Jean-Baptiste Chappe d'Auteroche
Encyclopedia
Jean-Baptiste Chappe d'Auteroche (23 March 1722 – 1 August 1769) was a French
astronomer
, best known for his observations of the transits of Venus
in 1761 and 1769.
region of central France. He entered the priesthood, probably as a jesuit
, and devoted himself to the study of astronomy. He was appointed assistant astronomer at the Royal Observatory
and admitted to the Royal Academy of Sciences
on 14 January 1759.
were reasonably well understood, but astronomers only had an approximate idea of its scale. If the distance between two planets could be measured, all the other distances would be known from Kepler's laws of planetary motion
. The best candidate for an accurate measurement was the distance between the Earth and Venus
, which could be calculated from observations of transits of Venus
, when Venus passes directly between the Earth and the Sun, appearing as a small black dot moving across the face of the Sun.
However, transits of Venus are very rare. Before 1761, the previous transit had been in 1639; after 1769, the next transit would be in 1874. The importance of the measurement led to an unprecedented international effort to obtain as many observations as possible from different points in the world – points as far apart from one another as possible. Despite the Seven Years' War
which was raging throughout most of the world, astronomers were given letters of introduction and safe passage to enable them to reach their observation points and make their observations under the coordination of the various learned societies
.
in Siberia
to observe the transit of Venus
expected for 6 June 1761. The trip was arduous and Chappe arrived in Tobolsk with little time to spare, although he was able to observe the lunar eclipse
of 18 May, which enabled him to calculate the longitude
of Tobolsk. The spring floods of the Tobol
and Irtysh rivers had been particularly severe that year, and some of the local peasants blamed the foreigner with his strange equipment who was "messing with the Sun": Chappe had to be protected by a cordon of armed Cossacks to make his observations. Fortunately, the weather conditions were excellent, and Chappe was able to observe the entire transit. He published his results from Saint Petersburg
(Mémoire du passage de Vénus sur le soleil, avec des observations sur l'astronomie et la déclinaison de la boussole faites à Tobolsk, en Sibérie), and didn't return to France until 1763.
Chappe published an account of his travels through Russia (Voyage en Sibérie fait en 1761 (avec la description du Kamtschatka, trad. du russe de Khracheninnikow)) in 1768. The text is hardly a flattering description of the country, and an anonymous pamphlet (Antidote ou Réfutation du mauvais livre superbement imprimé intitulé : Voyage en Sibérie, etc.) was soon circulating whose authorship is often attributed to Catherine the Great
herself (although Count Andrey Petrovich Shuvalov is more likely the polemicist).
had been at the heart of astronomical research for a century or more, and marine chronometer
s were steadily becoming more accurate. Chappe and physicist Henri-Louis Duhamel du Monceau
(1700–82) were selected to test one such chronometer, made by Swiss
watchmaker
Ferdinand Berthoud
(1727–1807) on board the corvette L'Hirondelle in 1764.
of San José del Cabo
at the tip of the Baja California
peninsula in modern-day Mexico
. The journey and observation were uneventful. However, as the expedition was packing to return, an outbreak of fever (possibly yellow fever
) hit the area. Chappe stayed to tend the sick, but was infected and died on 1 August. Only one member of the expedition made it back to Paris alive with Chappe's observations and notes. Chappe's account of his journey (Voyage en Californie, pour l'observation du passage de Vénus sur le disque du soleil) was published posthumously by his colleague César Cassini de Thury
.
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...
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...
, best known for his observations of the transits of Venus
Transit of Venus
A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and Earth, becoming visible against the solar disk. During a transit, Venus can be seen from Earth as a small black disk moving across the face of the Sun...
in 1761 and 1769.
Early life
Little is known of Chappe's early life. He was born into a noble family in the AuvergneAuvergne (province)
Auvergne was a historic province in south central France. It was originally the feudal domain of the Counts of Auvergne. It is now the geographical and cultural area that corresponds to the former province....
region of central France. He entered the priesthood, probably as a jesuit
Society of Jesus
The Society of Jesus is a Catholic male religious order that follows the teachings of the Catholic Church. The members are called Jesuits, and are also known colloquially as "God's Army" and as "The Company," these being references to founder Ignatius of Loyola's military background and a...
, and devoted himself to the study of astronomy. He was appointed assistant astronomer at the Royal Observatory
Paris Observatory
The Paris Observatory is the foremost astronomical observatory of France, and one of the largest astronomical centres in the world...
and admitted to the Royal 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...
on 14 January 1759.
Distance from the Earth to the Sun
In the mid-18th century, the dynamics of the Solar SystemSolar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
were reasonably well understood, but astronomers only had an approximate idea of its scale. If the distance between two planets could be measured, all the other distances would be known from Kepler's laws of planetary motion
Kepler's laws of planetary motion
In astronomy, Kepler's laws give a description of the motion of planets around the Sun.Kepler's laws are:#The orbit of every planet is an ellipse with the Sun at one of the two foci....
. The best candidate for an accurate measurement was the distance between the Earth and Venus
Venus
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after Venus, the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows...
, which could be calculated from observations of transits of Venus
Transit of Venus
A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and Earth, becoming visible against the solar disk. During a transit, Venus can be seen from Earth as a small black disk moving across the face of the Sun...
, when Venus passes directly between the Earth and the Sun, appearing as a small black dot moving across the face of the Sun.
However, transits of Venus are very rare. Before 1761, the previous transit had been in 1639; after 1769, the next transit would be in 1874. The importance of the measurement led to an unprecedented international effort to obtain as many observations as possible from different points in the world – points as far apart from one another as possible. Despite the Seven Years' War
Seven Years' War
The Seven Years' War was a global military war between 1756 and 1763, involving most of the great powers of the time and affecting Europe, North America, Central America, the West African coast, India, and the Philippines...
which was raging throughout most of the world, astronomers were given letters of introduction and safe passage to enable them to reach their observation points and make their observations under the coordination of the various learned societies
Learned society
A learned society is an organization that exists to promote an academic discipline/profession, as well a group of disciplines. Membership may be open to all, may require possession of some qualification, or may be an honor conferred by election, as is the case with the oldest learned societies,...
.
Transit of Venus 1761
Chappe was chosen to go to TobolskTobolsk
Tobolsk is a town in Tyumen Oblast, Russia, located at the confluence of the Tobol and Irtysh Rivers. It is a historic capital of Siberia. Population: -History:...
in Siberia
Siberia
Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...
to observe the transit of Venus
Transit of Venus
A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and Earth, becoming visible against the solar disk. During a transit, Venus can be seen from Earth as a small black disk moving across the face of the Sun...
expected for 6 June 1761. The trip was arduous and Chappe arrived in Tobolsk with little time to spare, although he was able to observe the lunar eclipse
Lunar eclipse
A lunar eclipse occurs when the Moon passes behind the Earth so that the Earth blocks the Sun's rays from striking the Moon. This can occur only when the Sun, Earth, and Moon are aligned exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can only occur the night of a...
of 18 May, which enabled him to calculate the longitude
Longitude
Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....
of Tobolsk. The spring floods of the Tobol
Tobol River
Tobol is a river in Kurgan and Tyumen Oblasts in Russia and Kazakhstan, left tributary of the Irtysh. The length of the Tobol River is 1591 km. The area of its drainage basin is 426,000 km². Average discharge at mouth is 805 m³/s. The lower reaches of the river freeze up in late October -...
and Irtysh rivers had been particularly severe that year, and some of the local peasants blamed the foreigner with his strange equipment who was "messing with the Sun": Chappe had to be protected by a cordon of armed Cossacks to make his observations. Fortunately, the weather conditions were excellent, and Chappe was able to observe the entire transit. He published his results from Saint Petersburg
Saint Petersburg
Saint Petersburg is a city and a federal subject of Russia located on the Neva River at the head of the Gulf of Finland on the Baltic Sea...
(Mémoire du passage de Vénus sur le soleil, avec des observations sur l'astronomie et la déclinaison de la boussole faites à Tobolsk, en Sibérie), and didn't return to France until 1763.
Chappe published an account of his travels through Russia (Voyage en Sibérie fait en 1761 (avec la description du Kamtschatka, trad. du russe de Khracheninnikow)) in 1768. The text is hardly a flattering description of the country, and an anonymous pamphlet (Antidote ou Réfutation du mauvais livre superbement imprimé intitulé : Voyage en Sibérie, etc.) was soon circulating whose authorship is often attributed to Catherine the Great
Catherine II of Russia
Catherine II, also known as Catherine the Great , Empress of Russia, was born in Stettin, Pomerania, Prussia on as Sophie Friederike Auguste von Anhalt-Zerbst-Dornburg...
herself (although Count Andrey Petrovich Shuvalov is more likely the polemicist).
Longitude measurement
The problem of longitude measurementHistory of longitude
The history of longitude is a record of the effort, by navigators and scientists over several centuries, to discover a means of determining longitude....
had been at the heart of astronomical research for a century or more, and marine chronometer
Marine chronometer
A marine chronometer is a clock that is precise and accurate enough to be used as a portable time standard; it can therefore be used to determine longitude by means of celestial navigation...
s were steadily becoming more accurate. Chappe and physicist Henri-Louis Duhamel du Monceau
Henri-Louis Duhamel du Monceau
Henri-Louis Duhamel du Monceau , was a French physician, naval engineer and botanist. As a botanist his standard abbreviation is Duhamel...
(1700–82) were selected to test one such chronometer, made by Swiss
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
watchmaker
Watchmaker
A watchmaker is an artisan who makes and repairs watches. Since virtually all watches are now factory made, most modern watchmakers solely repair watches. However, originally they were master craftsmen who built watches, including all their parts, by hand...
Ferdinand Berthoud
Ferdinand Berthoud
Ferdinand Berthoud was a Swiss chronometer-maker.-Career:He was born at Plancemont, Neuchâtel, Switzerland. Having served his apprenticeship with his brother, Jean-Henri, a pendulum maker, he set up a clockmaking business in Paris in 1745 and gained a great reputation for the excellence and...
(1727–1807) on board the corvette L'Hirondelle in 1764.
Transit of Venus 1769
For the transit of Venus on 3 June 1769, Chappe's destination was the MissionMission (station)
A religious mission or mission station is a location for missionary work.While primarily a Christian term, the concept of the religious "mission" is also used prominently by the Church of Scientology and their Scientology Missions International....
of San José del Cabo
San José del Cabo
The city of San José del Cabo is located in Baja California Sur Mexico and is the seat of the municipality of Los Cabos at the south end of the Baja California peninsula. In the 2010 census it had a population of 69,788. Together with neighboring Cabo San Lucas it forms a major tourist destination...
at the tip of the Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
peninsula in modern-day Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
. The journey and observation were uneventful. However, as the expedition was packing to return, an outbreak of fever (possibly yellow fever
Yellow fever
Yellow fever is an acute viral hemorrhagic disease. The virus is a 40 to 50 nm enveloped RNA virus with positive sense of the Flaviviridae family....
) hit the area. Chappe stayed to tend the sick, but was infected and died on 1 August. Only one member of the expedition made it back to Paris alive with Chappe's observations and notes. Chappe's account of his journey (Voyage en Californie, pour l'observation du passage de Vénus sur le disque du soleil) was published posthumously by his colleague César Cassini de Thury
César-François Cassini de Thury
César-François Cassini de Thury , also called Cassini III or Cassini de Thury, was a French astronomer and cartographer.- Biography :...
.