INDEX 



astic advocate of the Darwinian 

 theory, 313, 414; favors the La- 

 niarckian theory of the origin of 

 favored species, 318. 



Hahnemann, Christian Samuel Fried- 

 rich, his belief in the prevalence 

 of the itch, 361. 



Hall, Asaph, his discovery of the 

 moons of Mars, 49. 



Hall, Marshall, his services in the 

 practice of medicine, 359, 360 ; his 

 important psychological discovery, 

 403, 404. 



Haller, Albrecht von, his idea of the 

 function of respiration, 39. . 



Harding, of Lilienthal, his discovery 

 of Juno, 47. 



Hartley, David, his associational the- 

 ory of psychology, 414. 



Heat, how regarded in the eighteenth 

 century, 24 ; Thompson's vibratory 

 theory of, 26, 27', the investigation 

 of, helps to solve the problem of 

 evaporation and precipitation, 171 ; 

 Humboldt's study of its distribu- 

 tion on the surface of the globe, 

 175-177; discovery of its nature 

 and properties, 222-224 ; the source 

 of animal heat discovered, 349. 



Heidenhain, Rudolf, his experi- 

 ments in hypnotism, 415, 416. 



Helmholtz, Hermann Ludwig Ferdi- 

 nand von, his theory as to the dis- 

 crepancy between the motion of 

 the earth and the moon, 51 ; his 

 theory of solar energy, 74, 437 ; 

 his share in the discovery of the 

 doctrine of the conservation of 

 energy, 214, 217, 221, 225, 437; 

 his electro-magnetic theory of light, 

 227, 228; his calculations to prove 

 the vortex theory of atoms, 238; 

 opposes the vitalistic conception of 

 fermentation, 379 ; his researches 

 and discoveries in psycho-physics, 

 407-409. 



Hencke, an amateur astronomer, dis- 

 covers a fifth asteroid, 47. 



Henderson, Thomas, Astronomer Roy- 

 al of Scotland, the first to success- 

 fully measure a star's parallax, 66. 



Henle, Friedrich Gustav Jakob, his 

 anatomical researches, 332 336, 



352 ; his study of the nervous sys- 

 tem, 404. 



Herbart, Johann Friedrich, founder 

 of mathematical psychology, 407. 



Herschel, Caroline, aiding William in 

 his investigations, 6, 7. 



Herschel, Sir John, his study of 

 double stars, 63, 64, 65 ; refuses to 

 accept the doctrine of the conserva- 

 tion of energy, 218 ; his improve- 

 ment of the microscope, 326, 327. 



Herschel, Sir William, his improve- 

 ment of the telescope and his 

 astronomical discoveries, 5-12, 

 226 ; his nebular hypothesis, 13- 

 16 ; his theory of the asteroids, 47 ; 

 his study of double stars and dis- 

 covery of their relative change of 

 positions, 63, 65 ; his unsuccessful 

 efforts to solve the problem of star 

 distance, 65 ; his study of sun- 

 spots, 166. 



Hertz, Heinrich, confirms Helmholtz's 

 electro-magnetic theory of light, 

 227, 228. 



Hinrichs, Gustav, his investigations 

 confirm the " law of octaves," 280. 



Histology. See Anatomy and Physi- 

 ology ; Psychology. 



Hooke, Robert, his happy guess as to 

 the nature of light, 198. 



Hooker, Sir Joseph Dalton, his aid 

 sought by Darwin in the publi- 

 cation of his Origin of Species, 

 307, 309, 310; becomes his con- 

 vert and disciple, 313. 



Howard, Edward, his conclusion as to 

 aerolites, 158. 



Howard, Luke, his classification of 

 clouds and his theory of their for- 

 mation, 169, 170; his theory of dew 

 formation, 170. 



Huggins, William, his spectroscopic 

 researches, 70, 80. 



Humboldt, Alexander von, his discov- 

 eries in terrestrial magnetism, 167; 

 his study of heat distribution and 

 its climatic effects, 175-177. 



Hunter, John, discovers the processes 

 of digestion, 39, 347. 



Hutton, James, his geological inves- 

 tigations and his Theory of the 

 Earth, 19-23, 123, 129, 153; gen- 



466 



