RET 
the optic nerve on the internal surface of 
the eye, whereupon the images of objects 
beihg painted, are impressed, and by that 
means conveyed to the common sensory in 
the brain, where the mind views and con- 
templates their ideas. See Optics. 
RETORNO habendo, in law. See Re- 
plevin. 
RETORT. See Laboratory. 
RETRAXIT, in law, is where the plain- 
tiff or demandant comes in petson into the 
court, and says he will proceed no further ; 
and this is a bar of Sll other actions of like 
or inferior nature. 
RETRENCHMENT, in the art of war, 
any kind of work raised to cover a post, 
and fortify it against the enemy, such as fas- 
cines loaded with earth, gabions> barrels of 
earth, sand-bags, and generally all things 
that can cover the men and stop the ene- 
my. But retrenchment is more particu- 
larly applicable to a foss bordered with a 
parapet ; and a post fortified thus is called 
post retrenched, or strong post. Retrench- 
ments are either general or particular : ge- 
neral reti’enchments are new fortifications 
made in a place besieged, to cover the be- 
siegers when the enemy become masters of 
a lodgment on the fortification, that they 
may be in a condition of disputing the 
ground inch by inch, and of putting a stop 
to the enemy’s progress in expectation of 
relief. Particular retrenchments are such 
as are made in the bastions, when the ene- 
my are masters of the breach. These can 
never be made but in new full bastions, for 
in empty, or hollow ones, there can only 
be made retirades. The particular re- 
trenchments are made several ways, ac- 
cording to the time they have to covep 
themselves ; sometimes they are made be- 
fore hand, which are certainly the best. 
The parapets of such retrenchments ought 
to be five or six feet thick, and five feet 
high, with a large and deep foss, from 
whence ought to run out small fougades 
and countermines. 
RETROGRADATION, in astronomy, 
is an apparent motion of the planets, by 
which they seem to go backwards in the 
ecliptic, and to move contrary to the order 
of the signs, as from Aries to Taurus ; from 
Taurus to Gemini, &c. which, from west to 
east, it is said to be direct. When it ap- 
pears for some days in the same place or 
point in the heavens, it is said to be sta- 
tionary ; and when it goes in antecenden- 
tia, or backwards, or contrary to the order 
of the signs, which is from east to west, it 
RET 
is said to be retrograde. Saturn continues 
retrograde about 140 days ; Jupiter 120 ; 
Mars 73; Venus 42 ; and Mercury 23. The 
interval between two retrogradations of the 
several planets are as follow : 
In Saturn it is about 378 days ; 
Jupiter 408 , 
Mars 780 
V enus 585 
Mercury 115 
RETROMINGENTS, in natural his- 
tory, a class or division of animals, whose 
characteristic it is that they stale, or make 
water backwards, both male and female. . 
RETURN, is most commonly used for 
the return of writs, which is the certificate 
of the Sheriflf made to the court of what he 
has done, touching the execution of any 
writ directed to him ; and where a writ is 
executed, or the defendant cannot be found, 
or the like, this fact is indorsed on the writ 
by the officer, and delivered into the court 
whence the writ issued, at the day of the 
return thereof, in order to be filed. 
RETURNING stroke, in electricity, is 
an expression used by Lord Mahon, (now 
Earl Stanhope), to denote the effect pro- 
duced by the return of the electric fluid 
into a body from which, under certain cir- 
cumstances, it has been expelled. 
To understand properly the meaning of 
these terms, it must be premised, that ac- 
cording to the author’s experiments, an in- 
sulated smooth body, immerged within the 
electrical atmosphere, but beyond the strik- 
ing distance of another body, charged po- 
sitively, is at the same time in a state of 
threefold electricity. The end next to the 
charged body acquires negative electricity ; 
the further end is positively electrified; 
while a certain part of the body, some- 
where between its two extremes, is in a na. 
tural, unelectrified, or neutral state; so 
that the two contrary electricities balance 
each other. It may further be added, that 
if the body be not insulated, but have a 
communication with the earth, the whole 
of it will be in a negative state. Suppose, 
then, a brass ball, which may be called A, 
to be constantly placed at the striking dis- 
tance of a prime conductor, so that the 
conductor, the instant when it becomes 
fully charged, explodes into it. Let ano- 
ther large or second conductor be suspend- 
ed in a perfectly insulated state, further 
from the prime conductor than the striking 
distance, but within its electrical atmo-. 
sphere : let a person, standing on an insn 
