Stephen Hales (1677-1761), English chemist, physiologist and clergyman. His book Vegetable Staticks (1727) describes 124 experiments on gases, which he made in several ways and collected using a pneumatic trough. He measured growth rates in plants, and showed that light is needed, and that water loss (by transpiration) is through the leaves and that this causes an upward flow of sap. Later he experimented on blood pressure in animals and investigated the vascular system in general. Other studies involved the preservation of foods, water purification, the ventilation of buildings and ships, and also the best way to support pie crusts.