HALES. 



her of the Royal Society, and in the fol- 

 lowing year he read before that body an 

 account of some experiments concerning 

 the effect of the sun's heat in raising the 

 sap in vegetables. The farther prose- 

 cution of these experiments gave rise to 

 an excellent work, published in 1727, en- 

 titled " Vegetable Statics, or an account 

 of some Statical experiments on the Sap 

 of Vegetables; being an Essay towards a 

 Natural History of Vegetation : also, a 

 Specimen of an attempt to Analyse the 

 Air by a variety of Chemico-Statical Ex- 

 periments, which were read at several 

 meetings before the Royal Society," 8vo. 

 This piece is justly esteemed a model of 

 experimental investigation. Haller cha- 

 racterizes it as " liber eximus, cusus pau- 

 cissimos habemus semulos qui toties potius 

 legi volet, quam decerpi." It begins by 

 ascertaining the vast quantity of watery 

 humour perspired by plants, sometimes 

 equalling their whole weight in a single 

 day. It then specifies the power with 

 which they attract the nutricious juice 

 through their capillary tubes, and consi- 

 ders the lateral motion of this juice from 

 trunk to branches, and vice versa. It dis- 

 proves any proper circulation of this fluid, 

 but establishes its ascent during the day, 

 and descent during the night. The leaves 

 are proved to be inspiratory organs, both 

 of air and water. There are besides a 

 number of curious remarks upon the ve- 

 getable system, as well as upon the con- 

 stitution of atmospherical air, into which 

 he was one of the experimental enquir- 

 ers. His experiments upon air relate in- 

 deed solely to its generation and absorp- 

 tion, its elastic and non-elastic states, and 

 do not proceed to the discovery of any 

 of those species of air or gases, which 

 have so much engaged the attention of 

 modern philosophers, though they mani- 

 festly led to such discoveries. A second 

 edition of this work appeared in 1731, and 

 in 1733 he published, as a kind of sequel 

 to it, his " Statical Essays, containing 

 Hzemastatics ; or an account of some Hy- 

 draulic and Hydrostatical experiments 

 made on the Blood and Blood-vessels of 

 Animals ; also, an Account of some Expe- 

 riments on Stones in the Kidneys and Blad- 

 der, &c." In this he discussed some fun- 

 damental points relative to physiology, as 

 the force and celerity with which the, blood 

 is propelled in the arteries, its retarda- 

 tion in the capillary vessels, the area of 

 the heart, and the weight of blood sus- 

 tained by it, the effects of respiration, and 

 the alteration of air by breathing, &c. His 

 enquiries concerning the urinary calcu- 



lus relates to Its chemical composition, 

 and to the means of dissolving it ; of 

 which, suggested by him, is fixed air, or 

 that produced by sulphuric acid and fix- 

 ed alkali in a state of effervescence. He 

 also proposes injections into the bladder, 

 and gives a contrivance for that purpose. 

 This subject he afterwards pursued more 

 particularly, and published an account of 

 some experiments on Mrs. Stephen's ce- 

 lebrated medicines, in 1740. The repu- 

 tation of this worthy man kept pace with 

 his useful labours. In 1732 he was ap- 

 pointed one of the trustees for settling a 

 colony in Georgia; and, in 1733, the 

 University of Oxford presented him with 

 the degree of D. D. He performed a va- 

 luable service to the health and morals 

 of the poor, by printing, anonymously, 

 " A Friendly admonition to the Drinkers 

 of Gin, Brandy, and other Spirituous Li- 

 quors," which has been several times re- 

 Erinted, and distributed gratis. In 1739 

 e printed "Philosophical Experiments 

 on Sea Water, Corn, Flesh, and other 

 Substances,'* 8vo. chiefly intended for 

 the use of navigators. A paper on a si- 

 milar subject, and the solution of the stone 

 in the bladder, obtained him, in the same 

 year, the gold medal from the Royal So- 

 ciety. One of the mos useful of Dr. 

 Hales' inventions was that of ventilators 

 for renewing the air in mines, prisons, 

 hospitals, and holds of ships, which he 

 disclosed to the Royal Society in 1741. 

 Some years afterwards his machines were 

 fixed on the Savoy and Newgate Prisons, 

 to the great benefit of the persons con- 

 fined in them, among whom the progress 

 of the gaol-fever was much diminished. 

 His plans for producing a free circulation 

 of air were also applied by him for the 

 cleansing and preservation of corn ; for 

 the former purpose he invented a ma- 

 chine, called a back-heaver, which he de- 

 scribed in the Gentleman's Magazine for 

 1745 and 1747. His attention to medical 

 subjects was farther evinced, by a paper 

 read before the Royal Society, in describ- 

 ing a method for conveying liquors into 

 the abdomen after tapping ; by some ex- 

 periments and observations on tar-water; 

 and a detection of some fallacious boasts 

 concerning the efficacy of a lithontriptic, 

 called the liquid shell. A sermon, which 

 he preached before the College of Phy- 

 sicians, in 1751, on Dr. Crown's founda- 

 tion, contains some curious physiological 

 remarks relative to the benevolence of 

 the Deity, as displayed in the human 

 frame. His literary honours were aug- 

 mented in 1753, by his election as a 



