There is a lot of advancement in the field of science and technology today because of which we are able to enjoy a lot of comforts and fulfill our needs We should be grateful to all those scientists who have worked for several years to give us all this. StephenHales was one such great scientist. He was the first person to measure blood pressure quantitatively. He invented many devices like ventilator, pneumatic trough and surgical scissors for the removal of gall bladder stones.  Can u believe that he was a clergyman and not a scientist by profession?? His interest in science made him create wonders. So let’s pay a tribute to such great person on his birthday by acknowledging his contributions.


Stephen Hales was an English clergyman born in a Kentish family in Bekesbourne, England. He was born on 17th September 1677. He was the sixth son of Thomas Hales. He made great contributions in various scientific fields that include Botany, Physiology and pneumatic chemistry. Hales went to Corpus Christi College, Cambridge in the year 1697 and pursed theology (Systemic and rational study of concept of gods). He took a degree in arts in 1703 and in the same year he was admitted as a fellow of Corpus Christi. Although Hales was studying about divinity, he was interested in astronomy, physics, chemistry as well as biology. While he continued his theological studies at Cambridge he became friends with William Stukeley, who was studying medicine. Hales attended chemistry lectures by Giovanni Francisco Vigani while he was at Cambridge.

Hales was ordained priest at Fulham in the year 1709. He left Cambridge as he was appointed as perpetual curate of a parish in Teddington. He took his bachelor degree in divinity in the year 1711. He earned his doctorate from Cambridge in the year 1733. He spent rest of his life in Teddington where he carried out most of his scientific work.

Works of Stephen Hales

Hales began his study on blood pressure in the year 1711; he measured the blood pressure of three horses and produced his first recorded estimates. Later, he performed a study on the pulse rate of various animals and then measured the capacity of the heart to pump blood through pulmonary veins. Hales also did a study on the effect of various drugs, heat and cold on the blood vessels.

Although some research on plants was carried out by Jan van Helmont and Marcello Malpighi, Hales completely deserved the title of Father of Plant Physiology since his work was unique. He became a member of Royal Society in the year 1718. He read a paper titled “Upon the Effect of ye Sun’s warmth in raising ye Sap in trees” after which he worked on velocity, sap pressure and circulation in plants. Pneumatic trough that is used in laboratory for collecting gases like nitrogen, hydrogen and oxygen was invented by Hales. He also developed various techniques for measuring sap pressure. Hales published his work in Vegetable Staticks in the year 1727. In the year 1733 his work was reissued into two volumes. Volume I was his statistical essays and volume II was haemastatics, a summary of his work on blood circulation. He received Copley Prize for his work in the year 1739.

During 18th century bad air was the major cause of ill-health and death. More number of deaths and diseases were seen in overcrowded ships and prisons. Hales developed ventilator to improve the quality of air. These ventilators were widely used in prisons, ships and mines to reduce the diseases. Hales also worked on ways to distill pure water from salt water and he was successful.

Hales was a philanthropist as well. After the death of his wife he became more involved in philanthropic causes. He also wrote a popular tract on alcoholic intemperance. Hales died on 4th January 1761 after a short illness. He was 84 when he passed away.


  • Hales’ fame as a scientist grew from 1718 onwards, and by the mid part of the h century he had achieved an international reputation.

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