first explained the use of the metacenter
Metacentric height
The metacentric height is a measurement of the static stability of a floating body. It is calculated as the distance between the centre of gravity of a ship and its metacentre . A larger metacentric height implies greater stability against overturning...
as a measure of ships' stability. His later writings were nearly all upon the theory of navigation and naval architecture.
In January, 1750 he was elected a Fellow of the Royal Society. A crater
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...
on Mars
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...
was named in his honor. A lunar crater
Bouguer (lunar crater)
Bouguer is a lunar impact crater that lies along the southern edge of the Mare Frigoris, to the north of the crater Bianchini. To the west-southwest of Bouguer, along the same shore of the mare, is the crater Foucault. Nearly due west is the more prominent Harpalus, and to the west is La...
was also named after him.
His name is also recalled as the meteorological term Bouguer's halo (also known as Ulloa's halo, after Antonio de Ulloa
Antonio de Ulloa
Antonio de Ulloa y de la Torre-Girault was a Spanish general, explorer, author, astronomer, colonial administrator and the first Spanish governor of Louisiana.Rebellion of 1768]]....
, a Spanish
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
member of his South American expedition) which an observer may see infrequently in fog when sun breaks through (for example, on a mountain) and looks down-sun—effectively a "Fog bow
Fog bow
A fog bow is a similar phenomenon to a rainbow, however, as its name suggests, it appears as a bow in fog rather than rain. Because of the very small size of water droplets that cause fog—smaller than —the fog bow has only very weak colors, with a red outer edge and bluish inner.In many cases when...
" (as opposed to a "rain-bow"). An infrequently observed meteorological phenomenon; a faint white, circular arc or complete ring of light that has a radius of 39 degrees and is centered on the antisolar point. When observed, it is usually in the form of a separate outer ring around an anticorona. Reference: Tricker, R. A. R., 1970: An Introduction to Meteorological Optics, pages 192–193.
- Ferreiro, Larrie. "Ships and Science: The Birth of Naval Architecture in the Scientific Revolution, 1600-1800". Cambridge: MIT Press, 2007
- Ferreiro, Larrie: Measure of the Earth: The Enlightenment Expedition that Reshaped Our World (New York: Basic Books, 2011) ISBN:9780465017232
- Lamontagne, Roland. "La vie et l’oeuvre de Pierre Bouguer (The life and work of Pierre Bouguer)" Montreal: Presses de l’Université de Montréal, 1964
- Lamontagne, Roland. "Pierre Bouguer, 1698-1758, un Blaise Pascal du XVIIIe siècle; Suivi d'une correspondence (Pierre Bouguer, 1698-1758, a Blaise Pascal of the 18th century; followed by correspondence)". Manuscript. Montreal: Université de Montreal, 1998