HID 



HEXACHORD, in ancient music, .a 

 concord called by the moderns a sixth. 

 The hexachord is twofold, greater and 

 less. The greater hexachord is composed 

 of two greater tones, and two less, and 

 one greater semitone, which make five 

 intervals. The less hexachord is of two 

 greater tones, one lesser, and two greater 

 semitones. 



HEXAEDRON, or HEXAHEDRON, one 

 of the five regular or platonic bodies; 

 being indeed the same as the cube ; and 

 is so called from its having six faces. 

 The square of the side or edge of a 

 hexaedron is one third of the square of 

 the diameter of the circumscribing sphere; 

 and hence the diameter of a sphere is to 

 the side of its inscribed hexahedron, as 



\/ 3 to 1. See BODY. 



HEXAGON, in geometry, a figure of 

 six sides and angles ; and if these sides 

 and angles be equal, it is called a regular 

 hexagon. The side of every regular 

 hexagon, inscribed in a circle, is equal 

 in length to the radius of that circle. 

 Hence, it is easy by laying off the radius 

 six times upon the circumference, to in- 

 scribe an hexagon in a circle. See GE- 



OMETRT. ' 



To describe a regular hexagon upon 

 a given line, describe an equilateral tri- 

 angle upon it, the vertex of which will 

 be the centre of the circumscribing cir- 

 cle. The side of a hexagon being s, the 



area will be 2.598 s* = - s 1 X tang. 60 



HEXAGON, in fortification, is a place de- 

 fended by six bastions. 



HEXAGYNIA, in botany, the name 

 of an order of plants, consisting of those, 

 which, besides their classical character, 

 have their flowers furnished with six 

 styles. 



HEXAMETER, in ancient poetry, a 

 kind of verse consisting of six feet ; the 

 first four of which may be indifferently 

 either spondees or dactyls ; the fifth is 

 generally a dactyl, and the sixth always a 

 spondee. Such is the following verse of 

 Horace : 



1 23456 



Autpro \desse vo\ lunt,aut\ dele\ ctarep\ etae. 



Sometimes, indeed, a spondee consti- 

 tutes the fifth foot : whence such hexame- 

 ter verses are called spondaic ; as in this 

 of Virgil: 



1 23 45 



Cara De\um sobo\ les ma\gnum Jovis\ incfe* 



6 

 mentum. 



Epic poems, as the Iliad, JEneid, &c. 

 consist wholly of hexameter verses; 

 whereas elegies and epistles consist 

 usually of hexameter and pentameter 

 verses alternately. 



HEXANDRIA, the name of the sixth 

 class in the Linnxan system, consisting 

 of plants with hermaphrodite flowers, 

 which are furnished with six stamina or 

 male organs that are of an equal length. 

 This numerous class of plants is divided 

 into five sections, from the number of 

 the styles or female organs : the narcis- 

 sus, snow-drop, tulip, hyacinth, &c. have 

 one style ; the rice, atraphaxis, &c. two ; 

 dock, star-flower, &c. three ; guinea-heh 

 weed, four; and water-plantain, five. 

 The Hexandria class is distinguished 

 from the Tetradynamia by the propor- 

 tion of the stamina, which in the former 

 are of an equal length, in the latter un- 

 equal, four stamina being long, and two 

 short. 



HIATUS, properly signifies an open- 

 ing, chasm, or gap ; but it is particularly 

 applied to those verses, where one word 

 ends with a vowel, and the following word 

 begins with one, and thereby occasion the 

 mouth to be more opened, and the sound 

 to be very harsh. 



The term hiatus is also used in speak- 

 ing of manuscripts, to denote their de- 

 fects, or the parts that have been lost or 

 effaced. 



HIBISCUS, in botany, a genus of the 

 Honadelphia Polyandria class and or- 

 der. Natural order of Columniferx. Mal- 

 vaceae, Jussieu. Essential character : ca- 

 lyx double; outer many-leaved; cap- 

 sule five-celled, with many seeds. There 

 are forty-five species, most of these are 

 perennials ; several of them have shrubby 

 stalks; and some are herbaceous; the 

 leaves are alternate, and commonly of a 

 soft texture. The flowers are of the 

 mallow kind, axillary, and terminating; 

 the bark in several is capable of being 

 drawn into threads, and manufactured 

 for packthread and ropes ; the capsule in 

 some is eatable ; others are much esteem- 

 *ed for their ornamental flowers. 



HIDE. SeeCuTis. 



HIDE. Hides are the skins of beasts : 

 but the denomination is particularly ap- 

 plied to those of large cattle, as bullooks* 

 cows, buffaloes, horses, &c. Raw hides 

 are still a considerable object in the Egyp- 

 tian trade : about 80,000 hides of buffa- 



