Stephen Hales was an English clergyman who made major contributions to a range of scientific fields including botany, pneumatic chemistry and physiology. He was the first person to measure blood pressure. He also invented several devices, including a ventilator, a pneumatic trough and a surgical forceps for the removal of bladder stones. In addition to these achievements, he was a philanthropist and wrote a popular tract on alcoholic intemperance.
Stephen Hales, aged 82, by J. McArdell after T. Hudson
St Marys Church, Teddington
Monument for Stephen Hales at St Mary's church, Teddington
From Vegetable Staticks, opposite page 262
In the history of science, pneumatic chemistry is an area of scientific research of the seventeenth, eighteenth, and early nineteenth centuries. Important goals of this work were the understanding of the physical properties of gases and how they relate to chemical reactions and, ultimately, the composition of matter. The rise of phlogiston theory, and its replacement by a new theory after the discovery of oxygen as a gaseous component of the Earth atmosphere and a chemical reagent participating in the combustion reactions, were addressed in the era of pneumatic chemistry.
Robert Boyle's air pump
The pneumatic trough, invented by Stephen Hales in the 1700s. This was the initial model, used for the collection of airs (gases) produced by combustion.