Professionally, Stephen Hales was a clergyman, serving as "perpetual curate" of Teddington, Middlesex, England, from 1709 until his death in 1761. Avocationally, Hales was a leading scientist of his time--the founder of plant physiology, a trailblazer in the study of blood circulation and blood pressure measurement, a pioneer in public health.

Hales was born in Bekesbourne of an old Kentish family. Little is known about him until he began studies at Cambridge in 1696. At the university, Hales enthusiastically immersed himself in scientific studies and biological experiments while also pursuing his clerical degree. He received his bachelor of arts degree in 1702 and his master 's degree in 1703; he was ordained a deacon in 1703 and in 1709 he went to the "perpetual" post in Teddington.

During his early years at Teddington, Hales continued experiments which he had begun at Cambridge, achieving the first blood pressure measurements with a glass-tube manometer. He also investigated...