Davy, Sir Humphry

Bibliography of Davy, Sir Humphry

Davy was born at Penzance in Cornwall on 17 December 1778. The parish register of Madron (the parish church) records ‘Humphry Davy, son of Robert Davy, baptized at Penzance, January 22nd, 1779.’ Robert Davy was a wood-carver at Penzance, who pursued his art rather for amusement than profit. As the representative of an old family (monuments to his ancestors in Ludgvan Church date as far back as 1635), he became possessor of a modest patrimony. His wife, Grace Millet, came of an old but no longer wealthy family. Her parents died within a few hours of each other from malignant fever, whereupon Grace and her two sisters were adopted by John Tonkin, an eminent surgeon in Penzance. Robert Davy and his wife became the parents of five children — two boys, Humphry, the eldest, and John, and three girls. In Davy's childhood the family moved from Penzance to Varfell, their family estate in Ludgvan. Davy's boyhood was spent partly with his parents and partly with Tonkin, who placed him at a preparatory school kept by a Mr. Bushell, who was so much struck with the boy's progress that he persuaded the father to send him to a better school. Davy was at an early age placed at the Penzance Grammar School, then under the care of the Rev. J. C. Coryton. Numerous anecdotes show that Davy was a precocious boy, possessing a remarkable memory and being singularly rapid in acquiring knowledge of books. He was especially attracted by the ‘Pilgrim's Progress,’ and he delighted in reading history. When but eight years of age he would collect a number of boys, and standing on a cart in the market-place address them on the subject of his latest reading. He delighted in the folklore of this remote district, and became, as he himself tells us, a ‘tale-teller.’ The ‘applause of my companions,’ he says, ‘was my recompense for punishments incurred for being idle.’ These conditions developed a love of poetry and the composition of verses and ballads.

At the same time Davy acquired a taste for experimental science. This was mainly due to a member of the Society of Friends named Robert Dunkin, a saddler and a man of original mind and of the most varied acquirements. Dunkin constructed for himself an electrical machine, voltaic piles, and Leyden jars, and made models illustrative of the principles of mechanics. By the aid of these appliances he instructed Davy in the rudiments of science. As professor at the Royal Institution, Davy repeated many of the ingenious experiments which he had learned from his Quaker instructor. From the Penzance school Davy went in 1793 to Truro, and finished his education under the Rev. Dr. Cardew, who, in a letter to Davies Gilbert, says: ‘I could not discern the faculties by which he was afterwards so much distinguished.’ Davy says himself: ‘I consider it fortunate I was left much to myself as a child, and put upon no particular plan of study. … What I am I made myself.’[5]
Apprentice and poet

After the death of Davy's father in 1794, Tonkin apprenticed the boy to John Bingham Borlase, a surgeon in large practice at Penzance. Davy's indenture is dated 10 February 1795. In the apothecary's dispensary Davy became a chemist, and a garret in Tonkin's house was the scene of his earliest chemical operations. Davy's friends would often say: ‘This boy Humphry is incorrigible. He will blow us all,’ and his eldest sister complained of the ravages made on her dresses by corrosive substances.[5]

Much has been said of Davy as a poet, and John Ayrton Paris somewhat hastily says that his verses ‘bear the stamp of lofty genius.’ Davy's first production preserved bears the date of 1795. It is entitled ‘The Sons of Genius,’ and is marked by the usual immaturity of youth. The poems, produced in the following years, especially those ‘On the Mount's Bay’ and ‘St. Michael's Mount,’ are pleasingly descriptive verses, showing sensibility, but no true poetic imagination. Davy soon abandoned poetry for science. While writing verses at the age of seventeen in honour of his first love, he was eagerly discussing with his Quaker friend the question of the materiality of heat. Dunkin once remarked: ‘I tell thee what, Humphry, thou art the most quibbling hand at a dispute I ever met with in my life.’ One winter day he took Dunkin to Larigan river,[6] to show him that the rubbing of two plates of ice together developed sufficient energy by motion to melt them, and that the motion being suspended the pieces were united by regelation. This was, in a rude form, an elementary version of an analogous experiment later exhibited by Davy in the lecture-room of the Royal Institution, which excited considerable attention.[5]
Early scientific interests

Davies Giddy, afterwards Davies Gilbert, accidentally saw Davy in Penzance, carelessly swinging on the half-gate of Dr Borlase's house. Gilbert was interested by the lad's talk, offered him the use of his library, and invited him to his house at Tredrea. This led to an introduction to Dr Edwards, who then resided at Hayle Copper House, and was also chemical lecturer in the school of St. Bartholomew's Hospital. Dr Edwards permitted Davy to use the apparatus in his laboratory, and appears to have directed his attention to the floodgates of the port of Hayle, which were rapidly decaying from the contact of copper and iron under the influence of seawater. This galvanic action was not then understood, but the phenomenon prepared the mind of Davy for his experiments on the copper sheathing of ships in later days. Gregory Watt, the son of James Watt, visited Penzance for his health's sake, and lodging at Mrs Davy's house became a friend of her son and gave him instructions in chemistry. Davy also formed a useful acquaintance with the Wedgwoods, who spent a winter at Penzance.[5]

Dr Thomas Beddoes and Professor Hailstone were engaged in a geological controversy upon the rival merits of the Plutonian and the Neptunist hypotheses. They travelled together to examine the Cornish coast accompanied by Davies Gilbert, and thus made Davy's acquaintance. Beddoes, who had recently established at Bristol a ‘Pneumatic Institution,’ required an assistant to superintend the laboratory. Gilbert recommended Davy for the post, and Gregory Watt, in 1798, showed Beddoes the ‘Young man's Researches on Heat and Light,’ which were subsequently published by him in the first volume of ‘West-Country Contributions.’ Prolonged negotiations were carried on, mainly by Gilbert. Mrs Davy and Borlase consented to Davy's departure, but Tonkin desired to fix him in his native town as a surgeon, and actually altered his will when he found that Davy insisted on going to Dr Beddoes.
The Pneumatic Institution

On 2 October 1798 Davy joined the ‘Pneumatic Institution’ at Bristol. This institution was established for the purpose of investigating the medical powers of factitious airs and gases, and to Davy was committed the superintendence of the various experiments. The arrangement concluded between Dr. Beddoes and Davy was a liberal one, and enabled Davy to give up all claims upon his paternal property in favour of his mother. He did not intend to abandon the profession of medicine, being still determined to study and graduate at Edinburgh. Davy threw himself energetically into the labours of the laboratory and formed a long friendship with Mrs Anna Beddoes who acted as his guide on walks and other fine sights of the locality [7]. During his residence at Bristol, Davy formed the acquaintance of the Earl of Durham, who became a resident for his health in the Pneumatic Institution, and of Samuel Taylor Coleridge and Robert Southey. In December 1799 Davy visited London for the first time, and his circle of friends was there much extended.[5]

In this year the first volume of the ‘West-Country Collections’ was issued. Half of the volume consisted of Davy's essays ‘On Heat, Light, and the Combinations of Light,’ ‘On Phos-oxygen and its Combinations,’ and on the ‘Theory of Respiration.’ On 22 February 1799 Davy, writing to Davies Gilbert, says: ‘I am now as much convinced of the non-existence of caloric as I am of the existence of light.’ In another letter written to Davies Gilbert, on 10 April, Davy informs him: I made a discovery yesterday which proves how necessary it is to repeat experiments. The gaseous oxide of azote (the laughing gas) is perfectly respirable when pure. It is never deleterious but when it contains nitrous gas. I have found a mode of making it pure.’ He then says that he breathed sixteen quarts of it for nearly seven minutes, and that it ‘absolutely intoxicated me.’ During this year Davy published his ‘Researches, Chemical and Philosophical, chiefly concerning Nitrous Oxide and its Respiration.’ In after years Davy regretted that he had ever published these immature hypotheses, which he himself subsequently designated as ‘the dreams of misemployed genius which the light of experiment and observation has never conducted to truth.’[5]
The Royal Institution


Satirical cartoon by James Gillray showing a Royal Institution lecture on pneumatics with Davy holding the bellows and Count Rumford looking on at extreme right. Dr Garnett is the lecturer holding the victim's nose

In 1800 Davy informed Davies Gilbert that he had been ‘repeating the galvanic experiments with success’ in the intervals of the experiments on the gases, which ‘almost incessantly occupied him from January to April.’ In these experiments Davy ran considerable risks. His respiration of nitrous oxide may have led, by its union with common air in the mouth, to the formation of nitrous acid (HNO2), which severely injured the mucous membrane, and in Davy's attempt to breathe carburetted hydrogen gas he ‘seemed sinking into annihilation.’ On being removed into the open air, Davy faintly articulated, ‘I do not think I shall die,’ but some hours elapsed before the painful symptoms ceased.[5] It is more likely that the nitrous oxide (N2O) he inhaled was contaminated by nitric oxide (NO), a toxic gas which combines with oxygen and water to form HNO3, a very strong acid and irritant, explaining the pain Davy felt.

Davy's ‘Researches,’ which was full of striking and novel facts, and rich in chemical discoveries, soon attracted the attention of the scientific world, and Davy now made his grand move in life. In 1799 Count Rumford had proposed the establishment in London of an ‘Institution for Diffusing Knowledge,’ i.e. the Royal Institution. The house in Albemarle Street was bought in April 1799. Rumford became secretary to the institution, and Dr. Garnett was the first lecturer. Garnett was forced to resign from ill-health in 1801. Rumford had already been empowered to treat with Davy. Personal interviews followed, and on 15 July 1801 it was resolved by the managers ‘that Humphry Davy be engaged in the service of the Royal Institution in the capacity of assistant lecturer in chemistry, director of the chemical laboratory, and assistant editor of the journals of the institution, and that he be allowed to occupy a room in the house, and be furnished with coals and candles, and that he be paid a salary of 100l. per annum.’[5]

In 1801 he was nominated professor at the Royal Institution of Great Britain and Fellow of the Royal Society, over which he would later preside. In 1810, he was elected a foreign member of the Royal Swedish Academy of Sciences.
Discovery of new elements


Sodium metal (ca. 10 g) under oil


A voltaic pile on display in the Tempio Voltiano.


Boron

Davy was a pioneer in the field of electrolysis using the voltaic pile to split up common compounds and thus prepare many new elements. He went on to electrolyse molten salts and discovered several new metals, especially sodium and potassium, highly reactive elements known as the alkali metals. Potassium was discovered in 1807 by Davy, who derived it from caustic potash (KOH). Before the 18th century, no distinction was made between potassium and sodium. Potassium was the first metal that was isolated by electrolysis. Sodium was first isolated by Davy in the same year by passing an electric current through molten sodium hydroxide. Davy went on to discover calcium in 1808 by electrolyzing a mixture of lime and mercuric oxide. Davy was trying to isolate calcium; when he heard that Berzelius and Pontin prepared calcium amalgam by electrolyzing lime in mercury, he tried it himself. He worked with electrolysis throughout his life and also discovered magnesium, boron and barium.
Discovery of chlorine

Chlorine was discovered in 1774 by Swedish chemist Carl Wilhelm Scheele, who called it dephlogisticated marine acid (see phlogiston theory) and mistakenly thought it contained oxygen. Scheele produced chlorine by reacting manganese dioxide (MnO2) with hydrogen chloride (HCl).
4 HCl + MnO2 → MnCl2 + 2 H2O + Cl2


Scheele observed several properties of chlorine gas, such as its bleaching effect on litmus, its deadly effect on insects, its yellow-green colour, and the similarity of its smell to that of aqua regia. However, Scheele was unable to publish his findings at the time.

In 1810, chlorine was given its current name by Humphry Davy, who insisted that chlorine was in fact an element. He also showed that oxygen could not be obtained from the substance known as oxymuriatic acid (HCl solution). This discovery overturned Lavoisier's definition of acids as compounds of oxygen.
Popular public figure

Davy revelled in his public status, as his lectures gathered many spectators. He became well known due to his experiments with the physiological action of some gases, including laughing gas (nitrous oxide), to which he was addicted, once stating that its properties bestowed all of the benefits of alcohol but was devoid of its flaws.

Davy later damaged his eyesight in a laboratory accident with nitrogen trichloride.[8] Pierre Louis Dulong first prepared this compound in 1812, and lost two fingers and an eye in two separate explosions with it. Davy's own accident induced him to hire Michael Faraday as a coworker.
European travels


Sir Humphry Davy, 1830 engraving based on the painting by Sir Thomas Lawrence (1769-1830)


A diamond crystal in its matrix

In 1812, Davy was knighted, gave a farewell lecture to the Royal Institution, and married a wealthy widow, Jane Apreece. (While generally acknowledged as being faithful to his wife, their relationship was stormy, and in his later years Davy travelled to continental Europe alone.) In October 1813, he and his wife, accompanied by Michael Faraday as his scientific assistant (and valet), travelled to France to collect a medal that Napoleon Bonaparte had awarded Davy for his electro-chemical work. While in Paris, Davy was asked by Gay-Lussac to investigate a mysterious substance isolated by Bernard Courtois. Davy showed it to be an element, which is now called iodine.

The party left Paris in December 1813, travelling south to Italy.[9] They sojourned in Florence, where, in a series of experiments conducted with Faraday's assistance, Davy succeeded in using the sun's rays to ignite diamond, proving it is composed of pure carbon.

Davy's party continued to Rome, and also visited Naples and Mount Vesuvius. By June 1814, they were in Milan, where they met Alessandro Volta, and then continued north to Geneva. They returned to Italy via Munich and Innsbruck, and when their plans to travel to Greece and Constantinople (Istanbul) were abandoned after Napoleon's escape from Elba, they returned to England.
Davy lamp


The Davy lamp
Main article: Davy lamp

After his return to England in 1815, Davy experimented with lamps for use in coal mines. There had been many mining explosions caused by firedamp or methane often ignited by open flames of the lamps then used by miners. In particular the Felling mine disaster in 1812 near Newcastle caused great loss of life, and action was needed to improve underground lighting and especially the lamps used by miners. Davy conceived of using an iron gauze to enclose a lamp's flame, and so prevent the methane burning inside the lamp from passing out to the general atmosphere. Although the idea of the safety lamp had already been demonstrated by William Reid Clanny and by the then unknown (but later very famous) engineer George Stephenson, Davy's use of wire gauze to prevent the spread of flame was used by many other inventors in their later designs. George Stephenson's lamp was very popular in the north-east coalfields, and used the same principle of preventing the flame reaching the general atmosphere, but by different means. Unfortunately, although the new design of gauze lamp initially did seem to offer protection, it gave much less light, and quickly deteriorated in the wet conditions of most pits. Rusting of the gauze quickly made the lamp unsafe, and the number of deaths from firedamp explosions rose yet further.

There was some discussion as to whether Davy had discovered the principles behind his lamp without the help of the work of Smithson Tennant, but it was generally agreed that the work of both men had been independent. Davy refused to patent the lamp, and its invention led to him being awarded the Rumford medal in 1816.[1]
Acid-base studies

In 1815 Davy suggested that acids were substances that contained replaceable hydrogen – hydrogen that could be partly or totally replaced by metals. When acids reacted with metals they formed salts. Bases were substances that reacted with acids to form salts and water. These definitions worked well for most of the nineteenth century.
Last years and death


Michael Faraday, portrait by Thomas Phillips c1841-1842[10]


Davy's gravesite in Geneva.

In January 1819, Davy was awarded a baronetcy, at the time the highest honour ever conferred on a man of science in Britain. A year later he became President of the Royal Society.

Davy's laboratory assistant, Michael Faraday, went on to enhance Davy's work and in the end he became the more famous and influential scientist – to the extent that Davy is supposed to have claimed Faraday as his greatest discovery. However, Davy later accused Faraday of plagiarism, causing Faraday (the first Fullerian Professor of Chemistry) to cease all research in electromagnetism until his mentor's death.

Of a sanguine, somewhat irritable temperament, Davy displayed characteristic enthusiasm and energy in all his pursuits. As is shown by his verses and sometimes by his prose, his mind was highly imaginative; the poet Coleridge declared that if he “had not been the first chemist, he would have been the first poet of his age,” and Southey said that “he had all the elements of a poet; he only wanted the art.” In spite of his ungainly exterior and peculiar manner, his happy gifts of exposition and illustration won him extraordinary popularity as a lecturer, his experiments were ingenious and rapidly performed, and Coleridge went to hear him “to increase his stock of metaphors.” The dominating ambition of his life was to achieve fame, but though that sometimes betrayed him into petty jealousy, it did not leave him insensible to the claims on his knowledge of the “cause of humanity,” to use a phrase often employed by him in connection with his invention of the miners' lamp. Of the smaller observances of etiquette he was careless, and his frankness of disposition sometimes exposed him to annoyances which he might have avoided by the exercise of ordinary tact.[11]

Davy died in Switzerland in 1829, his various inhalations of chemicals finally taking their toll on his health. He is buried in the Plainpalais Cemetery in Geneva.[12]

Curie, Pierre & Marie

Bibliography of Curie, Pierre & Marie

Eminent physicists, working in France, the Curies discovered radium and were awarded Nobel prizes, though they both turned down the offer of a Legion d’Honneur. Marie was the first woman scientist of international distinction. She once said, “Nothing in life is to be feared. It is only to be understood.” Neither of the Curies was a religious believer and their wedding was a secular one.

Today we take radio-therapy for granted in helping to detect and cure illnesses. However, the concept of using radio-active materials to help humanity has been known for only a hundred years. Its use was pioneered by two remarkable, and courageous, people, Marie and Pierre Curie. In 1903 Pierre and Marie Curie (jointly with another Frenchman, Henri Becquerel) were awarded the Nobel Prize for Physics, and eight years later Marie Curie became the first person to have the distinction of gaining two Nobel Prizes. This time it was for Chemistry, and acknowledged her discovery of new elements such as polonium and radium, later to be used widely in medicine in the treatment of diseases.

Pierre and Marie came from apparently very different backgrounds, she being Polish by birth and brought up in the Catholic faith, while he was French and from an anti-clerical and freethinking family. Marie's father, however, had a strong streak of rationalism in him and this, combined with the death of her mother and one of her sisters from tuberculosis when Marie was only eleven, turned her into an agnostic by the time she was fifteen.

From her early days, Marie, born Marie Slodowska in 1867, had an unusually enquiring mind - but in Poland, at that time part of the Russian Empire, it was impossible for a girl to acquire a scientific education. Eventually she was able to join her sister Bronja, who had gone to France to study medicine, and in Paris in 1891 her scientific career began. Studying chemistry, physics and mathematics, she realised that she wanted to spend her life in research. Before long she had met and started to work with Pierre Curie. He was already an established physicist with a particular love of symmetry in natural things - spiders' webs, the human hands, crystals. Their work on radioactivity was a response to the great puzzlement existing at that time about the structure of atoms.

They were married in 1895 in a simple civil ceremony, not a church one, because of their non-religious outlook. Marie asked for a practical dress for her wedding, one that she could wear afterwards for work in the lab! For many years the Curies were poor, suffering great adversity and hardship, but they took great pleasure in life not only from their pursuit of scientific understanding but also from the enjoyment of simple pleasures such as cycling in the French countryside. In her biography of Pierre, Marie wrote: “All my life through, the new sights of Nature made me rejoice like a child.” They had two daughters, Irene born in 1897, who herself became a Nobel prizewinner in 1935, and Eve, born in 1905, who became a writer and music critic.

Before the end of the century, both Pierre and Marie were suffering from occasional ill-health - aching joints, tiredness and anaemia. We know now that they must have been suffering from radiation sickness, but at that time such a danger was not recognised. Even if it had been, they would probably have been unwilling to restrict their work. Almost certainly, Pierre’s poor health contributed indirectly to his accidental death under the wheels of a horse-drawn cart in 1906. It was a devastating loss to Marie, but after a few weeks, and with the help of her sister Bronja, she was back at her work, even more committed to it. Her financial situation was much eased by her appointment as Professor to succeed her husband. At the outbreak of war in 1914, her research proved to be of positive service to humankind when she helped to set up mobile vans carrying X-ray equipment to field hospitals and instructed technicians in its use.

In later years, Marie Curie developed her earlier ideas. Particularly in America, she raised money for the Marie Curie Radium Fund and the Radium Institute in Paris. She lived until 1934, determinedly overcoming chronic illness due to radiation, carrying on work into her sixties. The motivation behind the work of Pierre and Marie Curie was originally the desire simply to know and understand more about the world. While retaining that desire throughout her life, Marie in later years also worked to ensure that her discoveries were used to improve or save lives.

"You cannot hope to build a better world without improving the individuals. To that end, each of us must work for our own improvement and, at the same time, share a general responsibility for all humanity, our particular duty being to aid those to whom we think we can be most useful." (Marie Curie)

Francis Harry Compton Crick

Bibliography of Francis Harry Compton Crick 

Francis Harry Compton Crick was born 8 June 1916 in Northampton, England. Having attended schools in Northampton and North London, in 1934, aged 18, Crick began studying physics at University College London, graduating in 1937.

Crick remained at UCL for graduate studies on the measurement of viscosity of water at high temperatures. These studies were nearly complete, but were interrupted by the outbreak of World War II. He joined the British Admiralty Research Laboratory, where he helped to design 'noncontact' magnetic and acoustic mines, and remained there for a time after the war, assigned to scientific intelligence.

In 1947, Crick moved to the Strangeways Laboratory, Cambridge, where he studied the physical properties of cytoplasm in cultured fibroblast cells with Arthur Hughes. Two years later he joined the Medical Research Unit at Cavendish Laboratory. There, a team led by Max Perutz was using X-ray crystallography to discover the structure of proteins – a subject that became the topic of Crick's PhD thesis.

In 1951, James Watson arrived at the Cavendish and met Crick. The two quickly became friends and embarked on an attempt to uncover the structure of DNA. Crick brought to the project his knowledge of X-ray diffraction, while Watson brought knowledge of phage and bacterial genetics.

Combining evidence from biochemistry, X-ray diffraction images created by Rosalind Franklin and Maurice Wilkins, and physical clues from molecular models, they determined the three-dimensional structure of the DNA molecule to be a double helix.

This discovery was published in the 25 April 1953 edition of the journal Nature. The order of the names on the paper (Watson and Crick) was decided by the flip of a coin. This paper was quickly followed by another that suggested a mechanism for the replication of DNA.

After the discovery of the double helix, Crick went to work on finding the relationship between DNA and genetic coding. In 1958, he proposed 'the sequence hypothesis' (that DNA sequence is the code for the amino acid sequence of a protein) and the 'central dogma' (that information goes from DNA to protein, but not back again).

In 1957, Crick began work with Sydney Brenner to determine how the sequence of DNA bases would specify the amino acid sequence in proteins. By 1961, they had shown that translation involves a three-nucleotide code.

In 1962, Crick, Watson and Wilkins are awarded the Nobel Prize in Physiology or Medicine "for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material".

Crick finally left Cambridge Laboratories in 1976 to become Kieckhefer Professor at Salk Institute for Biological Studies in San Diego, California. It was there that Crick began his studies of the brain and consciousness.

His goal was to understand how neurons operate with various chemical processes in the body, which may show us "exactly how these activities give us our vivid picture of the world and of ourselves and also allow us to act". His book 'The Astonishing Hypothesis: The Scientific Search for the Soul' (1993) further described his ideas.

In addition to the Nobel Prize, his honours included the Lasker Award, the Award of Merit from the Gairdner Foundation, and the Prix Charles Leopold Meyer of the French Academy of Sciences. He was a member of the US National Academy of Sciences, the Royal Society, the French Academy of Sciences and the Irish Academy.

Francis Crick died in July 2004, aged 88.
Francis Crick timeline
1916

Francis Harry Compton Crick is born 8 June in Northampton, England.
1930

Crick wins a scholarship to Mill Hill School, London.
1934

Crick studies physics at University College, London, graduating in 1937. He stays on to do graduate research under Professor E N da C Andrade.
1940

Crick joins the British Admiralty Research Laboratory, helping to design magnetic and acoustic mines.
1947-48

Moves to Strangeways Laboratory, Cambridge, to work with Arthur Hughes on the physical properties of cytoplasm in cultured fibroblast cells. Crick meets and becomes friends with Maurice Wilkins (King's College, London).
1949

Moves to the Medical Research Unit at Cavendish Laboratory, where Max Perutz was using X-ray crystallography to discover the three-dimensional structure of proteins.
1950

Crick begins his second stint as a PhD student (his thesis 'Polypeptides and proteins: X-ray studies' was submitted in July 1953).
1951

James Watson arrives at the Cavendish and meets Crick.

Rosalind Franklin arrives at King's College, London.

Crick and Watson begin work on their first DNA model.
1953

In April, Watson and Crick publish their seminal paper on the structure of DNA: 'Molecular structure of nucleic acids: a structure for deoxyribose nucleic acid'. They follow this in May with another paper that proposes a mechanism for DNA replication.
1955-58

Crick proposes the 'sequence hypothesis' (that DNA sequence is a code for protein sequence), predicts the existence of 'adaptors' (transfer RNAs), and proposes the 'central dogma' (that 'information' flows from DNA to protein, but not back again).
1961

Crick and Sydney Brenner discover that the genetic code is a triplet code.
1962

Crick, Watson and Wilkins are awarded the Nobel Prize in Physiology or Medicine "for their discoveries concerning the molecular structure of nucleic acids and its significance for information transfer in living material".
1976

Crick leaves Cambridge to become Kieckhefer Professor at Salk Institute for Biological Studies in San Diego, California. There, he begins his present studies of the brain.
1988

Crick publishes his intellectual autobiography 'What Mad Pursuit: A Personal View of Scientific Discovery' (New York: Basic Books).
1994

Crick publishes his views on consciousness: 'The Astonishing Hypothesis: The Scientific Search for the Soul' (New York: Charles Scriber's Sons).
2001

Crick's papers are purchased by the Wellcome Library.
2004

Francis Crick dies aged 88.

James Clerk Maxwell

Bibliography of James Clerk Maxwell

James Clerk Maxwell was one of the greatest scientists of the 19th century. He is best known for the formulation of the theory of electromagnetism and in making the connection between light and electromagnetic waves. He also made significant contributions in the areas of physics, mathematics, astronomy and engineering. He considered by many as the father of modern physics.

Maxwell was born in Edinburgh, Scotland in 1831. Even though most of his formal higher education took place in London, he was always drawn back to his family home in the hills of Scotland. As a young child, Maxwell was fascinated with geometry and mechanical models. When he was only 14 years old, he published his first scientific paper on the mathematics of oval curves and ellipses that he traced with pins and thread. Maxwell continued to publish papers on a variety of subjects. These included the mathematics of human perception of colors, the kinetic theory of gasses, the dynamics of a spinning top, theories of soap bubbles, and many others.

Maxwell's early education took place at Edinburgh Academy and the University of Edinburgh. In 1850 he went on to study at the University of Cambridge and, upon graduation from Cambridge, Maxwell became a professor of natural philosophy at Marischal College in Aberdeen until 1860. He then moved to London to become a professor of natural philosophy and astronomy at King's College. In 1865, Maxwell's father died and he returned to the family home in Scotland to devote his time to research. In 1871 he accepted a position as the first professor of experimental physics at Cambridge where he set up the world famous Cavendish Laboratory in 1874.

While at Aberdeen, Maxwell was challenged by the subject of the Adams Prize of 1857: the motion of Saturn's rings. He had previously thought and theorized about the nature of the rings when he was only 16 years old. He decided to compete for the prize, and the next two years were taken up with developing a theory to explain the physical composition of the rings. He was finally able to demonstrate, by purely mathematical reasoning, that the stability of rings could only be achieved if they consisted of numerous small particles. His theory won him the prize and, more significantly, nearly a hundred years later, the Voyager 1 space probe proved his theory right.

Much of modern technology has been developed from the basic principles of electromagnetism formulated by Maxwell. The field of electronics, including the telephone, radio, television, and radar, stem from his discoveries and formulations. While Maxwell relied heavily on previous discoveries about electricity and magnetism, he also made a significant leap in unifying the theories of magnetism, electricity, and light. His revolutionary work lead to the development of quantum physics in the early 1900's and to Einstein's theory of relativity.

Maxwell began his work in electromagnetism by extending Michael Faraday's theories of electricity and magnetic lines of force. He then began to see the connections between the approaches of Faraday, Reimann and Gauss. As a result, he was able to derive one of the most elegant theories yet formulated. Using four equations, he described and quantified the relationships between electricity, magnetism and the propagation of electromagnetic waves. The equations are now known as Maxwell's Equations.

One of the first things that Maxwell did with the equations was to calculate the speed of an electromagnetic wave and found that the speed of an electromagnetic wave was almost identical to the speed of light. Based on this discovery, he was the first to propose that light was an electromagnetic wave. In 1862 Maxwell wrote:

"We can scarcely avoid the conclusion that light consists in the transverse undulations of the same medium which is the cause of electric and magnetic phenomena."

This was a remarkable achievement, for it not only unifies the theories of electricity and magnetism, but of optics as well. Electricity, magnetism and light can now be understood as aspects of a single phenomenon: electromagnetic waves.

Maxwell also described the thermodynamic properties of gas molecules using statistical mechanics. His improvements to the kinetic theory of gases included showing that temperature and heat are caused only by molecular movement. Though Maxwell did not originate the kinetic theory, he was the first to apply probability and statistics to describe temperature changes at the molecular level. His theory is still widely used by scientists as a model for rarefied gases and plasmas.

Maxwell also contributed to the development of color photography. His analysis of color perception led to his invention of the trichromatic process. By using red, green and blue filters he created the first color photograph. The trichromatic process is the basis modern color photography.

Maxwell's particular gift was in applying mathematical reasoning in solving complex theoretical problems. Maxwell's Electromagnetic Equations are perfect examples of how mathematics can be used to provide relatively simple and elegant explanations of the complex mysteries of the universe. Richard Feynman wrote of Maxwell:

"From a long view of the history of mankind, seen from, say, ten thousand years from now, there can be little doubt that the most significant event of the 19th century will be judged as Maxwell's discovery of the laws of electrodynamics."

Maxwell continued his work at the Cavendish Laboratory until illness forced him to resign in 1879. He returned to Scotland and died soon afterwards. He was buried with little ceremony in a small churchyard in the village of Parton in Scotland.

Charles, Jacques Alexander César

Bibliography of Charles, Jacques Alexander César

 

The first we know of Jacques Charles is his appearance as a young man in Paris, where he worked briefly as a minor government official under King Louis XVI. When Benjamin Franklin visited France in 1779, Charles was inspired to study physics. He soon became an eloquent speaker to non-scientific audiences. His lectures and demonstrations attracted notable patrons and helped popularize Franklin's theory of electricity and other new scientific concepts.


But Charles was best known in his day for inventing the hydrogen balloon--and for being the first person to try it out. People had just begun to experiment with hot-air balloons, and Charles realized immediately that hydrogen would work better than hot air, because it is much lighter (as noted earlier by Henry Cavendish). Charles' first balloon was made of silk that was coated with rubber to prevent leaking. After an unmanned flight of some 15 miles (24 km), the balloon landed in a small village, where the peasants--who thought it was some sort of monster from the sky--attacked it with pitchforks and guns. After building a larger balloon, Charles and an assistant made their first ascent in December 1783.

Ballooning, as a science and a sport, quickly took off, and Charles invented most of the equipment that is still used in today's balloons. Fortunately, the French public's infatuation with ballooning saved Charles' life at one point. Because he had once enjoyed the king's patronage, Charles was approached by an angry mob of revolutionaries in 1792. He was able to calm them down by telling stories of his early balloon flights.

Perhaps because of his non-scientific background, Charles published very little of his work. In 1787, while experimenting with hydrogen, oxygen and nitrogen, he showed that, at a constant pressure, the volume of a gas increases in proportion to its absolute temperature. His findings were later duplicated and published by Joseph Gay-Lussac, who had improved upon Charles's experimental procedure. This fundamental concept of gas behavior is now known as Gay-Lussac's law but is still sometimes called Charles 's Law.

In addition to his contributions to ballooning and physics, Charles is credited with inventing some relatively minor but ingenious instruments, such as a device for measuring the angles of crystal (a goniometer). He also invented the megascope, which magnifies large objects, and he improved instruments for measuring specific gravity and for tracking the Sun's rays.

Cavendish, Henry

Bibliography of Cavendish, Henry

The English physicist and chemist Henry Cavendish determined the value of the universal constant of gravitation, made noteworthy electrical studies, and is credited with the discovery of hydrogen and the composition of water.

Early years

Henry Cavendish was born in Nice, France, on October 10, 1731, the oldest son of Lord Charles Cavendish and Lady Anne Grey, who died a few years after Henry was born. As a youth he attended Dr. Newcomb's Academy in Hackney, England. He entered Peterhouse, Cambridge, in 1749, but left after three years without taking a degree.

Cavendish returned to London, England to live with his father. There, Cavendish built himself a laboratory and workshop. When his father died in 1783, Cavendish moved the laboratory to Clapham Common, where he also lived. He never married and was so reserved that there is little record of his having any social life except occasional meetings with scientific friends.
Contributions to chemistry

During his lifetime Cavendish made notable discoveries in chemistry, mainly between 1766 and 1788, and in electricity, between 1771 and 1788. In 1798 he published a single notable paper on the density of the earth. At the time Cavendish began his chemical work, chemists were just beginning to recognize that the "airs" that were evolved in many chemical reactions were clear parts and not just modifications of ordinary air. Cavendish reported his own work in "Three Papers Containing Experiments on Factitious Air" in 1766. These papers added greatly to knowledge of the formation of "inflammable air" (hydrogen) by the action of dilute acids (acids that have been weakened) on metals.

Cavendish's other great achievement in chemistry is his measuring of the density of hydrogen. Although his figure is only half what it should be, it is astonishing that he even found the right order. Not that his equipment was crude; where the techniques of his day allowed, his equipment was capable of precise results. Cavendish also investigated the products of fermentation, a chemical reaction that splits complex organic compounds into simple substances. He showed that the gas from the fermentation of sugar is nearly the same as the "fixed air" characterized by the compound of chalk and magnesia (both are, in modern language, carbon dioxide).

Another example of Cavendish's ability was "Experiments on Rathbone-Place Water"(1767), in which he set the highest possible standard of accuracy. "Experiments" is regarded as a classic of analytical chemistry (the branch of chemistry that deals with separating substances into the different chemicals

Henry Cavendish.
Courtesy of the
Library of Congress
.
they are made from). In it Cavendish also examined the phenomenon (a fact that can be observed) of the retention of "calcareous earth" (chalk, calcium carbonate) in solution (a mixture dissolved in water). In doing so, he discovered the reversible reaction between calcium carbonate and carbon dioxide to form calcium bicarbonate, the cause of temporary hardness of water. He also found out how to soften such water by adding lime (calcium hydroxide).


One of Cavendish's researches on the current problem of combustion (the process of burning) made an outstanding contribution to general theory. In 1784 Cavendish determined the composition (make up) of water, showing that it was a combination of oxygen and hydrogen. Joseph Priestley (1733–1804) had reported an experiment in which the explosion of the two gases had left moisture on the sides of a previously dry container. Cavendish studied this, prepared water in measurable amount, and got an approximate figure for its volume composition.
Electrical research

Cavendish published only a fraction of the experimental evidence he had available to support his theories, but his peers were convinced of the correctness of his conclusions. He was not the first to discuss an inverse-square law of electrostatic attraction (the attraction between opposite—positive and negative—electrical charges). Cavendish's idea, however, based in part on mathematical reasoning, was the most effective. He founded the study of the properties of dielectrics (nonconducting electricity) and also distinguished clearly between the amount of electricity and what is now called potential.

Cavendish had the ability to make a seemingly limited study give far-reaching results. An example is his study of the origin of the ability of some fish to give an electric shock. He made up imitation fish of leather and wood soaked in salt water, with pewter (tin) attachments representing the organs of the fish that produced the effect. By using Leyden jars (glass jars insulated with tinfoil) to charge the imitation organs, he was able to show that the results were entirely consistent with the fish's ability to produce electricity. This investigation was among the earliest in which the conductivity of aqueous (in water) solutions was studied.

Cavendish began to study heat with his father, then returned to the subject in 1773–1776 with a study of the Royal Society's meteorological instruments. (The Royal Society is the world's oldest and most distinguished scientific organization.) During these studies he worked out the most important corrections to be employed in accurate thermometry (the measuring of temperature). In 1783 he published a study of the means of determining the freezing point of mercury. In it he added a good deal to the general theory of fusion (melting together by heat) and freezing and the latent heat changes that accompany them (the amount of heat absorbed by the fused material).

Cavendish's most celebrated investigation was that on the density of the earth. He took part in a program to measure the length of a seconds pendulum close to a large mountain (Schiehallion). Variations from the period on the plain would show the attraction put out by the mountain, from which the density of its substance could be figured out. Cavendish also approached the subject in a more fundamental way by determining the force of attraction of a very large, heavy lead ball for a very small, light ball. The ratio between this force and the weight of the light ball would result in the density of the earth. His results went unquestioned for nearly a century.
Unpublished works

Had Cavendish published all of his work, his already great influence would undoubtedly have been greater. In fact, he left in manuscript form a vast amount of work that often anticipated the work of those who followed him. It came to light only bit by bit until the thorough study undertaken by James Maxwell (1831–1879) and by Edward Thorpe (1845–1925). In these notes is to be found such material as the detail of his experiments to examine the conductivity of metals, as well as many chemical questions such as a theory of chemical equivalents. He even had a theory of partial pressures before John Dalton (1766–1844).

However, the history of science is full of instances of unpublished works that might have influenced others but in fact did not. Whatever he did not reveal, Cavendish gave other scientists enough to help them on the road to modern ideas. Nothing he did has been rejected, and for this reason he is still, in a unique way, part of modern life.

Bruno, Giordano

Bibliography of Bruno, Giordano

Bruno was the son of a professional soldier. He was named Filippo at his baptism and was later called "il Nolano," after the place of his birth. In 1562 Bruno went to Naples to study the humanities, logic, and dialectics (argumentation). He was impressed by the lectures of G.V. de Colle, who was known for his tendencies toward Averroism--i.e., the thought of a number of Western Christian philosophers who drew their inspiration from the interpretation of Aristotle put forward by the Muslim philosopher Averroes--and by his own reading of works on memory devices and the arts of memory (mnemotechnical works). In 1565 he entered the Dominican convent of San Domenico Maggiore in Naples and assumed the name Giordano. Because of his unorthodox attitudes, he was soon suspected of heresy. Nevertheless, in 1572 he was ordained as a priest. During the same year he was sent back to the Neapolitan convent to continue his study of theology. In July 1575 Bruno completed the prescribed course, which generated in him an annoyance at theological subtleties. He had read two forbidden commentaries by Erasmus and freely discussed the Arian heresy, which denied the divinity of Christ; as a result, a trial for heresy was prepared against him by the provincial father of the order, and he fled to Rome in February 1576. There he found himself unjustly accused of a murder. A second excommunication process was started, and in April 1576 he fled again. He abandoned the Dominican Order, and, after wandering in northern Italy, he went in 1578 to Geneva, where he earned his living by proofreading. Bruno formally embraced Calvinism; after publishing a broadsheet against a Calvinist professor, however, he discovered that the Reformed Church was no less intolerant than the Catholic. He was arrested, excommunicated, rehabilitated after retraction, and finally allowed to leave the city. He moved to France, first to Toulouse--where he unsuccessfully sought to be absolved by the Catholic Church but was nevertheless appointed to a lectureship in philosophy--and then in 1581 to Paris. In Paris Bruno at last found a congenial place to work and teach. Despite the strife between the Catholics and the Huguenots (French Protestants), the court of Henry III was then dominated by the tolerant faction of the Politiques (moderate Catholics, sympathizers of the Protestant king of Navarre, Henry of Bourbon, who became the heir apparent to the throne of France in 1584). Bruno's religious attitude was compatible with this group, and he received the protection of the French king, who appointed him one of his temporary lecteurs royaux. In 1582 Bruno published three mnemotechnical works, in which he explored new means to attain an intimate knowledge of reality. He also published a vernacular comedy, Il candelaio (1582; "The Candlemaker"), which, through a vivid representation of contemporary Neapolitan society, constituted a protest against the moral and social corruption of the time.



In the spring of 1583 Bruno moved to London with an introductory letter from Henry III for his ambassador Michel de Castelnau. He was soon attracted to Oxford, where, during the summer, he started a series of lectures in which he expounded the Copernican theory maintaining the reality of the movement of the Earth. Because of the hostile reception of the Oxonians, however, he went back to London as the guest of the French ambassador. He frequented the court of Elizabeth I and became associated with such influential figures as Sir Philip Sidney and Robert Dudley, the earl of Leicester.



WORKS



In February 1584 he was invited by Fulke Greville, a member of Sidney's circle, to discuss his theory of the movement of the Earth with some Oxonian doctors; but the discussion degenerated into a quarrel. A few days later he started writing his Italian dialogues, which constitute the first systematic exposition of his philosophy. There are six dialogues, three cosmological--on the theory of the universe--and three moral. In the Cena de le Ceneri (1584; "The Ash Wednesday Supper"), he not only reaffirmed the reality of the heliocentric theory but also suggested that the universe is infinite, constituted of innumerable worlds substantially similar to those of the solar system. In the same dialogue he anticipated his fellow Italian astronomer Galileo Galilei by maintaining that the Bible should be followed for its moral teaching but not for its astronomical implications. He also strongly criticized the manners of English society and the pedantry of the Oxonian doctors. In the De la causa, principio e uno (1584; Concerning the Cause, Principle, and One) he elaborated the physical theory on which his conception of the universe was based: "form" and "matter" are intimately united and constitute the "one." Thus, the traditional dualism of the Aristotelian physics was reduced by him to a monistic conception of the world, implying the basic unity of all substances and the coincidence of opposites in the infinite unity of Being. In the De l'infinito universo e mondi (1584; On the Infinite Universe and Worlds), he developed his cosmological theory by systematically criticizing Aristotelian physics; he also formulated his Averroistic view of the relation between philosophy and religion, according to which religion is considered as a means to instruct and govern ignorant people, philosophy as the discipline of the elect who are able to behave themselves and govern others. The Spaccio de la bestia trionfante (1584; The Expulsion of the Triumphant Beast), the first dialogue of his moral trilogy, is a satire on contemporary superstitions and vices, embodying a strong criticism of Christian ethics--particularly the Calvinistic principle of salvation by faith alone, to which Bruno opposes an exalted view of the dignity of all human activities. The Cabala del cavallo Pegaseo (1585; "Cabal of the Horse Pegasus"), similar to but more pessimistic than the previous work, includes a discussion of the relationship between the human soul and the universal soul, concluding with the negation of the absolute individuality of the former. In the De gli eroici furori (1585; The Heroic Frenzies), Bruno, making use of Neoplatonic imagery, treats the attainment of union with the infinite One by the human soul and exhorts man to the conquest of virtue and truth.



In October 1585 Bruno returned to Paris, where he found a changed political atmosphere. Henry III had abrogated the edict of pacification with the Protestants, and the King of Navarre had been excommunicated. Far from adopting a cautious line of behaviour, however, Bruno entered into a polemic with a protigi of the Catholic party, the mathematician Fabrizio Mordente, whom he ridiculed in four Dialogi, and in May 1586 he dared to attack Aristotle publicly in his Centum et viginti articuli de natura et mundo adversus Peripateticos ("120 Articles on Nature and the World Against the Peripatetics"). The Politiques disavowed him, and Bruno left Paris.



He went to Germany, where he wandered from one university city to another, lecturing and publishing a variety of minor works, including the Articuli centum et sexaginta (1588; "160 Articles") against contemporary mathematicians and philosophers, in which he expounded his conception of religion--a theory of the peaceful coexistence of all religions based upon mutual understanding and the freedom of reciprocal discussion. At Helmstedt, however, in January 1589 he was excommunicated by the local Lutheran Church. He remained in Helmstedt until the spring, completing works on natural and mathematical magic (posthumously published) and working on three Latin poems--De triplici minimo et mensura ("On the Threefold Minimum and Measure"), De monade, numero et figura ("On the Monad, Number, and Figure"), and De immenso, innumerabilibus et infigurabilibus ("On the Immeasurable and Innumerable")--which reelaborate the theories expounded in the Italian dialogues and develop Bruno's concept of an atomic basis of matter and being. To publish these, he went in 1590 to Frankfurt am Main, where the senate rejected his application to stay. Nevertheless, he took up residence in the Carmelite convent, lecturing to Protestant doctors and acquiring a reputation of being a "universal man" who, the Prior thought, "did not possess a trace of religion" and who "was chiefly occupied in writing and in the vain and chimerical imagining of novelties."



FINAL YEARS



In August 1591, at the invitation of the Venetian patrician Giovanni Mocenigo, Bruno made the fatal move of returning to Italy. At the time such a move did not seem to be too much of a risk: Venice was by far the most liberal of the Italian states; the European tension had been temporarily eased after the death of the intransigent pope Sixtus V in 1590; the Protestant Henry of Bourbon was now on the throne of France, and a religious pacification seemed to be imminent. Furthermore, Bruno was still looking for an academic platform from which to expound his theories, and he must have known that the chair of mathematics at the University of Padua was then vacant. Indeed, he went almost immediately to Padua and, during the late summer of 1591, started a private course of lectures for German students and composed the Praelectiones geometricae ("Lectures on Geometry") and Ars deformationum ("Art of Deformation"). At the beginning of the winter, when it appeared that he was not going to receive the chair (it was offered to Galileo in 1592), he returned to Venice, as the guest of Mocenigo, and took part in the discussions of progressive Venetian aristocrats who, like Bruno, favoured philosophical investigation irrespective of its theological implications. Bruno's liberty came to an end when Mocenigo--disappointed by his private lessons from Bruno on the art of memory and resentful of Bruno's intention to go back to Frankfurt to have a new work published--denounced him to the Venetian Inquisition in May 1592 for his heretical theories. Bruno was arrested and tried. He defended himself by admitting minor theological errors, emphasizing, however, the philosophical rather than the theological character of his basic tenets. The Venetian stage of the trial seemed to be proceeding in a way that was favourable to Bruno; then, however, the Roman Inquisition demanded his extradition, and on Jan. 27, 1593, Bruno entered the jail of the Roman palace of the Sant'Uffizio (Holy Office). During the seven-year Roman period of the trial, Bruno at first developed his previous defensive line, disclaiming any particular interest in theological matters and reaffirming the philosophical character of his speculation. This distinction did not satisfy the inquisitors, who demanded an unconditional retraction of his theories. Bruno then made a desperate attempt to demonstrate that his views were not incompatible with the Christian conception of God and creation. The inquisitors rejected his arguments and pressed him for a formal retraction. Bruno finally declared that he had nothing to retract and that he did not even know what he was expected to retract. At that point, Pope Clement VIII ordered that he be sentenced as an impenitent and pertinacious heretic. On Feb. 8, 1600, when the death sentence was formally read to him, he addressed his judges, saying: "Perhaps your fear in passing judgment on me is greater than mine in receiving it." Not long after, he was brought to the Campo de' Fiori, his tongue in a gag, and burned alive.



INFLUENCE



Bruno's theories influenced 17th-century scientific and philosophical thought and, since the 18th century, have been absorbed by many modern philosophers. As a symbol of the freedom of thought, Bruno inspired the European liberal movements of the 19th century, particularly the Italian Risorgimento (the movement for national political unity). Because of the variety of his interests, modern scholars are divided as to the chief significance of his work. Bruno's cosmological vision certainly anticipates some fundamental aspects of the modern conception of the universe; his ethical ideas, in contrast with religious ascetical ethics, appeal to modern humanistic activism; and his ideal of religious and philosophical tolerance has influenced liberal thinkers. On the other hand, his emphasis on the magical and the occult has been the source of criticism as has his impetuous personality. Bruno stands, however, as one of the important figures in the history of Western thought, a precursor of modern civilization.

Tycho Brahe

Bibliography of Tycho Brahe

Tycho Brahe is probably the most famous observational astronomer of the sixteenth-century, although is not always clear whether he is better remembered for the fact that his data provided the basis for the work of Johannes Kepler (1571-1630), or because of the more colourful aspects of his life and death. Born into the high nobility of his native Denmark in 1546, he was groomed by his family for a career at court, but from an early age showed greater interest in astronomy than law, the discipline of choice for aspiring royal councillors and administrators. After three years at the University of Copenhagen, he spent much of the period from 1562 to 1576 travelling in Germany, studying at the Universities of Leipzig, Wittenberg, and Rostock, and working with other scholars in Basle, Augsburg, and Kassel. It was in Rostock in 1566 that he lost part of his nose in a duel, and subsequently wore a prosthesis.

The appearance in 1572 of a "new star" (in fact a supernova) prompted Tycho's first publication, which was issued by a Copenhagen printer in 1573. In 1574, he gave some lectures on astronomy at the University of Copenhagen. Already he was of the opinion that the world-system of Copernicus was mathematically superior to that of Ptolemy, but physically absurd. In 1576, his permanent relocation to Basle, which he considered the most suitable place for him to continue his astronomical studies, was forestalled by King Frederick II, who offered him in fief the island of Hven in the Danish Sound. With generous royal support, Tycho constructed there a domicile and observatory which he called Uraniborg, and developed a range of instruments of remarkable size and precision which he used, with the aide of numerous assistants and students, to observe comets, stars, and planets.

In 1588, Tycho issued from his press a work on the comet which had appeared, causing a flurry of other publications, in 1577. The eighth chapter of this book also contained Tycho's system of the world, which retained the earth as the unmoving centre of the universe but rendered the other planets satellites of the Sun. In 1596 he published a volume of his correspondence with another noble-astronomer, Wilhelm IV of Hesse-Kassel, and Wilhelm's mathematician Christoph Rothmann. The latter was a committed Copernican, and Tycho's forceful arguments for the superiority of his own cosmology was one reason for his publication of the letters. Other works begun on Hven were the Astronomiae instauratae mechanica (1598), an illustrated account of his instruments and observatories, and the Astronomiae instauratae progymnasmata (1602), which contained his theory of lunar and solar motions, part of his catalogue of stars, and a more detailed analysis of the supernova of 1572. However, the erosion of Tycho's funding and standing following King Christian IV's attainment of his majority caused the astronomer to leave Denmark in 1597. In 1599 he settled near Prague, having been appointed Imperial Mathematician by Emperor Rudolph II, and was joined by Johannes Kepler the following year. He died of uraemia in 1601.

Robert Boyle

Bibliography of Robert Boyle

Boyle, Robert (1627–1691), natural philosopher and lay theologian. Boyle was born in Ireland, the youngest son of Richard Boyle (1566–1643), earl of Cork, and was raised as an aristocrat. After attending Eton, Robert Boyle embarked on a grand tour. When his travels were cut short as a result of the economic upheavals caused by the Irish Rebellion, he made his way back to England, where he found his sister, Katherine Ranelagh, living in London. After a brief stay with her (during which he became acquainted with the Puritan reformers of the Dury Circle), Boyle moved in 1645 to "Stalbridge," the estate in Dorset he had inherited from his father. There he wrote a number of ethical treatises and other moralistic pieces before becoming more interested in experimental philosophy. In 1649 he set up a laboratory at Stalbridge and began systematic studies in chemistry (and alchemy).

In 1655 or 1656 Boyle moved to Oxford, where he became a part of the experimental natural philosophy group. There he published some of his more important works in natural philosophy, including New Experiments Physico-Mechanical Touching the Spring of Air and Its Effects (1660), The Sceptical Chymist (1661), and The Origin of Forms and Qualities according to the Corpuscular Philosophy (1666). In 1668 Boyle moved back to London, where he became one of the founding members of the Royal Society of London. He established a laboratory in his sister's home and lived with her for the remainder of his life. Boyle continued his experiments and publications in natural philosophy and in addition published a number of works that were either primarily theological in nature or works in which it is impossible to separate his theological concerns from his work in natural philosophy. Among these are The Excellency of Theology Compar'd with Natural Philosophy (1674), A Free Enquiry into the Vulgarly Receiv'd Notion of Nature (1686), A Discourse of Things above Reason (1681), A Disquisition about the Final Causes of Natural Things (1688), and The Christian Virtuoso (1690).

As a natural philosopher, Boyle is best remembered for Boyle's Law, for advocating a corpuscularian matter theory, and for being extremely influential in the development of an empirical and experimental method. He had a marked aversion to speculative metaphysics, and in Notion of Nature argued against attributing any ontological status to either the Aristotelian notion of "nature" (as in "Nature abhors a vacuum") or to the "hylarchic principle" (or "plastick nature") of the Cambridge Platonists. Boyle argued that entities such as these are not needed to explain the phenomena and ought not be admitted into a theory of nature on the grounds of Ockham's razor (the principle that entities ought not to be multiplied beyond necessity).

Boyle is still honored in introductory chemistry texts as the "father of modern chemistry," the natural philosopher who successfully separated chemistry from its alchemical antecedents. This claim, however, is based on the fact that the work in which he is supposed to have done this, The Sceptical Chymist, was misinterpreted until the late twentieth century. Rather than being an attack on alchemy, the work is instead an attack only on certain practitioners and textbook writers—most specifically those who divorced alchemy from any theoretical underpinning. Indeed Boyle was quite involved in alchemical pursuits throughout his life, both in attempts to transmute base metals into gold and in the investigation of alchemical processes for medicinal purposes.

During his lifetime and after his death Boyle was honored as much for his piety as for his work as an experimental philosopher. Boyle considered the investigation of the world God created as a way of worshiping God, seeing the created world as a temple and the investigator of that world as a priest. He was painfully aware of the growing suspicion that the revival of Epicureanism (in the form of the corpuscular philosophy) might lead to a materialist worldview and an accompanying atheism, and he published work after work in which he attempted to show that the astute natural philosopher would become a more devout Christian rather than being led to question God's existence or providence. He advocated a natural theology that was typical of the time, showing that reason alone could prove God's existence and the immateriality of the soul.

Boyle was quite clear, however, that this natural philosophy was only the first step toward belief and that its main purpose was to serve as a bridge to revelation. As Boyle expressed it, knowing that God exists and having come to admire his workmanship, one naturally wants to learn more about the deity, and fortunately God has provided that knowledge via revelation. Boyle wrote extensively in an attempt to privilege the mysteries of Christianity from rational scrutiny, arguing that just as there are aspects of nature that human beings cannot (yet) understand, so too are there mysteries revealed in Scripture that human beings cannot (yet) understand. Indeed Boyle went so far as to argue that, where revelation is concerned, it is sometimes necessary for human reason to affirm apparently contradictory truths, such as God's prescience and human beings' free will (emphasizing that God, in his infinite wisdom, understands how such apparent contradictions are in fact consistent).

The unity of Boyle's thought is revealed in his voluntarism (his emphasis on God's will and power rather than on God's goodness and reason). In Boyle's view God was free to create any world whatsoever. The only way to discover the nature of God's creation is to investigate it, and (because the world was created commensurate to God's infinite understanding rather than to finite human understanding), there will always be aspects of this world that humans are unable to comprehend. The same thing is true of the mysteries of Christianity. God has reserved a full understanding of both nature and theology for the afterlife, thereby providing an incentive for godly living and belief.

Max Born

Bibliography of Max Born

Max Born was born in Breslau on the 11th December, 1882, to Professor Gustav Born, anatomist and embryologist, and his wife Margarete, née Kauffmann, who was a member of a Silesian family of industrialists.

Max attended the König Wilhelm's Gymnasium in Breslau and continued his studies at the Universities of Breslau (where the well-known mathematician Rosanes introduced him to matrix calculus), Heidelberg, Zurich (here he was deeply impressed by Hurwitz's lectures on higher analysis), and Göttingen. In the latter seat of learning he read mathematics chiefly, sitting under Klein, Hilbert, Minkowski, and Runge, but also studied astronomy under Schwarzschild, and physics under Voigt. He was awarded the Prize of the Philosophical Faculty of the University of Göttingen for his work on the stability of elastic wires and tapes in 1906, and graduated at this university a year later on the basis of this work.

Born next went to Cambridge for a short time, to study under Larmor and J.J. Thomson. Back in Breslau during the years 1908-1909, he worked with the physicists Lummer and Pringsheim, and also studied the theory of relativity. On the strength of one of his papers, Minkowski invited his collaboration at Göttingen but soon after his return there, in the winter of 1909, Minkowski died. He had then the task of sifting Minkowski's literary works in the field of physics and of publishing some uncompleted papers. Soon he became an academic lecturer at Göttingen in recognition of his work on the relativistic electron. He accepted Michelson's invitation to lecture on relativity in Chicago (1912) and while there he did some experiments with the Michelson grating spectrograph.

An appointment as professor (extraordinarius) to assist Max Planck at Berlin University came to Born in 1915 but he had to join the German Armed Forces. In a scientific office of the army he worked on the theory of sound ranging. He found time also to study the theory of crystals, and published his first book, Dynamik der Kristallgitter (Dynamics of Crystal Lattices), which summarized a series of investigations he had started at Göttingen.

At the conclusion of the First World War, in 1919, Born was appointed Professor at the University of Frankfurt-on-Main, where a laboratory was put at his disposal. His assistant was Otto Stern, and the first of the latter's well-known experiments, which later were rewarded with a Nobel Prize, originated there.

Max Born went to Göttingen as Professor in 1921, at the same time as James Franck, and he remained there for twelve years, interrupted only by a trip to America in 1925. During these years the Professor's most important works were created; first a modernized version of his book on crystals, and numerous investigations by him and his pupils on crystal lattices, followed by a series of studies on the quantum theory. Among his collaborators at this time were many physicists, later to become well-known, such as Pauli, Heisenberg, Jordan, Fermi, Dirac, Hund, Hylleraas, Weisskopf, Oppenheimer, Joseph Mayer and Maria Goeppert-Mayer. During the years 1925 and 1926 he published, with Heisenberg and Jordan, investigations on the principles of quantum mechanics (matrix mechanics) and soon after this, his own studies on the statistical interpretation of quantum mechanics.

As were so many other German scientists, he was forced to emigrate in 1933 and was invited to Cambridge, where he taught for three years as Stokes Lecturer. His main sphere of work during this period was in the field of nonlinear electrodynamics, which he developed in collaboration with Infeld.

During the winter of 1935-1936 Born spent six months in Bangalore at the Indian Institute of Science, where he worked with Sir C.V. Raman and his pupils. In 1936 he was appointed Tait Professor of Natural Philosophy in Edinburgh, where he worked until his retirement in 1953. He is now living at the small spa town, Bad Pyrmont.

Max Born has been awarded fellowships of many academies - Göttingen, Moscow, Berlin, Bangalore, Bucharest, Edinburgh, London, Lima, Dublin, Copenhagen, Stockholm, Washington, and Boston, and he has received honorary doctorates from Bristol, Bordeaux, Oxford, Freiburg/Breisgau, Edinburgh, Oslo, Brussels Universities, Humboldt University Berlin, and Technical University Stuttgart. He holds the Stokes Medal of Cambridge, the Max Planck Medaille der Deutschen Physikalischen Gesellschaft (i.e. of the German Physical Society); the Hughes Medal of the Royal Society, London, the Hugo Grotius Medal for International Law, and was also awarded the MacDougall-Brisbane Prize and the Gunning-Victoria Jubilee Prize of the Royal Society, Edinburgh. In 1953 he was made honorary citizen of the town of Göttingen and a year later was granted the Nobel Prize for Physics. He was awarded the Grand Cross of Merit with Star of the Order of Merit of the German Federal Republic in 1959.

The year 1913 saw his marriage to Hedwig, née Ehrenberg, and there are three children of the marriage.

Niels Bohr

Bibliography of Neils Bohr

Bohr was born in Copenhagen, Denmark, in 1885. His father, Christian Bohr, a devout Lutheran, was professor of physiology at the University of Copenhagen (it is his name which is given to the Bohr shift or Bohr effect), while his mother, Ellen Adler Bohr, came from a wealthy Jewish family prominent in Danish banking and parliamentary circles. His brother was Harald Bohr, a mathematician and Olympic footballer who played on the Danish national team. Niels Bohr was a passionate footballer as well, and the two brothers played a number of matches for the Copenhagen-based Akademisk Boldklub, with Niels in goal. There is, however, no truth in the oft-repeated claim that Niels Bohr emulated his brother Harald by playing for the Danish national team [2].

In 1903 Bohr enrolled as an undergraduate at Copenhagen University, initially studying philosophy and mathematics. In 1905, prompted by a gold medal competition sponsored by the Royal Danish Academy of Sciences and Letters, he conducted a series of experiments to examine the properties of surface tension, using his father's laboratory in the university, familiar to him from assisting there since childhood. His essay won the prize, and it was this success that decided Bohr to abandon philosophy and adopt physics.[3] As a student under Christian Christiansen he received his doctorate in 1911. As a post-doctoral student, Bohr first conducted experiments under J. J. Thomson at Trinity College, Cambridge. He then went on to study under Ernest Rutherford at the University of Manchester in England. On the basis of Rutherford's theories, Bohr published his model of atomic structure in 1913, introducing the theory of electrons traveling in orbits around the atom's nucleus, the chemical properties of the element being largely determined by the number of electrons in the outer orbits. Bohr also introduced the idea that an electron could drop from a higher-energy orbit to a lower one, emitting a photon (light quantum) of discrete energy. This became a basis for quantum theory.

Niels Bohr and his wife Margrethe Nørlund Bohr had six sons. Their oldest died in a tragic boating accident and another died from childhood meningitis. The others went on to lead successful lives, including Aage Bohr, who became a very successful physicist and, like his father, won a Nobel Prize in physics, in 1975.
Physics

In 1916, Niels Bohr became a professor at the University of Copenhagen. With the assistance of the Danish government and the Carlsberg Foundation, he succeeded in founding the Institute of Theoretical Physics in 1921, of which he became its director.[4] In 1922, Bohr was awarded the Nobel Prize in physics "for his services in the investigation of the structure of atoms and of the radiation emanating from them." Bohr's institute served as a focal point for theoretical physicists in the 1920s and '30s, and most of the world's best known theoretical physicists of that period spent some time there.


Niels Bohr as a young man. Exact date of photo not known.


Niels Bohr and Albert Einstein debating quantum theory at Paul Ehrenfest's home in Leiden (December 1925).

Bohr also conceived the principle of complementarity: that items could be separately analyzed as having several contradictory properties. For example, physicists currently conclude that light behaves either as a wave or a stream of particles depending on the experimental framework — two apparently mutually exclusive properties — on the basis of this principle. Bohr also found philosophical applications for this daringly original principle.[specify] Albert Einstein much preferred the determinism of classical physics over the probabilistic new quantum physics (to which Max Planck and Einstein himself had contributed). He and Bohr had good-natured arguments over the truth of this principle throughout their lives (see Bohr–Einstein debates).

Werner Heisenberg worked as an assistant to Bohr and university lecturer in Copenhagen from 1926 to 1927. It was in Copenhagen, in 1927, that Heisenberg developed his uncertainty principle, while working on the mathematical foundations of quantum mechanics. Heisenberg was later to be head of the German atomic bomb project. In 1941, during the German occupation of Denmark in World War II, Bohr was visited by Heisenberg in Copenhagen (see section below). In 1943, shortly before he was to be arrested by the German police, Bohr escaped to Sweden, and then traveled to London.
Atomic research

Niels Bohr worked at the top-secret Los Alamos laboratory in New Mexico, U.S., on the Manhattan Project, where he was known by the assumed name of Nicholas Baker for security reasons.[5] His role in the project was important and was a knowledgeable consultant or "father confessor" on the project. He was concerned about a nuclear arms race, and is quoted as saying, "That is why I went to America. They didn't need my help in making the atom bomb."[6]

Bohr believed that atomic secrets should be shared by the international scientific community. After meeting with Bohr, J. Robert Oppenheimer suggested Bohr visit President Franklin D. Roosevelt to convince him that the Manhattan Project should be shared with the Russians in the hope of speeding up its results. Roosevelt suggested Bohr return to the United Kingdom to try to win British approval. Winston Churchill disagreed with the idea of openness towards the Russians to the point that he wrote in a letter: "It seems to me Bohr ought to be confined or at any rate made to see that he is very near the edge of mortal crimes."[7]

After the war Bohr returned to Copenhagen, advocating the peaceful use of nuclear energy. When awarded the Order of the Elephant by the Danish government, he designed his own coat of arms which featured a taijitu (symbol of yin and yang) and the Latin motto contraria sunt complementa: opposites are complementary.[8] He died in Copenhagen in 1962 of heart failure.[9] He is buried in the Assistens Kirkegård in the Nørrebro section of Copenhagen.
Contributions to physics
The Bohr model of the atom, the theory that electrons travel in discrete orbits around the atom's nucleus.
The shell model of the atom, where the chemical properties of an element are determined by the electrons in the outermost orbit.
The correspondence principle, the basic tool of Old quantum theory.
The liquid drop model of the atomic nucleus.
Identified the isotope of uranium that was responsible for slow-neutron fission - 235U.[10]
Much work on the Copenhagen interpretation of quantum mechanics.
The principle of complementarity: that items could be separately analyzed as having several contradictory properties.
Kierkegaard's influence on Bohr

It is generally accepted that Bohr read the 19th century Danish philosopher Søren Kierkegaard. Richard Rhodes argues in The Making of the Atomic Bomb that Bohr was influenced by Kierkegaard via the philosopher Harald Høffding, who was strongly influenced by Kierkegaard and who was an old friend of Bohr's father. In 1909, Bohr sent his brother Kierkegaard's Stages on Life's Way as a birthday gift. In the enclosed letter, Bohr wrote, "It is the only thing I have to send home; but I do not believe that it would be very easy to find anything better.... I even think it is one of the most delightful things I have ever read." Bohr enjoyed Kierkegaard's language and literary style, but mentioned that he had some "disagreement with [Kierkegaard's ideas]."[11]

Given this, there has been some dispute over whether Kierkegaard influenced Bohr's philosophy and science. David Favrholdt[12] argues that Kierkegaard had minimal influence over Bohr's work; taking Bohr's statement about disagreeing with Kierkegaard at face value, while Jan Faye[13] endorses the opposing point of view by arguing that one can disagree with the content of a theory while accepting its general premises and structure.[14]
Relationship with Heisenberg

Bohr and Werner Heisenberg enjoyed a strong mentor/protégé relationship up to the onset of World War II. Heisenberg had made Bohr aware of his talent during a lecture in 1922 in Göttingen. During the mid-1920s, Heisenberg worked with Bohr at the institute in Copenhagen. Heisenberg, like most of Bohr's assistants, learned Danish. Heisenberg's uncertainty principle was developed during this period, as was Bohr's complementarity principle.

By the time of World War II, the relationship became strained; this was in part because Bohr, with his partially-Jewish heritage, remained in occupied Denmark, while Heisenberg remained in Germany and became head of the German nuclear effort. Heisenberg made a famous visit to Bohr in September 1941 and during a private moment it seems that he began to address nuclear energy and morality as well as the war. Neither Bohr nor Heisenberg spoke about it in any detail or left written records of this part of the meeting and they were alone and outside.[15] Bohr seems to have reacted by terminating that conversation abruptly while not giving Heisenberg hints in any direction.

While some suggest that the relationship became strained at this meeting, other evidence shows that the level of contact had been reduced considerably for some time already. Heisenberg suggested that the fracture occurred later. In correspondence to his wife, Heisenberg described the final visit of the trip: "Today I was once more, with Weizsaecker, at Bohr's. In many ways this was especially nice, the conversation revolved for a large part of the evening around purely human concerns, Bohr was reading aloud, I played a Mozart Sonata (A-Major)."[16] Ivan Supek, one of Heisenberg's students and friends, claimed that the main figure of the meeting was actually Weizsäcker who tried to persuade Bohr to mediate peace between Great Britain and Germany.[17]
Tube Alloys

"Tube Alloys" was the code-name for the British nuclear weapon program. British intelligence inquired about Bohr's availability for work or insights of particular value. Bohr's reply made it clear that he could not help. This reply, like his reaction to Heisenberg, made sure that if Gestapo intercepted anything attributed to Bohr it would point to no knowledge regarding nuclear energy as it stood in 1941. This does not exclude the possibility that Bohr privately made calculations going further than his work in 1939 with Wheeler.

After leaving Denmark in the dramatic day and night (October 1943) when most Jews were able to escape to Sweden due to exceptional circumstances (see Rescue of the Danish Jews), Bohr was quickly asked again to join the British effort and he was flown to the UK. He was evacuated from Stockholm in 1943 in an unarmed De Havilland Mosquito operated by British Overseas Airways Corporation (BOAC). Passengers on BOAC's Mosquitos were carried in an improvised cabin in the bomb bay. The flight almost ended in tragedy as Bohr did not don his oxygen equipment as instructed and passed out at high altitude. He would have died had not the pilot surmising from Bohr's lack of response to intercom communication that he had lost consciousness, descended to a lower altitude for the remainder of the flight. Bohr's comment was that he had slept like a baby for the entire flight.

As part of the UK team on "Tube Alloys" Bohr went to Los Alamos. Oppenheimer credited Bohr warmly for his guiding help during certain discussions among scientists there. Discreetly, he met President Franklin D. Roosevelt and later Winston Churchill to warn against the perilous perspectives that would follow from separate development of nuclear weapons by several powers rather than some form of controlled sharing of the knowledge, which would spread quickly in any case. Only in the 1950s after the immense surprise that the Soviets developed the weapons independently, was it possible to create the International Atomic Energy Agency along the lines of Bohr's suggestion.
Speculation

In 1957, while the author Robert Jungk was working on the book Brighter Than a Thousand Suns, Heisenberg wrote to Jungk explaining that he had visited Copenhagen to communicate to Bohr his view that scientists on either side should help prevent development of the atomic bomb, that the German attempts were entirely focused on energy production and that Heisenberg's circle of colleagues tried to keep it that way.[18] Heisenberg acknowledged that his cryptic approach of the subject had so alarmed Bohr that the discussion failed. Heisenberg nuanced his claims and avoided the implication that he and his colleagues had sabotaged the bomb effort; this nuance was lost in Jungk's original publication of the book, which implied that the German atomic bomb project was obstructed by Heisenberg.

When Bohr saw Jungk's erroneous depiction in the Danish translation of the book, he disagreed. He drafted (but never sent) a letter to Heisenberg, stating that while Heisenberg had indeed discussed the subject of nuclear weapons in Copenhagen, Heisenberg had never alluded to the fact that he might be resisting efforts to build such weapons. Bohr dismissed the idea of any pact as hindsight.[19]

Michael Frayn's play Copenhagen, which was performed in London (for five years), Copenhagen, Gothenburg, Rome, Athens, Geneva and on Broadway in New York, explores what might have happened at the 1941 meeting between Heisenberg and Bohr. Frayn points in particular to the onus of being one of the few to understand what it would mean to create a nuclear weapon.

Daniel Bernoull

Bibliography of Daniel Bernoull

Daniel Bernoulli was the son of Johann Bernoulli. He was born in Groningen while his father held the chair of mathematics there. His older brother was Nicolaus(II) Bernoulli and his uncle was Jacob Bernoulli so he was born into a family of leading mathematicians but also into a family where there was unfortunate rivalry, jealousy and bitterness.

When Daniel was five years old the family returned to their native city of Basel where Daniel's father filled the chair of mathematics left vacant on the death of his uncle Jacob Bernoulli. When Daniel was five years old his younger brother Johann(II) Bernoulli was born. All three sons would go on to study mathematics but this was not the course that Johann Bernoulli planned for Daniel.

Johann Bernoulli's father had tried to force Johann into a business career and he had resisted strongly. Rather strangely Johann Bernoulli now tried exactly the same with his own son Daniel. First however Daniel was sent to Basel University at the age of 13 to study philosophy and logic. He obtained his baccalaureate examinations in 1715 and went on to obtain his master's degree in 1716. Daniel, like his father, really wanted to study mathematics and during the time he studied philosophy at Basel, he was learning the methods of the calculus from his father and his older brother Nicolaus(II) Bernoulli.

Johann was determined that Daniel should become a merchant and he tried to place him in an apprenticeship. However Daniel was as strongly opposed to this as his own father had been and soon Johann relented but certainly not as far as to let Daniel study mathematics. Johann declared that there was no money in mathematics and so he sent Daniel back to Basel University to study medicine. This Daniel did spending time studying medicine at Heidelberg in 1718 and Strasbourg in 1719. He returned to Basel in 1720 to complete his doctorate in medicine.

By this stage Johann Bernoulli was prepared to teach his son more mathematics while he studied medicine and Daniel studied his father's theories of kinetic energy. What he learned on the conservation of energy from his father he applied to his medical studies and Daniel wrote his doctoral dissertation on the mechanics of breathing. So like his father Daniel had applied mathematical physics to medicine in order to obtain his medical doctorate.

Daniel wanted to embark on an academic career like his father so he applied for two chairs at Basel. His application for the chair of anatomy and botany was decided by drawing of lots and he was unlucky in this game of chance. The next chair to fall vacant at Basel that Daniel applied for was the chair of logic, but again the game of chance of the final selection by drawing of lots went against him. Having failed to obtain an academic post, Daniel went to Venice to study practical medicine.

In Venice Daniel was severely ill and so was unable to carry out his intention of travelling to Padua to further his medical studies. However, while in Venice he worked on mathematics and his first mathematical work was published in 1724 when, with Goldbach's assistance, Mathematical exercises was published. This consisted of four separate parts being four topics that had attracted his interest while in Venice.

The first part described the game of faro and is of little importance other than showing that Daniel was learning about probability at this time. The second part was on the flow of water from a hole in a container and discussed Newton's theories (which were incorrect). Daniel had not solved the problem of pressure by this time but again the work shows that his interest was moving in this direction. His medical work on the flow of blood and blood pressure also gave him an interest in fluid flow. The third part of Mathematical exercises was on the Riccati differential equation while the final part was on a geometry question concerning figures bounded by two arcs of a circle.

While in Venice, Daniel had also designed an hour glass to be used at sea so that the trickle of sand was constant even when the ship was rolling in heavy seas. He submitted his work on this to the Paris Academy and in 1725, the year he returned from Italy to Basel, he learnt that he had won the prize of the Paris Academy. Daniel had also attained fame through his work Mathematical exercises and on the strength of this he was invited to take up the chair of mathematics at St Petersburg. His brother Nicolaus(II) Bernoulli was also offered a chair of mathematics at St Petersburg so in late 1725 the two brothers travelled to St Petersburg.

Within eight months of their taking up the appointments in St Petersburg Daniel's brother died of fever. Daniel was left, greatly saddened at the loss of his brother and also very unhappy with the harsh climate. He thought of returning to Basel and wrote to his father telling him how unhappy he was in St Petersburg. Johann Bernoulli was able to arrange for one of his best pupils, Leonard Euler, to go to St Petersburg to work with Daniel. Euler arrived in 1727 and this period in St Petersburg, which Daniel left in 1733, was to be his most productive time.

One of the topics which Daniel studied in St Petersburg was that of vibrating systems. As Straub writes in [1]:-

From 1728, Bernoulli and Euler dominated the mechanics of flexible and elastic bodies, in that year deriving the equilibrium curves for these bodies. ... Bernoulli determined the shape that a perfectly flexible thread assumes when acted upon by forces of which one component is vertical to the curve and the other is parallel to a given direction. Thus, in one stroke he derived the entire series of such curves as the velaria, lintearia, catenaria...

While in St Petersburg he made one of his most famous discoveries when he defined the simple nodes and the frequencies of oscillation of a system. He showed that the movements of strings of musical instruments are composed of an infinite number of harmonic vibrations all superimposed on the string.

A second important work which Daniel produced while in St Petersburg was one on probability and political economy. Daniel makes the assumption that the moral value of the increase in a person's wealth is inversely proportional to the amount of that wealth. He then assigns probabilities to the various means that a person has to make money and deduces an expectation of increase in moral expectation. Daniel applied some of his deductions to insurance.

Undoubtedly the most important work which Daniel Bernoulli did while in St Petersburg was his work on hydrodynamics. Even the term itself is based on the title of the work which he produced called Hydrodynamica and, before he left St Petersburg, Daniel left a draft copy of the book with a printer. However the work was not published until 1738 and although he revised it considerably between 1734 and 1738, it is more the presentation that he changed rather then the substance.

This work contains for the first time the correct analysis of water flowing from a hole in a container. This was based on the principle of conservation of energy which he had studied with his father in 1720. Daniel also discussed pumps and other machines to raise water. One remarkable discovery appears in Chapter 10 of Hydrodynamica where Daniel discussed the basis for the kinetic theory of gases. He was able to give the basic laws for the theory of gases and gave, although not in full detail, the equation of state discovered by Van der Waals a century later.

Daniel Bernoulli was not happy in St Petersburg, despite the obvious scientific advantage of working with Euler. By 1731 he was applying for posts in Basel but probability seemed to work against him and he would lose out in the ballot for the post. The post was neither one in mathematics nor physics but Daniel preferred to return to Basel and give lectures on botany rather than remain in St Petersburg. By this time his younger brother Johann(II) Bernoulli was also with him in St Petersburg and they left St Petersburg in 1733, making visits to Danzig, Hamburg, Holland and Paris before returning to Basel in 1734.

Daniel Bernoulli submitted an entry for the Grand Prize of the Paris Academy for 1734 giving an application of his ideas to astronomy. This had unfortunate consequences since Daniel's father, Johann Bernoulli, also entered for the prize and their entries were declared joint winners of the Grand Prize. The result of this episode of the prize of the Paris Academy had unhappy consequences for Daniel. His father was furious to think that his son had been rated as his equal and this resulted in a breakdown in relationships between the two. The outcome was that Daniel found himself back in Basel but banned from his father's house. Whether this caused Daniel to become less interested in mathematics or whether it was the fact that his academic position was a non mathematical one, certainly Daniel never regained the vigour for mathematical research that he showed in St Petersburg.

Although Daniel had left St Petersburg, he began an immediate correspondence with Euler and the two exchanged many ideas on vibrating systems. Euler used his great analytic skills to put many of Daniel's physical insights into a rigorous mathematical form. Daniel continued to work on polishing his masterpiece Hydrodynamica for publication and added a chapter on the force of reaction of a jet of fluid and the force of a jet of water on an inclined plane. In this chapter, Chapter 13, he also discussed applications to the propulsion of ships.

The 1737 prize of the Paris Academy also had a nautical theme, the best shape for a ship's anchor, and Daniel Bernoulli was again the joint winner of this prize, this time jointly with Poleni. Hydrodynamica was published in 1738 but, in the following year Johann Bernoulli published Hydraulica which is largely based on his son's work but Johann tried to make it look as if Daniel had based Hydrodynamica on Hydraulica by predating the date of publication on his book to 1732 instead of its real date which is probably 1739. This was a disgraceful attempt by Johann to gain credit for work which was not his and at the same time to discredit his own son and shows the depths to which the bad feeling between them had reached.

It is fair to say that there is no evidence that Daniel was in any way to blame for the breakdown of relationships with his father. Rather the reverse since there is evidence that he tried to mend the relationship with such acts as describing himself on the frontispiece of Hydrodynamica as 'Daniel Bernoulli, son of Johann'. Another sign that Daniel was not jealous of members of his own family in the way the Johann Bernoulli and Jacob Bernoulli had been is the fact that he did produce joint work with his younger brother Johann(II) Bernoulli.

Botany lectures were not what Daniel wanted and things became better for him in 1743 when he was able to exchange these for physiology lectures. In 1750, however, he was appointed to the chair of physics and taught physics at Basel for 26 years until 1776. He gave some remarkable physics lectures with experiments performed during the lectures. Based on experimental evidence he was able to conjecture certain laws which were not verified until many years later. Among these was Coulomb's law in electrostatics.

Daniel Bernoulli did produce other excellent scientific work during these many years back in Basel. In total he won the Grand Prize of the Paris Academy 10 times, for topics in astronomy and nautical topics. He won in 1740 (jointly with Euler) for work on Newton's theory of the tides; in 1743 and 1746 for essays on magnetism; in 1747 for a method to determine time at sea; in 1751 for an essay on ocean currents; in 1753 for the effects of forces on ships; and in 1757 for proposals to reduce the pitching and tossing of a ship in high seas.

Another important aspect of Daniel Bernoulli's work that proved important in the development of mathematical physics was his acceptance of many of Newton's theories and his use of these together with the tolls coming from the more powerful calculus of Leibniz. Daniel worked on mechanics and again used the principle of conservation of energy which gave an integral of Newton's basic equations. He also studied the movement of bodies in a resisting medium using Newton's methods.

He also continued to produce good work on the theory of oscillations and in a paper he gave a beautiful account of the oscillation of air in organ pipes. His strengths and weaknesses are summed up by Straub in [1]:-

Bernoulli's active and imaginative mind dealt with the most varied scientific areas. Such wide interests, however, often prevented him from carrying some of his projects to completion. It is especially unfortunate that he could not follow the rapid growth of mathematics that began with the introduction of partial differential equations into mathematical physics. Nevertheless he assured himself a permanent place in the history of science through his work and discoveries in hydrodynamics, his anticipation of the kinetic theory of gases, a novel method for calculating the value of an increase in assets, and the demonstration that the most common movement of a string in a musical instrument is composed of the superposition of an infinite number of harmonic vibrations...

Daniel Bernoulli was much honoured in his own lifetime. He was elected to most of the leading scientific societies of his day including those in Bologna, St Petersburg, Berlin, Paris, London, Bern, Turin, Zurich and Mannheim.