Stephen Hales

Stephen Hales

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Stephen Hales, FRS (17 September 1677 – 4 January 1761) was an English
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 physiologist, chemist
A chemist is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties such as density and acidity. Chemists carefully describe the properties they study in terms of quantities, with detail on the level of molecules and their component atoms...

 and inventor.

Hales studied the role of air and water in the maintenance of both plant and animal life. He gave accurate accounts of the movements of water in plants, and demonstrated that plants absorb air. Hales discovered the dangers of breathing stale air, and invented a ventilator which improved survival rates when employed on ships, in hospitals and in prisons.

Hales is also credited with important work in pneumatic chemistry
Pneumatic chemistry
Pneumatic chemistry is a term most-closely identified with an area of scientific research of the seventeenth, eighteenth, and early nineteenth centuries. Important goals of this work were an understanding of the physical properties of gases and how they relate to chemical reactions and,...

, especially the development of the pneumatic trough
Pneumatic trough
A pneumatic trough is a piece of laboratory apparatus used for collecting gases, such as hydrogen, oxygen, and nitrogen. Pneumatic troughs require a liquid such as water. Scientists also have used mercury in pneumatic troughs, but usually only for the collection of water-soluble gases...

, used for collecting gases generated in laboratory experiments.

Hales most important invention was the surgical forceps.


Hales is best known for his Statical Essays. The first volume, Vegetable Staticks (1727), contains an account of numerous experiments in plant physiology
Plant physiology
Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants. Closely related fields include plant morphology , plant ecology , phytochemistry , cell biology, and molecular biology.Fundamental processes such as photosynthesis, respiration, plant nutrition,...

 — the loss of water in plants by evaporation
Evaporation is a type of vaporization of a liquid that occurs only on the surface of a liquid. The other type of vaporization is boiling, which, instead, occurs on the entire mass of the liquid....

, the rate of growth of shoots and leaves, and variations in root force at different times of the day. The second volume (1733) on Haemastaticks, containing experiments on the "force of the blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

" in various animals, its rate of flow, and the capacity of the different vessels.

Stephen Hales died on 4 January 1761 in Teddington at the age of 83. He was buried under the tower of the church where he had worked many years.


From the Nobel Prize in Medicine acceptance speech given by Werner Forssmann
Werner Forssmann
Werner Theodor Otto Forßmann, was a physician from Germany who shared the 1956 Nobel Prize in Medicine for developing a procedure that allowed for cardiac catheterization. In 1929, he put himself under local anesthetic and inserted a catheter into his own arm...

 in 1956:
The genus of trees Halesia
Halesia , also known as is a small genus of four or five species of deciduous large shrubs or small trees in the family Styracaceae, native to eastern Asia and eastern North America...

is named after him.

Further reading

  • Hales, Stephen (1727) Vegetable Staticks, London: W. and J. Innys — from the Missouri Botanical Garden's library
  • Hales, Stephen (1738). "Philosophical experiments: containing useful, and necessary instructions for such as undertake long voyages at sea. Shewing how sea-water may be made fresh and wholsome: and how fresh water may be preserv'd sweet. How biscuit, corn, &c. may be secured from the weevel, meggots, and other insects. And flesh preserv'd in hot climates, by salting animals whole. To which is added, an account of several experiments and observations on chalybeate or steel-waters ... which were read before the Royal-society, at several of their meetings", London: W. Innys and R. Manby
  • Parascandola, John and Ihde, Aaron J. (1969). "History of the Pneumatic Trough", Isis, vol. 60, no. 3, pages 351–361
  • Stephen Hales at the Galileo Project — details on Hales's life and work

  • For a calendar of manuscript correspondence and writing of Stephen Hales see: D.G.C. Allan and R.E. Schofield, Stephen Hales. Scientist and philanthropist (London: Scolar Press, 1980), p. 178, and for his published writing see ibid p. 191
  • For Hales’s work as parish priest of Teddington see: David G.C. Allan, Science, Philanthropy and Religion in 18th century Teddington: Stephen Hales DD, FRS, (1677–1761) (Twickenham: Borough of Twickenham Local History Society, 2004). This work contains reconstructions of the enlargement of St Mary’s Church, Hale’s copyhold parsonage house and a map of his drainage scheme (Map by Ken Howe).
  • For a general assessment see: David G.C. Allan, Hales, Stephen (1677–1761) in Oxford Dictionary of National Biography.
  • For the 2009 celebration of his life and work see The William Shipley
    William Shipley
    William Shipley was an English drawing master, social reformer and inventor who, in 1754, founded an arts society in London that became The Royal Society of Arts, or Royal Society for the encouragement of Arts, Manufactures & Commerce, .-Early years, training and career:Shipley was born in...

     Group for RSA History Newsletter no. 22 (Nov 2009)
  • For Hales’s association with the Society of Arts see David G.C. Allan, ‘Founder of the Society of Arts’ group article in Oxford Dictionary of National Biography (online supplement, 2008)

External links