John_Dalton

John Dalton (6 September 1766 - 27 July 1844) was an English chemist, meteorologist and physicist. He was a self-educated chemist who evolved the Atomic Theory, central to modern scientific thought. Dalton was the son of an impoverished Quaker weaver of little or no education who despite his own disadvantages ensured that his sons were provided with ample reading material to pursue their own learning paths. At the astounding age of twelve, Dalton was given charge of a Quaker school at Eaglesfield and two years later he and his brother were appointed teachers at a school in Kendal, where he was to remain for twelve years! At that time, the universities were closed to all but members of the Anglican Church, but he was fortunate to become a teacher of mathematics and natural philosophy at New College, Manchester, an institution founded for the education of Nonconformists. Dalton's first scientific work, which he began in 1787 and continued until his death was a journal of 200,000 entries on meteorological observations recording the unpredictable climate of the English Lake District. In 1793 He published Meteorological Observations and Essays, which contained the nucleus of several of his later discoveries. Inspired by a spectacular aurora borealis appearance in 1787, he began observations about aurora phenomena--luminous, colourful displays in the sky caused by electrical disturbances in the atmosphere. His writings on this subject show the nature of the man. He was self-reliant, unwilling to depend on the work of others. He was assiduous in his work and determined to find the explanation of the phenomenon. As Dalton himself wrote, "Having been in my progress so often misled by taking for granted the results of others, I have determined to write as little as possible but what I can attest by my own experience." It was this approach, which led Dalton to one of the greatest scientific discoveries of the Nineteenth Century, The Atomic Theory, which laid the basis for modern chemical analysis. His early work on gases and his copious notes thereon showed that the relative weights of various elements follow a numerical and proportionate pattern, which can be naturally arranged in a table. Following this discovery Dalton progressed to deduce that all matter is composed of minute particles known as atoms and that the atoms of each element are uniform in every respect. Furthermore the elements can combine with other elements to form compounds and that all matter consists of elements or compounds of elements. Before Dalton's theory, chemistry had been based of the speculation of ancient Greek philosophers. Now the foundations were laid for modern scientific investigation. In 1800, he progressed to become secretary of The Manchester Literary and Philosophical Society and a teacher of mathematics and chemistry and in 1817, he became President of The Philosophical Society, a position that he held until his last breath. Dalton's researches were not confined to inanimate materials. He attempted to explain the medical disorder known as colour blindness, a condition from which he and several members of his family suffered. In his publication, Extraordinary Facts Relating to the Vision of Colours, Dalton hypothesized that inability to discern colours was the result of discoloration of the liquid medium of the eyeball. Although he was not able to prove this theory during his lifetime, Dalton ordered that his eyes should be examined posthumously in an attempt to discover the cause of his colour-blindness. However, post-mortem examination showed that the humours of the eye were normal. One eye was preserved at the Royal Institution, and a twentieth Century study on DNA taken from the eye showed that Dalton had lacked the essential pigment that gives sensitivity to green, the classic condition known as a deuteranope. Despite Dalton's inability to find a cure for colour blindness, the term Daltonism has become a common term for that condition. Dalton will be remembered not only for his great scientific discovery but also for his perseverance in rising to scientific prominence from the most unprivileged beginning.