HELMHOLTZ 



2765 



HEMATITE 



rifle ball, however, these ancient devices were 

 rendered useless. 



LATER HELMETS 



(a) Great Britain, 1805; (&) France, 1870; 

 (c) Italy, 1870; (d) Germany, 1914. 



HELMHOLTZ, helm' holts, HERMANN VON 

 (1821-1894), a German scientist, distinguished 

 equally in physiology, mathematics and in ex- 

 perimental and mathematical physics. He and 

 his pupils gave to mathematical physics its 

 commanding position among the sciences. His 

 physiological works are chiefly concerned with 

 the eye, the ear and the nervous system. He 

 was born at Potsdam and educated at Berlin. 

 In 1849 he became professor of physiology at 

 Konigsberg, and later acted in the same capac- 

 ity at Bonn and at Heidelberg. In 1871 he was 

 appointed professor of physics at Berlin, and 

 through his efforts that city became the great- 

 est center in the world during his time for the 

 study of physics through experiment. Among 

 his many contributions to the sciences of which 

 he made such exhaustive study are The Con- 

 servation of Force, Manual oj Optics, Popular 

 Lectures on Scientific Subjects and the Sensa- 

 tions of Tone as a Physiological Basis for the 

 History of Music. Helmholtz was also greatly 

 interested in music, in literature and philosophy. 



HELOISE, aloeez' . See ABELARD, PIERRE. 



HELOTS, hel'ots, or he' lots, the third and 

 lowest class of society in ancient Sparta, com- 

 posed of slaves who labored on the estates of 

 the higher classes. They were the property of 

 the state, and not of the individual Spartans, 

 among whom they were distributed by lot. 

 The Helots were treated very cruelly, for they 

 had no rights which their masters felt bound 

 to respect. They were watched with distrust 

 and once, when they grew too numerous for 

 the safety of the state, 2,000 of the leaders were 

 massacred to decrease their apparently danger- 

 ous numbers. In time of war they were obliged 

 to bear arms for the state. In 464 B. c. they re- 

 volted against their masters, but after an eight- 

 years' war were subdued. Thus they remained 

 slaves until after the Spartans were overthrown 

 at the battle of Leuctra in 371 B. c., when they 

 were freed by Epaminondas. 



HELSINGFORS, hel sing fors, the capital and 

 most important port and commercial center 



of Finland, Russia. It is beautifully situated 

 on the northern shore of the Gulf of Finland, 

 191 miles northwest of Petrograd, and has one 

 of the best harbors on the Baltic Sea. A large 

 trade in agricultural products is conducted with 

 Petrograd, England and Sweden. The chief 

 manufactures consist of sugar, tobacco, linen 

 and carpets. As a naval station it ranks next 

 in importance to Kronstadt, and its fortifica- 

 tions, from the standpoint of the world before 

 the War of the Nations (1914), were regarded 

 as impregnable. Helsingfors is the center of 

 education and culture in Finland, and is a fine 

 city with broad, regular and clean streets. 

 Population in 1910, 147,218. 



HELVETII, helve' she i, an ancient Celtic 

 people who succeeded the early inhabitants of 

 the Alpine region now known as Switzerland. 

 The name means hilly country. According to 

 Caesar they occupied the country between the 

 Rhine on the east, the Jura Mountains on the 

 west and the Rhone River on the south. While 

 Caesar was governor of Gaul they tried to gain 

 new territory, but were defeated and almost 

 exterminated. Caesar then subjected the coun- 

 try to Roman domination and established sev- 

 eral colonies. The Helvetii were mercilessly 

 punished a second time for refusing to recognize 

 and salute Vitellius as emperor after the death 

 of Nero, and as a nation they soon after dis- 

 appeared, being succeeded by the Alemanni, 

 who, in turn, succumbed to the power of the 

 Franks in A.D. 496. 



HEMANS, hem' aw, FELICIA DOROTHEA (1793- 

 1835), an English poet whose work made her 

 beloved in England and America, was born in 

 Liverpool. Many of her shorter poems, such as 

 The Treasures oj the Deep, The Better Land, 

 The Voice oj Spring and The Homes of Eng- 

 land, have become standard English lyrics, upon 

 which her reputation rests. Her first volume, 

 Juvenile Poems, was published when she was 

 fourteen years of age. Her principal works are 

 The Forest Sanctuary; Songs of the Affections; 

 Hymns for Childhood; National Lyrics and 

 Songs for Music, and Scenes and Hymns of 

 Life. For her play, The Vespers of Palermo, 

 Sir Walter Scott wrote an epilogue, and this 

 marked the beginning of a long friendship be- 

 tween them. Her poetry, though without great 

 originality, is sweet, natural and pleasing; it 

 was the outcome of a beautiful life spent in 

 seclusion away from the world of big experi- 

 ences. 



HEMATITE, hem'atite, the ore from which 

 most of the world's iron and steel is obtained. 



