Stephen Hales

Born in Kent in 1677, Stephen Hales was an English priest who became one of the most original experimental scientists of the 18th century. He studied at Corpus Christi College, Cambridge, was ordained in 1703, and spent much of his life as the curate of Teddington. In 1718 he was elected a Fellow of the Royal Society, a sign of how highly his scientific work was valued.

Hales is best known for bringing careful measurement into biology. In Vegetable Staticks and later Haemastaticks, he investigated how water moves through plants and how blood circulates in animals, helping lay foundations for plant physiology and cardiovascular science. He is often remembered as the first person to measure blood pressure directly.

He also cared deeply about practical public health. Hales designed ventilators for places such as ships, prisons, and hospitals, hoping to reduce the dangers of foul air. That mix of curiosity, precision, and usefulness makes him an especially appealing figure: a parish priest whose experiments changed the way living things were studied.