# Young, John Radford (DNB00)

**YOUNG**, JOHN RADFORD (1799–1885), mathematician, ‘born of humble parents’ in London in April 1799, was almost entirely self-educated. At an early age he became acquainted with Olinthus Gilbert Gregory [q. v.], who perceived his mathematical ability, and assisted him in his studies. In 1823, while holding a post at a private establishment for the deaf and dumb in Walworth Road, he published ‘An Elementary Treatise on Algebra’ (London, 8vo), with a dedication to Gregory. An American edition appeared at Philadelphia in 1832, and a second English edition in 1834. This treatise was followed by a series of elementary works, in which, following in the steps of Robert Woodhouse [q. v.], Young rendered important service to English mathematical study by familiarising students with continental methods of analysis. In 1833 he was appointed professor of mathematics at Belfast College. In 1849, on the opening of Queen's College, the presbyterian party which controlled the professorial nominations prevented Young's reappointment as professor in the new establishment. From that time he devoted himself more completely to the study of mathematical analysis, and made several original discoveries. In 1847 he published in the ‘Transactions of the Cambridge Philosophical Society’ a paper ‘On the Principle of Continuity in reference to certain Results of Analysis,’ and in 1848 in the ‘Transactions of the Royal Irish Academy’ a paper ‘On an Extension of a Theorem of Euler.’ As early as 1844 he had discovered and published a proof of Newton's rule for determining the number of imaginary roots in an equation. In 1866 he completed his proof, publishing in ‘The Philosophical Magazine’ a demonstration of a principle which in his earlier paper he had assumed as axiomatic. In 1868 he contributed to the ‘Proceedings of the Royal Irish Academy’ a memoir ‘On the Imaginary Roots of Numerical Equations.’ Young died at Peckham on 5 March 1885. He was married and left issue.

Besides the works already mentioned Young's principal publications were: 1. ‘Elements of Geometry,’ London, 1827, 12mo. 2. ‘Elements of Analytical Geometry,’ London, 1830, 12mo. 3. ‘An Elementary Essay on the Computation of Logarithms,’ London, 1830, 12mo. 4. ‘The Elements of the Differential Calculus,’ London, 1831, 12mo. 5. ‘The Elements of the Integral Calculus,’ London, 1831, 12mo. 6. ‘The Elements of Mechanics, comprehending Statics and Dynamics,’ London, 1832, 12mo. 7. ‘Elements of Plane and Spherical Trigonometry,’ London, 1833, 12mo, with ‘Some Original Researches in Spherical Geometry,’ by Thomas Stephens Davies [q. v.], appended. 8. ‘On the Theory and Solution of Algebraical Equations,’ London, 1835, 12mo; 2nd edit. London, 1843, 8vo. 9. ‘Mathematical Dissertations for the Use of Students in the Modern Analysis,’ London, 1841, 8vo. 10. ‘On the General Principles of Analysis. … Part I.: The Analysis of Numerical Equations,’ London, 1850, 8vo. No more parts appeared. 11. ‘An Introductory Treatise on Mensuration,’ Belfast, 1850, 12mo. 12. ‘An Introduction to Algebra and to the Solution of Numerical Equations,’ London, 1851, 12mo. 13. ‘Rudimentary Treatise on Arithmetic,’ London, 1858, 8vo; 10th edit. 1882. 14. ‘A Compendious Course of Mathematics,’ London, 1855, 8vo. 15. ‘The Theory and Practice of Navigation and Nautical Astronomy,’ London, 1856, 8vo; new edit. 1882. 16. ‘The Mosaic Cosmogony not “adverse to Modern Science,”’ London, 1861, 8vo. 17. ‘Science elucidative of Scripture and not antagonistic to it,’ London, 1863, 8vo. 18. ‘Modern Scepticism viewed in relation to Modern Science,’ London, 1865, 8vo.

[Young's works; Times, 23 March 1885; Men of the Time, 1884.]