HEX 
to those who inhabit the southern tem- 
perate zone, and they are heteroscii with 
respect to us. Hence it follows, that only 
the inhabitants of the two temperate zones 
are heteroscii, though in reality there is al- 
ways one part of the torrid zone whose in- 
habitants are heteroscii with respect to those 
of the rest, and with regard to those of one 
of the temperate zones, except at the time 
of the solstice, and even at this time all of 
the torrid zone are heteroscii with regard to 
those of one of the temperate zones ; but as 
the people of the torrid zone have their sha- 
dows now on this, and then on that side, they 
are called amphiscii. 
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 hexahedron, is one- 
third of the square of the diameter of the 
circumscribing sphere ; and hence the dia- 
meter of a sphere is to the side of its in- 
scribed hexahedron, as tj 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 hexa- 
gon. 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 inscribe an hexagon in a 
circle. See Geometry. 
To describe a regular hexagon upon a 
given line, describe an equilateral triangle 
upon it, the vertex of which will be the 
centre of the circumscribing circle. The 
side of a hexagon being s, the area will be 
2.598 s* = ? s 2 X tang. 60°= ^s 2 3. 
Hexagon, in fortification, is a place de- 
fended by six bastions. 
HEXAGYN1A, in botany, the name of 
an order of plants, consisting of those which, 
besides their classical character, have their 
flowers furnished with six styles. 
H EX A M ETE K , 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 
HID 
dactyl, and the sixth always a spondee. Such 
is the following verse of Horace : 
12 3 4 5 6 
Aut pro\desse vo\lunt, aut\dele\ctare po\elrr. 
Sometimes, indeed, a spondee constitutes 
the fifth foot; whence such hexameter 
verses are called spondaic; as in this of 
Virgil. 
1 2 3 4 5 
Cara De\um $obo\les tna\gnum Jovis | incre-\ 
6 
mentum. 
Epic poems, as the Iliad, iEneid, &c. 
consist wholly of hexameter verses ; where- 
as elegies and epistles consist usually of hex- 
ameter and pentameter verses, alternately. 
HEXANDRIA, the name of the sixth 
class in the Linnaean system, consisting of 
plants with hermaphrodite flowers, which 
are furnished with six stamina or male or- 
gans that are of an eqnal length. This nu- 
merous class of plants is divided into five 
sections, from the number of the styles or 
female organs : the narcissus, snow-drop, 
tulip, hyacinth, &c. have one style ; the 
rice, atraphaxis, &c. two ; dock, star-flower, 
&c. three ; guinea-lien weed, four ; and wa- 
ter-plantain five. The Hexandria class is 
distinguished from the Tetradynamia by the 
proportion of the stamina, which in the for- 
mer are of an equal length, in the latter un- 
equal, four stamina being long, and twoshort. 
HIATUS, properly signifies an opening, 
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 speaking of 
manuscripts, to denote their defects, or the 
parts that, have been lost or effaced. 
HIBISCUS, in botany, a genus of the 
Monadelphia Polvandria class and order. 
Natural order of Columniferae. Malvace®, 
Jussieu. Essential character: calyx double; 
outer many-leaved ; capsule five-celled, 
with many seeds. There are forty-five 
species, most of these are perennials ; seve- 
ral 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 manufac- 
tured for packthread and ropes ; the cap- 
sule in some is eatable ; others are much 
esteemed for their ornamental flowers. 
HIDE. See Cutis. 
Hide. Hides are the skins of beasts : 
