JUP 
It is seldom that a satellite can be dis- 
covered upon the disk of Jupiter, even by 
the best telescopes, excepting at its first 
entrance, when by reason of its being more 
directly illuminated by the rays of the sun 
than the planet itself, it appears like a lucid 
spot upon it. Sometimes, however, a satel- 
lite in passing over the disk appears like 
a dark spot, and is easily to be distinguisli- 
ed. This is supposed to be owing to spots 
on the body of these secondary planets ; 
and it is remarkable, that the same satellite 
has been known to pass over the disk at 
one time as a dark spot, and at another so 
luminous that it could not be distinguished 
from Jupiter himself, except at its coming 
on and going off. When tlie satellites pass 
through their inferior semi-circles, they 
may cast a shadow upon their primary, 
and thus cause an eclipse of the sun to his 
inhabitants if there are any ; and in some 
situations this shadow may be observed 
going before or following the satellite. On 
the otlier hand, in passing through their 
supoior semi-circles, the satellites may be 
eclipsed in the same manner as our moon, 
by passing through the shadow of Jupiter ; 
and this is actually the case with the first, 
second, and third of these bodies; but the 
fourth, by reason of the largeness of its 
orbit, passes sometimes above or below the 
shadow, as is the case with our moon. 
The beginnings and endings of these eclip- 
ses are easily seen by a telescope when the 
earth is in a proper situation with regard 
to Jupiter and the sun ; but when this or 
any other planet is in conjunction with the 
sun, the superior brightness of that lumi- 
nary renders both it and the satellites in- 
visible. From the time of its first appear- 
ing after a conjunction until near the op- 
position, only the immersions of the satel- 
lites into his shadow, or the beginnings of 
the eclipses, are visible; at the opposition, 
only the occultations of the satellites, by 
going behind or coming before their pri- 
mary, are observable : and from the ap- 
position to the conjunction, only the im- 
mersions, or end of the eclipses, are to be 
seen. This is exactly true in the first 
satellite, of which we can never see an im- 
mersion with its immediately subsequent 
emersion ; and it is but rarely that they 
can be both seen in the second ; as, in order 
to their being so, that satellite must be near 
one of its limits, at the same time that the 
planet is near his perihelion and quadrature 
with the sun. With regard to the third, 
when Jupiter is more than forty-six degrees 
JUR 
from conjunction with, or opposition te 
the sun, both its immersions and immediate- 
ly subsequent emersions are visible ; as they 
likewise are in the fourth, when the distance 
of Jupiter from conjunction or opposition 
is twenty-four degrees. 
JURATS, magistrates in the nature of 
Aldermen, for the government of several 
corporations. Thus we meet with the Mayor 
and Jurats of Maidstone, Rye, &c. 
JURY, a certain number of persons 
sworn to inquire of and try some matter 
of fact, and to declare the truth upon such 
evidence as shall be laid before them. The 
jury are sworn judges upon all evidence in 
any matter of fact. Juries may be divided 
into two kinds, common and special. A 
common jury is such as is returned by the 
sheriff, according to the directions of the 
statute 3 George II. cap. 25, which ap- 
points that the sheriff’s officer shall not re- 
turn a separate pannel for every separate 
cause, but one and the same pannel for 
every cause to be tried at the same assizes, 
containing not less than forty-eight, nor 
more than seventy-two jurors ; and then- 
names being written on tickets shall be put 
into a box or glass, and when each cause 
is called, twelve of those persons whose 
names shall be first drawn out of the box 
shall be sworn upon a jury, unless absent, 
challenged, or excused. When a sufficient 
number of persons are impannelled, they 
are then separately sworn well and truly to 
try the issue between the parties, and a 
true verdict give according to the evi- 
dence. 
Special juries were originally introduced 
in trials at bar, when the causes were of 
too great nicety for the discussion of ordi- 
nary freeholders. To obtain a special jury, 
a motion is made in court, and a rule is 
granted thereupon, for the sheriff to at- 
tend the master, prothonotary, or other 
proper officer, with his freeholder’s book, 
and the officer is to take indifferently forty- 
eight of the principal freeholders, in the 
presence of the attornies on both sides, who 
are each of them to strike off twelve, and 
the remaining twenty-four are returned up- 
on the pannel. 
Jurors are punishable for .sending for, or 
receiving, instructions from either of the 
parties concerning the matter in question. 
In causes of nisi prius, every person 
whose name shall be drawn, and who shall 
not appear after being openly called three 
times, shall, on oath made of his having 
been lawfully summoned, forfeit a sum not 
