KEY AND INDEX 



been believed by many, even in the Eighteenth 

 Century, and made pioneer observations in near- 

 ly every branch of astronomy. 



Hertz, Heinrich Rudolf, iii, 247. Born at Ham- 

 burg, Germany, Feb. 22, 1857; died at Bonn, 

 Jan. I, 1894. German physicist. In 1883 ne be- 

 gan studies in Maxwell's electro-magnetic the- 

 ory, and finally established the fact that "ordi- 

 nary light consists of electrical vibrations in an 

 all-pervading ether, which possesses the proper- 

 ties of an insulator and of a magnetic medium." 

 The results of his observations have been turned 

 to practical account in the wireless telegraph and 

 telephone systems of the present time. 



Hevelius, Johannes, iii, 3. Born at Dantzic, 

 Prussia, Jan. 28, 1611; died at Dantzic, Jan. 28, 

 1687. A Polish astronomer. His fame as an 

 astronomer rests largely on his accurate descrip- 

 tion of the face and the spots of the moon. He 

 was a friend and coworker of Edmund Halley, 

 the English astronomer. 



Hewitt, Peter Cooper, vi, 236. Born at New 

 York. American electrician. Inventor of the 

 mercury-vapor electric light, in which mercury 

 vapor takes the place of the carbon or metal fila- 

 ment of the incandescent lamp. 



Hildanes, Fabricius, ii, 183. Born in 1560; 

 died in 1639. A German physician and surgeon. 

 He invented many useful surgical instruments, 

 several of them for locating and removing bul- 

 lets. Contrary to the teachings of his time he 

 was an ardent advocate of the study of anato- 

 my. He was first to use a magnet for removing 

 particles of metal from the eye. 



Hinrichs, Professor Gustav, iv, 67. An Amer- 



[no] 



