ABE 
3 
ABE 
whereas abdication is done without any such 
view In this sense, Dioclesian is said to 
hare abdicated the crown; hut Philip IV. of 
Spun resigned it. The parliament of Eng- 
lani voted that James li. having endea- 
voured • to subvert the constitution of the 
kingdom, had abdicated the government, 
and that the throne was thereby vacant. 
Abdication is also used by civilians, 
for a father’s discarding his son. This, 
cal ed likewise a famiiia alienatio, was dif- 
ferent from exheredation, or disinheriting, as 
being done in the father’s life time ; whereas 
exheredation never took place till his death: 
so that an abdicated son was actually disin- 
herited, but not vice versa. 
Abdication, among the Romans, was 
also used for a citizen's renouncing Iris li- 
berty, and voluntarily becoming a slave. 
ABDOMEN, the lower part of the trunk 
of the body, reaching from the thorax to the 
bottom of the pelvis. See Anatomy. 
For diseases and wounds of the abdomen, 
See Medicine and Surgery. 
ABDUCTION, in logic, a form of rea- 
soning called by the Greeks apagogue ; by 
which from a certain or undeniable proposi- 
tion, we infer the truth of something sup- 
posed to be contained in that proposition : 
thus in this syllogisn : 
Whatever God has revealed is certainly 
true : 
Now, God has revealed a future retribu- 
bution ; 
Therefore a future retribution is certainly 
true. 
In arguments of this kind, it is always ne- 
cessary to prove the minor proposition to be 
contained in the major, or undeniable one, 
otherwise the reasoning loses all its force. 
Abduction, in surgery, a kind of frac- 
ture, wherein the bone being entirely broken 
near a joint, the two stumps recede consi- 
derably from each other, bee Surgery. 
ABDUCTOR, or Abducent, in anato- 
niv, a name given to several muscles on ac- 
count of their serving to withdraw, open, or 
pull back the parts to which they are lixed. 
See Anatomy. 
ABEL-TREE. See Populus. 
ABELONIANS, a sect of heretics, called 
ids.) abelians an d+abelaite$, whose distin- 
guishing doctrine was to marry, and yet live 
in professed abstinence ; a tenet which, ac- 
cording to some authors, they founded on 
that text, 1 Cor. vii. 29- Let them that have 
wives be as though they had none. To per - 
petuate the sect, they allowed each man and 
woman to adopt a boy and a girl, who were to 
be their heirs, and who were to marry under 
the same obligation of continence. 
ABERRATION, in astronomy, an appa- 
rent motion of the celestial bodies, occasion- 
ed by the progressive motion of light, and 
the earth’s annual advance in her orbit. 
This effect may be explained by the mo- 
tion of a line parallel to itself, in a way si- 
milar to the explanation of the composition 
and resolution of forces in mechanics. Let 
the proportion of the velocity of a ray of 
light, to that of the earth in her orbit, be as 
BC (see Plate IX. figure 2.) to the line AC; 
then, by the composition of these two mo- 
tions, the ray will seem to describe BA or 
DC, instead of its real course BC, and will 
appear in the direction A B, instead of its 
true direction C B. Therefore if AB repre- 
sent a tube, carried with a parallel motion by 
an observer along the line A C, in the time 
that a particle of light would move over the 
space B C, the different places of the tube 
being Ab, ab, c d, C D ; and when the eye, 
or end of the tube, is at A, let a particle of 
light be supposed to enter at B ; then when 
the tube is at a b, the particle will be at e, in 
the axis of the tube ; and when the tube is at 
c d, the particle of light will be at/; and 
when the tube has arrived at C D, the par- 
ticle will be at C, and will appear to come in 
the direction DC of the tube, instead of the 
true direction BC. Thus one particle suc- 
ceeding another, forms a continued stream 
of light in the apparent direction DC. So 
that the apparent angle made by the ray of 
light with the line A E, is the angle D C E, 
instead of the true angle BCE; and the 
difference BCD, or A B C, is the quantity 
of the aberration. 
We are indebted for this great discovery 
to the late Dr. Bradley, astronomer royal, 
who was led to it by the result of observa- 
tions made with a view of determining the 
annual parallax of the fixed stars, or that 
which arises from the motion of the earth in 
its annual orbit about the sun. See Paral- 
lax. 
Aberration of the Planets, is equal to 
the geocentric motion of the planet, or the 
space it appears to move as seen from the 
earth, during the time that the light em- 
ploys in passing from the planet to the earth. 
Thus in the sun, the aberration in longitude 
is constantly 20" ; that being the space mov- 
ed by the sun, or, which is the same thing, 
by the earth, in eight minutes and seven se- 
conds, which is the time that light takes in 
passing from the sun to the earth. Hence 
the aberration of the other planets is found : 
for knowing the distance of the sun from the 
earth, it will be by common proportion, as 
the distance of the earth from the sun is to 
the distance of the planet, so is 8' 7" , to the 
time of light’s passing from the planet to the 
earth ; then computing the planet’s geocen- 
tric motion in this time, that will be the 
aberration of the planet, whether it be in 
longitude, latitude, right ascension, or de- 
clination. 
The aberration will be greatest in the lon- 
gitude, and very small in latitude, because 
the planets deviate very little from the plane 
of the ecliptic ; so that the aberration in the 
latitude ot the planets may be neglected as 
insensible; the greatest in Mercury being only 
4j", and much less in the other planets. The 
aberration in declination and right ascension, 
depend on the situation of the planet in the 
zodiac. The aberration in longitude, being 
equal to the geocentric motion, will be more 
or less, according as that motion may be. It 
will be least when the planet is stationary ; 
and greatest in the superior planets, when 
they are in opposition; but in the inferior 
planets the aberration is greatest at the time of 
their superior conjunction. The maxima of 
aberration for the several planets, when their 
distance from the sun is least, are as follow 
Saturn - - - 21' 0 
Jupiter - - - 29 8 
Mars - - - 37 8 
Venus - - - 43 2 
Mercury - - - 59 0 
The Moon - 0 40 
Between these numbers and nothing, the 
A 2 
A B I 
aberrations of the planets in longitude vary 
according to their situations. But that of the 
sun is always 20 // : the sun may, however, 
alter his declination by a quantity which 
varies from 0 to nearly 8", being the greatest 
about the equinoxes, and vanishing in the 
solstices. _ 
Aberration, in optics, a deviation of 
the rays of light, whereby they are pre- 
ventecl from meeting in the same point. 
Aberrations are of two kinds ; one arising 
from the figure of the reflecting body, the 
other from the different refrangibility of the 
rays themselves : this last is called the New- 
tonian aberration, from the name of the 
discoverer. 
With regard to the former species of 
aberration, or that arising from the figure, 
we may observe, that if rays issue from a 
point at a given distance, then they will be 
reflected into the other focus of an ellipse, 
when the luminous point is^ in one focus ;"br 
directly from the other focus of art hyper- 
bola, and will be variously dispersed by all 
other figures. If the luminous point is in- 
finitely distant or the incident rays parallel, 
then they will be reflected by a parabola into 
its focus. These figures being difficult to 
form, curved specula are commonly made 
spherical ; the figure of which is generated 
by the revolution of a circular arc, which 
produces an aberration of all rays, whether 
they are parallel or not : and therefore it has 
no accurate geometrical focus, which is com- 
mon to all rays. 
Aberration, croton of, is a luminous 
circle about the real disk of the sun, and 
depending on the aberration of the solar 
rays, by which his apparent diameter is en- 
larged. 
ABETTOR, or Abbettor, the person 
who promotes a crime or procures it to be 
committed : thus, an abettor of murder is 
one who commands or counsels another to- 
commit it. An abettor, according as he is 
present or absent, at the time of committing 
the fact, is punishable as a principal or ac- 
cessary. 
An abettor is the same with one who is 
deemed art and part by the law of Scotland. 
ABEYANCE, Abeiance, or Abbay- 
ance, in law, the expectancy of an estate 
or possession : thus, when a parson dies, the 
fee of the glebe belonging to his church is 
said to be in abeyance during the time the 
parsonage is void, 
It is a fixed principle of law, that the fee- 
simple of all lands is in somebody, or else 
in abeyance. 
ABHORRERS, a name given to a party 
in England about the year 1680, in opposi- 
tion to those who petitioned for a redress of 
grievances. 
ABIB, the first month of the ecclesiastical- 
year among the Hebrews. It was after- 
wards called Nisan, and answered to our 
March. 
ABIGEAT, abigeatus, the crime of steal- 
ing or driving oil' cattle in droves, otherwise 
called abactus. It was more severely pu- 
nished than simple theft, viz. by condemna- 
tion to the mines, banishment, or even death. 
ABILITY, in a law sense, is the power of 
doing certain actions, principally with regard 
to the acquisition or transfer of property. 
Every person is supposed to have this power* 
who is not disabled by any specific law. 
