[48] Hales made use of a rough pneumatic trough, the invention of which is usually ascribed to Priestley (Thorpe's History of Chemistry, i. p. 79).
[49] He speaks here merely of the apples used in a certain experiment, but it is clear that he applies the conclusion to other plants.
[50] Vegetable Staticks, p. 313. It should be noted that Hales speaks of organic as well as inorganic substances.
[51] Proc. R. Soc. lxxii., p. 30, 1903.
[52] The above account of Hales' connexion with the Royal Gardens at Kew is from the Kew Bulletin, 1891, p. 289.
[53] I am indebted to Sir E. Thorpe for a definition of statical. "Statical (Med.) noting the physical phenomena presented by organised bodies in contradiction to the organic or vital." (Worcester's Dictionary, 1889.)
[54] Arbeiten, I.
[55] Borelli, De Motu Animalium, Pt ii. Ch. xiii. According to Sachs, Ges. d. Botanik, p. 582, Mariotte (1679) had suggested the same idea.
[56] Nägeli, Stärkekorner, p. 279
[57] See his Philosophical Experiments, 1739.