H E T 
tree ; and the myrtus, myrtle ; allspice or pi- 
mento. The plants of this order are. of the 
shrub and tree-kind, and chiefly ever- 
green. The bark of the stalks is slender ; 
the leaves are generally opposite, but in the 
myrtle, the leaves are placed opposite at the 
bottom of the stalks, and alternate above. 
The buds are generally conical, concealed 
in the cavity, which is formed by the foot- 
stalk of each leaf at its origin. The flowers 
are commonly hermaphrodite : in a species 
of the myrtus, however, they are male and 
female upon different roots.- The calyx is 
placed above the seed-bnd : the petals are 
three, four or five in number ; the stamina 
are upwards of twenty, nearly equal, and 
attached in several rows to the middle of 
the tube of the calyx. The seed-bud is 
large, and placed below the receptacle of 
the flower ; the style is single, of the length 
of the stamina, and terminated with a single 
stigma. The seed vessel it sometimes a 
berry, sometimes a capsule, and sometimes 
a stone. 
HESPERIS, in botany, English rocket, 
or dames violet, a genus of the Tetradyna- 
mia Siloqnosa class and order. Natural 
order of Siliquosae. Cruciformes, Ttnlrne- 
fort. Cruciferas, Jussieu. Essential cha- 
racter : petals bent obliquely ; a gland 
within the shorter stamens ; siliqua stiff ; 
stigma with a forked base, and converging 
tip ; calyx closed. There are 'seven spe- 
cies. These plants are much cultivated for 
the great fragrancy of the flowers : th < 
ladies in Germany have pots of it placed i 
their apartments, whence it obtained the 
name of dames violet. 
HETEROCLITE, among grammarians, 
one of the three variations in irregular 
nouns, and defined by Mr. Ruddiman, a 
noun that varies in declension. Other 
grammarians take the word lieteroclite in a 
larger sense, apply ingit to all irregular nouns. 
HETEROGENOUS, or Heteroge- 
neal, something that consists of parts of 
dissimilar kinds, in opposition to homoge- 
neous. 
Heterogeneous, in mechanics, such 
bodies whose density is unequal in different 
parts of their bulk ; or they are such whose 
gravities in different parts are not propor- 
tionable to the bulks thereof ; whereas bo- 
dies equally dense or solid in every part, or 
whose gravity is proportionable to their 
bulk, are said to be homogeneous. 
Heterogeneous light, is, by Sir Isaac 
Newton, said to be that which consists of 
rays of different degrees of refrangibility : 
thus the common light of the sun or clouds 
HET 
is heterogeneous ; being a mixture of all 
sorts of rays. 
Heterogeneous nouns, one of the three 
Variations in irregular nouns; or such as 
are of one gender in the singular number, 
and of another in the plural. Heteroge- 
neous, under which are comprehended 
mixed nouns, are six-fold. 1. Those which 
are of the masculine gender in the singular 
number, and neuter in the plural. 2. Those 
which are masculine in the singular num- 
ber, but masculine and neuter in the plural. 
3. Such as are feminine in the singular num- 
ber, but neuter in the plural. 4. Snch 
nouns as are neuter in the singular number, 
but masculine in the plural. 3. Such as are 
neuter in the singular, but neuter and mas- 
culine in the plural. 6. Snch as are neuter 
in the singular, but feminine in the plural 
number. 
Heterogeneous numbers, mixed num- 
bers consisting of integers and fractions. 
Heterogeneous , quantities, are those 
which are of such different kinds, as that 
one of them taken any number of times, 
never equals or exceeds the other. 
Heterogeneous surds, are such as have 
different radical signs, as J/ a a, £/ b b, 
*y 9, V 18, &e. See Surd. 
If the indices of the powers of the hetero- 
geneous surds be divided by their greatest 
common divisor, and the quotients be set 
under the dividends ; and those indices be 
multiplied crosswise by each others quoti- 
j ents ; and before the products be set the 
common radical sign y', with its proper in- 
dex ; and if the powers of the given roots 
be involved alternately, according to the 
index of each others quotient, and the com- 
mon radical sign be prefixed before those 
products, then will those two surds be re- 
duced to others, having but one common 
radical sign. 
HEUCHERA, in botany, a genus of the 
Pentandria Digynia class and order. Na- 
tural order of Succulent®. Saxifragae, 
Jussieu. Essential character : petals five ; 
capsule two-beaked, two-celled. There are 
two species, viz. H. americana, American 
heuchera or sanicle, and H. dichotoma. 
HETEROSCII, in geography, a term of 
relation denoting such inhabitants of the 
earth as have their shadows falling but one 
way, as those who live between the tropics 
and polar circles, whose shadows at noon, in 
north latitude, are always to the north- 
ward ; and in south latitude, to the south- 
ward. Thus we who inhabit the northern 
temperate zone, are heteroscii with regard 
