690 
F A JB 
FAB 
F A 
them against external injuries: so in those 
creatures whose head, like their eyes and the 
rest of their body, is soft and without bones, 
nature has provided for this necessary and 
tender organ a wonderful kind of guard, by 
enduing tue creature with a faculty of with- 
drawing his eyes into his head, and lodging 
them in the same safety within his body. 
We have a very beautiful example of this in 
snails, whose eyes are lodged in four horns, 
like atramentous spots, one at the end of 
each horn, which they can retract at plea- 
sure, when in any danger. Here it may be 
also observed, that the cornea in all ani- 
mals that want eyelids, as fishes, exeactly re- 
sembles in hardness the horn of a lanthorn ; 
and therefore is not hurt by such particles as 
their eyes are commonly exposed to. And 
in the mole, because this animal lives under 
ground, it was necessary its eyes should be 
well guarded and defended against the many 
dangers and inconveniences to which its man- 
ner of living exposes it : this is the reason 
why. its eyes are so small, and that they are 
situated so far in the head, and covered so 
strongly with hair ; and besides they can pro- 
trude and retract them at pleasure. See 
Comparative Anatomy. 
III. The third and last reflection we shall 
make upon the external motion of our eyes, 
is what regards a problem which has very 
much perplexed both physicians and philoso- 
phers, viz. What is the cause of the uniform 
motion of both eyes? 
In some creatures, such as fishes, birds, 
and among quadrupeds, the hare, cameleon, 
&c. the eyes are moved differently ; the one 
towards one object, and the other towards 
another. JBut in man, sheep, oxen, and 
dogs, the motions are so uniform that they 
never fail to turn both towards the same 
place : lienee in operations upon the eye that 
require it to be kept immoveable, sometimes 
it is necessary to tie up the sound eye with a 
compress, by which means the other is easier 
kept fixed and immoveable. . 
The final cause of this uniform motion is, 
1, That the sight may be thence rendered 
more strong and perfect : for since each eye 
apart impresses the mind with an idea of the 
same object, the impression must be more 
strong and lively when both eyes concur ; and 
that both may concur, it is necessary that 
T the sixth letter of the alphabet. As a I 
’ numeral it denotes 40, and with a dash 
over it thus F, denotes 40,000 : in music it 
stands for the bass-clef; and frequently for 
forte, as ff does for forte forte. 
F, in medicine, stands for fiat, let it be 
done: thus F. S.A. stands forfiat secundum 
artem, let it be done according to art. 
As an abbreviation, F stands for filius, fel- 
low, Ac.: thus F.R. S. signifies Fellow of the 
Royal Society. 
FA, in music, one of the syllables invented 
by Guido Aretine, to mark the fourth note 
of the modern scale, which rises thus, ut, re, 
mi, fa. Musicians distinguish two fa’s, 
viz. the flat, marked with a b, or ; and 
they move uniformly ; for though the retina, 
or immediate organ of vision, is expanded 
upon the whole bottom of the eye, as far as 
the ligamentum ciliare, yet nothing is clearly 
and distinctly seen but what the eye is di- 
rected to. 2. A second advantage we, reap 
from the uniform motion of the eyes, which 
is more considerable than the former, consists 
in our being thereby enabled to judge with 
more certainty of the distance of objects. 
See Optics. 
There is yet another advantage, full as 
considerable as any of the former, that is 
thought to arise from the uniform motion of 
our eyes, and that is, the single appearance 
1 of objects seen with both our eyes ; which, 
though at first view it does not appear pro- 
bable, is true : for if in looking at an object 
you turn one of your eyes aside with 
your linger, and alter its direction, every 
thing will be seen double. 
By the internal motions of the eye we un- 
derstand those motions which only happen 
to some of its internal parts, such as the 
crystalline and iris; or to the whole eye 
when it changes its spherical figure, and be- 
comes oblong or fiat. The internal motions 
of our eyes are either such as respect the 
change of conformation that is necessary for 
seeing distinctly at different distances, or 
such as only respect the dilatation and con- 
traction of the pupil. 
That our eyes change their conformation, 
and accommodate themselves to the various 
distances of objects, will be evident to any 
person, who but reflects on the manner and 
most obvious phenomena of vision. 
Authors are very much divided in their 
opinions with regard to the mechanism by 
which this change is introduced, as well as 
what parts it consists in : for some are of opi- 
nion that the whole globe changes its form, 
by being lengthened into an oblong figure 
when objects are near, and by becoming fiat 
when they are removed to a greater dis- 
tance ; and others are of a quite contrary 
opinion. 
"With regard to the change of the crystal- 
line, and the mechanism by which it is pro- 
duced, some maintain, that according as ob- 
jects are at different distances this humour 
becomes more or less convex, which does in- 
deed very well account for distinct vision at | 
the sharp or natural, marked thus , and 
called biquadro. 
Fa fin'to, a feigned F, or a feint upon 
that note: this is the case of every note that 
has the mark t> before it ; but more espe- 
cially mi and si, or our E and B, and is what 
we commonly call the flat of any note. 
FABA, the bean. See Vicia. 
FABLE, fabula, a tale or feigned narra- 
tion, designed either to instruct or amuse, 
disguised under the allegory of an action. 
See. Fables were the first pieces of wit that 
made their appearance in the world, and 
have been still highly valued, not only in 
times of the greatest simplicity, but among 
the most polite ages of the world. Jotham’s 
all distances ; for objects painted on a sheet 
of white paper, by means' of a lens placed in 
the hole of a window-shutter, in a dark 
room, have their images always distinct, at 
whatever distance they may be from the win- 
dow, provided the lens is of a convexity an- 
swerable to that distance. 
Eye, in architecture, is used to signify 
any round window, made in a pediment, an 
attic, the reins of a vault, Ac. 
Eye of a dome, an aperture at the top of 
a dome, as that of the Pantheon at Rome*- ] 
or of St. Paul’s at London : it is usually co- 
vered with a lanthorn. 
Eye of the volute, in architecture, is the 
centre of the volute, or that point in which 
the helix, or spiral of which it is formed, 
commences : or it is the little circle in the 
middle of the volute, in which are found the 
thirteen centres for describing the circum- 
volutions of it. 
Eye, in agriculture and gardening, signi- 
fies a little bud or shoot inserted into a tree 
by way of graft. 
Eye-brxght. See Eupjhrasia. 
Eye of the anchor, on board a ship, the 
hole in which the ring of the anchor is put 
into the shank. 
Eye of the strap, on board a ship, the ring 
or round which is left to the strap to which 
any block is seized. 
Eye, in printing, is sometimes used for 
the thickness of the types ; or, more pro- 
perly, it signifies the graving in relievo on 
the top of the letter, otherwise called its 
face : the eye of the e is the small opening 
at the head of that letter, which distinguishes 
it from the c. 
Eye-glass, in the microscope. See Mi- 
croscope. 
EYRE, or eire, in law, the court of iti- 
nerant justices. See Justices. 
EZAN, in the Mahometan theology, a 
hymn containing the profession of their faith, 
which is repeated five times a day, to call the 
people to prayers. 
EZEKIEL’S reed, or rod, a measure ] 
of length mentioned by that prophet, and ; 
computed to be nearly "equal to two English 
feet. 
fable of the trees is the oldest that is extant, 
and as beautiful as any that has been made 
since. Nathan’s fable of the poor man is 
next in antiquity, and had so good an effect 
as to convey instruction to the ear of a king. 
We find Asop in the most distant ages of 
Greece ; and in the early days of the Roman 
commonwealth, we read of a mutiny ap- 
peased by the fable of the belly and the mem- 
bers. There is scarcely a book in the whole 
compass of profane literature which contains 
a greater store of moral wisdom, frequently 
seasoned with no small share of wit, than 
iEsop’s fables. It is injudiciously put into 
the hands of children who cannot understand 
it : its object is to instruct men. 
