n y o 
A, fiw. 23, represents a thin piece of 
snonae^so cut as to contain as large a super- 
ficies as possible. r l bis hangs by a line thread 
of ilk, upon the beam B, and. is exactly ba- 
lanced from another thread ot silk at D, strung 
with the smallest lead shot, at equal dis- 
tances, and so adjusted as to cause the index 
to point at G, in the middle of the gradu- 
ated arch F G H, when the air is m a middle 
state between the greatest moisture and tne 
greatest dryness. I, shews a little table or 
shelf for that part of the silk and shot which is 
not suspended to rest upon. 
Both Dr. Hales and Dr. Desaguliers 
contrived another form of sponge hygrome- 
ter, on this principle. r i hey made an hori- 
zontal axis, ha vine a small part of its length 
cylindrical, and the remainder tapering coni- 
cally with a spiral thread cut in it, after the 
manner of the fuzee of a watch. See tig. 24. 
The sponge is suspended by a fine silx thread 
to the" cy lindrical part of the axis upon which 
it winds. This is balanced by a small weight 
W, suspended also by a thread, which winds 
upon the spiral fuzee. Then when the sponge 
grows heavier, in moist weathei, it descends 
and turns the axis, and so draws up the 
weight; which coming to a thicker part of 
the axis it becomes a balance to the sponge, 
and its motion is shewn by an attached scale: 
and vice versa when the air becomes drier. 
Salt of tartar, or any other salt, or pot-ashes, 
may he put into the scale of a balance, and 
used instead ot the sponge. 
HYMEN. See Anatomy. 
IIYMEN.TA, the bastard locust tree; a 
■genus of the menogynia order, in the decan- 
dria class of plants; and in the natural me- 
thod ranking under the 33d order, lomenta- 
ceie. The calyx is quinquepartite ; there 
are five petals, nearly equal; the style is in- 
torted; the legumen full of mealy pulp. 
There is but one species, the courbaril, 
which is a large tree growing naturally in the 
Spanish West Indies. The trunk is covered 
with a light ash-coloured bark, is often more 
than sixty teet high, and Lhiee in diameter. 
The seeds are covered with a light brown 
sugary substance, which the Indians scrape 
off and eat with great avidity, and which is 
very agreeable. At the principal roots un- 
derground, is found collected in large lumps 
a yellowish red transparent gum, which dis- 
solved in rectified spirit of wine affords a most, 
•excellent varnish, and is the gum anirae ot 
the shops. . , . . , 
HYMENOPTERA, derived from v/w 
membrane and wreppy wing, in the Tin mean 
system of natural history, is an order of in- 
sects having four membranaceous wings, and 
the tails of the females are furnished with 
stings, which 'in some are used for instilling 
poison, and in others for merely piercing the 
bark and leaves of trees, and the bodies of 
•other animals, in which they deposit their 
^ S tIYOBANCHE, a genus of the angios- 
permia order, in the didynamia class of plants. 
The calyx is heptaphyllous; the corolla rin 
gent, with no under lip. The capsule bilo- 
cular, and polyspermous. There is one spe- 
cies a parasitical plant of the Cape. 
HYOIDES. See Anatomy. 
HYOSCYAMUS, henbane, in botany, a 
genus of the monogynia order, in the pen- 
tandria class of plants; and in the natural 
method ranking under the 2btli older, luikkc. 
K Y P 
H Y P 
9 5 5 
The corolla is funnel-shaped and obtuse ; the 
stamina inclining to one side; the capsule co- 
vered and bilocular. There are eight spe- 
cies, one of which, viz. the niger, or common 
henbane, is a native of Britain. It grows on 
road-sides, and among rubbish. It is a bien- 
nial plant, with long fleshy roots which strike 
deep into the ground, sending out several 
large soft leaves, deeply flashed on their 
edges: the following spring the stalks come 
up, which are about two teet high, with yel- 
low flowers standing on one side in a double 
row, sitting close to the stalks alternately. 
The seeds, leaves, and roots of this plant, as 
well as of all other species of this genus, are 
poisonous: and many well-attested instances ot 
their bad effects are recorded ; madness, con- 
vulsions, and death, being the common conse- 
quence. Tn a smaller dose they occasion gid- 
diness and stupor. It is said that the leaves 
scattered about a house will drive away mice. 
The juice of the plant evaporated to an ex- 
tract is prescribed in some cases as a narco- 
tic; in which respect undoubtedly it maybe 
a powerful medicine if properly managed. 
The dose is from half a scruple to half a dram. 
The roots are used for anodyne necklaces. 
Goats are not fond of the 'plant ; horses, 
cows, sheep, and swine refuse it. 
HYOSERIS, a genus of the polygamia 
squabs order, in the syngenesia class of 
plants; and in the natural method ranking 
under the 49th order, composite. The re- 
ceptacle is naked, the calyx nearly equal ; the 
pappus hairy, or scarce perceptible. There 
are ten species, resembling dandelion. 
HYOTHYROIDES. See Anatomy. 
HYPALLAGE, among grammarians, a 
species of hyperbaton, consisting in a mutual 
permutation otMiae case for another. I hus, 
Virgil says J/Mpti'iz classibus austros,” for 
“ dare clas^PKstris and again, “necdum 
illis labra admcfvi,” for “ necdum ilia labris 
adinovi.” 
HYPECOUM, wild cummin; a genus of 
the digynia order, in the tetrandria class of 
plants f and in the natural method ranking 
under the 2 4th order, corydales. The calyx 
is diphyllous; the petals four; the exterior 
two larger and trifid ; the fruit a pod. There 
are three species, all of them low herbaceous 
plants with yellow flowers. The juice of 
these plants is of a yellow colour, resembling 
that of celandine, and is affirmed by some 
eminent physicians to be as narcotic as opi- 
um. From the nectarium of the blossom the 
bees collect great quantities of honey. 
HYPERBATON, in grammar, a figura- 
tive construction inverting the natural and 
proper order of words and sentences. J he 
several species of the hyperbaton are the 
anastrophe, the hysteron-proteron, the hy- 
pallage, synchysis’ tmesis, parenthesis, and 
the hyperbaton, strictly so called. 
Hyperbaton, strictly so called, is a long 
retention of the verb, which completes the 
sentence, as in the following example from 
Virgil: 
Interea rrges : ingenti mole Tatums 
Quadrijugo vehitur curru, cui tempora civ- 
cum 
Aurati bis sex radii fulgentia cingunt 
Solis avi specimen: bigis itTurnus in albis, 
Bina manu lato crispans hastiba ferro : 
Hinc pater /Eneas Romanic stirpis origo, 
Sidereo flaoxans clypeo*& ccelestibus arrais; 
fi E 2 
F.t juxta Ascanius imagine spes altera Roma*; 
Procedunt castris. 
HYPERBOLA, in geometry, the section 
of a cone made by a plane, so that the axis of 
the section inclines to the opposite leg of the 
cone, which in the parabola is parallel to iu 
and in the ellipsis intersects it. The axis of 
the hyperbolical section will meet also with 
the opposite side ol the cone, when produced 
above the vertex. See Conic Sections. 
HYPERBOLE, in rhetoric, a figure, 
whereby the truth and reality of things arc 
excessively either enlarged or diminished. 
HYPERBOLIC Cylindroid, is a solid 
figure, whose generation is given by Sir 
Christopher Wren, in the Philosophical 
Transactions. Thus, two opposite hyper- 
bolas being jeined by the transverse axis, 
and through the centre a right line being 
drawn at right angles to that axis; and about 
that, as an axis, the hyperbolas being sup- 
posed to revolve; by such revolution, a body 
will be generated, which is called the hyper- 
bolic cylindroid, whose bases, and all sec- 
tions parallel to them, will be circles. In a 
subsequent transaction, the same author ap- 
plies it to grinding of hyperbolical glasses ; 
affirming, that they must be formed this way, 
or not at all. Hyperbolic leg of a curve, 1 * 
that which approaches infinitely near to sonic 
asymptote. Sir Isaac Newton reduces all 
curves, both of the first and higher kinds, 
into those with hyperbolic legs, and those 
with parabolic ones. 
Hyperbolic line is used by some authors 
for what we call the hyperbola itself. In this 
sense, the plane surface, terminated by the 
curve line, is called the hyperbola, or hyper- 
bolic space; and the curve line that termi- 
nates it the hyperbolic line. 
HYPERBOLOIDES, are hyperbolas of the 
higher kind, the nature of which is expressed by 
my n 
(a + x"y. espe* 
e. g- a y z — 
this equation : ay 
cially if m ~7 1, 
{a .*). 
HYPERICUM, St. John’s wort* -a genus 
of the polyndria order, in the polvdelphia 
class of plants; and in the natural method 
ranking under the 20th order, rotaceax '1 he 
calyx is quinquepartite ; the petals five ■; the 
filaments many, and coalited at the base into 
five pencils; the seed-vessel is a pencil-. ^ Of 
this genus there are 57 species, most ol them 
hardy deciduous shrubs. The most remark- 
able are, 1. The hircinum, or stinking St. 
John’s wort. Of this there are three va- 
rieties; one with strong stalks, six or eight 
feet high, broad leaves and large flowers ; the 
other with strong stalks, broad leaves, and 
without any disagreeable odour; the third 
has variegated leaves. All these varieties are 
shrubby, and flower in June and July in such 
numerous cluster^, that the shrubs appear co- 
vered with them; and produce abundance of 
seed in autumn. 2. The canariensis has shrub- 
by stalks, and at the ends of the branches, clus- 
ters of yellow flowers appearing in June and 
July. 3- The ascyron, or dwarf American 
St. John’s wort, has spreading roots, sending 
up numerous slender square stalks, a foot 
long, and at the end of the stalks large yel- 
low flowers. 4. The androsaemum, com- 
monly called tutsan, or park-leaves, has clus- 
ters of small yellow flowers appearing in July 
and August, and succeeded by roundish ber- 
ry-like black capsules. This grows naturally 
