Page:Dictionary of National Biography volume 13.djvu/435

 of six born to Joseph and Deborah Dalton. While attending a quakers' school kept by Mr. John Fletcher at Pardshaw Hall, he entered, at the age of ten, the service of Mr. Elihu Robinson, a quaker gentleman of fortune and scientific attainments, whose notice was quickly attracted by Dalton's love of study. He gave him evening lessons in mathematics, and so effectually stimulated the boy's desire for self-improvement, that, on Fletcher's retirement in 1778, he was able to set up school on his own account. His first schoolroom was a barn at Eaglesfield, soon exchanged for the quakers' meeting-house. His pupils were boys and girls of all ages, from infants whom he held on his knee while he taught them their letters, to robust youths who met his reprimands with pugilistic challenges. The weekly pence gathered from them, to the total amount of about five shillings, were eked out with the sale of stationery; while his own education was pursued with a zeal exemplified by his copying out verbatim a number of the ‘Ladies' Diary’ which fell into his hands.

After two years the school was closed, and Dalton took to field work as a means of subsistence. In 1781, however, he joined his brother Jonathan as assistant in a school at Kendal, which they carried on independently on the retirement, in 1785, of the master and their cousin, George Bewley. Their sister Mary acted as housekeeper, and their parents visited them from time to time, bringing home-produce, and accomplishing the distance of forty-four miles from Eaglesfield on foot in one day. About sixty pupils of both sexes attended, including some boarders, and the profits reached one hundred guineas in the first year. But the popularity of the brothers did not increase. They were uncompromising in their discipline, and somewhat over stern in punishment, although John was the milder of the two, and was, besides, too much absorbed in private study to look out for delinquencies. His progress may be judged of from a syllabus of a course of lectures on natural philosophy issued by him 26 Oct. 1787, including mechanics, optics, pneumatics, astronomy, and the use of the globes. They were repeated in 1791, when the price of admittance was reduced from one shilling to sixpence.

Dalton probably read more in the twelve years he spent at Kendal than in the fifty of his remaining life. There was gathered the stock of knowledge which served as the basis of all his future researches. There also he acquired habits of close and meditative observation. His acquaintance with Gough, the blind philosopher described by Wordsworth in the ‘Excursion’—‘Methinks I see him how his eyeballs roll'd,’ &c.—was of material assistance to him. He acquired with Gough's help a little Latin, French, and Greek, mastered fluxions, and studied the chief works of English mathematicians. Between 1784 and 1794 he tried his powers by diligently answering questions in the ‘Gentleman's’ and ‘Ladies' Diaries,’ winning by his solutions two high prizes. From Gough, too, he learned to keep a meteorological journal. The first entry commemorated an aurora borealis, 24 March 1787, and during the ensuing fifty-seven years two hundred thousand observations were recorded in it. He made hygrometers of whipcord, and supplied his friend Mr. Peter Crosthwaite, whom he engaged to make simultaneous observations at Keswick, with a rude barometer and thermometer of his own construction. Zoology and botany came in for a share of his attention. He furnished specimens of butterflies and dried plants to Mr. Crosthwaite's museum; compiled a ‘Hortus Siccus’ in eleven volumes, possessed a few years ago by Mr. T. P. Heywood of the Isle of Man; while his ‘Herbarium’ is still preserved in the Manchester Public Library.

Discouraged by his friends' advice from taking a learned profession, he accepted in 1793 a professorship of mathematics and natural philosophy in New College, Manchester, offered to him on Gough's recommendation. The proofs of his first book accompanied him on his removal from Kendal. The ‘Meteorological Observations and Essays’ (London, 1793) contained, as the author remarked forty years later, the germs of most of the ideas afterwards expanded by him into discoveries. A prominent section comprised the results of six years' auroral observations. He had detected independently the magnetic relations of the phenomenon, and concluded thence auroral light to be of purely electrical origin, and auroral arches and streamers to be composed of an elastic fluid of a ferruginous nature existing above our atmosphere. This hypothesis was further developed by Biot in 1820. From simultaneous observations at Kendal and Keswick Dalton derived for the aurora of 15 Feb. 1793 a height of a hundred and fifty miles; and recurring to the subject in later life, he calculated that the display of 29 March 1826 occurred a hundred miles above the earth's surface (Phil. Trans. cxviii. 302).

The essay in the same volume on evaporation was remarkable for the then novel assertion that aqueous vapour exists in the air as an independent elastic fluid, not chemically combined, but mechanically mixed with the