Henry Cavendish ( ; 10 October 1731 – 24 February 1810) was an English natural philosopher and scientist who was an important experimental and theoretical

chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties. Chemists carefully describe th ...

and

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate caus ...

. He is noted for his discovery of

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...

, which he termed "inflammable air". He described the density of inflammable air, which formed water on combustion, in a 1766 paper, ''On Factitious Airs''.

Antoine Lavoisier Antoine-Laurent de Lavoisier ( , ; ; 26 August 17438 May 1794), When reduced without charcoal, it gave off an air which supported respiration and combustion in an enhanced way. He concluded that this was just a pure form of common air and th ...

later reproduced Cavendish's experiment and gave the element its name. A shy man, Cavendish was distinguished for great accuracy and precision in his researches into the composition of

atmospheric air The atmosphere of Earth is the layer of gases, known collectively as air, retained by Gravity of Earth, Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating Atmo ...

, the properties of different gases, the synthesis of water, the law governing electrical attraction and repulsion, a mechanical theory of heat, and calculations of the

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...

(and hence the

mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different elementar ...

) of the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

. His experiment to measure the density of the Earth (which, in turn, allows the

gravitational constant The gravitational constant (also known as the universal gravitational constant, the Newtonian constant of gravitation, or the Cavendish gravitational constant), denoted by the capital letter , is an empirical physical constant involved in ...

to be calculated) has come to be known as the

Cavendish experiment The Cavendish experiment, performed in 1797–1798 by English scientist Henry Cavendish, was the first experiment to measure the force of gravity between masses in the laboratory and the first to yield accurate values for the gravitational con ...

Early life

Henry Cavendish was born on 10 October 1731 in

Nice Nice ( , ; Niçard: , classical norm, or , nonstandard, ; it, Nizza ; lij, Nissa; grc, Νίκαια; la, Nicaea) is the prefecture of the Alpes-Maritimes department in France. The Nice agglomeration extends far beyond the administrative c ...

, where his family was living at the time. His mother was Lady Anne de Grey, fourth daughter of

Henry Grey, 1st Duke of Kent Henry Grey, 1st Duke of Kent, KG, PC (16715 June 1740) was a British politician and courtier. None of his sons outlived him, so his new title became extinct on his death. Though the house he built at Wrest Park in Bedfordshire has gone, parts ...

, and his father was

Lord Charles Cavendish Lord Charles Cavendish FRS (17 March 1704 – 28 April 1783) was a British nobleman and Whig politician. Cavendish was the youngest son of William Cavendish, 2nd Duke of Devonshire, and Rachel Russell. On 9 January 1727, Lord Charles Cavendis ...

, the third son of

William Cavendish, 2nd Duke of Devonshire William Cavendish, 2nd Duke of Devonshire (1672 – 4 June 1729) was a British nobleman and politician. He was the eldest son of William Cavendish, 1st Duke of Devonshire and Lady Mary Butler. A prominent Whig, he was sworn of the Privy Counc ...

. The family traced its lineage across eight centuries to

Norman Norman or Normans may refer to: Ethnic and cultural identity * The Normans, a people partly descended from Norse Vikings who settled in the territory of Normandy in France in the 10th and 11th centuries ** People or things connected with the Norm ...

times, and was closely connected to many aristocratic families of Great Britain. Henry's mother died in 1733, three months after the birth of her second son, Frederick, and shortly before Henry's second birthday, leaving Lord Charles Cavendish to bring up his two sons. Henry Cavendish was styled as "The Honourable Henry Cavendish". From the age of 11 Henry attended

Newcome's School Newcome's School was a fashionable boys' school in Hackney, then to the east of London, founded in the early 18th century. A number of prominent Whig families sent their sons there. The school closed in 1815, and the buildings were gutted in 182 ...

, a private school near London. At the age of 18 (on 24 November 1748) he entered the

University of Cambridge , mottoeng = Literal: From here, light and sacred draughts. Non literal: From this place, we gain enlightenment and precious knowledge. , established = , other_name = The Chancellor, Masters and Schola ...

in St Peter's College, now known as

Peterhouse Peterhouse is the oldest constituent college of the University of Cambridge in England, founded in 1284 by Hugh de Balsham, Bishop of Ely. Today, Peterhouse has 254 undergraduates, 116 full-time graduate students and 54 fellows. It is quite o ...

, but left three years later on 23 February 1751 without taking a degree (at the time, a common practice). He then lived with his father in London, where he soon had his own laboratory. Lord Charles Cavendish spent his life firstly in politics and then increasingly in science, especially in the

Royal Society The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...

of London. In 1758, he took Henry to meetings of the Royal Society and also to dinners of the Royal Society Club. In 1760, Henry Cavendish was elected to both these groups, and he was assiduous in his attendance after that. He took virtually no part in politics, but followed his father into science, through his researches and his participation in scientific organisations. He was active in the Council of the Royal Society of London (to which he was elected in 1765). His interest and expertise in the use of scientific instruments led him to head a committee to review the Royal Society's meteorological instruments and to help assess the instruments of the Royal Greenwich Observatory. His first paper, ''Factitious Airs'', appeared in 1766. Other committees on which he served included the committee of papers, which chose the papers for publication in the ''

Philosophical Transactions of the Royal Society ''Philosophical Transactions of the Royal Society'' is a scientific journal published by the Royal Society. In its earliest days, it was a private venture of the Royal Society's secretary. It was established in 1665, making it the first journa ...

'', and the committees for the

transit of Venus frameless, upright=0.5 A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and a superior planet, becoming visible against (and hence obscuring a small portion of) the solar disk. During a trans ...

(1769), for the gravitational attraction of mountains (1774), and for the scientific instructions for Constantine Phipps's expedition (1773) in search of the

North Pole The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is the point in the Northern Hemisphere where the Earth's axis of rotation meets its surface. It is called the True North Pole to distinguish from the Mag ...

and the

Northwest Passage The Northwest Passage (NWP) is the sea route between the Atlantic and Pacific oceans through the Arctic Ocean, along the northern coast of North America via waterways through the Canadian Arctic Archipelago. The eastern route along the Arc ...

. In 1773, Henry joined his father as an elected trustee of the

British Museum The British Museum is a public museum dedicated to human history, art and culture located in the Bloomsbury area of London. Its permanent collection of eight million works is among the largest and most comprehensive in existence. It docum ...

, to which he devoted a good deal of time and effort. Soon after the Royal Institution of Great Britain was established, Cavendish became a manager (1800) and took an active interest, especially in the laboratory, where he observed and helped in

Humphry Davy Sir Humphry Davy, 1st Baronet, (17 December 177829 May 1829) was a British chemist and inventor who invented the Davy lamp and a very early form of arc lamp. He is also remembered for isolating, by using electricity, several elements for t ...

's chemical experiments.

Chemistry research

About the time of his father's death, Cavendish began to work closely with Charles Blagden, an association that helped Blagden enter fully into London's scientific society. In return, Blagden helped to keep the world at a distance from Cavendish. Cavendish published no books and few papers, but he achieved much. Several areas of research, including

mechanics Mechanics (from Ancient Greek: μηχανική, ''mēkhanikḗ'', "of machines") is the area of mathematics and physics concerned with the relationships between force, matter, and motion among physical objects. Forces applied to objects r ...

optics Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviole ...

, and

magnetism Magnetism is the class of physical attributes that are mediated by a magnetic field, which refers to the capacity to induce attractive and repulsive phenomena in other entities. Electric currents and the magnetic moments of elementary particles ...

, feature extensively in his manuscripts, but they scarcely feature in his published work. Cavendish is considered to be one of the so-called pneumatic chemists of the eighteenth and nineteenth centuries, along with, for example,

Joseph Priestley Joseph Priestley (; 24 March 1733 – 6 February 1804) was an English chemist, natural philosopher, separatist theologian, grammarian, multi-subject educator, and liberal political theorist. He published over 150 works, and conducted exp ...

Joseph Black Joseph Black (16 April 1728 – 6 December 1799) was a Scottish physicist and chemist, known for his discoveries of magnesium, latent heat, specific heat, and carbon dioxide. He was Professor of Anatomy and Chemistry at the University of Glas ...

, and

Daniel Rutherford Daniel Rutherford (3 November 1749 – 15 December 1819) was a Scottish physician, chemist and botanist who is known for the isolation of nitrogen in 1772. Life Rutherford was born on 3 November 1749, the son of Anne Mackay and Professor John ...

. Cavendish found that a definite, peculiar, and highly inflammable gas, which he referred to as "Inflammable Air", was produced by the action of certain

acid In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...

s on certain

metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...

s. This gas was

, which Cavendish correctly guessed was proportioned two to one in water. Although others, such as

Robert Boyle Robert Boyle (; 25 January 1627 – 31 December 1691) was an Anglo-Irish natural philosopher, chemist, physicist, alchemist and inventor. Boyle is largely regarded today as the first modern chemist, and therefore one of the founders of ...

, had prepared hydrogen gas earlier, Cavendish is usually given the credit for recognising its elemental nature. In 1777, Cavendish discovered that air exhaled by mammals is converted to "fixed air" (

carbon dioxide Carbon dioxide (chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is transpar ...

), not "phlogisticated air" as predicted by Joseph Priestley. Also, by dissolving

alkali In chemistry, an alkali (; from ar, القلوي, al-qaly, lit=ashes of the saltwort) is a basic, ionic salt of an alkali metal or an alkaline earth metal. An alkali can also be defined as a base that dissolves in water. A solution of a ...

s in acids, Cavendish produced carbon dioxide, which he collected, along with other gases, in bottles inverted over water or mercury. He then measured their solubility in water and their

specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water (molecule), wa ...

, and noted their

combustibility A combustible material is something that can burn (i.e., ''combust'') in air. A combustible material is flammable if it ignites easily at ambient temperatures. In other words, a combustible material ignites with some effort and a flammable mat ...

. He concluded in his 1778 paper "General Considerations on Acids" that respirable air constitutes acidity. Cavendish was awarded the Royal Society's

Copley Medal The Copley Medal is an award given by the Royal Society, for "outstanding achievements in research in any branch of science". It alternates between the physical sciences or mathematics and the biological sciences. Given every year, the medal is t ...

for this paper. Gas chemistry was of increasing importance in the latter half of the 18th century, and became crucial for Frenchman

Antoine-Laurent Lavoisier Antoine-Laurent de Lavoisier ( , ; ; 26 August 17438 May 1794),
CNRS (

chemical revolution The chemical revolution, also called the ''first chemical revolution'', was the early modern reformulation of chemistry that culminated in the law of conservation of mass and the oxygen theory of combustion. During the 19th and 20th century, thi ...

. In 1783, Cavendish published a paper on eudiometry (the measurement of the goodness of gases for breathing). He described a new eudiometer of his invention, with which he achieved the best results to date, using what in other hands had been the inexact method of measuring gases by weighing them. Then, after a repetition of a 1781 experiment performed by Priestley, Cavendish published a paper on the production of pure water by burning hydrogen in " dephlogisticated air" (air in the process of combustion, now known to be

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

). Quoting from the monograph by

James Riddick Partington James Riddick Partington (30 June 1886 – 9 October 1965) was a British chemist and historian of chemistry who published multiple books and articles in scientific magazines. His most famous works were ''An Advanced Treatise on Physical Chemis ...

, ''The Composition of Water'', G. Bell and Sons, 1928, . Cavendish concluded that rather than being synthesised, the burning of hydrogen caused water to be condensed from the air. Some physicists interpreted hydrogen as pure

phlogiston The phlogiston theory is a superseded scientific theory that postulated the existence of a fire-like element called phlogiston () contained within combustible bodies and released during combustion. The name comes from the Ancient Greek (''burni ...

. Cavendish reported his findings to Priestley no later than March 1783, but did not publish them until the following year. The Scottish inventor

James Watt James Watt (; 30 January 1736 (19 January 1736 OS) – 25 August 1819) was a Scottish inventor, mechanical engineer, and chemist who improved on Thomas Newcomen's 1712 Newcomen steam engine with his Watt steam engine in 1776, which was fun ...

published a paper on the composition of water in 1783; controversy about who made the discovery first ensued. In 1785, Cavendish investigated the composition of common (i.e. atmospheric)

air The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing f ...

, obtaining impressively accurate results. He conducted experiments in which hydrogen and ordinary air were combined in known ratios and then exploded with a spark of electricity. Furthermore, he also described an experiment in which he was able to remove, in modern terminology, both the oxygen and nitrogen gases from a sample of atmospheric air until only a small bubble of unreacted gas was left in the original sample. Using his observations, Cavendish observed that, when he had determined the amounts of phlogisticated air (

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

) and dephlogisticated air (oxygen), there remained a volume of gas amounting to 1/120 of the original volume of nitrogen. By careful measurements he was led to conclude that "common air consists of one part of dephlogisticated air xygen mixed with four of phlogisticated itrogen. In the 1890s (around 100 years later) two British physicists,

William Ramsay Sir William Ramsay (; 2 October 1852 – 23 July 1916) was a Scottish chemist who discovered the noble gases and received the Nobel Prize in Chemistry in 1904 "in recognition of his services in the discovery of the inert gaseous element ...

and

Lord Rayleigh John William Strutt, 3rd Baron Rayleigh, (; 12 November 1842 – 30 June 1919) was an English mathematician and physicist who made extensive contributions to science. He spent all of his academic career at the University of Cambridge. Am ...

, realised that their newly discovered

inert gas An inert gas is a gas that does not readily undergo chemical reactions with other chemical substances and therefore does not readily form chemical compounds. The noble gases often do not react with many substances and were historically referred to ...

argon Argon is a chemical element with the symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third-most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as abu ...

, was responsible for Cavendish's problematic residue; he had not made an error. What he had done was perform rigorous quantitative experiments, using standardised instruments and methods, aimed at reproducible results; taken the mean of the result of several experiments; and identified and allowed for sources of error. The balance that he used, made by a craftsman named Harrison, was the first of the precision balances of the 18th century, and as accurate as Lavoisier's (which has been estimated to measure one part in 400,000). Cavendish worked with his instrument makers, generally improving existing instruments rather than inventing wholly new ones. Cavendish, as indicated above, used the language of the old phlogiston theory in chemistry. In 1787, he became one of the earliest outside France to convert to the new antiphlogistic theory of Lavoisier, though he remained sceptical about the nomenclature of the new theory. He also objected to Lavoisier's identification of heat as having a material or elementary basis. Working within the framework of Newtonian mechanism, Cavendish had tackled the problem of the nature of heat in the 1760s, explaining heat as the result of the motion of matter. In 1783, he published a paper on the temperature at which mercury freezes and in that paper made use of the idea of

latent heat Latent heat (also known as latent energy or heat of transformation) is energy released or absorbed, by a body or a thermodynamic system, during a constant-temperature process — usually a first-order phase transition. Latent heat can be underst ...

, although he did not use the term because he believed that it implied acceptance of a material theory of heat. He made his objections explicit in his 1784 paper on air. He went on to develop a general theory of heat, and the manuscript of that theory has been persuasively dated to the late 1780s. His theory was at once mathematical and mechanical: it contained the principle of the conservation of heat (later understood as an instance of

conservation of energy In physics and chemistry, the law of conservation of energy states that the total energy of an isolated system remains constant; it is said to be ''conserved'' over time. This law, first proposed and tested by Émilie du Châtelet, means th ...

) and even included the concept (although not the label) of the

mechanical equivalent of heat In the history of science, the mechanical equivalent of heat states that motion and heat are mutually interchangeable and that in every case, a given amount of work would generate the same amount of heat, provided the work done is totally convert ...

Density of the Earth

Following his father's death, Henry bought another house in town and also a house in

Clapham Common Clapham Common is a large triangular urban park in Clapham, south London, England. Originally common land for the parishes of Battersea and Clapham, it was converted to parkland under the terms of the Metropolitan Commons Act 1878. It is of gr ...

(built by

Thomas Cubitt Thomas Cubitt (25 February 1788 – 20 December 1855) was a British master builder, notable for his employment in developing many of the historic streets and squares of London, especially in Belgravia, Pimlico and Bloomsbury. His great-great-g ...

), at that time to the south of London. The London house contained the bulk of his library, while he kept most of his instruments at Clapham Common, where he carried out most of his experiments. The most famous of those experiments, published in 1798, was to determine the density of the Earth and became known as the

. The apparatus Cavendish used for weighing the Earth was a modification of the

torsion balance A torsion spring is a spring that works by twisting its end along its axis; that is, a flexible elastic object that stores mechanical energy when it is twisted. When it is twisted, it exerts a torque in the opposite direction, proportional ...

built by Englishman and geologist

John Michell John Michell (; 25 December 1724 – 21 April 1793) was an English natural philosopher and clergyman who provided pioneering insights into a wide range of scientific fields including astronomy, geology, optics, and gravitation. Considered "o ...

, who died before he could begin the experiment. The apparatus was sent in crates to Cavendish, who completed the experiment in 1797–1798 and published the results. The experimental apparatus consisted of a torsion balance with a pair of 2-inch 1.61-pound lead spheres suspended from the arm of a torsion balance and two much larger stationary lead balls (350 pounds). Cavendish intended to measure the force of

gravitation In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stron ...

al attraction between the two. He noticed that Michell's apparatus would be sensitive to temperature differences and induced air currents, so he made modifications by isolating the apparatus in a separate room with external controls and telescopes for making observations. Using this equipment, Cavendish calculated the attraction between the balls from the period of oscillation of the torsion balance, and then he used this value to calculate the density of the Earth. Cavendish found that the Earth's average density is 5.48 times greater than that of water.

John Henry Poynting John Henry Poynting FRS (9 September 185230 March 1914) was an English physicist. He was the first professor of physics at Mason Science College from 1880 to 1900, and then the successor institution, the University of Birmingham until his deat ...

later noted that the data should have led to a value of 5.448, and indeed that is the average value of the twenty-nine determinations Cavendish included in his paper. The published number was due to a simple

arithmetic Arithmetic () is an elementary part of mathematics that consists of the study of the properties of the traditional operations on numbers— addition, subtraction, multiplication, division, exponentiation, and extraction of roots. In the 19th ...

error on his part. What was extraordinary about Cavendish's experiment was its elimination of every source of error and every factor that could disturb the experiment, and its precision in measuring an astonishingly small attraction, a mere 1/50,000,000 of the weight of the lead balls. The result that Cavendish obtained for the density of the Earth is within 1 percent of the currently accepted figure. Cavendish's work led others to accurate values for the

(''G'') and Earth's mass. Based on his results, one can calculate a value for G of 6.754 × 10⁻¹¹N-m²/kg², which compares favourably with the modern value of 6.67428 × 10⁻¹¹N-m²/kg². Books often describe Cavendish's work as a measurement of either ''G'' or the Earth's mass. Since these are related to the Earth's density by a trivial web of algebraic relations, none of these sources are wrong, but they do not match the exact word choice of Cavendish, and this mistake has been pointed out by several authors. Cavendish's stated goal was to measure the Earth's density. The first time that the constant got this name was in 1873, almost 100 years after the Cavendish experiment. Cavendish's results also give the Earth's mass.

Electrical research

Cavendish's electrical and chemical experiments, like those on heat, had begun while he lived with his father in a laboratory in their London house. Lord Charles Cavendish died in 1783, leaving almost all of his very substantial estate to Henry. Like his theory of heat, Cavendish's comprehensive theory of electricity was mathematical in form and was based on precise quantitative experiments. Working with his colleague, Timothy Lane, he created an artificial

torpedo fish The electric rays are a group of rays, flattened cartilaginous fish with enlarged pectoral fins, composing the order Torpediniformes . They are known for being capable of producing an electric discharge, ranging from 8 to 220 volts, depending o ...

that could dispense electric shocks to show that the source of shock from these fish was electricity. He published an early version of his theory of electricity in 1771, based on an expansive electrical fluid that exerted pressure. He demonstrated that if the intensity of electric force were inversely proportional to distance, then the electric fluid more than that needed for electrical neutrality would lie on the outer surface of an electrified sphere; then he confirmed this experimentally. Cavendish continued to work on electricity after this initial paper, but he published no more on the subject. Cavendish wrote papers on electrical topics for the Royal Society but the bulk of his electrical experiments did not become known until they were collected and published by

James Clerk Maxwell James Clerk Maxwell (13 June 1831 – 5 November 1879) was a Scottish mathematician and scientist responsible for the classical theory of electromagnetic radiation, which was the first theory to describe electricity, magnetism and ligh ...

a century later, in 1879, long after other scientists had been credited with the same results. Cavendish's electrical papers from the ''Philosophical Transactions of the Royal Society of London'' have been reprinted, together with most of his electrical manuscripts, in ''The Scientific Papers of the Honourable Henry Cavendish, F.R.S.'' (1921). According to the 1911 edition of

Encyclopædia Britannica The (Latin for "British Encyclopædia") is a general knowledge English-language encyclopaedia. It is published by Encyclopædia Britannica, Inc.; the company has existed since the 18th century, although it has changed ownership various time ...

, among Cavendish's discoveries were the concept of

electric potential The electric potential (also called the ''electric field potential'', potential drop, the electrostatic potential) is defined as the amount of work energy needed to move a unit of electric charge from a reference point to the specific point in ...

(which he called the "degree of electrification"), an early unit of

capacitance Capacitance is the capability of a material object or device to store electric charge. It is measured by the change in charge in response to a difference in electric potential, expressed as the ratio of those quantities. Commonly recognized are ...

(that of a sphere one inch in diameter), the formula for the capacitance of a plate

capacitor A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals. The effect of ...

, the concept of the

dielectric constant The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the electric permittivity of a vacuum. A dielectric is an insulating material, and the dielectric constant of an insulat ...

of a material, the relationship between electric potential and current (now called

Ohm's Law Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points. Introducing the constant of proportionality, the resistance, one arrives at the usual mathematical equat ...

) (1781), laws for the division of current in parallel circuits (now attributed to

Charles Wheatstone Sir Charles Wheatstone FRS FRSE DCL LLD (6 February 1802 – 19 October 1875), was an English scientist and inventor of many scientific breakthroughs of the Victorian era, including the English concertina, the stereoscope (a device for di ...

), and the inverse square law of variation of electric force with distance, now called

Coulomb's Law Coulomb's inverse-square law, or simply Coulomb's law, is an experimental law of physics that quantifies the amount of force between two stationary, electrically charged particles. The electric force between charged bodies at rest is convention ...

Death

Cavendish died at

Clapham Clapham () is a suburb in south west London, England, lying mostly within the London Borough of Lambeth, but with some areas (most notably Clapham Common) extending into the neighbouring London Borough of Wandsworth. History Early history T ...

on 24 February 1810 (as one of the wealthiest men in Britain) and was buried, along with many of his ancestors, in the church that is now

Derby Cathedral The Cathedral Church of All Saints Derby, better known as Derby Cathedral, is a cathedral church in the city of Derby, England. In 1927, it was promoted from parish church status, to a cathedral, creating a seat for the Bishop of Derby, w ...

. The road he used to live on in Derby has been named after him. The University of Cambridge's Cavendish Laboratory was endowed by one of Cavendish's later relatives,

William Cavendish, 7th Duke of Devonshire William Cavendish, 7th Duke of Devonshire, (27 April 1808 – 21 December 1891), styled as Lord Cavendish of Keighley between 1831 and 1834 and known as Earl of Burlington between 1834 and 1858, was a British landowner, benefactor, nobleman, ...

(Chancellor of the University from 1861 to 1891).

Personality and legacy

Cavendish inherited two fortunes that were so large that

Jean Baptiste Biot Jean-Baptiste Biot (; ; 21 April 1774 – 3 February 1862) was a French physicist, astronomer, and mathematician who co-discovered the Biot–Savart law of magnetostatics with Félix Savart, established the reality of meteorites, made an early b ...

called him "the richest of all the savants and the most knowledgeable of the rich". At his death, Cavendish was the largest depositor in the

Bank of England The Bank of England is the central bank of the United Kingdom and the model on which most modern central banks have been based. Established in 1694 to act as the English Government's banker, and still one of the bankers for the Government of ...

. He was a shy man who was uncomfortable in society and avoided it when he could. He could speak to only one person at a time, and only if the person were known to him and male. He conversed little, always dressed in an old-fashioned suit, and developed no known deep personal attachments outside his family. Cavendish was taciturn and solitary and regarded by many as eccentric. He communicated with his female servants only by notes. By one account, Cavendish had a back staircase added to his house to avoid encountering his housekeeper, because he was especially shy of women. The contemporary accounts of his personality have led some modern commentators, such as

Oliver Sacks Oliver Wolf Sacks, (9 July 1933 – 30 August 2015) was a British neurologist, naturalist, historian of science, and writer. Born in Britain, Sacks received his medical degree in 1958 from The Queen's College, Oxford, before moving to the Uni ...

, to speculate that he had

Asperger syndrome Asperger syndrome (AS), also known as Asperger's, is a former neurodevelopmental disorder characterized by significant difficulties in social interaction and nonverbal communication, along with restricted and repetitive patterns of beha ...

, a form of

autism The autism spectrum, often referred to as just autism or in the context of a professional diagnosis autism spectrum disorder (ASD) or autism spectrum condition (ASC), is a neurodevelopmental condition (or conditions) characterized by difficulti ...

. His only social outlet was the Royal Society Club, whose members dined together before weekly meetings. Cavendish seldom missed these meetings, and was profoundly respected by his contemporaries. However, his shyness made those who "sought his views... speak as if into vacancy. If their remarks were...worthy, they might receive a mumbled reply, but more often than not they would hear a peeved squeak (his voice appears to have been high-pitched) and turn to find an actual vacancy and the sight of Cavendish fleeing to find a more peaceful corner".Bryson, B. (2003), "The Size of the Earth": ''A Short History of Nearly Everything'', 59–62. Cavendish's religious views were also considered eccentric for his time. He was considered to be agnostic. As his biographer, George Wilson, comments, "As to Cavendish's religion, he was nothing at all." The arrangement of his residence reserved only a fraction of space for personal comfort as his library was detached, the upper rooms and lawn were for astronomical observation and his drawingroom was a laboratory with a forge in an adjoining room. He also enjoyed collecting fine furniture, exemplified by his purchase of a set of "ten inlaid satinwood chairs with matching

cabriole leg A cabriole leg is one of (usually) four vertical supports of a piece of furniture shaped in two curves; the upper arc is convex, while lower is concave; the upper curve always bows outward, while the lower curve bows inward; with the axes of the ...

ged sofa".McCormmach, R and Jungnickel, C (1996)
''Cavendish''
American Philosophical Society, Philadelphia, , pp. 242, 337. Because of his asocial and secretive behaviour, Cavendish often avoided publishing his work, and much of his findings were not told even to his fellow scientists. In the late nineteenth century, long after his death,

looked through Cavendish's papers and found observations and results for which others had been given credit. Examples of what was included in Cavendish's discoveries or anticipations were Richter's law of reciprocal proportions,

Ohm's law Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points. Introducing the constant of proportionality, the resistance, one arrives at the usual mathematical equat ...

Dalton's law Dalton's law (also called Dalton's law of partial pressures) states that in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases. This empirical law was observed by Jo ...

of partial pressures, principles of

electrical conductivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allow ...

(including

Coulomb's law Coulomb's inverse-square law, or simply Coulomb's law, is an experimental law of physics that quantifies the amount of force between two stationary, electrically charged particles. The electric force between charged bodies at rest is convention ...

), and

Charles's Law Charles's law (also known as the law of volumes) is an experimental gas law that describes how gases tend to expand when heated. A modern statement of Charles's law is: When the pressure on a sample of a dry gas is held constant, the Kelvin t ...

of gases. A manuscript "Heat", tentatively dated between 1783 and 1790, describes a "mechanical theory of heat". Hitherto unknown, the manuscript was analysed in the early 21st century. Historian of science

Russell McCormmach Russell Keith McCormmach (born 9 October 1933), the husband of the late Christa Jungnickel, is an American historian of physics. McCormmach grew up in Walla Walla, Washington and studied physics at Washington State College with bachelor's degree i ...

proposed that "Heat" is the only 18th-century work prefiguring

thermodynamics Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of the ...

. Theoretical physicist Dietrich Belitz concluded that in this work Cavendish "got the nature of heat essentially right". As Cavendish performed his famous density of the Earth experiment in an outbuilding in the garden of his Clapham Common estate, his neighbours would point out the building and tell their children that it was where the world was weighed. In honour of Henry Cavendish's achievements and due to an endowment granted by Henry's relative William Cavendish, 7th Duke of Devonshire, the

's physics laboratory was named the Cavendish Laboratory by Maxwell, the first

Cavendish Professor of Physics The Cavendish Professorship is one of the senior faculty positions in physics at the University of Cambridge. It was founded on 9 February 1871 alongside the famous Cavendish Laboratory, which was completed three years later. William Cavendish, 7th ...

and an admirer of Cavendish's work.

Selected writings

* – edited by James Clerk Maxwell and revised by Joseph Larmor * – edited by James Clerk Maxwell and revised by Joseph Larmor * – edited by

File:Cavendish-1.jpg, 1879 copy of ''"The Electrical Researches of the Honourable Henry Cavendish F.R.S"'' File:Cavendish-3.jpg, Title page of a 1879 copy of ''"The Electrical Researches of the Honourable Henry Cavendish F.R.S"'' File:Cavendish-2.jpg, First page of a 1879 copy of ''"The Electrical Researches of the Honourable Henry Cavendish F.R.S"''

Notes and references

External links

* * * * – Alembic Club reprint number 3 * * * {{DEFAULTSORT:Cavendish, Henry 1731 births 1810 deaths People from Nice English agnostics English physicists Discoverers of chemical elements Recipients of the Copley Medal Fellows of the Royal Society Alumni of Peterhouse, Cambridge

Henry Cavendish Henry Cavendish ( ; 10 October 1731 – 24 February 1810) was an English natural philosopher and scientist who was an important experimental and theoretical chemist and physicist. He is noted for his discovery of hydrogen, which he termed "infl ...

18th-century English chemists 19th-century English chemists People educated at Newcome's School Reputed virgins