# Dictionary of National Biography, 1885-1900/Daniell, John Frederic

​DANIELL, JOHN FREDERIC (1790–1845), physicist, was born in Essex Street, Strand, on 12 March 1790, his father being a bencher of the Inner Temple. Early showing a bias towards science, he was placed in the sugar-refining establishment of a relative, and introduced important improvements in the manufacture. He did not long continue connected with business, which was distasteful to him. At the age of twenty-three he was elected fellow of the Royal Society, and soon commenced his valuable publications on meteorology. In 1820, by the invention of the hygrometer which bears his name, Daniell first gave precision to the means of ascertaining the moisture of the atmosphere. In 1823 he published his ‘Meteorological Essays,’ being the first attempt to collect scattered facts on the subject, and to explain the main phenomena of the atmosphere by physical laws. He insisted on the paramount importance of extreme accuracy in meteorological observations, and himself kept a model record of atmospheric changes. He organised the plan adopted by the Horticultural Society for their annual meteorological reports, which plan became the model from which the Greenwich meteorological reports were developed. In 1824 he communicated to the Horticultural Society an essay on ‘Climate, considered with reference to Horticulture,’ which was published in the society's ‘Transactions,’ vol. vi. In this paper Daniell called attention to the necessity of attending to the moisture of hothouses, and caused a revolution in hothouse management. A silver medal was awarded to the author by the society. In 1830 Daniell constructed a water-barometer for the Royal Society, after great practical difficulties had been overcome; it is described in ‘Phil. Trans.,’ 1832, pp. 538–574. In 1830 he described in the ‘Philosophical Transactions’ a new pyrometer for measuring great degrees of heat, which won him the Rumford medal.
On the establishment of King's College, London, in 1831, Daniell was appointed professor of chemistry, and became a very successful teacher. Besides making many original contributions to chemistry, he worked zealously at electricity, and invented the constant battery, universally known by his name, for which the Royal Society awarded the Copley medal in 1836. Papers on voltaic combinations and on electrolysis won him the Royal Society's royal medal in 1842. He was foreign secretary of the society 1839–45.
On several occasions Daniell rendered important aid to the government. He drew up the meteorological portion of the directions for scientific observations to be made by government officers, published in 1840. In 1839 he was a member of the admiralty commission on the best mode of protecting ships from lightning. Later, he investigated for the admiralty the causes of the rapid corrosion of ships’ sheathing on the African station. In 1839 also he published his ‘Introduction to Chemical Philosophy,’ the most original book on the subject published at that period. In 1842 he received the honorary D.C.L. of Oxford.
Daniell's death was very sudden. On 13 March 1845, after lecturing at King's College, apparently in perfect health, he attended a council meeting of the Royal Society, of which he was foreign secretary, and shortly after speaking on business was seized with symptoms of apoplexy, and in five minutes was dead. His death was a great shock to the scientific world, and cut short a brilliant career from which much more was expected. His scientific attainments were associated with a lofty moral and religious character. By his wife, who died eleven years before him, Daniell left two sons and five daughters. Daniell's ‘Meteorological Essays’ reached a third edition in 1845, his ‘Introduction to Chemical Philosophy’ a second edition in 1843. He wrote a little book on chemistry for the Useful Knowledge Society in 1829. Most of his writings, however, were published in scientific journals and transactions, especially in the ‘Quarterly Journal of Science;’ a list will be found in the Royal Society's ‘Catalogue of Scientific Papers,’ vol. ii.
[Proceedings of Royal Society, v. 577–80.]
G. T. B.