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John Dalton

John Dalton FRS (; 6 September 1766 – 27 July 1844) was an English chemist, physicist, and meteorologist. He is best known for proposing the modern atomic theory and for his research into colour blindness, sometimes referred to as Daltonism in his honour.

Early life

John Dalton was born into a Quaker family in Eaglesfield, near Cockermouth, in Cumberland, England. His father was a weaver. He received his early education from his father and from Quaker John Fletcher, who ran a private school in the nearby village of Pardshaw Hall. Dalton's family was too poor to support him for long and he began to earn his living at the age of ten in the service of a wealthy local Quaker, Elihu Robinson. It is said he began teaching at a local school at age 12, and became proficient in Latin at age 14.

Early careers

When he was 15, Dalton joined his older brother Jonathan in running a Quaker school in Kendal, about from his home. Around the age of 23 Dalton may have considered studying law or medicine, but his relatives did not encourage him, perhaps because being a Dissenter, he was barred from attending English universities. He acquired much scientific knowledge from informal instruction by John Gough, a blind philosopher who was gifted in the sciences and arts. At the age of 27 he was appointed teacher of mathematics and natural philosophy at the "New College" in Manchester, a dissenting academy (the lineal predecessor, following a number of changes of location, of Harris Manchester College, Oxford). He remained there until the age of 34, when the college's worsening financial situation led him to resign his post and begin a new career as a private tutor in mathematics and natural philosophy.

Scientific contributions

Meteorology

Dalton's early life was influenced by a prominent Eaglesfield Quaker, Elihu Robinson, a competent meteorologist and instrument maker, who interested him in problems of mathematics and meteorology. During his years in Kendal, Dalton contributed solutions to problems and answered questions on various subjects in The Ladies' Diary and the Gentleman's Diary. In 1787 at age 21 he began his meteorological diary in which, during the succeeding 57 years, he entered more than 200,000 observations. He rediscovered George Hadley's theory of atmospheric circulation (now known as the Hadley cell) around this time. George Hadley Encyclopædia Britannica. Accessed 30 April 2009. In 1793 Dalton's first publication, Meteorological Observations and Essays, contained the seeds of several of his later discoveries but despite the originality of his treatment, little attention was paid to them by other scholars. A second work by Dalton, Elements of English Grammar, was published in 1801.

Measuring mountains

After leaving the Lake District, Dalton returned annually to spend his holidays studying meteorology, something which involved a lot of hill-walking. Until the advent of aeroplanes and weather balloons, the only way to make measurements of temperature and humidity at altitude was to climb a mountain. Dalton estimated the height using a barometer. The Ordnance Survey did not publish maps for the Lake District until the 1860s. Before then, Dalton was one of the few authorities on the heights of the region's mountains. He was often accompanied by Jonathan Otley, who also made a study of the heights of the local peaks, using Dalton's figures as a comparison to check his work. Otley published his information in his map of 1818. Otley became both an assistant and a friend to Dalton.Thomas Fletcher Smith Jonathan Otley, Man of Lakeland, publ. Bookcase, 2007ISBN 978-1-904147-23-7

Colour blindness

In 1794, shortly after his arrival in Manchester, Dalton was elected a member of the Manchester Literary and Philosophical Society, the "Lit & Phil", and a few weeks later he communicated his first paper on "Extraordinary facts relating to the vision of colours", in which he postulated that shortage in colour perception was caused by discoloration of the liquid medium of the eyeball. As both he and his brother were colour blind, he recognised that the condition must be hereditary. Although Dalton's theory lost credence in his lifetime, the thorough and methodical nature of his research into his visual problem was so broadly recognised that Daltonism became a common term for colour blindness. Examination of his preserved eyeball in 1995 demonstrated that Dalton had a less common kind of colour blindness, deuteroanopia, in which medium wavelength sensitive cones are missing (rather than functioning with a mutated form of pigment, as in the most common type of colour blindness, deuteroanomaly). Besides the blue and purple of the optical spectrum he was only able to recognise one colour, yellow, or, as he said in a paper,

Gas laws

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This article based upon the http://en.wikipedia.org/wiki/John_Dalton, the free encyclopaedia Wikipedia and is licensed under the GNU Free Documentation License.
Further informations available on the list of authors and history: http://en.wikipedia.org/w/index.php?title=John_Dalton&action=history
presented by: Ingo Malchow, Mirower Bogen 22, 17235 Neustrelitz, Germany