Jules Henri Poincaré was a French mathematician, theoretical physicist and philosopher of science. He is described as a polymath, in mathematics as "The Last Universalist," since he excelled in all fields of the discipline as it existed during his lifetime; as a mathematician and physicist, he made many original fundamental contributions to pure and applied mathematics, mathematical physics, celestial mechanics. He was responsible for formulating the Poincaré conjecture, one of the most famous unsolved problems in mathematics until it was solved in 2002–2003 by Grigori Perelman. In his research on the three-body problem, Poincaré became the first person to discover a chaotic deterministic system which laid the foundations of modern chaos theory, he is considered to be one of the founders of the field of topology. Poincaré made clear the importance of paying attention to the invariance of laws of physics under different transformations, was the first to present the Lorentz transformations in their modern symmetrical form.
Poincaré discovered the remaining relativistic velocity transformations and recorded them in a letter to Hendrik Lorentz in 1905. Thus he obtained perfect invariance of all of Maxwell's equations, an important step in the formulation of the theory of special relativity. In 1905, Poincaré first proposed gravitational waves emanating from a body and propagating at the speed of light as being required by the Lorentz transformations; the Poincaré group used in physics and mathematics was named after him. Poincaré was born on 29 April 1854 in Cité Ducale neighborhood, Meurthe-et-Moselle into an influential family, his father Leon Poincaré was a professor of medicine at the University of Nancy. His younger sister Aline married the spiritual philosopher Emile Boutroux. Another notable member of Henri's family was his cousin, Raymond Poincaré, a fellow member of the Académie française, who would serve as President of France from 1913 to 1920, he was raised in the Roman Catholic faith. During his childhood he was ill for a time with diphtheria and received special instruction from his mother, Eugénie Launois.
In 1862, Henri entered the Lycée in Nancy. He spent eleven years at the Lycée and during this time he proved to be one of the top students in every topic he studied, he excelled in written composition. His mathematics teacher described him as a "monster of mathematics" and he won first prizes in the concours général, a competition between the top pupils from all the Lycées across France, his poorest subjects were music and physical education, where he was described as "average at best". However, poor eyesight and a tendency towards absentmindedness may explain these difficulties, he graduated from the Lycée in 1871 with a bachelor's degree in sciences. During the Franco-Prussian War of 1870, he served alongside his father in the Ambulance Corps. Poincaré entered the École Polytechnique in 1873 and graduated in 1875. There he studied mathematics as a student of Charles Hermite, continuing to excel and publishing his first paper in 1874. From November 1875 to June 1878 he studied at the École des Mines, while continuing the study of mathematics in addition to the mining engineering syllabus, received the degree of ordinary mining engineer in March 1879.
As a graduate of the École des Mines, he joined the Corps des Mines as an inspector for the Vesoul region in northeast France. He was on the scene of a mining disaster at Magny in August 1879, he carried out the official investigation into the accident in a characteristically thorough and humane way. At the same time, Poincaré was preparing for his Doctorate in Science in mathematics under the supervision of Charles Hermite, his doctoral thesis was in the field of differential equations. It was named Sur les propriétés des fonctions. Poincaré devised a new way of studying the properties of these equations, he not only faced the question of determining the integral of such equations, but was the first person to study their general geometric properties. He realised that they could be used to model the behaviour of multiple bodies in free motion within the solar system. Poincaré graduated from the University of Paris in 1879. After receiving his degree, Poincaré began teaching as junior lecturer in mathematics at the University of Caen in Normandy.
At the same time he published his first major article concerning the treatment of a class of automorphic functions. There, in Caen, he met his future wife, Louise Poulin d'Andesi and on 20 April 1881, they married. Together they had four children: Jeanne, Henriette, Léon. Poincaré established himself among the greatest mathematicians of Europe, attracting the attention of many prominent mathematicians. In 1881 Poincaré was invited to take a teaching position at the Faculty of Sciences of the University of Paris. During the years of 1883 to 1897, he taught mathematical analysis in École Polytechnique. In 1881–1882, Poincaré created a new branch of mathematics: qualitative theory of differential equations, he showed how it is possible to derive the most important information about the behavior of a family of solutions without having to solve the equation. He used this approach to problems in celestial mechanics and mathematical physics, he never aban
Navigation is a field of study that focuses on the process of monitoring and controlling the movement of a craft or vehicle from one place to another. The field of navigation includes four general categories: land navigation, marine navigation, aeronautic navigation, space navigation, it is the term of art used for the specialized knowledge used by navigators to perform navigation tasks. All navigational techniques involve locating the navigator's position compared to known locations or patterns. Navigation, in a broader sense, can refer to any skill or study that involves the determination of position and direction. In this sense, navigation includes pedestrian navigation. In the European medieval period, navigation was considered part of the set of seven mechanical arts, none of which were used for long voyages across open ocean. Polynesian navigation is the earliest form of open-ocean navigation, it was based on memory and observation recorded on scientific instruments like the Marshall Islands Stick Charts of Ocean Swells.
Early Pacific Polynesians used the motion of stars, the position of certain wildlife species, or the size of waves to find the path from one island to another. Maritime navigation using scientific instruments such as the mariner's astrolabe first occurred in the Mediterranean during the Middle Ages. Although land astrolabes were invented in the Hellenistic period and existed in classical antiquity and the Islamic Golden Age, the oldest record of a sea astrolabe is that of Majorcan astronomer Ramon Llull dating from 1295; the perfecting of this navigation instrument is attributed to Portuguese navigators during early Portuguese discoveries in the Age of Discovery. The earliest known description of how to make and use a sea astrolabe comes from Spanish cosmographer Martín Cortés de Albacar's Arte de Navegar published in 1551, based on the principle of the archipendulum used in constructing the Egyptian pyramids. Open-seas navigation using the astrolabe and the compass started during the Age of Discovery in the 15th century.
The Portuguese began systematically exploring the Atlantic coast of Africa from 1418, under the sponsorship of Prince Henry. In 1488 Bartolomeu Dias reached the Indian Ocean by this route. In 1492 the Spanish monarchs funded Christopher Columbus's expedition to sail west to reach the Indies by crossing the Atlantic, which resulted in the Discovery of the Americas. In 1498, a Portuguese expedition commanded by Vasco da Gama reached India by sailing around Africa, opening up direct trade with Asia. Soon, the Portuguese sailed further eastward, to the Spice Islands in 1512, landing in China one year later; the first circumnavigation of the earth was completed in 1522 with the Magellan-Elcano expedition, a Spanish voyage of discovery led by Portuguese explorer Ferdinand Magellan and completed by Spanish navigator Juan Sebastián Elcano after the former's death in the Philippines in 1521. The fleet of seven ships sailed from Sanlúcar de Barrameda in Southern Spain in 1519, crossed the Atlantic Ocean and after several stopovers rounded the southern tip of South America.
Some ships were lost, but the remaining fleet continued across the Pacific making a number of discoveries including Guam and the Philippines. By only two galleons were left from the original seven; the Victoria led by Elcano sailed across the Indian Ocean and north along the coast of Africa, to arrive in Spain in 1522, three years after its departure. The Trinidad sailed east from the Philippines, trying to find a maritime path back to the Americas, but was unsuccessful; the eastward route across the Pacific known as the tornaviaje was only discovered forty years when Spanish cosmographer Andrés de Urdaneta sailed from the Philippines, north to parallel 39°, hit the eastward Kuroshio Current which took its galleon across the Pacific. He arrived in Acapulco on October 8, 1565; the term stems from the 1530s, from Latin navigationem, from navigatus, pp. of navigare "to sail, sail over, go by sea, steer a ship," from navis "ship" and the root of agere "to drive". The latitude of a place on Earth is its angular distance north or south of the equator.
Latitude is expressed in degrees ranging from 0° at the Equator to 90° at the North and South poles. The latitude of the North Pole is 90° N, the latitude of the South Pole is 90° S. Mariners calculated latitude in the Northern Hemisphere by sighting the North Star Polaris with a sextant and using sight reduction tables to correct for height of eye and atmospheric refraction; the height of Polaris in degrees above the horizon is the latitude of the observer, within a degree or so. Similar to latitude, the longitude of a place on Earth is the angular distance east or west of the prime meridian or Greenwich meridian. Longitude is expressed in degrees ranging from 0° at the Greenwich meridian to 180° east and west. Sydney, for example, has a longitude of about 151° east. New York City has a longitude of 74° west. For most of history, mariners struggled to determine longitude. Longitude can be calculated. Lacking that, one can use a sextant to take a lunar distance that, with a nautical almanac, can be used to calculate the time at zero longitude.
Reliable marine chronometers were unavailable until the late 18th century and not affordable until the 19th century. For about a hundred years, from about 1767 until about 1850, mariners lacking a chronometer used the method of lunar distances to determine Greenwich time to find their longitude. A mariner with a chronometer could check its reading using a lunar determination of Greenwich tim
Lazare Nicolas Marguerite, Count Carnot was a French mathematician and politician. He was known as the Organizer of Victory in the French Revolutionary Wars and Napoleonic Wars. Born on May 13, 1753 in the village of Nolay, Côte-d'Or, Carnot was the son of local judge and royal notary, Claude Carnot and his wife, Marguerite Pothier, he was the second oldest of seven children. At the age of fourteen and his brother were enrolled at the Collège d’Autun, in Burgundy where he focused on the study of philosophy and the classics, he held a strong belief in stoic philosophy and was influenced by Roman civilization. When he turned fifteen, he left the Collège d’Autun to strengthen his philosophical knowledge and study under the Society of the Priests of Saint Sulpice. During his short time with them, he studied logic and theology under the Abbe Bison. After being impressed with Lazare’s work as a scholar, the Duke D’Aumont recommended a military career for the young one and was soon sent by his father to the Aumont residence to further his education.
Here, he was enrolled in M. de Longpres pension school in 1770 until he was ready to enter one of two prestigious engineering and artillery schools in Paris. A year in February 1771, he was ranked the third highest among twelve who were chosen out of his class of more than one hundred who took the entrance exams, it was at this point when he entered the Mézières School of Engineering appointed as second lieutenant. Studies at the Mézières included geometry, geometrical designing, geography and material preparation. On January 1, 1773, he graduated, he was eighteen years old. It was here where he met and studied with Benjamin Franklin and at the age of twenty and obtained commission as a lieutenant in the Prince of Condé’s engineer corps. At this moment, he made a name for himself both in the line of theoretical engineering and in his work in the field of fortifications. While in the army, he continued his study of mathematics. In 1784 he published his first work Essay on Machines, which contained a statement that foreshadowed the principle of energy as applied to a falling weight, the earliest proof that kinetic energy is lost in the collision of imperfectly elastic bodies.
This publication earned him the honor of admittance to a literary society. Another turning point was his essay on Vauban in which he praises the engineer on his works while at the same time developing his own career as a writer/engineer. Vauban's work had a profound effect on his work as a engineer. In that same year, he received a promotion to the rank of captain. At the outbreak of the French Revolution in 1789, Carnot entered political life, he became a delegate to the Legislature in 1791. While a member of the Legislative Assembly, Carnot was elected to the Committee for Public Instruction, he believed that all citizens should be educated and as a member of that committee, he wrote a series of reforms for the teaching and educational systems, but they were not implemented due to the violent social and economic climate of the Revolution. After the Legislative Assembly was dissolved, Carnot was elected to the National Convention in 1792, he spent the last few months of 1792 on a mission to Bayonne, organizing the military defense effort in an attempt to ward off any possible attacks from Spain.
Upon returning to Paris, Carnot voted for the death of King Louis XVI, although he had been absent for the debates surrounding the king’s trial. On 14 August 1793 Carnot was elected to the Committee of Public Safety, where he took charge of the military situation as one of the Ministers of War. With the establishment of the Directory in 1795, Carnot became one of the five initial directors. For the first year, the Directors did well working harmoniously together as well as with the Councils. However, difference of political views led to a schism between Carnot and Étienne-François Letourneur, followed by François de Barthélemy, on the one side, the triumvirate of Paul François Jean Nicolas, vicomte de Barras, Jean-François Rewbell, Louis Marie de La Révellière-Lépeaux on the other side. Carnot and Barthélemy supported concessions to end the war, hoped to oust the triumvirate and replace them with more conservative men. After Letourneur had been replaced by another close collaborator of Carnot, François de Barthélemy, both of them, alongside many deputies in the Council of Five Hundred, were ousted in the Coup of 18 Fructidor, engineered by Generals Napoleon Bonaparte and Pierre François Charles Augereau.
Carnot took refuge in Geneva, there in 1797 issued his La métaphysique du calcul infinitésimal. The creation of the French Revolutionary Army was due to his powers of organization and enforcing discipline. In order to raise more troops for the war, Carnot introduced conscription: the levée en masse approved by the National Convention was able to raise France’s army from 645,000 troops in mid-1793 to 1,500,000 in September 1794, he was the first to execute the modern waging of war with mass armies and strategic planning realized by the Revolution. As a military engineer, Carnot favored defensive strategies, he developed innovative defensive designs including the Carnot wall, called after him. However, with the constant invasions he decided to take his strategic planning to an offensive strike. From his intellect sprang the maneuvers and organization that turned the tides of war from 1793 to 1794; the basic idea was to have a massive army separated into several units that could move more than the enemy and attack from the flanks rather than head on, which had led to resounding defeats before Carnot was
Astronomy is a natural science that studies celestial objects and phenomena. It applies mathematics and chemistry in an effort to explain the origin of those objects and phenomena and their evolution. Objects of interest include planets, stars, nebulae and comets. More all phenomena that originate outside Earth's atmosphere are within the purview of astronomy. A related but distinct subject is physical cosmology, the study of the Universe as a whole. Astronomy is one of the oldest of the natural sciences; the early civilizations in recorded history, such as the Babylonians, Indians, Nubians, Chinese and many ancient indigenous peoples of the Americas, performed methodical observations of the night sky. Astronomy has included disciplines as diverse as astrometry, celestial navigation, observational astronomy, the making of calendars, but professional astronomy is now considered to be synonymous with astrophysics. Professional astronomy is split into theoretical branches. Observational astronomy is focused on acquiring data from observations of astronomical objects, analyzed using basic principles of physics.
Theoretical astronomy is oriented toward the development of computer or analytical models to describe astronomical objects and phenomena. The two fields complement each other, with theoretical astronomy seeking to explain observational results and observations being used to confirm theoretical results. Astronomy is one of the few sciences in which amateurs still play an active role in the discovery and observation of transient events. Amateur astronomers have made and contributed to many important astronomical discoveries, such as finding new comets. Astronomy means "law of the stars". Astronomy should not be confused with astrology, the belief system which claims that human affairs are correlated with the positions of celestial objects. Although the two fields share a common origin, they are now distinct. Both of the terms "astronomy" and "astrophysics" may be used to refer to the same subject. Based on strict dictionary definitions, "astronomy" refers to "the study of objects and matter outside the Earth's atmosphere and of their physical and chemical properties," while "astrophysics" refers to the branch of astronomy dealing with "the behavior, physical properties, dynamic processes of celestial objects and phenomena."
In some cases, as in the introduction of the introductory textbook The Physical Universe by Frank Shu, "astronomy" may be used to describe the qualitative study of the subject, whereas "astrophysics" is used to describe the physics-oriented version of the subject. However, since most modern astronomical research deals with subjects related to physics, modern astronomy could be called astrophysics; some fields, such as astrometry, are purely astronomy rather than astrophysics. Various departments in which scientists carry out research on this subject may use "astronomy" and "astrophysics" depending on whether the department is affiliated with a physics department, many professional astronomers have physics rather than astronomy degrees; some titles of the leading scientific journals in this field include The Astronomical Journal, The Astrophysical Journal, Astronomy and Astrophysics. In early historic times, astronomy only consisted of the observation and predictions of the motions of objects visible to the naked eye.
In some locations, early cultures assembled massive artifacts that had some astronomical purpose. In addition to their ceremonial uses, these observatories could be employed to determine the seasons, an important factor in knowing when to plant crops and in understanding the length of the year. Before tools such as the telescope were invented, early study of the stars was conducted using the naked eye; as civilizations developed, most notably in Mesopotamia, Persia, China and Central America, astronomical observatories were assembled and ideas on the nature of the Universe began to develop. Most early astronomy consisted of mapping the positions of the stars and planets, a science now referred to as astrometry. From these observations, early ideas about the motions of the planets were formed, the nature of the Sun and the Earth in the Universe were explored philosophically; the Earth was believed to be the center of the Universe with the Sun, the Moon and the stars rotating around it. This is known as the geocentric model of the Ptolemaic system, named after Ptolemy.
A important early development was the beginning of mathematical and scientific astronomy, which began among the Babylonians, who laid the foundations for the astronomical traditions that developed in many other civilizations. The Babylonians discovered. Following the Babylonians, significant advances in astronomy were made in ancient Greece and the Hellenistic world. Greek astronomy is characterized from the start by seeking a rational, physical explanation for celestial phenomena. In the 3rd century BC, Aristarchus of Samos estimated the size and distance of the Moon and Sun, he proposed a model of the Solar System where the Earth and planets rotated around the Sun, now called the heliocentric model. In the 2nd century BC, Hipparchus discovered precession, calculated the size and distance of the Moon and inven
France the French Republic, is a country whose territory consists of metropolitan France in Western Europe and several overseas regions and territories. The metropolitan area of France extends from the Mediterranean Sea to the English Channel and the North Sea, from the Rhine to the Atlantic Ocean, it is bordered by Belgium and Germany to the northeast and Italy to the east, Andorra and Spain to the south. The overseas territories include French Guiana in South America and several islands in the Atlantic and Indian oceans; the country's 18 integral regions span a combined area of 643,801 square kilometres and a total population of 67.3 million. France, a sovereign state, is a unitary semi-presidential republic with its capital in Paris, the country's largest city and main cultural and commercial centre. Other major urban areas include Lyon, Toulouse, Bordeaux and Nice. During the Iron Age, what is now metropolitan France was inhabited by a Celtic people. Rome annexed the area in 51 BC, holding it until the arrival of Germanic Franks in 476, who formed the Kingdom of Francia.
The Treaty of Verdun of 843 partitioned Francia into Middle Francia and West Francia. West Francia which became the Kingdom of France in 987 emerged as a major European power in the Late Middle Ages following its victory in the Hundred Years' War. During the Renaissance, French culture flourished and a global colonial empire was established, which by the 20th century would become the second largest in the world; the 16th century was dominated by religious civil wars between Protestants. France became Europe's dominant cultural and military power in the 17th century under Louis XIV. In the late 18th century, the French Revolution overthrew the absolute monarchy, established one of modern history's earliest republics, saw the drafting of the Declaration of the Rights of Man and of the Citizen, which expresses the nation's ideals to this day. In the 19th century, Napoleon established the First French Empire, his subsequent Napoleonic Wars shaped the course of continental Europe. Following the collapse of the Empire, France endured a tumultuous succession of governments culminating with the establishment of the French Third Republic in 1870.
France was a major participant in World War I, from which it emerged victorious, was one of the Allies in World War II, but came under occupation by the Axis powers in 1940. Following liberation in 1944, a Fourth Republic was established and dissolved in the course of the Algerian War; the Fifth Republic, led by Charles de Gaulle, remains today. Algeria and nearly all the other colonies became independent in the 1960s and retained close economic and military connections with France. France has long been a global centre of art and philosophy, it hosts the world's fourth-largest number of UNESCO World Heritage Sites and is the leading tourist destination, receiving around 83 million foreign visitors annually. France is a developed country with the world's sixth-largest economy by nominal GDP, tenth-largest by purchasing power parity. In terms of aggregate household wealth, it ranks fourth in the world. France performs well in international rankings of education, health care, life expectancy, human development.
France is considered a great power in global affairs, being one of the five permanent members of the United Nations Security Council with the power to veto and an official nuclear-weapon state. It is a leading member state of the European Union and the Eurozone, a member of the Group of 7, North Atlantic Treaty Organization, Organisation for Economic Co-operation and Development, the World Trade Organization, La Francophonie. Applied to the whole Frankish Empire, the name "France" comes from the Latin "Francia", or "country of the Franks". Modern France is still named today "Francia" in Italian and Spanish, "Frankreich" in German and "Frankrijk" in Dutch, all of which have more or less the same historical meaning. There are various theories as to the origin of the name Frank. Following the precedents of Edward Gibbon and Jacob Grimm, the name of the Franks has been linked with the word frank in English, it has been suggested that the meaning of "free" was adopted because, after the conquest of Gaul, only Franks were free of taxation.
Another theory is that it is derived from the Proto-Germanic word frankon, which translates as javelin or lance as the throwing axe of the Franks was known as a francisca. However, it has been determined that these weapons were named because of their use by the Franks, not the other way around; the oldest traces of human life in what is now France date from 1.8 million years ago. Over the ensuing millennia, Humans were confronted by a harsh and variable climate, marked by several glacial eras. Early hominids led a nomadic hunter-gatherer life. France has a large number of decorated caves from the upper Palaeolithic era, including one of the most famous and best preserved, Lascaux. At the end of the last glacial period, the climate became milder. After strong demographic and agricultural development between the 4th and 3rd millennia, metallurgy appeared at the end of the 3rd millennium working gold and bronze, iron. France has numerous megalithic sites from the Neolithic period, including the exceptiona
French colonial empire
The French colonial empire constituted the overseas colonies and mandate territories that came under French rule from the 16th century onward. A distinction is made between the "first colonial empire," that existed until 1814, by which time most of it had been lost, the "second colonial empire", which began with the conquest of Algiers in 1830; the second colonial empire came to an end after the loss in wars of Indochina and Algeria, peaceful decolonizations elsewhere after 1960. Competing with Spain, the Dutch United Provinces and England, France began to establish colonies in North America, the Caribbean and India in the 17th century. A series of wars with Britain and others resulted in France losing nearly all of its conquests by 1814. France rebuilt a new empire after 1850, concentrating chiefly in Africa as well as Indochina and the South Pacific. Republicans, at first hostile to empire, only became supportive when Germany started to build their own colonial empire; as it developed, the new empire took on roles of trade with France supplying raw materials and purchasing manufactured items as well as lending prestige to the motherland and spreading French civilization and language and the Catholic religion.
It provided manpower in the World Wars. A major goal was the ‘Mission civilisatrice’ the mission to spread French culture and religion, this proved successful. In 1884, the leading proponent of colonialism, Jules Ferry, declared. Full citizenship rights – assimilation – were offered, although in reality "assimilation was always receding the colonial populations treated like subjects not citizens." France sent small numbers of settlers to its empire, contrary to Great Britain and Spain and Portugal, with the only notable exception of Algeria, where the French settlers nonetheless always remained a small minority. At its apex, it was one of the largest empires in history. Including metropolitan France, the total amount of land under French sovereignty reached 11,500,000 km2 in 1920, with a population of 110 million people in 1939. In World War II, Charles de Gaulle and the Free French used the overseas colonies as bases from which they fought to liberate France. Historian Tony Chafer argues: "In an effort to restore its world-power status after the humiliation of defeat and occupation, France was eager to maintain its overseas empire at the end of the Second World War."
However, after 1945 anti-colonial movements began to challenge European authority. The French constitution of 27 October 1946, established the French Union which endured until 1958. Newer remnants of the colonial empire were integrated into France as overseas departments and territories within the French Republic; these now total altogether 119,394 km², which amounts to only 1% of the pre-1939 French colonial empire's area, with 2.7 million people living in them in 2013. By the 1970s, says Robert Aldrich, the last "vestiges of empire held little interest for the French." He argues, "Except for the traumatic decolonization of Algeria, what is remarkable is how few long-lasting effects on France the giving up of empire entailed." During the 16th century, the French colonization of the Americas began. Excursions of Giovanni da Verrazzano and Jacques Cartier in the early 16th century, as well as the frequent voyages of French boats and fishermen to the Grand Banks off Newfoundland throughout that century, were the precursors to the story of France's colonial expansion.
But Spain's defense of its American monopoly, the further distractions caused in France itself in the 16th century by the French Wars of Religion, prevented any constant efforts by France to settle colonies. Early French attempts to found colonies in Brazil, in 1555 at Rio de Janeiro and in Florida, in 1612 at São Luís, were not successful, due to a lack of official interest and to Portuguese and Spanish vigilance; the story of France's colonial empire began on 27 July 1605, with the foundation of Port Royal in the colony of Acadia in North America, in what is now Nova Scotia, Canada. A few years in 1608, Samuel De Champlain founded Quebec, to become the capital of the enormous, but sparsely settled, fur-trading colony of New France. New France had a rather small population, which resulted from more emphasis being placed on the fur trade rather than agricultural settlements. Due to this emphasis, the French relied on creating friendly contacts with the local First Nations community. Without the appetite of New England for land, by relying on Aboriginals to supply them with fur at the trading posts, the French composed a complex series of military and diplomatic connections.
These became the most enduring alliances between the First Nation community. The French were, under pressure from religious orders to convert them to Catholicism. Through alliances with various Native American tribes, the French were able to exert a loose control over much of the North American continent. Areas of French settlement were limited to the St. Lawrence River Valley. Prior to the establishment of the 1663 Sovereign Council, the territories of New France were developed as mercantile colonies, it is only after the arrival of intendant Jean Talon in 1665 that France gave its American colonies the proper means to develop population colonies comparable to that of the British. Acadia itself was lost to the British in the Treaty of Utrecht in 1713. Back in France there was littl
A day is the period of time during which the Earth completes one rotation around its axis. A solar day is the length of time which elapses between the Sun reaching its highest point in the sky two consecutive times. In 1960, the second was redefined in terms of the orbital motion of the Earth in year 1900, was designated the SI base unit of time; the unit of measurement "day", was symbolized d. In 1967, the second and so the day were redefined by atomic electron transition. A civil day is 86,400 seconds, plus or minus a possible leap second in Coordinated Universal Time, plus or minus an hour in those locations that change from or to daylight saving time. Day can be defined as each of the twenty-four-hour periods, reckoned from one midnight to the next, into which a week, month, or year is divided, corresponding to a rotation of the earth on its axis; however its use depends on its context, for example when people say'day and night','day' will have a different meaning. It will mean the interval of light between two successive nights.
However, in order to be clear when using'day' in that sense, "daytime" should be used to distinguish it from "day" referring to a 24-hour period. The word day may refer to a day of the week or to a calendar date, as in answer to the question, "On which day?" The life patterns of humans and many other species are related to Earth's solar day and the day-night cycle. Several definitions of this universal human concept are used according to context and convenience. Besides the day of 24 hours, the word day is used for several different spans of time based on the rotation of the Earth around its axis. An important one is the solar day, defined as the time it takes for the Sun to return to its culmination point; because celestial orbits are not circular, thus objects travel at different speeds at various positions in their orbit, a solar day is not the same length of time throughout the orbital year. Because the Earth orbits the Sun elliptically as the Earth spins on an inclined axis, this period can be up to 7.9 seconds more than 24 hours.
In recent decades, the average length of a solar day on Earth has been about 86 400.002 seconds and there are about 365.2422 solar days in one mean tropical year. Ancient custom has a new day start at either the setting of the Sun on the local horizon; the exact moment of, the interval between, two sunrises or sunsets depends on the geographical position, the time of year. A more constant day can be defined by the Sun passing through the local meridian, which happens at local noon or midnight; the exact moment is dependent on the geographical longitude, to a lesser extent on the time of the year. The length of such a day is nearly constant; this is the time as indicated by modern sundials. A further improvement defines a fictitious mean Sun that moves with constant speed along the celestial equator. A day, understood as the span of time it takes for the Earth to make one entire rotation with respect to the celestial background or a distant star, is called a stellar day; this period of rotation is about 4 minutes less than 24 hours and there are about 366.2422 stellar days in one mean tropical year.
Other planets and moons have solar days of different lengths from Earth's. A day, in the sense of daytime, distinguished from night time, is defined as the period during which sunlight directly reaches the ground, assuming that there are no local obstacles; the length of daytime averages more than half of the 24-hour day. Two effects make daytime on average longer than nights; the Sun has an apparent size of about 32 minutes of arc. Additionally, the atmosphere refracts sunlight in such a way that some of it reaches the ground when the Sun is below the horizon by about 34 minutes of arc. So the first light reaches the ground when the centre of the Sun is still below the horizon by about 50 minutes of arc. Thus, daytime is on average around 7 minutes longer than 12 hours; the term comes from the Old English dæg, with its cognates such as dagur in Icelandic, Tag in German, dag in Norwegian, Danish and Dutch. All of them from the Indo-European root dyau which explains the similarity with Latin dies though the word is known to come from the Germanic branch.
As of October 17, 2015, day is the 205th most common word in US English, the 210th most common in UK English. A day, symbol d, defined as 86 400 seconds, is not an SI unit, but is accepted for use with SI; the Second is the base unit of time in SI units. In 1967–68, during the 13th CGPM, the International Bureau of Weights and Measures redefined a second as … the duration of 9 192 631 770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the caesium 133 atom; this makes the SI-based day last 794 243 384 928 000 of those periods. Due to tidal effects, the