Hales, Stephen

Hales, Stephen

▪ English scientist
born Sept. 7/17, 1677, Bekesbourne, Kent, Eng.
died Jan. 4, 1761, Teddington, near London
 English botanist (botany), physiologist, and clergyman who pioneered quantitative experimentation in plant and animal physiology.

      While a divinity student at Corpus Christi College, Cambridge, he studied science, particularly botany and chemistry. Ordained in 1703, he was appointed in 1709 to the parish of Teddington, where he remained until his death.

      Hales introduced new techniques of measurement to the study of plant physiology. One of the best-known of these concerned the measurement of water vapour emitted by plants. He measured this emission, known as transpiration, finding that it was the leaves that transpired and that this process encouraged a continuous upward flow of water and dissolved nutrients from the roots. He determined the direction in which sap flows in plants (it flows upward), and he measured the sap's pressure. He also measured the rates of growth of shoots and leaves and the pressure roots exert on sap, and he investigated plant respiration.

 Hales devised several apparatuses which he used to collect the gases that were produced by various chemical reactions; these instruments were forerunners of the pneumatic trough, now used for the same purpose. His research in plant physiology was published in Vegetable Staticks (1727) and reappeared in 1733 as volume 1 of his Statical Essays. Volume 2, Hæmastaticks, was the most important contribution to the physiology of blood circulation since that of William Harvey. Hales was the first to quantitatively measure blood pressure, which he did by inserting a tube into a blood vessel and allowing the blood to rise up the tube. In addition, he measured the capacity of the left ventricle of the heart, the output of the heart per minute, and the speed and resistance to flow of blood in the vessels. As an inventor, he developed an artificial ventilator (a modified organ bellows) that could convey fresh air into prisons, ships' holds, and granaries.

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Universalium. 2010.

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  • Hales , Stephen — (1677–1761) English plant physiologist and chemist Born at Bekesbourne in Kent, Hales entered Cambridge University in 1696 to study theology. He was ordained in 1703 and appointed curate at Teddington, near London, in 1708 (or 1709). During his… …   Scientists

  • Hales, Stephen — ► (1677 1761) Físico y naturalista británico. Halló el hidrógeno sulfurado y el ácido carbónico …   Enciclopedia Universal

  • HALES, STEPHEN —    scientist, born at Beckesbourn, Kent; became a Fellow of Cambridge in 1702; took holy orders, and in 1710 settled down in the curacy of Teddington, Middlesex; science was his ruling passion, and his Vegetable Staticks is the first work to… …   The Nuttall Encyclopaedia

  • Hales — Hales, Stephen …   Enciclopedia Universal

  • Stephen Hales — (* 17. September oder 7. September 1677 bei Beckesbourn, Kent; † 4. Januar 1761 in Teddington, Middlesex) war ein englischer Physiologe und Physiker …   Deutsch Wikipedia

  • Stephen Hales — (1677–1761) Nacimiento 1677 Bekesbourne, Kent Fallecimiento …   Wikipedia Español

  • Stephen Hales — (17 septembre 1677 à Bekesbourne dans le Kent 4 janvier 1761 à Teddington dans le Middlesex) est un physiologiste, chimiste et inventeur britannique …   Wikipédia en Français

  • Hales (surname) — Hales is a surname, and may refer to* Derek Hales * E. E. Y. Hales, English historian * John Hales, English theologian * John Hales (d.1571) * Randy Hales * Robert Hales * Robert Hales (director) * Robert D. Hales * R. Stanton Hales * Stephen… …   Wikipedia

  • HALES (S.) — HALES STEPHEN (1677 1761) Physiologiste, chimiste et inventeur anglais, né à Bekesbourne, dans le comté de Kent. Après des études au collège Corpus Christi à Cambridge, Stephen Hales devient pasteur et, en 1709, il obtient la charge perpétuelle… …   Encyclopédie Universelle

  • Hales — (Stephen) (1677 1761) naturaliste et physicien anglais. Il mesura, le premier, la pression sanguine (sur des chevaux) et les forces qui font monter la sève dans les plantes …   Encyclopédie Universelle

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