AOR 
prove their subject, and greatly heighten 
the pleasure of the reader, by the pleasing 
opposition of their characters and descrip- 
tions. 
The beautiful antithesis of Cicero, in his 
second Cartilinarian, may serve for an ex- 
ample : “ On the one side stands modesty, 
on the other impudence ; on the one fide- 
lity, on the other deceit; here piety, there 
sacrilege ; here continency, there lust, Sec. 
And Virgil, in his admirable description of 
Dido’s despair, the night before her death, 
represents all the rest of the creation enjoy- 
ing profound tranquillity, to render the dis- 
quietude of that miserable queen the more 
affecting. 
ANTOECI, in geography, an appellation 
given to those inhabitants of the earth who 
live under the same meridian, but on diffe- 
rent sides of the equator, and at equal dis- 
tances from it. 
These have noon, and midnight, and all 
hours at the same time, but contrary sea- 
sons of the year ; that is, when it is spring 
with the one, it is autumn with the other ; 
when summer with the one, winter with the 
other. And the days of the one-are equal 
to the nights of the other, and vice versa. 
ANTONOMASIA, in rhetoric, a figure 
by which the proper name of one thing is 
applied to several others ; or, on the con- 
trary, the name of several things to one. 
Tnas we call a cruel person, a Nero ; and 
we say the philosopher, to denote Aristotle. 
ANTS, acid of. See Formic acid. 
ANVIL, an iron instrument on which 
smiths hammer or forge their work, and 
usually mounted on a firm wooden block. 
A forged anvil is reckoned better than one 
of cast work. 
ANUS, in anatomy, the extremity of the 
intestinum rectum, or orifice of the funda- 
ment. See Anatomy. 
AORIST, among grammarians, a tense 
peculiar to the Greek language, compre- 
hending all the tenses ; or rather, express- 
ing an action in an indeterminate manner, 
without any regard to past, present, or future. 
AORTA, in anatomy, called also arteria 
magna, a large artery arising with a single 
trunk from the left ventricle of the heart 
above its valves, called semilunares, and 
serves to convey the mass of blood to all 
parts of the body. 
After ascending a little upwards, its trunk 
is bent, in manner of an arch, and from this 
part it sends, in human subjects, usually 
three ascending branches. This is called 
the aorta ascendens. 
APH 
The descendens is that part of the trunk 
which, after the arch-like inflection, descends 
through the thorax and the abdomen down 
to the os sacrum, and is usually larger in 
women than in men. The aorta hath four 
tunics, a nervous, a glandulous, a muscular, 
and a membranous one. See Anatomy. 
APACTIS, in botany, a genus of the Do- 
decandria Monagynia class and order. No 
calyx ; petals four, crenate, unequal ; germ 
superior ; fruit. There is but a single spe- 
cies, viz. the Japonica, a tree found, as its 
name imports, in Japan. 
APALUS, in natural history, a genus of 
insects of the order Coleoptera. Gen. char, 
antennae filiform ; feelers equal, filiform ; 
jaw horny, one-toothed; lip membrana- 
ceous, truncate, entire. There are two spe- 
cies, maculatus and the bimaculatus. 
APARGIA, in botany, a genus of the 
Syngenesia /Equalis class and order. Recep- 
tacle naked ; calyx imbricate ; down fea- 
thery, sessile. There are 17 species. 
APATITE, in mineralogy, one of the 
species of the Phosphates, occurs in tin 
veins, and is found in Cornwall and Ger- 
many. Colours white, green, blue, and red, 
of various shades. The primitive form of 
its crystals is a regular six-sided prism. 
Specific gravity between 2.8 and 3.2. 
When laid on ignited coals it emits a green 
light, and is almost entirely soluble in nitric 
acid. By rubbing it shews signs of elec- 
tricity. It was formerly considered as a 
species of schorl, afterwards, on account of 
its colour and crystallization, it was arrang- 
ed with beryll ; others described it as fluor, 
but Werner soon found that it was a new 
species. Its fallacious resemblance to other 
minerals induced Werner to give it this 
name, which is derived from anaiaw , “ to 
deceive.” 
APE. See Simia. 
APETALOSE, or Apetalous, among 
botanists, an appellation given to such plants 
as have no flower leaves. 
APEX, in antiquity, the crest of a hel- 
met, but more especially a kind of cap 
worn by the flamens. 
APH/ERESIS, in grammar, -a figure by 
which a letter or syllable is cut off from the 
beginning of a word. 
Apiizeresis, that part of surgery which 
teaches to take away superfluities. 
APUELIUM, or Aphelion, in astro- 
nomy, is that point in any planet’s orbit, in 
wliich it is farthest distant from the sun ; 
being in the new astronomy, that end of the 
