John Allen (1771-1843), political and historical writer, was born at Redford near Edinburgh, and after an apprenticeship with an Edinburgh surgeon he studied medicine at the University. To supplement his income he lectured on medical subjects, and he published a translation of the introduction to Georges Cuvier's Leçons d'anatomie comparée, under the title Introduction to the Study of the Animal Economy (Edinburgh: printed for Ross and Blackwood, 1801).
In 1801-5 Allen accompanied Lord Holland on an extended tour abroad, and he continued to enjoy Holland's patronage for several years afterwards. He wrote extensively for the Edinburgh Review, but is best known for an Inquiry into the Rise and Growth of the Royal Prerogative in England (1830). He served as warden of Dulwich College from 1811 to 1820, and was master from 1820 until his death in 1843.
Source: W.P. Courtney, 'Allen, John (1771-1843)', rev. H.C.G. Matthew, Oxford Dictionary of National Biography (Oxford: Oxford University Press, 2004); online edn, Jan 2008.
William Henry (1774-1836), chemist, was the son of Thomas Henry, an apothecary and chemist in Manchester. He studied medicine and chemistry at Edinburgh University, and took his MD in 1807 with a dissertation on uric acid. He spent much of his career engaged in chemical work; in 1801 he published his Epitome of Chemistry, based upon a series of lectures delivered in 1798-99; in 1803 he communicated to the Royal Society his work on the absorption of gases by water; and in 1804 he stated Henry's law: 'at a given temperature water dissolves the same volume of a compressed gas as of that gas under normal pressure'. He was awarded the Copley Medal by the Royal Society in 1808, he was elected FRS the following year. He also undertook research on coal gas and several other kinds of illuminating gas: work of significant commercial and social value. Henry was a member of the Manchester Literary and Philosophical Society and played a leading role in the intellectual life of the city during a period of rapid growth and industrialization.
William Henry was a physician at Manchester Royal Infirmary from 1808 to 1817. Although he was always more interested in chemistry, he undertook researches into combating contagious diseases. At the height of the cholera epidemics of the 1830s he experimented on the heating of infected clothing. He shot himself in 1836 and was buried at Cross Street Unitarian Chapel, Manchester.
Source: Frank Greenaway, 'Henry, William (1774-1836)', Oxford Dictionary of National Biography (Oxford: Oxford University Press, 2004); online edn, Oct 2007.