Jean-André Deluc
Encyclopedia
Jean-André Deluc or de Luc (8 February 1727 – 7 November 1817) was a 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....

 geologist
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

 and meteorologist.

Life

He was born at Geneva
Geneva
Geneva In the national languages of Switzerland the city is known as Genf , Ginevra and Genevra is the second-most-populous city in Switzerland and is the most populous city of Romandie, the French-speaking part of Switzerland...

, descended from a family which had emigrated from Lucca
Lucca
Lucca is a city and comune in Tuscany, central Italy, situated on the river Serchio in a fertile plainnear the Tyrrhenian Sea. It is the capital city of the Province of Lucca...

 and settled at Geneva in the 15th century. His father, François Deluc, was the author of some publications in refutation of Mandeville and other rationalistic writers, which are best known through Rousseau's humorous account of his ennui in reading them; and he gave his son an excellent education, chiefly in mathematics and natural science. On completing it Jean-André engaged in commerce, which principally occupied the first forty-six years of his life, without any other interruption than that which was occasioned by some journeys of business into the neighboring countries, and a few scientific excursions among the Alps
Alps
The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....

.

During these, however, he collected by degrees, in conjunction with his brother Guillaume Antoine Deluc, a splendid museum of mineralogy and of natural history in general, which was afterwards increased by his nephew J. André Deluc (1763–1847), who was also a writer on geology. He at the same time took a prominent part in politics. In 1768 he was sent to Paris on an embassy to the duc de Choiseul, whose friendship he succeeded in gaining. In 1770 he was nominated one of the Council of Two Hundred.

Three years later unexpected reverses in business made it advisable for him to quit his native town, which he only revisited once for a few days. The change was welcome insofar as it set him entirely free for scientific pursuits, and it was with little regret that he removed to England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 in 1773. He was made a fellow 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"...

 in the same year, and received the appointment of reader to Queen Charlotte
Charlotte of Mecklenburg-Strelitz
Charlotte of Mecklenburg-Strelitz was the Queen consort of the United Kingdom as the wife of King George III...

, which he continued to hold for forty-four years, and which afforded him both leisure and a competent income.

In the latter part of his life he obtained leave to make several tours in Switzerland, France, Holland and Germany. In Germany he passed the six years from 1798 to 1804; and after his return he undertook a geological tour through England. When he was at Göttingen
Göttingen
Göttingen is a university town in Lower Saxony, Germany. It is the capital of the district of Göttingen. The Leine river runs through the town. In 2006 the population was 129,686.-General information:...

, in the beginning of his German tour, he received the compliment of being appointed honorary professor of philosophy and geology in that university; but he never entered upon the active duties of a professorship. He was also a correspondent of 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...

, and a member of several other scientific associations. He died at Windsor, Berkshire
Windsor, Berkshire
Windsor is an affluent suburban town and unparished area in the Royal Borough of Windsor and Maidenhead in Berkshire, England. It is widely known as the site of Windsor Castle, one of the official residences of the British Royal Family....

, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 in 1817.

Works

His favorite studies were geology and meteorology. The situation of his native country had naturally led him to contemplate the peculiarities of the earths structure, and the properties of the atmosphere, as particularly displayed in mountainous countries, and as subservient to the measurement of heights. According to Georges Cuvier
Georges Cuvier
Georges Chrétien Léopold Dagobert Cuvier or Jean Léopold Nicolas Frédéric Cuvier , known as Georges Cuvier, was a French naturalist and zoologist...

, he ranked among the first geologists of his age. His principal geological work, Lettres physiques et morales sur les montagnes et sur l'histoire de la terre et de l'homme, first published in 1778, and in a more complete form in 1779, was dedicated to Queen Charlotte. It dealt with the appearance of mountains and the antiquity of the human race, explained the six days of the Mosaic creation as so many epochs preceding the actual state of the globe, and attributed the deluge to the filling up of cavities supposed to have been left void in the interior of the earth. He published later an important series of volumes on geological travels in the north of Europe (1810), in England (1811), and in France, Switzerland and Germany (1813). These were translated into English.

Deluc's original experiments relating to meteorology were valuable to the natural philosopher; and he discovered many facts of considerable importance relating to heat and moisture. He noticed the disappearance of heat in the thawing of ice about the same time that Joseph Black
Joseph Black
Joseph Black FRSE FRCPE FPSG was a Scottish physician and chemist, known for his discoveries of latent heat, specific heat, and carbon dioxide. He was professor of Medicine at University of Glasgow . James Watt, who was appointed as philosophical instrument maker at the same university...

 founded on it his ingenious hypothesis of latent heat
Latent heat
Latent heat is the heat released or absorbed by a chemical substance or a thermodynamic system during a process that occurs without a change in temperature. A typical example is a change of state of matter, meaning a phase transition such as the melting of ice or the boiling of water. The term was...

. He ascertained that water was denser about 40 F. (4 C.) than at the temperature of freezing, expanding equally on each side of the maximum; and he was the originator of the theory, afterward readvanced by John Dalton
John Dalton
John Dalton FRS was an English chemist, meteorologist and physicist. He is best known for his pioneering work in the development of modern atomic theory, and his research into colour blindness .-Early life:John Dalton was born into a Quaker family at Eaglesfield, near Cockermouth, Cumberland,...

, that the quantity of aqueous vapour contained in any space is independent of the presence or density of the air, or of any other elastic fluid.

His Recherches sur les modifications de l'atmosphere (2 vols. 4to, Geneva, 1772; 2nd ed., 4 vols. 8vo, Paris, 1784) contains many accurate and ingenious experiments upon moisture, evaporation and the indications of hygrometer
Hygrometer
A hygrometer is an instrument used for measuring the moisture content in the environmental air, or humidity. Most measurement devices usually rely on measurements of some other quantity such as temperature, pressure, mass or a mechanical or electrical change in a substance as moisture is absorbed...

s and thermometer
Thermometer
Developed during the 16th and 17th centuries, a thermometer is a device that measures temperature or temperature gradient using a variety of different principles. A thermometer has two important elements: the temperature sensor Developed during the 16th and 17th centuries, a thermometer (from the...

s, applied to the barometer
Barometer
A barometer is a scientific instrument used in meteorology to measure atmospheric pressure. Pressure tendency can forecast short term changes in the weather...

 employed in determining heights. In. the Phil. Trans., 1773, appeared his account of a new hygrometer, which resembled a mercurial thermometer, with an ivory bulb, which expanded by moisture, and caused the mercury to descend. The first correct rules ever published for measuring heights by the barometer were those he gave in the Phil. Trans., 1771, p. 158. His Lettres sur l'histoire physique de la terre (8vo, Paris, 1798), addressed to Professor Johann Friedrich Blumenbach
Johann Friedrich Blumenbach
Johann Friedrich Blumenbach was a German physician, physiologist and anthropologist, one of the first to explore the study of mankind as an aspect of natural history, whose teachings in comparative anatomy were applied to classification of what he called human races, of which he determined...

, contains an essay on the existence of a General Principle of Morality. It also gives an interesting account of some conversations of the author with Voltaire
Voltaire
François-Marie Arouet , better known by the pen name Voltaire , was a French Enlightenment writer, historian and philosopher famous for his wit and for his advocacy of civil liberties, including freedom of religion, free trade and separation of church and state...

 and Rousseau. Deluc was an ardent admirer of Bacon, on whose writings he published two works; Bacon tel quil est (8vo, Berlin, 1800), showing the bad faith of the French translator, who had omitted many passages favorable to revealed religion, and Prcis de la philosophic de Bacon (2 vols 8vo, Paris, 1802), giving an interesting view of the progress of natural science. Lettres sur le Christianisme (Berlin and Hanover, iSo,, 1803) was a controversial correspondence with Dr Teller
Teller
Teller may refer to:* Teller * Teller , of Penn & Teller* Bank teller** Automated teller machine* Teller * Teller, Alaska* Teller County, Colorado* Teller Amendment* Teller mine...

 of Berlin in regard to the Mosaic cosmogony. His Trail elementaire de geologie (8vo, Paris, 1809, also in English, by de la Fite, the same year) was principally intended as a refutation of James Hutton
James Hutton
James Hutton was a Scottish physician, geologist, naturalist, chemical manufacturer and experimental agriculturalist. He is considered the father of modern geology...

 and John Playfair
John Playfair
John Playfair FRSE, FRS was a Scottish scientist and mathematician, and a professor of natural philosophy at the University of Edinburgh. He is perhaps best known for his book Illustrations of the Huttonian Theory of the Earth , which summarized the work of James Hutton...

. They had shown that geology was driven by the operation of internal heat and erosion. Their system required much more time than Deluc's Mosaic
Mosaic
Mosaic is the art of creating images with an assemblage of small pieces of colored glass, stone, or other materials. It may be a technique of decorative art, an aspect of interior decoration, or of cultural and spiritual significance as in a cathedral...

 variety of Neptunism
Neptunism
Neptunism is a discredited and obsolete scientific theory of geology proposed by Abraham Gottlob Werner in the late 18th century that proposed rocks formed from the crystallisation of minerals in the early Earth's oceans....

 allowed.

He sent to the Royal Society, in 1809, a long paper on separating the chemical from the electrical effect of the dry pile a form of Voltaic pile
Voltaic pile
A voltaic pile is a set of individual Galvanic cells placed in series. The voltaic pile, invented by Alessandro Volta in 1800, was the first electric battery...

, with a description of the electric column and aerial electroscope, in which he advanced opinions so little in unison with the latest discoveries of the day, that the council deemed it inexpedient to admit them into the Transactions. The paper was afterwards published in Nicholson's Journal (xxvi.), and the dry column described in it was constructed by various experimental philosophers. His improvements to the dry pile has been regarded as his most important work although he was not in fact its inventor.

Many other of his papers on subjects kindred to those already mentioned are to be found in the Transactions and in the Philosophical Magazine. See Philosophical Magazine (November 1817).

External links

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