GEYLS Stephen (Hales Stephen)

(1677-1761)
Born Sept. 7, 1677 in Beksborne (Kent). In 1696 went to Cambridge University, where he studied theology and natural sciences. In 1703 was ordained, in 1709 became vicar in Teddington (Middlesex). Investigating the evaporation of water by plants (transpiration), showed that the main role in this process belongs to the leaves; calculated the rate of evaporation, using 'hemostatic method', to determine the pressure of plant sap moving from roots to stem. Measured the rate of growth of shoots and leaves of plants in different conditions. Studying the breath of plants, showed that they absorb carbon dioxide from the air. Geylz first measured blood pressure in animals. For this he put in a blood vessel of a glass tube and determined at what altitude the blood rises. The first measured the cardiac output, blood velocity and resistance, which she feels when moving through the vessels.
In 1718 Geyls was elected a member of the Royal Society of London and presented it to the attention of his first article on the influence of solar heat on the rise of vegetable juice in the trees. In 1727 his book Static Plant (Vegetable Staticks), and in 1733 - Gemostatika (Haemastaticks), which were summarized his experiments on animals. In the same year Geyls was awarded the Copley medal, but not for research on the physiology of plants and animals, and for his work on the well-known at the time of 'magical' means Mrs. Stephens for the treatment of urolithiasis.

Geyls constructed several devices for the collection of gases evolved in the course of chemical reactions, has invented an artificial ventilator to supply fresh air to the premises. He wrote pamphlets about the dangers of alcohol. Died Geyls in Teddington near London on Jan. 4, 1761.