II E M 
H E P 
HER 007 
The larva, when batched, finds there its food 
in (he midst of plant-lice. In 15 or 16 days 
it has attained to its full growth. With its 
spinning-wheel at its tail, it makes itself a 
small, round, white, silky cod, of a close 
texture. In summer, at the end of three 
weeks, the hemerobius issues forth with its 
wings ; but when the cod has not been spun 
till autumn, the chrysalis remains in it the 
whole winter, and does not undergo its final 
metamorphosis till the ensuing spring. The 
flight of this insect is heavy: some species 
have an excrementitious smell. One goes by 
the name of the water-hemerobius, because it 
lives mostly at the water-side. See Plate 
Nat. Hist. fig. 224. 
HEMEROCALLIS, day-lily, or lily-as- 
'phodd, a genus of the monogynia order, in 
the hexandria class of plants, and in the na- 
tural method ranking under the 10th order, 
eoronarue. The corolla is campanil lated, 
with the tube cylindrical; the stamina de- 
clining downard. There are tive species, of 
which two are common here, viz. 
1. The flava, or yellow day-lily, with strong 
fibrous roots, sending up large hollow keel- 
shaped leaves, two feet long, upright, leafless 
firm stajks, two feet high, dividing at top 
into several foot-stalks, each terminated by 
one large liliaceous yellow flower, of an 
agreeable odour. Of this there is a variety 
called the hemerocallis minor, or small yel- 
low day-lily. 
2. The fulva, reddish, or copper-coloured 
day-lily, has roots composed ot strong fleshy 
fibres, and large oblong tubes ; radical, keel- 
shaped, hollow, pointed leaves, a yard long, 
reflected at top, with leafless stalks, three or 
four feet high, and large copper-coloured 
liliaceous flowers. These have large stamina, 
charged with a kind of brown-coloured farina, 
which, on being touched ©r smelled to, is 
discharged in great plenty all over the hands 
and face. Both these species are hardy, and 
will thrive any where. They may be easily 
propagated by parting their roots in autumn, 
or almost any Tune alter flowering, or before 
they begin to flower. 
3. The japonica is a greenhouse plant, 
producing beautiful white flowers. 
HEMERODROMI, in Grecian antiquity, 
centinels and guards appointed for the secu- 
rity and preservation of cities and other 
places. They went out of the city every 
morning as soon as the gates were opened, 
and kept patrolling all day about the place: 
sometimes also making excursions further 
into the country, to see that there were no 
enemies lying in wait to surprise them. 
Hemerodromi were also a sort of cou- 
riers among the antients, who only travelled 
one day, and then delivered their packets or 
dispatches to a fresh man, who run his day, 
and so on to the end of the journey. 
HEMICYCLE. See Architecture. 
HEMTMERIS, a genus of the angiosper- 
mia order, in the didynamia class of plants. 
The capsule is bilocular, with one of the cells 
more gibbous than the other; the corolla is 
wheel-shaped, with one division greater, and 
inverse heart-shaped ; the interstice of the 
divisions nectar-bearing. There are three 
species, herbaceous plants of the Cape. 
HEMINA, in Roman antiquity, a liquid 
measure which, according to Arbuthnot, was 
equal to half a wine-pint English measure ; 
its contents being 2,3 18 solid inches. 
HEMIONITIS, a genus of the natural or* 
der of iilices, belonging 10 the cryptogaraia 
class of plants. The fructifications are in 
lines, decussating or crossing each other. 
There are eight species, natives of the West 
Indies. 
HEMIPLEGIA. See Medicine. 
HEMIPTER A, derived from ^lamlmlf, 
Whpoi wing, in the Linnaean system, the se- 
cond order of insects, comprehending twelve 
genera, viz. the blatta, mantis, gryllus, ful- 
gora, cicada, notonecta, nepa, cimex, aphis, 
chermes, coccus, and thrips, and a great 
number of species. 
HEMISPHERE, in geometry, the half of 
a globe or sphere, when it is supposed to be 
cut through its centre in the plane of one of 
its great circles. Thus the equator divides 
the terrestrial globe into the northern and 
southern hemisphere: in the same manner 
the meridian divides the globe into the east- 
ern and western hemisphere; and the hori- 
zon into two hemispheres, distinguished by 
the epithets upper and lower. The centre 
of gravity of an hemisphere is five-eights of 
the radius distant from the vertex. 
Hemisphere is also used to denote a 
projection of half the terrestrial globe, or half 
the celestial sphere, on a plane, and frequent- 
ly called planisphere. 
HEMISTICH, in poetry, denotes half a 
verse, or a verse not completed. Of this 
there are frequent examples in Virgil’s 
iEneid; but whether they were left unfinish- 
ed by design or not, is disputed among the 
learned: such are Ferro accincta vocat, 
Aril. II. v. 614. And, Italiam non sponte 
seqiior, TEn. IV. v. 361. 
In reading common English verses, a short 
pause is required at the end of each hemi- 
stich,. or half verse. 
HEMLOCK. See Cicuta. 
HEMP and Flax. No hemp or flax is 
to be watered in any river, runniug water, 
stream, brook, or pond, where beasts are 
used to be watered, but only in their several 
ponds for that purpose, on pain of 20 s. 33 
Hen. VIII. c. 17. 
Any persons may, in any place, corporate 
town, privileged or unprivileged, set up ma- 
nufactories of hemp or flax ; and persons 
coming from abroad, using the trade of hemp 
or flax-dressing, and of making thread, weav- 
ing cloth made of hemp or flax, or making 
tapestry hangings, twine or nets tor fishery, 
cordage, &c. after three years, shall have the 
privileges of natural-born subjects. 15 Car. 
II. c. 15. 
HEN. See Phasianus. 
HENDECAGON, in geometry, a figure 
that has eleven sides, and as many angles. 
In fortification, hendecagon denotes a place 
defended by eleven bastions. 
HENOTlCON, in church history, a de- 
cree or edict of the emperor Zeno, made at 
Constantinople, in the year 482, by which 
he pretended to reconcile all parties under 
one faith. 
IiEPAR, a name formerly given to the 
combination of sulphur and alkali. It is now 
called sulphuret of potass. 
HEPATIC gas, the old name for the gas 
separated from sulphuret of alkali. It is now 
called sulphurated hydrogen gas. 
HEPATIC A. See Anemone. 
HEPATITIS. See Medicine. 
5 Y 2 
HEPTAGON, in geometry, a figure of 
seven sides and seven angles. When those 
sides and angles are all equal, the heptagon 
is said to be regular, otherwise it -is irregular. 
In a regular heptagon, the angle C, Plate 
Miscel. fig. 122, at the centre is 51°-3., the 
angle DAB of the polygon is — 128°^., and its 
half CAB = (>4 r '-j. Also the area is — the square 
of the side AB 2 * 4 * x 3.6339124, or — AB 2 X 
where t is the tangent of the angle CAB of 64°^. 
to the radius 1; or £>is the .root of the equation; 
t u — ‘26t'° -f l'43t 8 * * * * * * — 245/ 6 -|- 143P — -f- 
1 = 0 ; or t — y* 
1 -f- .v 
1 X 
1 + v'i - y 
y 
— , where the value of x and j are 
tire roots of the equations 
V — 5 M -f f V — 1 =1 0, 
4 15 4 6 
/ = i y* + 1 y 2 — - 6 7 T = °- 
- Heptagon, in Fortification, a place fortified 
or strengthened with seven bastions for its de- 
fence. 
IIEPTAGONAL, Numbers, are a kind of 
polygonal numbers in which the difference of 
the terms of the corresponding arithmetical pro- 
gression is 5. Thus, 
Arithmetical®, 1, 6, 11, 16, 21, 26, Ac. 
Heptagonals, 1, 7, 18, 34, 55, 81, & c. 
where the heptagonals arc formed by adding 
continually the terms of the ai'ithme'dcals, above 
them, whose common difference is 5. 
One property, among many others, of these 
heptagonal numbers is, that if any one of them 
be multiplied by 40, and to the product add 9, 
the sum will be a square number. 
Tlius 1 X 40 4- 9 — 49 = 7 2 ; 
and 7 X 40 -j- 9 = 289 = 17 2 ; 
and 18 X 40 4- 9 =: 729 27 2 ; 
and 34 X 40 -j- 9 = 1369 =. 37 2 ; Ac. 
Where it is remarkable that the series of squares 
so formed is 7 2 , 17 2 , 27 2 , 37 2 , Ac , the common 
difference of whose roots is 10, the double of the 
common difference of the arithmetical series 
from which the heptagonals are formed. See 
Poi.ygo-nals. 
HEPTAMERIS, in music, the seventh 
part of a meris, being, according to M. Sau- 
veur, the forty-third part of the octave. 
HEPTANDRIA, from «n>«, septem, and 
a ytp, a man, the seventh class in Linnaeus’s 
sexual method, consisting of plants with her- 
maphrodite flowers, which have seven stamina 
or male organs. The orders are four, derived 
from the number of styles or female organs. 
See Botany. 
HEPTANGULAR figure, in geome- 
try, is one that has seven angles, and there- 
fore also seven sides. 
HERACLEUM, a genus of the pentan- 
dria digynia class of plants, the general flower 
of which is dilform and radiated ; the single 
flowers of the disc consist each of live equal 
petals, but those of the radius consist of live 
unequal petals, The fruit is elliptic, com- 
pressed, and striated on each side in the 
middle, and contains two oval compressed 
seeds. To this genus belongs the spflondy- 
lium or cow’s parsnep of authors, There are 
six species, 
IiERACLIDiE, or return of the Hera- 
cudte into Peloponnesus, in chronology, a 
famous epocha, that constitutes the begin- 
ning of prophane history; all the time pre- 
ceding that period being accounted fabulous. 
This return happened in the year of the 
world 2S62, an hundred years after they 
