HELMHOLTZ. 745 fiir die Theorie tier Uusik, appeared in 1803, and several other editions and translations have since been puhlisheil. Tlie llniidhiivli ih r phyniohi- gischcn Optik was pnblished in lS(i7, and Helni- holtz's (Icsaiii incite aism ii.sclutftHchr Ahli<ni<l- hiiigcn in 1882-83. Helndioltz was a eontributor to the leading seientitic journals of the world, and was the recipient of many honors. An inter- esting biographical sketch, by Prof. A. W. Riicker, F.R.S.. was published in the t'ortnhihthj Rcvicio for November, 18SI4, and reprinted in the Umith- soniini I'cport of the same year. HELMOLD, hel'niolt. A twelfth-century Ger- man historian of the Slavs, lie was born in Hidstcin. and was a ]iriest at Biisau. He was intimate with (Jcrold, the Bishop of LiibecU, who had done missionary work among the Slavs, and who urged him to write a history of the wars with tliem and the missions among them. This history. Chronica fUtiioruiii. covered the period from Charlemagne to Helmold's own time and the days of Henry the Lion (1172), and was continued to 1209 by Arnold von Liibeck (q.v.). It is best edited by Lappenberg (18G8), separately, and in vol. xxi. of Monumenta Ger- manice. HELMOLT, hel'niolt, Hans F. (1865—). A German editor and historian, born at Dresden. He obtained a university education, and was ap- pointed to an editorial post in tlie Bibliographic Institute at Leipzig. His publications include historical studies, such as Koniri liuprcchls Ziig nach Italien (1892), and Fabriciiis mid Sihcr (1895), and the compendious Wcltrjeschichte (1899-1901), a work based on an ethnographic method, in the preparation of which he was as- sisted by German and other specialists. HELMOND, hel'mont, Fr. pron. el'mSN'. A town in the Province of North Brabant. Holland, situated on the Zuid Willems Canal. 23 miles by rail northwest of Venlo (Map: Netherlands, D 3). There are a number of extensive textile mills, dyeing establishments, cigar-factories, and various other maniifacturing establishments. Population, in 1890, 9029; in 1900, 11,436. HELMONT, hel'mont, ,1an Baptista van (1577-1044). A Belgian physician and chemist, born at Brussels. He studied at Louvain. and on the completion of his education accepted the chair of surgery in that university, the duties of which he discharged for two years. The study of the work of Paracelsus seems to have turned his attention to chemistry and natural philosophy, and in the pursuit of these sciences he spent several years in difTerent universities of Italy and France: after which he returned home, mar- ried Margaret van Ranst, a noble lady of Bra- bant, ami settled down at his estate near Vil- vorde, where he spent the remainder of his life in investigations of various kinds. Writers of the history of chemistry regarded him as one of the greatest chemists who preceded Lavoisier. He paid much attention to the study of gases, and is supposed to have been the first to use the word (inn as a generic name for all elastic aeriform fluids. Of these gases he distinguished several kinds. He was also the first to take the melting- point of ice and the boiling-point of water as standards of the measurement of temperature. In his works the term 'saturation' was first em- ployed to signify the combination of an acid with a base, and he was an early investigator of the HELODERMA. chemistry of the fluids of the human body. Along with other pliysiologists of his day, he .-peculated nuieh on the seal of the soul, which he jilaced in the stomach, liis reasons are cliielly these two: (1) It lannol exist in the brain, be- cause, as he thought, that organ contains no blood ; ( 2 ) it does exist in the stomach, be- cause, when we hear bad news, we lose our appe- tite. The most important of his works is his Ortus McdicincF. which was pid)lishcd by his son, four years after his death: it i)assed through a very large miniber of editions, and was translated into Dutch, French. German, and Knglish. A curious vidunie, containing translations of some of his works, was also pul)lished bj' W. Charlton, in 1050. under the title of The Ternary of Para- doxes; the Magnetic Cure of Wounds; the Na- tirity of Tartar in M'ine; and the Image of God in Man. HELMSTEDT, helm'stet. A town in the Duchy of Brunswick. Germany, situated 25 miles by rail from the city of Brunswick (Map: Ger- many, D 2). It was formerly famous for its university, founded here in 1575, and suppressed in 1809. The university buildings now contiiin the remnants of the university library. Helm- stedt manufactures agricultural machinery, pot- tery, woolens, soap, etc. About two miles from the town are the Helmstedt springs, whose waters, containing iron salts, are much used. Population, in 18(10, 10,955; in 1900, 14,259. HEL'MUND, or HIL'MEND. The largest river of Afglianistan. It rises in the Koh- i-Baba chain, and flows southwest, receiving nu- merous tributaries by which it drains the south- ern part of the country (Map: Asia, Central, J 5). It discharges into the lake, or rather swamp, of Savaran, near the Persian frontier. Its total length is estimated at over 600 miles. The channel of its lower course is very wide and dee]), but is filled only during the summer. The region traversed by the lower course of the Hel- nuuid is well populated, and the water-power of the river is used by numerois mills. HEL'MXJTH, William Ton (18.33-1902). An American homeopathic physician. He was born in Philadelphia, and studied medicine there and in San Francisco. In 1888 he received the degree of LL.D. from Yale. He was dean and jirofessor of surgery in the New York Homcoi>athic iledi- eal College, had several hospital positions, and published numerous essays, both literary and medical, such as: ficralches of a fiurgcon (1879) ; -1 SIcniner Book (1880); Diphtheria: Medical I'oin posit y ; System of Surgery; Siiprapnhic t.ilhotomii : and some verses, ^yith the Pousse- Cafe. HE'LODERTaA (Neo-Lat., from Gk. ^Xoj, helos, nail, wart + Sipiia, derma, skin). A ge- nus of North .ineric;iii lizards, with two species, of which one is the poisonous Gil.a monster. It represents, according to Cope, a family (Ileloder- matidip) and superfamily (Ilcloderinatoidea ) , characterized prominently by the fact that the eight to ten acrodont teeth in each jaw are anehy- losed by oblique ba~es. and each is fang-like and grooved both before and behind, as if designed for condiictiuL' fluid pcii^on. For full structural de- tails, consult Cope. Crneoililinns. I.irnrds. and Snakes (Smithsonian Institution, Washington,
