840 A Q_ U 
whom Jupiter raviftied under the fhape of an eagle, and 
carried away into heaven to ferve as a cup-bearer, inftead 
of Hebe and Vulcan; whence the name. Others hold,, 
that the figrr was thus called, becaufe that, when it appears 
in the horizon, the weather commonly proves rainy. The 
ffars in the conffellation Aquarius, are, in Ptolemy’s cata¬ 
logue, forty-five; in Tycho’s, forty-one; in Hevelius’s, 
forty-feven; and, in Flamffead’s, 108. 
AQUAR'TIA,/. [fo named by Jacquin, in honour of 
his friend Aquart , merchant of Martinico, who alfifted him 
in his botanical refearches.] In botany, a genus of the te- 
trandria monogynia clafs, ranking in the natural order of 
foianeie. The generic characters are—Calyx : perianthi- 
um monophyllous, permanent; tube bell-fhaped; limb 
fubquadrifid, expanding^ two oppolite divifions obfolete. 
Corolla: monopetalous, rotate; tube very flrort; limb 
quadrifid ; divifions linear, widely fpreading. Stamina : 
filaments fiiort; anther® eredl, very large, linear. Piftil- 
Jum : germ ovate ; (iyle filiform, declined, the length of 
corolla; (tigma (imple. Pericarpiurri: berry globular, 
one-celled. Seeds: very many, comprefled— EJ/entiai Cha- 
raEler. Calyx, bell-fhaped ; corolla, wheel-fliaped with 
linear divifions; berry, many-feeded. 
There is but one fpecies, known by the name of aquar- 
tia aculeata. It is a perennial aculeate plant, unarmed at 
top. Leaves alternate, ovate, obtufe, petioled. The na¬ 
ture of Jolanum. A native of South America. Swartz is 
of opinion, that it is rather a fpecies of folanum, with four 
ftamens to the flower ; differing from it in number, in the 
fegments of the corolla being linear, and the calyx bell- 
fhaped ; the habit however is quite the fame. 
AQUA'TIC, adj. [ aquaticus , Lat. from aqua, water.] 
That which inhabits the water.—The vaft variety of 
worms found in animals, as well terreftrial as aquatic, are 
taken into their bodies by meats and drinks. Ray. —Ap¬ 
plied to plants, that which grows in the water. — Flags, and 
fuch-like aquatics, are heft deftroyed by draining. Mortimer. 
A'QTJATILE, adj. \_aquatilis, Lat.] That which inha¬ 
bits the water.—We behold many millions of the aquatile 
er water frog in ditches and (landing plafhes. Brown. 
AQUATIN'TA ,f. a method of etching on copper, 
lately invented, and by which a foft and beautiful effedt 
is produced, refembling a fine drawing in water-colours or 
Indian ink. Previous to the operation upon the plate, the 
following powder muft he prepared. Take equal parts of 
afphaltum and fine tfanfparent rofrn, and powder them fe- 
parately in a mortar. Through a muflin lieve fift upon a 
fheet of paper a thin flratum of the afphaltum, above 
which fift a fimilar layer of the rofin, and upon this ano¬ 
ther layer of afphaltum, continuing thefe alternate layers 
till both of the powders are exhaufted. Then pafs the 
mixture both together through the fame fieve fo as to mix 
them fufficiently for life. Some, inflead of the above mix¬ 
ture, ufed powdered gum fandarach only. 
The procefs is as follows: A copper plate being polifhed 
in the ufual way, lay the etching-ground upon it, and etch 
the outlines of your delign in the manner diredled under 
the article Etching. The ground is then to be foftened 
with a little greafe,. and wiped off' with a piece of rag ; 
leaving, however, as much greafe upon the plate as juft to 
dim the copper. Next fift the powder upon the furface 
of the plate; after which, ftrike the other fide of it pretty 
fmartly again!! the edge of a table to difeharge it of the 
loofe powder. This done, with a hand-vice hold the back 
of the plate over a chaffing-dilh of burning charcoal, till 
it becomes fo hot as to give pain upon being touched with 
the back of the hand; and the powder which adhered to 
the greafe will now be fixed to the plate. The plate be¬ 
ing then- fuffered to cool, take turpentine-varnifh mixed 
'with ivory black ; and with a hair-pencil dipped in it cover 
all the lights or places where there is no work or fhade. 
A rim or border of bees-wax is now to be raifed round 
the plate ; and, having reduced a quantity of aquafortis to 
a proper fti^ength with water, pour it on, and let it (land 
five minutes for .the firfl or lighteft (hade; after which, 
A Q_ U 
pour it off; and, having wafiied the plate with water, let 
it edgewife to dry. Then with varnifh flop out all the 
light (hades, pour on the aqrta fortis for the fecond tint, 
and let it ftand five minutes more ; proceeding in the fame 
mariner for every tint till you produce the darkeft (hades. 
If a bold open ground is wanted in any part, this requires 
an after-operation. The ground muft'be laid as in the- 
other cafe, by fitting on the powder; only this powder 
. muft be much coarfer, and the plate more heated in order 
that the particles of tire powder may fpread, and form 
fmal 1 circles: even good clean rofin will do by itfelf. In 
etching landfcapes, the (kv and diftant objedts are alfo per¬ 
formed by a fecond operation, and the powder is lifted 
upon the plate with a finer fieve. If the trees or any part 
of the fore-ground require to be finifhed higher, the plate 
muft be entirely cleanfed from greafe with bread, and a 
ground laid in the common way of etching; when you 
may finifh as highly and neatly as you pleafe with the nee¬ 
dle or point, by ftippling with dots, and biting in thofe 
parts, or by a rolling-wheel, which is more expeditious. 
If different colours are to be exprelfed in aquatinta, there 
will be required fo many different plates, each having only 
that part etched upon it which is defigned to be charged- 
with its proper colour. It may happen however in parti¬ 
cular fubjedts that fome of the colours are fo diftant from 
each other as to allow the printer room to rub them in 
without blending; in which cafe, two or three different co¬ 
lours may be printed from the fame plate at once. Where 
different plates are neceffary, a feparate one, having a pin 
in each corner, muff be provided as a foie or bottom to the 
aquatinta plates; and thefe again muff be exadtly fitted, 
having each a fmall hole in their corners for palling over 
the pins of the foie : the faid pins ferving the doubfe pur- 
pofe of retaining the plates fucceffively in their due pofi- 
tion, and of directing the printer in placing the paper 
exadtly on each plate fo as not to fhift; by which means 
each tint or colour will be exadtly received on its proper 
place. This is the method pradtifed with fo much beauty 
and effedt in France. A landfcape or any fimilar fubjedt 
may be printed off at once in its different proper colours, 
by laying thefe upon the plate. In this cafe, the colours 
muff be pretty thick in their confidence; and the plate 
muft be carefully wiped in the ufual way, after the laying- 
on of each tint, as well as receive a general wipe when 
charged with all the tints. 
The art of engraving in aquatinta is kept a fecret by 
thofe artifts who pradtife it. In order to fucceed in it, great 
care and judgment are requifite; and much depends upon 
a certain nicety of management, which is only attainable 
by pradlice. 
AQUAVI'VA,\a town of the kingdom of Naples, and 
province of Barri. 
A'QUEDUCT, f. \_aqumduHus , Lat.] A conduit,, or 
conltrudtion of done or timber, built on an uneven ground, 
to preferve the level of water, and convey it, by a canal, 
from one place to another. Aquedudts are either vifible, 
or fubterraneous : vifible,.when conftrudfed above-ground, 
and fupported by arches or arcades; fubterraneous, whet} 
formed by piercing through rocks or mountains, or any 
elevated ground; which, in the conftrudtion of navigabls 
canals, is called Tunnelling.. 
Aqtiedudts were long ago the wonders of Rome; the 
quantity of them which they had; the prodigious expence 
employed in condudting waters over arcades from one place 
to another, at the diftance of even 100 miles, by cutting 
through mountains, and piercing rocks; were performances 
which juftly excite our admiration. Appias the cenfor 
advifed and conftrudfed the firft aquedudt. His example 
gave the public luxury a hint to cultivate thefe objedts; 
and the force of prodigious and indefatigable labour di¬ 
verted the courfes of rivers and floods to Rome. Agrippa, 
in that year when he was asdile, put the laft hand to 
the magnificence of thefe works. It is chiefly in this re- 
fpedl that the modern fo much refembles the ancient city 
of Rome, For this advantage, (lie is peculiarly indebted 
to 
