"Green Teddington's serene retreat
For philosophy studies meet
Where the good pastor Stephen Hales
Weighed moisture in a pair of scales"


Stephen Hales

Just inside the bell tower of the church of St Mary with St Alban in Teddington is a small plaque commemorating Revd. Stephen Hales DD FRS “Minister of this parish fifty one years”. It is a modest memorial for a modest man who was a dedicated cleric, a social reformer, a philanthropist and one of the greatest scientists of his time.

Memorial inside bell tower

Stephen Hales was born on the 17th September 1677 in Kent. After an education with private tutors he went to Corpus Christi College Cambridge where in 1702 he became a Fellow. In 1709 Hales was ordained and offered the “Perpetual Curacy” of Teddington, a ministry he was to hold for 51 years.

In 1717 he was elected Fellow of the Royal Society, for a series of important experiments he made on the circulation of the blood. So significant were these that nearly 240 years later they were referred to by the physician Werner Forssman when he accepted the 1956 Nobel Prize in Medicine.

Pneumatic Trough

“The credit for carrying out the first catheterization of the heart of a living animal for a definite experimental purpose is due to an English parson, the Reverend Stephen Hales. This scientifically interested layman undertook in Tordington (sic) in 1710, 53 years after the death of William Harvey (1578-1657), the first precise definition of the capacity of a heart.”

Stephen Hales is perhaps best known for his ‘Statical Essays’. The first volume ‘Vegetable Staticks’ published in 1727, was a record of a great number of experiments – measuring transpiration in plants and root-pressure, the force of upward sap pressure in stems and the rate of growth of shoots and leaves. Realising that “plants draw through their leaves some part of their nourishment from the air”, he was able to show “how great a proportion air is wrought into the composition of animal, vegetable and mineral substances.” For this part of his work Hales invented the ‘Pneumatic Trough’ to collect gases. It is now a standard piece of kit in most laboratories.

Vegetables statics

The second volume appeared in 1733 under the title “Haemastaticks”. This was an account of experiments looking at the arterial systems of animals. Hales noted how blood pressure changed with the contractions and dilations of the heart and its effect on arteries and veins. To do this in 1727 he developed a device to measure arterial blood pressure.

Reading about Hales and his work one gets the sense that he was driven by an unstoppable curiosity, a willingness to invent and experiment and the desire to make life better. In 1734 he published anonymously “Admonition to the Drinkers of Gin, Brandy, etc.” warning of the perils of excessive alcohol consumption. In 1739 Hales received the Royal Society’s Copley Medal for his investigations into kidney and bladder stones. Having failed to develop a medicine that would dissolve the stones he invented a set of forceps that according to John Ranby, sergeant-surgeon to George II, extracted stones with “great ease and readiness.”

Hales also developed a new type of ventilator using a modified organs bellow. When the ventilator was installed in prisons, hospitals and ships it helped reduce mortality. In between all this Reverend Hales also found time to devise a ‘sea gauge’ for measuring depths of oceans, developed improved methods for preserving food and suggested to cooks that an inverted teacup placed in a pie dish would prevent the crust from becoming soggy. Stephen Hales was also active within the Society for the Promotion of Christian Knowledge and a committed opponent of slavery. In 1751 he was appointed Clerk of the Close, or Chaplain to Augusta, the Princess of Wales.

Meanwhile, back home at Teddington, Hale supervised the construction of a system of ditches that brought a new water supply to the village from a series of springs. He also was closely involved with repairs to the church tower under which he was buried after his death in 1761at the age of 84. Charles Wesley described him as “a truly pious, humble Christian.” Perhaps someone should have added, “and a hard worker too!”

Memorial in Teddington

Although Stephen Hales achievements are only modestly recorded at Teddington – which is probably how he wanted them to be – there is a grander monument to him in Westminster Abbey, raised to his memory by Princess Augusta, the mother of King George 3rd. The inscription says…

“At the tomb of Hales… do Piety, venerable Faith, and mighty Virtue – a sacred company – shed perpetual tears. Above the dead, divine Wisdom proclaims a prophet. Well versed was he in ministering to the ills of mankind, in exploring the works of the Lord: the passing of ages shall not diminish your praise and renown, O Hales. It is England’s boast to number you among her distinguished sons, alongside her dear Newton: O proud land of England”.

“The farthest researches we make into this admirable scene of things, the more beauty and harmony we see in them.”

REVD STEPHEN HALES DD FRS “Vegetable Staticks” 1727

— from Martyn Day

Credit: Photographs of Hales Memorial in Teddington by Amanda Day