A HISTORY OF SCIENCE 



table physiology, ii. 298; study 

 of the elasticity of air, iv. n. 



Hall, Marshall, and physical 

 diagnosis, iv. 203; observa- 

 tions on reflex action, iv. 

 251-258. 



Haller, Albrecht von, iv. 73- 

 75; doctrine of irritability, iv. 

 74; discoveries in embryology, 

 iv. 75; first to use the watch 

 in counting the pulse, iv. 76. 



Halley, his observations on the 

 change in the variations of the 

 compass, iii. 4 ; his observations 

 on the transit of Mercury, iii. 

 5 ; his discovery of a method of 

 determining the parallax of the 

 planets, ibid.; calculated the 

 orbit of a comet, iii. 6; specu- 

 lations concerning meteors, iii. 

 7 ; showed that fixed stars have 

 an actual or "proper" motion 

 in space, iii. 57. 



Haly, Abbas, author of The 

 Royal Book, ii. 24. 



Hamilton's, Sir William, col- 

 lection acquired for British 

 Museum, v. 5. 



Hampson, Dr. William, improved 

 method of liquefaction of 

 gases, v. 44; his apparatus for 

 liquefying air, v. 45. 



Hansen, Christian August, in- 

 ventor of an electrical ma- 

 chine, ii. 274. 



Harets ben Kaladah, physician 

 of Mohammed, ii. 23. 



Hartley, Dr., his famous vibra- 

 tion theory, iv. 268. 



Harvey, William, life of, ii. 169; 

 his discovery of the circula- 

 tion of the blood, ii. 171-178. 



Hauksbee, Francis, his mer- 

 curial fountain, ii. 259; dis- 

 covery of "induction," ii. 

 259-262. 



Heat, Count Rumford's experi- 

 ments with, iii. 209. 



Heidenham, Dr. Rudolf, on the 

 phenomena of hypnotism, iv. 

 269. 



Heliocentric theory, i. 217. 



Helmholtz, Hermann von, his 

 theory of solar energy, iii. 65; 

 renounced all claim to the 

 discovery of the conservation 

 of energy in favor of Mayer, 

 iii. 269; found that a vortex 

 whirl once established in a 

 frictionless medium must go 

 on forever, iii . 290 ; his measure- 

 ment of speed of nervous im- 

 pulses, iv. 262; explanation of 

 the continued heat of the sun, 

 v. 207. 



Henderson, Thomas, his work 

 at the Cape of Good Hope in 

 detecting and measuring the 

 parallax of a star, iii. 61. 



Henry, Joseph, his experi- 

 ments with electric magnets, 

 iii. 239. 



Heraclides first to point out the 

 value of opium in certain 

 diseases, i. 196. 



Hero, a pupil of Ctesibius, i. 243 ; 

 an explicit champion of the 

 molecular theory of matter, i. 

 245 ; his experiments with water 

 and gases, i. 246; his experi- 

 ments with heated air to 

 produce motor power, i. 247; 

 his experiments with air under 

 pressure, i. 248; his steam- 

 engine, i. 250; the inventor of 

 the penny-in-the-slot machine, 

 i. 251. 



Herodotus, his visit to Babylon, 



i- 57. I0 3- 



Herophilus, his records are the 

 first we have of the dissection 

 of the human body, i. 194; 

 handed condemned criminals 

 over to the medical profession 

 to be operated on, i. 195. 



Herschel, John, in collaboration 

 with James South he dis- 

 covered many double stars, 

 iii. 58; his improvement of the 

 microscope, iv. in. 



Herschel, William, his positive 

 genius for sidereal discovery, 

 iii. 19; discovered the planet 

 Uranus, iii. 20; conceived the 



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