C E N 
two forces, viz. the centrifugal and centripetal, are equal 
and contrary to each other, fince neither of them gains up¬ 
on the other, the body being in a manner equally balanced 
by them. But when, in revolving, the body recedes far¬ 
ther from the centre, then the centrifugal exceeds the 
centripetal force 5 as in a body revolving from the lower 
to the higher apfis, in an ellipfe, and refpe&ing the focus 
as the centre. And when the revolving body approaches 
nearer to the centre, the centrifugal is lefs than the cen¬ 
tripetal force ; as while the body moves from the farther 
to the nearer extremity of the tranfverfe axis of the el¬ 
lipfe : the two forces being equal to each other only at the 
very extremities of that axis. It is one of the eftablifhed 
laws of nature, that all motion is of itfelf rectilinear, 
and that the moving body never recedes from its firft right 
line, til! lome new impulfe be fuperadded in a different 
direftion : after that new impuife the motion becomes 
compounded, bur it is Hill rectilinear, though not in the 
lame line or direction as before See Mechanics. 
CENTRIS'CUS,/. the Trumpet Fish, in ichthyolo¬ 
gy, a genus belonging to the order of amphibia nantes. 
The generic chara&ers are, the body is laterally compreff- 
ed, and the head terminated like the beak of a fnipe. 
Some are covered with bony plates like armour, others 
with fcales. There are no teeth in the mouth ; and the 
lower jaw is the loygeft. They live principally onworms, 
and are not above fix or feven inches long;; and chiefly 
abound in the Mediterranean and Eaft-Indian feas. There 
are only two fpecies known, 
1. Centrifcus icolopax, the trumpet or bellows filh. 
The fcales on the body form the fpecific character : they 
are hard, flia'rp, and, (landing pretty thick, make the fifh 
rough if rubbed againlt the grain. There are four rays 
in the membrane of the gills, lixteen in the peftoial 
fin, five in the ventral, eighteen in the anal, nine in the 
tail, four in the firft dorfal, feventeen in the fecond. The 
body is fhort and broad, laterally compreffed, and very 
much refembles a pair of bellows in fhape ; it is of a pale- 
red colour. The head, which is broadifh above, ends in 
a bent cylinder below ; and the aperture of the mouth, 
which is final], is at the end of the long beak ; the aper¬ 
ture is clofed by the lower jaw, which flints into the up¬ 
per like the lid of a fnuff-box. The noftrils are double, 
and lie near the eyes; the eyes are large, with a black 
pupil and a pale-red iris. The gill-covert is fingle ; the 
aperture is large, and covers the membrane which lies 
underneath. This fifh can hide its fmall ventral fins in a 
bony furrow which lies behind them ; all the fins are of a 
grey colour. This fifh haunts the Mediterranean fea ; it 
is tender, well-tafted, and eafy of digeftion ; but, being- 
very thin, it is generally fold with other fmall fifh qt a low 
price. As the fins are very final 1 in proportion to the 
other parts, fo that it cannot fwim faft enough to avoid its 
enemies, Providence has given it a moveable fpine for its 
defence. 
2. Centrifcus fcutatus, the armed fnipe or trumpet fifh. 
The finooth armour with which this fifh is covered dif- 
tinguifh it fpecifically from the preceding. The offeous 
plates are fo joined, that they look like one piece, and 
give the fifh the appearance of the folen fxliqua, or knife- 
handle :and it may be regarded as forming the connecting 
link between fhell and other fifh. There are eleven rays 
in the pedoral fin, five in the ventral, thirteen in the anal, 
twelve in the tail, three in the firft dorfal, and eleven in 
the fecond. The head is long, terminating in a cylindri¬ 
cal fnout or beak, turned up at the end ; the mouth is 
fmall, and the under jaw is the longeft. The eye has a 
black pupil, in a yellowifh-wbite iris, and covered with 
a pellicle or membrane ; the noftrils are double, and are 
near the eyes. The gill-covert is fmooth, and tranfparent 
like horn ; the aperture is large, ancl placed at the fide. 
There is a .(harp fpine, which is a continuation of the 
back, and runs out beyond the tail; it is probably a wea¬ 
pon of defence. The back is of a brownifn colour; the 
iides are brown mixed with a little filver, and reddifh to- 
C E N 3.1 
wards thebelly ; fome white lines are formed by the join¬ 
ings in the armour. The filh is very thin, and the fides 
end (harp at top. When held up to the light, one part 
near the back is tranfparent. The (hell every where fiiir.es 
like gold. The under furface, which is brown, confifts 
ufually of ten or twelve plates ; at the lower edge is a thin 
fkin which reaches from the fnout to the anal fin ; and 
near this f-kin the pieces are feparated, and the anus lies 
between them. The iltuation of thefinsis remarkable in 
this fifh ; the peCloral fin is very far from the aperture of 
the gills, and the dorfal fins lie under the fhell, clofe to 
the tail-fin. The peftoral, ventral, and dorfal, fins, are 
yellowifh ; the others brown. This fifh is found in the 
Eaft Indies, and grows fix or eight inches long ; it mud 
be nourifhed by luftion, as no tongue can be perceived ; 
it feeds only on dime and fome fmall aquatic animals-. 
When the armour or fhell is taken off from the belly, the 
flefli underneath is fo thin as to weigh hut a few grains ; 
it is of a fliining white colour. The ftomach is fmall, 
long, and round ; and little crabs are often found therein. 
CENTRON, a village of Savoy, in the Tarantaife, 
formerly a capital town of a people called Centrones : three 
miles eaft-north-eaft of Monftier. 
CENTRO'NIA, a name by which the echini marine 
have been claffed by Dr. Hill. 
CEN'TRY or Sentry,/. See Sentinel. 
The thoughtlefs wits (hall frequent forfeits pay. 
Who’gainft the centry's boxdilcharge their tea. Gay* 
CENTUMCEL'LAi, in the ancient geography, Tra¬ 
jan’s villa in Tufcany, on the coaft, three miles from 
Algae ; with an excellent port, called Trajanv.s Porting 
now Ci-vita Vecchia. 
CENTUM'VIRI, the members of a court of juftice at 
Rome. They were originally chofen, three from the 35 
tribes of the people, and though 105 they were always 
called Centumvirs. They -were afterwards encreafed to 
the number, of 180, and ftiil kept their original name. 
Thepretor fent to their tribunal caufes of the greateft im¬ 
portance, as their knowledge of the law was extenfive. 
They were generally fummoned by the Decemviri, who 
feemed to be the chiefeft among them ; and they affembled 
in the Bafilica, or public court, and had their tribunal 
diftinguifhed by a fpear with an iron head, whence a de¬ 
cree of their court was called hafta judicium : their fen- 
tences were very impartial, and without appeal. Cicero. 
CENTUN'CULUS, f. [the name of a plant in Pliny.] 
In botany, a genus of the clafs tetrandria, order mono- 
gynia, natural order of rotaceas. The generic characters 
are—Calyx : perianthium four-cleft, fpreading, permanent; 
divifions acute, lanceolate, longer than the corolla. Co¬ 
rolla : monopetalous, rotated Tube fubglobular ; border 
four-cleft, flat ; divifions fubovate. Stamina : filaments 
four, almoft the length of the corolla. Anthers Ample, 
Piftillum : germ roundifh, within the tube of the corolla. 
Style filiform, length of the corolla, permanent. Stigma 
Ample. Pericarpium : capfule globular, unilocular, open¬ 
ing horizontally. Seeds : very many, very fmall —EJJential 
Character. Calyx: four-cleft; corolla four-cleft, fpread¬ 
ing ; (lamina fhort ; caplule one-celled, opening hori¬ 
zontally. 
There is but one fpecies, called centunculus minimus, 
or bailard pimpernel. Root annual. Stem from half of. 
an inch to an inch in height or more, Ample or branched 
at bottom, rather upright, round and fmooth. Leaves al¬ 
ternate, feflile, ovate, pointed,, entire, fmooth, fomewhat 
flefhy, fpreading ; iometimvs onpofite towards the bottom, 
pellucid at the edge, brownifh underneath. Flowers very mi¬ 
nute, folitary, axillary,feflile. Calyxdivided fometimes into 
four, but generally into five, narrow fegments to thebafe. 
The whole corolla is only one line in diameter, and hyaline 
or of a clearwater 01-glafs colour : the fegments equal and 
much pointed, very thin and tranfparent. 1 he yellow 
anthers clofe the mouth of the tube ; and the border does 
not expand, unlefs the fun fliines itrongly on. it. The 
globular. 
