DICTIONARY 
OF 
i 
ARTS AND SCIENCES. 
ABA 
A the first letter of the alphabet, is used, 
, } on many occasions, as a mark, or ab- 
breviation. T hus, in the calendar, it is the 
first of the dominical letters: among logi- 
cians, it denotes an universal affirmative 
proposition : as a . numeral, A signified one 
ajmong the Greeks ; but among the Homans 
it denoted 500, and with a dash over it, 
thus, a, 5000. The Romans also used it on 
public occasions for antiquare, to antiquate 
or reject a proposed law ; as did the judges 
of the same people for absolvo, I absolve or 
acquit; Whence it had the name of liter a 
satularis. A is frequently also met with, 
denoting Aldus, Augustus, Ager, Aiunt, tk c. 
A. A. stands for August i ; A. A. A. for aunun, 
argentum as ; and, among chemists, for 
amalgama. A.M. is used for anno mundi, ar- 
tium magister, or ante meridiem ; A.A.U.C. 
for anno ab urbe condita; A.B. for alia 
1mm, or artium baccalaureus ; A.C. for acta 
causa, alius civ is, or ante Christum ; and 
A.D. for anno domini. On antient medals, 
A stands for. Argus , and sometimes for 
Athens ; but on French coins of modern 
date, it is the mark of the mint of Paris. A, 
a, or ad, among physicians, denote ana, or 
an equal weight or quantity of several in- 
gredients. The letter A is also used by mer- 
chants, to signify accepted. 
AAM, a measure of capacity used by the 
Dutch, otherwise called Imam ; it contains 
128 mingles, or 288 English pints. 
AAVORA, a fruit of a kind of palm-tree, 
found in the West Indies and in Africa.. It 
is of the size of a hen’s' egg, and is included 
with others in a large shefl. In the middle 
of the fruit there is a hard nut, which con- 
tains a white almond, very astringent, and 
used in cases of diarrhoea. 
AB, in the Hebrew chronology, the ele- 
venth month of the civil, and the fifth of the 
ecclesiastical year ; it comprehended part of 
July and August, and contained thirty days. 
ABAC AT U A1 A. See Zeus. 
ABACK, a sea term,' which signifies the 
situation of the sails in a ship, when the sur- 
faces are driven by the wind fiat against. the 
mast. They may be brought aback by a 
sudden change ot the wind, or an alteration 
in the ship’s course.. 
ABA 
ABACOT, the name of the antient co- 
ronet, or cap of state, worn by the English 
kings, the upper part of which was made up 
in the form ol a double crown. 
ABACTORS, drivers away and stealers 
of cattle in herds, or great numbers. In 
Spain this crime is very common, and the 
punishment severe. 
ABACUS, in architecture, the uppermost 
member of the capital of a column. In the 
Tuscan, Doric, and Ionic orders, the abacus 
is flat and square ; but in the richer orders, its 
four sides, or faces, are arched inwards, with 
some ornament, as a rose or other flower, in 
the middle of each arch, and its four corners 
cut off. 
According to Vitruvius, the abactis was 
originally intended to represent a square flat 
tile, laid over an urn or a basket. The in- 
vention is ascribed to Callimachus: who ob- 
served a small basket covered with a tile, 
over the root of an acanthus plant which 
grew on the grave of a young lady ; the 
plant shooting up encompassed the basket, 
till meeting the tile, it turned back in the 
form of scrolls. The philosopher took the 
hint, and executed a capital on this plan, 
representing the tile by the abacus, the 
leaves of the acanthus by the volutes, and 
the basket by the body of the capital. See 
Architecture. 
Seamozzi also uses abacus for a concave 
moulding in the capital of the Tuscan pe- 
destal. 
Abacus, or Abaciscus, in the antient 
architecture, likewise denoted certain com- 
partments in mosaic pavements, and the like. 
Abacus, among the antient mathemati- 
cians, was a table strewed over with dust, or 
sand, on which they drew their figures or 
schemes. 
Abacus, an instrument for facilitating the 
operations, of arithmetic, by means of count- 
ers.. Its form is various ; but that chiefly 
used in Europe, is made by drawing parallel 
lines, distant from each other at least twice 
the diameter of a counter ; which placed on 
the lowermost line, signifies 1 ; on the se- 
cond, 10; on the third, 100; on the fourth, 
1000 ; and so on. Again, a counter, placed 
in the spaces between the lines, signifies only 
ABA 
the half of what it would do on the next su- 
perior line. According to this notation, the 
same number, 1806 for example, may be 
represented by different dispositions of 
counters. See A and B, in Plate IX. fig. 1. 
Abacus pt/thagoricus, a multiplication- 
table, or a table of numbers ready cast up, 
to facilitate operations in arithmetic. 
Abacus logisticus, is also a kind of mul- 
tiplication-table, in form of a right-angled, 
triangle ; each side contains the numbers 
from 1 to 60, and its area the product of 
each two opposite numbers. 
ABAFT, in sea language, a term applied 
to any thing situated towards the stern of a< 
vessel: thus, a thing is said to be abaft the 
foremast, or main-mast, when placed be- 
tween the fore-mast, or main-mast, and the 
stern. 
Abaft the beam, denotes the relative si- 
tuation of any object with the ship, whim it 
is placed in that part of the horizon which is- 
contained between a line at right angles with 
the keel, and. that point of the compass- 
which is directly opposite to the ship’s 
course. 
ABACI, a silver coin, current in Georgia, 
worth about 18 pence. 
ABA RCA, a kind of shoe, made of raw 
hides, formerly worn by the peasants of 
Spain. Some mention another kind of abar- 
ca, made of wood, like the French sabots. 
ABAS, a Persian weight, used in weighing 
pearls. It is one-eighth less than the Euro- 
pean carat. 
ABASED, abaisse, in heraldry, is said of 
the wings of eagles, &c. when the tip inclines, 
downwards to the point of the shield; or 
when the wings are shut ; the natural way of 
bearing them being spread. A chevron d, 
pale, bend, &c. are also said to be abased,, 
when their points terminate in or below the 
centre of the shield. Lastly, an abased or- 
dinary, is one placed below its due situation. 
ABASSI, or Abassis, a silver coin, cur- 
rent in Persia, worth from 16 to 18 pence 
English. It derives its name from Shak 
Abbas II. under whom it was first struck. 
ABATE, in the manege. A horse is said 
to abate, or take down his curvets, when he 
puts both his lund-legs to the ground, at 
