John Leslie (physicist)
Encyclopedia
Sir John Leslie was a Scottish
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...

 mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....

 and physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...

 best remembered for his research into heat
Heat
In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...

.

Leslie gave the first modern account of capillary action
Capillary action
Capillary action, or capilarity, is the ability of a liquid to flow against gravity where liquid spontanously rise in a narrow space such as between the hair of a paint-brush, in a thin tube, or in porous material such as paper or in some non-porous material such as liquified carbon fiber, or in a...

 in 1802 and froze water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

 using an air-pump
Pump
A pump is a device used to move fluids, such as liquids, gases or slurries.A pump displaces a volume by physical or mechanical action. Pumps fall into three major groups: direct lift, displacement, and gravity pumps...

 in 1810, the first artificial production of ice
Ice
Ice is water frozen into the solid state. Usually ice is the phase known as ice Ih, which is the most abundant of the varying solid phases on the Earth's surface. It can appear transparent or opaque bluish-white color, depending on the presence of impurities or air inclusions...

.

In 1804, he experimented with radiant heat using a cubical
Cube
In geometry, a cube is a three-dimensional solid object bounded by six square faces, facets or sides, with three meeting at each vertex. The cube can also be called a regular hexahedron and is one of the five Platonic solids. It is a special kind of square prism, of rectangular parallelepiped and...

 vessel filled with boiling water. One side of the cube is composed of highly polished metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

, two of dull metal (copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

) and one side painted black
Black
Black is the color of objects that do not emit or reflect light in any part of the visible spectrum; they absorb all such frequencies of light...

. He showed that radiation was greatest from the black side and negligible from the polished side. The apparatus is known as a Leslie cube
Leslie cube
A Leslie cube is a device used in the measurement or demonstration of the variations in energy radiating from different surfaces. In an experiment described by Tyndall, one of the cube's vertical sides is coated with a layer of gold, another with a layer of silver, a third with a layer of copper,...

.

Early life

Leslie was born of humble parentage at Largo
Lower Largo
Lower Largo or Seatown of Largo is a village in Fife, Scotland situated on Largo Bay on the north side of the Firth of Forth. An ancient fishing village, Lower Largo has gained fame as the 1676 birthplace of Alexander Selkirk, the inspiration for Daniel Defoe's Robinson Crusoe.The arrival of the...

 in Fife and received his early education there and at Leven
Leven, Fife
Leven is a seaside town in Fife, set in the east Central Lowlands of Scotland. It lies on the coast of the Firth of Forth at the mouth of the River Leven, north-east of Kirkcaldy and east of Glenrothes....

. In his thirteenth year, encouraged by friends who had even then remarked his aptitude for mathematical and physical science, he entered the University of St Andrews
University of St Andrews
The University of St Andrews, informally referred to as "St Andrews", is the oldest university in Scotland and the third oldest in the English-speaking world after Oxford and Cambridge. The university is situated in the town of St Andrews, Fife, on the east coast of Scotland. It was founded between...

. On the completion of his arts course, he nominally studied divinity at Edinburgh until 1787.

From 1788-1789 he spent rather more than a year as private tutor in a Virginian family, and from 1791 till the close of 1792 he held a similar appointment at Etruria, Staffordshire
Etruria, Staffordshire
Etruria is a suburb of Stoke-on-Trent, Staffordshire, England.-Home of Wedgwood:Etruria was the fourth and penultimate site for the Wedgwood pottery business. Josiah Wedgwood, who was previously based in Burslem, opened his new works in 1769. It was named after the Italian district of Etruria,...

, with the family of Josiah Wedgwood
Josiah Wedgwood
Josiah Wedgwood was an English potter, founder of the Wedgwood company, credited with the industrialization of the manufacture of pottery. A prominent abolitionist, Wedgwood is remembered for his "Am I Not A Man And A Brother?" anti-slavery medallion. He was a member of the Darwin–Wedgwood family...

, employing his spare time in experimental research and in preparing a translation of Buffon
Georges-Louis Leclerc, Comte de Buffon
Georges-Louis Leclerc, Comte de Buffon was a French naturalist, mathematician, cosmologist, and encyclopedic author.His works influenced the next two generations of naturalists, including Jean-Baptiste Lamarck and Georges Cuvier...

's Natural History of Birds, which was published in nine volumes in 1793, which brought him money.

Middle years

For the next twelve years (passed chiefly in London or at Largo, with an occasional visit to the continent of Europe) he continued his physical studies, which resulted in numerous papers contributed by him to Nicholson
William Nicholson (chemist)
William Nicholson was a renowned English chemist and writer on "natural philosophy" and chemistry, as well as a translator, journalist, publisher, scientist, and inventor.-Early life:...

's Philosophical Journal, and in the publication (1804) of the Experimental Inquiry into the Nature and Properties of Heat, a work which gained him the Rumford Medal
Rumford Medal
The Rumford Medal is awarded by the Royal Society every alternating year for "an outstandingly important recent discovery in the field of thermal or optical properties of matter made by a scientist working in Europe". First awarded in 1800, it was created after a 1796 donation of $5000 by the...

 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"...

 of London.

In 1805 he was elected to succeed 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...

 in the chair of mathematics at Edinburgh, not, however, without violent, though unsuccessful, opposition on the part of a narrow-minded clerical party who accused him of heresy in something he had said as to the unsophisticated notions of mankind about the relation of cause and effect.

During his tenure of this chair he published two volumes of A Course of Mathematics-the first, entitled Elements of Geometry, Geometrical Analysis and Plane Trigonometry, in 1809, and the second, Geometry of Curve Lines, in 1813; the third volume, on Descriptive Geometry and the Theory of Solids was never completed. With reference to his invention (in 1810) of a process of artificial ice-making, he published in 1813 A Short Account of Experiments and Instruments depending on the relations of Air to Heat and Moisture; and in 1818 a paper by him, On certain impressions of cold transmitted from the higher atmosphere, with an instrument (the aethrioscope) adapted to measure them, appeared in the Transactions of the Royal Society of Edinburgh.

Later years

When Playfair died in 1819, Leslie was promoted to the more congenial chair of natural philosophy, which he held until his death. He published a famous book about multiplication table The Philosophy of Arithmetic in 1820.In 1823 he published, chiefly for the use of his class, the first volume of his never-completed Elements of Natural Philosophy.

Leslie's main contributions to physics were made by the help of the differential thermometer, an instrument whose invention was contested with him by Count Rumford
Benjamin Thompson
Sir Benjamin Thompson, Count Rumford , FRS was an American-born British physicist and inventor whose challenges to established physical theory were part of the 19th century revolution in thermodynamics. He also served as a Lieutenant-Colonel in the Loyalist forces in America during the American...

. By adapting to this instrument various ingenious devices, Leslie was able to employ it in a great variety of investigations, connected especially with photometry, hygroscopy and the temperature of space. In 1820 he was elected a corresponding member of the Institute of France, the only distinction of the kind which he valued, and early in 1832 he was knighted.

Leslie died at Coates, a small property he had acquired near Largo, at the age of 66.

Selected works


  • Elements of Geometry, Geometrical Analysis, and Plane Trigonometry (ca. 1811)
Second edition (1811)


  • Philosophy of Arithmetic; Exhibiting a Progressive View of the Theory and Practice of Calculation, with an Enlarged Table of the Products of Numbers under One Hundred (1817).
Second edition (1820)

  • Geometrical Analysis and Geometry of Curve Lines being Volume the Second of A Course of Mathematics and designed as an Introduction to the Study of Natural Philosophy [Edinburgh Printed for W and C Tait, Prince's Street and Longman Hurst Rees Orme and Brown, London 1821]

External links

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