Although Stephen Hales (1677–1761) was a priest of the Church of England for his entire life, he made great strides in the understanding of plant and animal biology when he wasn’t performing his official church duties.
Hales never had any official medical or scientific training, but his common-sense research contributed greatly to what is known about plants, animals, and gases. In fact, his observations and experiments eventually gave way to the discovery of oxygen and other gases.
Hales was born in Bekesbourne, Kent, England in 1677 as the sixth son to Thomas and Mary Hales. He received an education from Kensington and Orpington before choosing to go to Corpus Christi College, Cambridge.
At Cambridge, Hales studied divinity and also explored mathematics, philosophy, and the natural sciences, including botany and biology. He became interested in the work of Isaac Newton, as Newton had left the school in the same year that Hales arrived.
During his college years, Hales befriended fellow scientist William Stukeley, who helped him with various experiments in animal physiology.
During his college years, Hales’s reputation grew as people learned of his research. In 1703, Hales earned both his bachelor’s and master’s degree at Cambridge and was ordained the same year. In 1709, he was appointed to the parish of Teddington, where he would remain for the rest of his life.
Scientific Inventions
“His whole mind seemed replete with experiment which of course gave a tincture and turn to his conversation often somewhat peculiar, but always interesting,” naturalist Gilbert White once said of Hales, according to an article published in “A Journal of Medical Humanities.”While experimenting with animals nearing the end of life, Hales learned extensively about how animals and the human body works. In 1718, he was elected a fellow of the Royal Society, Great Britain’s national academy of the sciences, even before most of his works were published in the 1720s and 1730s.
Hales was the first to measure blood pressure and to determine how fast blood flows through an animal. He also discovered that electric impulses flow through an animal’s body via the nervous system.
What Hales learned about animals he then applied to plants. Hales discovered that water and sap move upward through plants, and that they, too, exchange gases.
With one discovery leading to another experiment, Hales moved his attention to gases. He made an artificial diaphragm, and in using it, learned that humans cannot survive by breathing in the same air we breathe out. Using this principle, he was then able to devise a system to filter air, which he coined the “ventilator.”
Throughout his successful scientific career, Hales stayed true to his faith and focused on giving back and donating to charity. His invention of the ventilator was eventually used to clean air. It was installed in ships, prisons, and hospitals to help fight airborne diseases, long before the discovery of germs. He also conducted experiments to come up with ways to distill salt water and make it drinkable.
Hales continued his work as a priest in Teddington until he passed away in 1761 after a short illness.
Throughout his life, Hales’s quest to give spiritual support to those in his care also guided him to learn more about the natural world. His contributions to the scientific world ensured that his his commitment to helping mankind continued even after his death.
