Stephen Gray (scientist)

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Stephen Gray
BornDecember 1666 (1666-12)
Died7 February 1736 (1736-02-08) (aged 69)
London, England
Known forBeing the 'father' of electricity
Electrical conductivity
Awards Copley medal (1731, 1732)
Scientific career
Fields Chemistry
Institutions Trinity College, Cambridge
Academic advisors Roger Cotes
John Theophilus Desaguliers
Influences John Flamsteed

Stephen Gray (December 1666 – 7 February 1736) was an English dyer and astronomer who was the first to systematically experiment with electrical conduction. Until his work in 1729 the emphasis had been on the simple generation of static charges and investigations of the static phenomena (electric shocks, plasma glows, etc.). He also first made the distinction between conduction and insulation, and discovered the action-at-a-distance phenomenon of electrostatic induction.

Dyeing process of adding color to textile products like fibers, yarns, and fabrics

Dyeing is the application of dyes or pigments on textile materials such as fibers, yarns, and fabrics with the objective of achieving color with desired fastness. Dyeing is normally done in a special solution containing dyes and particular chemical material. Dye molecules are fixed to the fibre by absorption, diffusion, or bonding with temperature and time being key controlling factors. The bond between dye molecule and fibre may be strong or weak, depending on the dye used. Dyeing and printing are different applications; in printing color is applied to a localized area with desired patterns and in dyeing it is applied to the entire textile.

Astronomer Scientist who studies celestial bodies

An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets, and galaxies – in either observational or theoretical astronomy. Examples of topics or fields astronomers study include planetary science, solar astronomy, the origin or evolution of stars, or the formation of galaxies. Related but distinct subjects like physical cosmology, which studies the Universe as a whole.

Static electricity imbalance of electric charges within or on the surface of a material

Static electricity is an imbalance of electric charges within or on the surface of a material. The charge remains until it is able to move away by means of an electric current or electrical discharge. Static electricity is named in contrast with current electricity, which flows through wires or other conductors and transmits energy.


Early life

Gray was born in Canterbury, Kent, and after some basic schooling, he was apprenticed to his father (and later his elder brother) in the cloth-dyeing trade. His interests lay with natural science and particularly with astronomy; he managed to educate himself in these developing disciplines, mainly through wealthy friends in the district, who gave him access to their libraries and scientific instruments. Science was very much a rich-man's hobby at this time.

He ground his own lenses and constructed his own telescope, and with this instrument he made a number of minor discoveries (mainly in the area of sunspots), gaining a reputation for accuracy in his observations. Some of his reports were published by the Royal Society through the agency of a friend, Henry Hunt, who was a member of the Society's secretarial staff.

Royal Society English learned society for science

The President, Council and Fellows of the Royal Society of London for Improving Natural Knowledge, commonly known as the Royal Society, is a learned society. Founded on 28 November 1660, it was granted a royal charter by King Charles II as "The Royal Society". It is the oldest national scientific institution in the world. The society is the United Kingdom's and Commonwealth of Nations' Academy of Sciences and fulfils a number of roles: promoting science and its benefits, recognising excellence in science, supporting outstanding science, providing scientific advice for policy, fostering international and global co-operation, education and public engagement.

Introduction to Flamsteed

Some of Gray's output came to the notice of John Flamsteed, a relative of some Kent friends of Gray and the first English Astronomer Royal, who was building the new Royal Greenwich Observatory. Flamsteed was attempting to construct a detailed and accurate star-map of the heavens, in the hope that this would eventually solve the problem of longitude determination for ocean navigators. Gray helped him with many of the observations and calculations (possibly without being paid).

John Flamsteed English astronomer and the first Astronomer Royal

John Flamsteed FRS was an English astronomer and the first Astronomer Royal. His main achievements were the preparation of a 3,000-star catalogue, Catalogus Britannicus, and a star atlas called Atlas Coelestis, both published posthumously. He also made the first recorded observations of Uranus, although he mistakenly catalogued it as a star, and he laid the foundation stone for the Royal Greenwich Observatory.

Astronomer Royal Position in the Royal Households of the United Kingdom

Astronomer Royal is a senior post in the Royal Households of the United Kingdom. There are two officers, the senior being the Astronomer Royal dating from 22 June 1675; the second is the Astronomer Royal for Scotland dating from 1834.

Gray and Flamsteed became constant correspondents and friends, and this seems to have created problems for Gray in being accepted formally into the world of science. Flamsteed was involved in a prolonged dispute with Sir Isaac Newton over access to preliminary star-chart data. This boiled over and became a factional war in the Royal Society, which Newton dominated (virtually excluding Flamsteed and his associates) for decades.

Isaac Newton Influential British physicist and mathematician

Sir Isaac Newton was an English mathematician, physicist, astronomer, theologian, and author who is widely recognised as one of the most influential scientists of all time, and a key figure in the scientific revolution. His book Philosophiæ Naturalis Principia Mathematica, first published in 1687, laid the foundations of classical mechanics. Newton also made seminal contributions to optics, and shares credit with Gottfried Wilhelm Leibniz for developing the infinitesimal calculus.

Gray worked for a while on the second English observatory, being built at Cambridge, but it was badly managed by Newton's friend and associate, Roger Cotes; the project finally collapsed, leaving Gray with little option but to return to his dyeing trade in Canterbury. Suffering from ill heallth, before long he was in London assisting John Theophilus Desaguliers, an acolyte of Isaac Newton and occasionally one of the Royal Society's demonstrators. Desaguliers acted as a scientific consultant, giving lectures around the country and on the Continent about new scientific discoveries; he also ran a boarding house for visiting gentlemen with scientific interests. Gray was not paid by Desaguliers, but provided with accommodation in exchange for his ability to discuss scientific subjects with the boarders.

Cambridge City and non-metropolitan district in England

Cambridge is a university city and the county town of Cambridgeshire, England, on the River Cam approximately 50 miles (80 km) north of London. At the United Kingdom Census 2011, its population was 123,867 including 24,506 students. Cambridge became an important trading centre during the Roman and Viking ages, and there is archaeological evidence of settlement in the area as early as the Bronze Age. The first town charters were granted in the 12th century, although modern city status was not officially conferred until 1951.

Roger Cotes English mathematician

Roger Cotes FRS was an English mathematician, known for working closely with Isaac Newton by proofreading the second edition of his famous book, the Principia, before publication. He also invented the quadrature formulas known as Newton–Cotes formulas and first introduced what is known today as Euler's formula. He was the first Plumian Professor at Cambridge University from 1707 until his death.

John Theophilus Desaguliers French-born British natural philosopher and clergyman

John Theophilus Desaguliers FRS was a French-born British natural philosopher, clergyman, engineer and freemason who was elected to the Royal Society in 1714 as experimental assistant to Isaac Newton. He had studied at Oxford and later popularized Newtonian theories and their practical applications in public lectures. Desaguliers's most important patron was James Brydges, 1st Duke of Chandos. As a Freemason, Desaguliers was instrumental in the success of the first Grand Lodge in London in the early 1720s and served as its third Grand Master.

Desaguliers' boarding house was demolished to make way for Westminster Bridge, and poverty intervened for Gray. In 1720, through the efforts of John Flamsteed and Sir Hans Sloane (later President of the Royal Society) he managed to obtain a pensioned position at the Charterhouse, [1] a home for destitute gentlemen who had served their country, also linked to a boys' school. During this time he began experimenting with static electricity again, using a glass tube as a friction generator.

Westminster Bridge bridge over the River Thames in London

Westminster Bridge is a road-and-foot-traffic bridge over the River Thames in London, linking Westminster on the west side and Lambeth on the east side.

London Charterhouse historic complex of buildings in Smithfield, London

The London Charterhouse is a historic complex of buildings in Smithfield, London, dating back to the 14th century. It occupies land to the north of Charterhouse Square, and lies within the London Borough of Islington.

Conduction discoveries

One night, in his Charterhouse rooms, he noticed that the cork at the end of his tube (needed to keep moisture and dust out) generated an attractive force on small pieces of paper and chaff when the tube was rubbed. Normally the cork would not have carried an electrical charge, but climatic conditions and variations in the materials meant that the cork was accumulating charge. When he extended the cork by inserting a small stick of fir, the charge manifested itself at the end of the stick, and then on an ivory ball (perforated with a hole) he had stuck on the end. he tried longer sticks, and finally added a length of an oily hemp pack-thread connected to the ivory ball. In the process he had discovered that the "electric virtue" was not just a 'static' phenomenon (like a local pin-prick), but rather a fluid-like substance that would carry over distance. The terminating ivory ball would still act to attract light objects in the same way as the electrified glass tube.

Over the next few days he extended the reach of his thread-wire (he only had a short piece of wire, and did not understand the significance of metal as a conductor) and found that it would carry from his balcony down into the courtyard below. He discovered that electricity would travel around bends in the thread and that it appeared unaffected by gravity. He was also able to transmit charges to metal objects (poker, tongs, kettle, etc.) which were generally regarded in those days as 'non-electrics' because they couldn't generate or hold static charge. He also discovered that silk would not carry the 'virtue', while the thicker pack-thread and wire could.

Then between 30 June and 2 July 1729 while in Kent he extended this first electrical network and made many new discoveries. On a visit to the Reverend Granville Wheler, a wealthy friend, member of the Royal Society and Famsteed's relative, the two men extended the conduction experiments through pack-thread laced up and down the length of a large gallery in Wheler's manor house, Otterden Place in Kent. In the process, Gray and Wheler discovered the importance of insulating their thread 'conductor' from earth contact (the wall of the house) by using silk for suspension. They noticed that if wire was used to support the pack-thread, all the 'electrical virtue' leaked away. Initially they thought the difference was due to the relative thicknesses of the silk, thread and wire, but later they realised that silk itself was much less conducting than the wire—so they used only silk to support (and thereby insulate) the hemp pack-thread used as their main conductor.

The next day they dropped the thread from the house tower to the garden and then extended it out across a paddock to a distance of 800 feet using paired garden-stakes with short spans of silk to keep the pack-thread from touching the ground. [2] [3] :242–247 Wheler reported this to many of his Royal Society friends, and Gray wrote the full details in a letter to Desaguliers.

From these experiments came an understanding of the role played by conductors and insulators (names applied by Desaguliers). Two French scientists, Abbe Nollet and C.F. du Fay, visited Gray and Wheler in 1732, saw the experiment, and returned to France where du Fay formulated the first comprehensive theory of electricity called the "two-fluid" theory. This theory was championed by Nollet and accepted by most experimenters in Europe for a time; later it was refined and then superseded by the ideas of the English experimenters John Bevis and William Watson, who were in correspondence with Benjamin Franklin's group in Philadelphia. They jointly devised a theory of a single-fluid/two-state: virtually, the super-abundance or absence of one fluid, which Watson later termed positive and negative. These ideas fitted the facts slightly better than the two-fluid concept, especially after the invention of the Leyden Jar, and this single-fluid theory eventually prevailed. We now know that both were almost equally incorrect.

Gray went on to make more electrical discoveries, the most noticeable being electrical induction (creating an electrical charge in a suspended object without contact). This experiment was widely celebrated around Europe as the famous "Flying Boy" demonstration: a boy was suspended on silk cords, and then charged by Gray bringing his rubbed tube (static electric generator) close to the boy's feet, but without touching. Gray showed that the boy's face and hands still attracted the chaff, paper and other materials. [4] Gray certainly realised that the phenomenon of 'electric virtue' was the same as lightning (as did most experimenters), many years before Franklin "flew his kite" and the French experimenters Dilibard and Delor captured a charge from lightning in a Leyden Jar.

When Sloane took over the Royal Society on Newton's death, Gray belatedly received the recognition denied him previously. Gray was too poor to pay the dues, so he was not a member of the Royal Society, and many of his experiments had been taken up and became part of the demonstration repertoire of Desaguliers. There is also a story that he was denied recognition by the Newton faction within the Royal Society because of his links to Flamsteed (who was constantly in dispute with Isaac Newton), but this can be dismissed as highly unlikely: Newton had died in March 1727, nearly two years before Gray began his conduction experiments, and Hans Sloan, who ran the Royal Society after Newton's death was a friend and financial supporter of Gray. The fact is that electricity was not considered that important at the time, and the Society's magazine was not published for a couple of years due to financial constraints.

Sloan took an active part in promoting Gray, who received the Royal Society's first Copley Medal in 1731 for his work on conduction and insulation, and also its second in 1732 for his induction experiments. In 1732 the Royal Society also admitted him as an honorary member; he died destitute a few years later, in 1736.

After his death

Despite the importance of his discoveries (it can be argued that he was the inventor of electrical communications), he received little credit, supposedly because of the factional dispute in the Royal Society, and the dominance of Newtonianism. Desaguliers achieved far more fame than Gray, and many of Gray's discoveries became attached to the name Desaguliers by virtue of his flamboyant demonstrations. By the time Gray's priority was publicly recognised, experiments in electricity had moved on and people were interested more in the spectacular feats by Franklin and others in capturing lightning in their Leyden Jars. Gray's discoveries tended to look trivial, and for this reason some historians tend to overlook his work.

There is no monument to Gray, and little recognition of what he achieved in his scientific discoveries. He is believed to be buried in a common grave in an old London cemetery, in an area reserved for pauper pensioners from the Charterhouse. In 2017 the School of Physical Sciences at the University of Kent, in Canterbury, initiated the Stephen Gray Lectures in his memory. [5]

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  1. Michael Ben-Chaim, 'Gray, Stephen', Oxford Dictionary of National Biography, Oxford University Press, 2004
  2. Bernal, John Desmond (1997). A History of Classical Physics: From Antiquity to the Quantum, p. 284. Barnes & Noble Books. ISBN   0-7607-0601-8.
  3. Heilbron (1 January 1979). Electricity in the 17th and 18th Centuries: A Study of Early Modern Physics. ISBN   9780520034785.
  4. Benjamin, Park (1898). A History of Electricity (the Intellectual Rise in Electricity) from Antiquity to the Days of Benjamin Franklin, pp. 470–71. New York: John Wiley & Sons.
  5. "Stephen Gray Lectures ", School of Physical Sciences at Kent blog, (accessed 4 July 2018).

Further reading