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A Q U 
A R JE 
A R A 
AQUARTIA, in botany, a genus of the 
class and order, tetandria nionogynia. The 
'essential character is, calyx bell-shaped, co- 
rolla wheel-shaped, with linear divisions, 
berry many seeded. There is one species, 
a native of South America. 
AQUATINTA, a method of engraving 
which very much resembles drawing in In- 
dian ink. This process consists in corroding 
the copper with aqua-fortis, in such a manner, 
that an impression from it has the appearance 
of a tint laid on the paper. This is effected 
by covering the copper with a substance, 
which takes a granulated form, so as to pre- 
vent the aquafortis from acting where the 
particles adhere, and by this means cause it 
to corrode the copper partially, and in inter- 
stices only. When these particles are ex- 
tremely minute, and near to each other, the 
impression from the plate appears to the 
naked eye like a wash of Indian ink. But 
when they are larger, the granulation is more 
distinct*, and as this may be varied at plea- 
sure, it is capable of being adapted to a va- 
riety of purposes and subjects. 
The matter generally used for this purpose, 
is composed of equal parts of asphalt um and 
transparent rosin, reduced to powder and 
sifted on the plate, (which has been previ- 
ously greased) through a tine sieve. The 
plate is then heated so as to make the powder 
adhere, and the artist scrapes it away when 
a verv strong shade is wanted, and covet* 
those "parts with varnish where he wishes a 
very strong light to appear. The aqua fortis 
properly diluted with water, is then put on 
within a fence of wax, as in common etching 
for engraving, and by repeated applications, 
covering the light parts still with varnish, 
the effect is produced. 
AQUEOUS humour, in anatomy, called 
also the albugineous matter, is the front of 
the three humours of the eye, and rills up 
the space between the cornea and crystalline. 
AQUILA, in astronomy, a constellation of 
the northern hemisphere, consisting of fif- 
teen stars in Ptolemy’s catalogue, of seven- 
teen in Tycho’s, and of seventy-one in the 
Britannic catalogue. 
AQUILARIA, a genus of the class and 
•rder decandria monogynia. The essential 
character is, calyx five cleft ; corolla, none ; 
nectarium pitcher shaped, half five cleft 
with bifid clefts; capsula superior, woody, 
two celled, two valved ; seeds solitary. 
There is only one species, a large tree, 
a native of the mountains of Malacca and 
Cochin China. The lignum aloes, or aloes 
wood, is a resinous matter produced by a 
disease in this tree, which finally kills it. The 
lignum aloes is highly esteemed in the east 
as a perfume, and from the bark of this tree 
is made the common paper, which the Co- 
chin-Chi nese use for writing. 
AQUILEGIA, Columbine, in botany, 
a genus of the pentagynia order, belonging 
to the polyandria class of plants ; and, in the 
natural method, ranking under the sixteenth 
order, Multisiliqua;. It has no calyx; the 
petgls are live, with a horn-iike nectarium 
inserted between each ; and there are five 
separate capsules. There are five spe- 
cies: 
L Aquilegia Alpina, grows naturally in 
Yorkshire. The flowery are much larger 
than those of the garden columbine. 
2. Aquilegia Canadensis, or Canada co- 
lumbine, flowers almost a month before the 
other sorts. 
3. Aquilegia Inversa, or garden colum- 
bine. Of this there are great varieties ; the 
colours are chesnut, blue, red, and white, 
and some are finely variegated. 
4. Aquilegia Vulgaris, or wild columbine, 
with blue flowers, is found growing wild in 
some woods of England. 
5. Aquilegia, viridiflora. 
AQUILICIUM, or Aquiliciana, in Ro- 
man antiquity, sacrifices performed in times 
of excessive drought, to obtain rain of thegods. 
ARA, in astronomy, a southern constel- 
lation, containing eight stars. 
ARABESQUE, or Moresque, denotes 
a style of painting, or of sculpture, so called 
from. the Arabians and Moors, who employed 
certain ornaments for want of human and 
animal representations, which their religion 
prohibited them from using. 
ARABIC characters or figures, are the 
numerical characters made use of in all our 
arithmetical computations. 
Arabic, gum, the name of a gum which 
distils from a species of mimosa. It is very 
common among us, but little is to be met 
with genuine; that is accounted the best 
which is in smaller pieces, and almost of a 
white colour. It is useful in all kinds of 
fluxes, paritcularly catarrhs. 
ARABICI, a sect of Christians, who held 
that the soul both dies and rises again with 
the body. 
ARABIS, bastard tower-mustard : a genus 
of the siliquose order, belonging to the tetra- 
dynamia class of plants ; and in the natural 
method ranking under the 39th order, sili- 
quose. The generic mark consists in 4 nec- 
tiferous glands which lie on the inside of 
each leaf of the calyx. There are 1 4 species ; 
but none of them remarkable for their beauty 
or their properties. Only one of these, viz. 
Arabis thaliana, or the mouse-ear, is a 
native of Britain. It grows naturally on 
sandy ground, or old walls. 
A R AC HIS, in botany, a genus of the 
diadelphia-decandria class of plants, the flower 
of which is papilionaceous, and consists of 
three petals ; and its fruit is an oblong uni- 
locular pod, contracted in the middle. There 
are 2 species chiefly cultivated in Peru, Brasil, 
and Carolina, for the seed, which constitutes 
a considerable article of food for the negroes. 
This seed is a kind of nut, which is perfected 
in a most extraordinary manner ; for as soon 
as the flower falls off, "the germ thrusts itself 
into the ground, and there the pod is formed 
and ripened, whence the popular name 
ground-nuts. 
ARACHNOIDES, in zoology, a name 
given to shose echini marini, or sea-hedge- 
hogs, which are of a circular form, but 
variously indented at the edges. 
Arachnoides, is a also a species of Ma- 
drepora, found fossil. The stars are very 
small, crowded, and flattened ; rays undu- 
lated, short and equal. 
Arachnoides, in anatomy, an appel- 
lation given to several different membranes, 
in the tunic of the crystalline humour of the 
eye, the external lamina of the pia mater, 
and one of the coverings of the spinal mar- 
row. 
ARAEOMETER, an instrument to mea- 
sure the gravity of liquors, which is usually 
made of a thin glass ball, with a taper neck, 5 
sealed at the top, there being first as much 
mercury put into it as will keep it swimming 
in an erect posture. The neck is divided 
into parts, which are numbered, that so !>y I 
the depths of its descent into any liquor, its 
lightness may be known by these divisions, 
for that fluid in which it sinks the least, must 
be heaviest, and that in which it sinks low- 
est is the lighest. See Hydrometer. 
AR iEOST Y LE, in architecture, a term 
used by Vitruvius, to signify the greatest inter- j 
val which can be made between columns, I 
which consists of eight modules or four dia- | 
meters. 
ARAIGNEE, in fortification, signifies the : 
branch, return, or gallery of a mine. 
ARALIA, in botany, a genus of plants j 
with ro.aceous flowers, and succulent ber- j 
lies, containing each a single oblong, and ! 
hard seed. It belongs to the pentandria- j 
pentagi/nia class of Linnaius. The essential j 
character is flowers, in an umbellule, with an j 
involucrum ; cal. 5 toothed superior; cor. 5 
petalled ; berry 5 seeded. There are 9 species, I 
most of them shrubs and natives of China ■ 
and America; some are hardy enough to 
stand our climate in sheltered situations. 
ARAMPO, or Man-eater, a name given 
by the negroes oh the coast of Africa, to a 
long slender animal, in shape resembling a j 
weasel, with a long tail, and large brush at 
its extremity. It takes its name from digging 
up graves and devouring human flesh. 
ARANEA concha, the spider-shell, a name 
given to several kinds ofmurex. 
Aranea, a genus of apterous insects, well 
known by the common name of spider. The j 
mouth is furnished with short horny jaws ; I 
lip rounded at the apex ; feelers two, in- j 
curved, jointed, v r y acute at the tip, clubbed \ 
with the genitalia in the male ; no antennae ; ] 
the eyes are eight, or rarely six ; feet eight, j 
the anus furnished with papilla', or teats for 
spinning. r l hey iix the ends ot their threads 
by applying these nipples to any substance, 
and the thread lengthens in proportion as 
the animal recedes from it. r I hey can stop ; 
the issuing of the threads by contracting the j 
nipples, and rcascend by means of the claws! 
on their feet, much in the same manner 
as sailors warp up a rope. 
The darting out of long threads, which has 
been observed by naturalists, and by means 
of which some species of spiders can convey] 
themselves to great distances, deserves par- 
ticular notice. Dr. Lister tells us, that at- 
tending closely to a spider weaving a net, he 
observed it suddenly to desist in the mid- 
work ; and turning its tail to the wind, it 
darted out a thread with the violence and 
stream we see water spout out of a jet: this 
thread, taken up by the wind, was immedi- 
ately carried to some fathoms loug ; still 
issuing out of the bellv of the animal. By- 
and-by the spider leaped into the air, and 
the thread mounted her up swiftly. After 
this discovery, he made the like observation 
on near thirty different species of spiders ; and 
found the air filled with young and old, sail- 
ing on their threads, and doubtless seizing 
gnats and other insects in their passage, there 
being often manifest signs of slaughter, legs,, 
and wings of flies, & c. on these threads, as 
well as in their webs below. The matter of 
which the spider’s threads are formed, is a 
viscid juice, elaborated in the body of the 
