John Dalton (1766 - 1844)
John Dalton was born into a Quaker family in Eaglesfield, near Cockermouth, in the county of 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. With his family too poor to support him for long, he began to earn his living at the age of ten in the service of a wealthy local Quaker, Elihu Robinson. He began teaching at a local school at age 12, and was proficient in Latin at age 14.
He joined his older brother Jonathan at age 15 in running a Quaker school in Kendal, about forty five miles from his home. Around age 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 age 27 he was appointed teacher of mathematics and natural philosophy at the "New College" in Manchester, a dissenting academy. He remained there until age 34, when the college's worsening financial situation led him to resign his post and begin a new career as a private tutor for mathematics and natural philosophy.
While young, he was highly influenced by a prominent Eaglesfield Quaker named Elihu Robinson, a competent meteorologist and instrument maker, who got him interested in problems of mathematics and meteorology. During his years in Kendal, Dalton contributed solutions of problems and questions on various subjects to The Ladies' Diary and the Gentleman's Diary. In 1787 at age 21 he began to keep a meteorological diary in which, during the succeeding 57 years, he entered more than 200,000 observations. His last observations were taken the night before he died. He also rediscovered George Hadley's theory of atmospheric circulation (now known as the Hadley cell) around this time. Dalton's first publication was Meteorological Observations and Essays at age 27 in 1793. A second work by Dalton, Elements of English Grammar, was published at age 35 in 1801.
Dalton never married and had only a few close friends. All in all as a Quaker he lived a modest and unassuming personal life. For the twenty-six years prior to Dalton's death, he lived in a room in the home of the Rev. (and Mrs.) W. Johns, a published botanist, in George Street, Manchester. He presented papers to, and played an increasingly important role in, the Manchester Literary and Philosophical Society, with an extended period as its President.
Dalton was a skilled experimenter and In the preface to the second part of Volume I of his New System, he says he had so often been misled by taking for granted the results of others that he determined to write "as little as possible but what I can attest by my own experience", to the extent that it appeared as a lack of openness to the ideas of others (such as Gay-Lussac's conclusions as to the combining volumes of gases).
He made contributions to a wide variety of subjects in science, most importantly the development of atomic theory, the concept of atomic weights and the gas laws. Other contributions included studies of colour blindness, rain and dew and the origin of springs; on heat, the color of the sky, steam, and the reflection and refraction of light.
In 1803, he was chosen to give a course of lectures on natural philosophy at the Royal Institution in London, and he delivered another course of lectures there in 1809–1810. However, some witnesses reported that he was deficient in the qualities that make an attractive lecturer, being harsh and indistinct in voice, ineffective in the treatment of his subject, and singularly wanting in the language and power of illustration. In 1810, Sir Humphry Davy asked him to offer himself as a candidate for the fellowship of the Royal Society, but Dalton declined, possibly for financial reasons. However, in 1822 he was proposed without his knowledge, and on election paid the usual fee. Six years previously he had been made a corresponding member of the French Académie des Sciences, and in 1830 he was elected as one of its eight foreign associates in place of Davy. In 1833, at age 67 Earl Grey's government conferred on him a pension of £150, raised in 1836 to £300. He was elected a Foreign Honorary Member of the American Academy of Arts and Sciences in 1834 at age 68.
Dalton suffered a minor stroke in 1837, and a second one in 1838 left him with a speech impairment, though he remained able to perform experiments. In May 1844 he had yet another stroke; on 26 July 1844 he recorded with trembling hand his last meteorological observation. On 27 July 1844, in Manchester, Dalton fell from his bed and was found lifeless by his attendant.
In England in 1700 there was still some controversy about the nature of the hydrological cycle. Oliver and Oliver (2003) note that Dalton set out to resolve this in his 1799 paper on the origin of springs presented to the Manchester Literary and Philosophical Society (published as Dalton, 1802a). He opened with an elegant introduction: ``It is scarcely possible to contemplate without admiration the beautiful system of nature by which the surface of the Earth is continually supplied with water and that unceasing circulation of a fluid so essentially necessary to the very being of the animal and vegetable kingdoms takes place. Naturalists, however, are not unanimous in their opinions whether the rain that falls is sufficient to supply the demands of springs and rivers, and to afford to the earth besides such a large portion for evaporation as is known to be raised daily. To ascertain this point is an object of importance to the science of agriculture, and to every concern in which the procuration and management of water makes a part, whether for domestic purposes or for the arts and manufactures’’.
He provides a map of the hydrological regions of England and Wales based on the drainage basins of the major catchments (reproduced in Duffy, 2017) and derives an estimate of the annual rainfall as 31in (787 mm), using the short and patchy datasets available at the time and correcting for missing areas, to which he added 5 in (127 mm) for dewfall. Annual evaporation, derived mainly from his own observations on soil-filled containers, was set at 30in (762 mm). Using a corrected version of Halley’s estimate for the flow of the Thames and multiplying this up to account for the other main river basins, he estimated the annual flow to the sea as 13in (330mm). These calculations give a discrepancy between input (36in (914 mm)) and output (43in (1092mm)) of 7in (178mm). Dalton suggested that this difference could be accounted for mainly from errors in the evaporation. He therefore concludes: ``Upon the whole then I think that we can finally conclude that the rain and dew of this country are equivalent to the quantity of water carried off by evaporation and by the rivers. And as nature acts upon general laws, we ought to infer it must be the case in every other country until the contrary is proved’’ (Dalton 1802a).
In the autumn of 1801 he presented three evenings of lectures on the properties of gases, published as four essays in the Society proceedings. In the first essay he describes his method of measuring the temperature dependence of ``the force of vapour from water’’, i.e. saturated vapour pressure. This was achieved by the introduction of water into a barometer column and noting the depression of the column for a range of temperatures. He publishes the resulting table of saturated vapour pressures for a wide temperature range. In his final essay he presents ``a true theory of evaporation’’ . He describes the results of evaporation experiments using containers of water under different temperatures and wind speeds. Explaining that account must be taken of ambient vapour pressure, he formulated his law of evaporation: ``The evaporating force must be universally equal to that of the temperature of the water, diminished by that already in the atmosphere’’ (Dalton 1802b). He provides a table giving the evaporation rates from water into dry air for a wide temperature range and for low, medium and high wind speeds.
While in Kendal, Dalton had worked at perfecting the construction of a barometer, and he realised that this could be used to measure the heights of mountains. He made use of the technique to measure the heights if peaks on annual visits to the Lake District. Dalton carried out many such measurements, the best of which relied on simultaneous pressure readings from two inter-calibrated and temperature-corrected barometers. It was while climbing Skiddaw with his barometer in July 1812 that he first came across the Lake District geologist and guide Jonathan Otley. Subsequently Otley frequently acted as companion and paid guide to Dalton on many of his climbs between 1812 and 1836.
The European Geophysical Union named one of its hydrological medals after John Dalton 
Oliver, H R and Oliver, S., Meteorologist’s profile – John Dalton, Weather June 58:206-211, 2003
Manley,G. (1944) JohnDalton:1766-1844.Q.J.R. Meteorol.Soc.,70,pp.235± 239
Dooge, J. C. I. (1974) The development of hydrological concepts in Britain and Ireland between 1674 and 1874. Hydrol. Sci. Bull., XIX, pp.279-302
Henry, W. C. (1854) Memoirs of the life and scientific researches of John Dalton. Cavendish Society, Harrison, London
Leitch, D. and Williamson, A. (1991) The Dalton tradition. John Rylands University Library of Manchester
Rodda, J. C. (1963) Eighteenth century evaporation experiments.Weather,18,pp.264-269
Smyth, A. L. (1997) John Dalton 1776-1844. Manchester Literary and Philosophical Publications Ltd
Duffy, C J (2017) The terrestrial hydrologic cycle: an historical sense of balance, WIREs Water 2017, e1216. doi: 10.1002/wat2.1216
Dalton, J. (1793) Meteorological observations and essays. Richardson, London and Pennington, Kendal
Dalton, J. (1802a) Experiments and observations to determine whether the quantity of rain and dew is equal to the quantity of water carried off by the rivers and raised by evaporation; with an enquiry into the origin of springs. Mem. Lit. Philos. Soc. Manchester,V,II,pp.346-372
Dalton, J. (1802b) Experimental essays on the constitution of mixed gases; on the force of steam or vapour from water and other liquids in different temperatures, both in a Torricellian vacuum and in air; on evaporation expansion of gases by heat. Mem. Lit. Philos. Soc. Manchester, V, II, pp.535-602
Dalton, J. (1819) Observations of the barometer, thermo- meter and rain at Manchester from 1794 to 1818 inclusive. Mem. Lit. Philos. Soc. Manchester, secondseries,III,pp.483-509
Dalton, J. (1824) Observations in meteorology, particularly in regard to the dew-point, or quantity of vapour in the atmosphere; made on the mountains in the north of England from 1803 to 1820. Mem. Lit. Philos. Soc. Manchester, second series, IV, pp.104-124
Dalton, J. (1831) Summary of the rain &c at Geneva and at the elevated station of the Pass of Great St. Bernard. Mem. Lit. Philos. Soc. Manchester, second series,V,pp.233-240
Dalton, J.(1842) Observations of the barometer, thermometer, & rain at Manchester from the year 1794 to 1840 inclusive being a summary of essays in meteorology. Mem. Lit. Philos. Soc. Manchester, secondseries,VI,pp.561-589