CENT, in coinmerce, an abridgment of 
eentum, is used to express the profit or loss 
arising from tlie sale of any commodity. 
Thus we say, there is 10 per cent, profit, or 
10 per cent, loss ; which is ^ profit, or ^ 
loss, upon the sale of the whole. 
CENTAUREA, in botany, a genus of 
the Syngenesia Polygamia Frustranea class 
and order. Natural order of compound 
flowers. Cinarocephalse, Jussieu. There 
are seventy-seven species, of which we shall 
only mention C. moschata, purple sweet 
centaury, which is an annual, and has been 
many years propagated in the English gar- 
dens, under the title of Sultan flower, or 
sweet Sultan. It was brought from the Le- 
vant, where it grows naturally in arable 
land among the com ; it sends up a round, 
channelled stalk, nearly three feet high, 
which divides into many branches, from 
the sides of which come out long naked pe- 
duncles, each sustaining a single head of 
flowers ; they have a strong odour, so as to 
be very offensive to many people ; they are 
purple, white, or flesh-coloured; there is al- 
so a variety with fistula flowers, and another 
with fringed flowers ; but these degenerate 
in a few years, however carefully the seeds 
may be saved. 
CENTER, or Centre, in geometry, a 
point equally distant from the extremities 
of a line, figure, or body. 
Center of a circle, a point in the middle 
of a circle, or circular figure, from which all 
lines drawn to tlie circumference are equal. 
Center of a conic section, a point where- 
in the diameters intersect each other. In 
the ellipsis, this point is within the figure, 
and in the hyperbola, without. 
Center of a curve (f the higher kind, the 
point where two diameters concur. When 
all the diameters concur in tlie same point, 
Sir Isaac Newton calls it the general center. 
Center of an ellipsis, the point where 
the transverse and conjugate diametere in- 
tersect each other. 
Center of gravitation and attraction, in 
physics, that point to which the revolving 
planet or comet is impelled or attracted by 
the Impetus of gravity. 
Center of gravity, in mechanics, that 
point about which all the parts of a body 
do, in any situation, exactly balance each 
other. Hence, 1. If a body be suspended 
by this point as the center of motion, it will 
remain at rest in any position indifferently. 
2. If'-.' body be suspended in any other 
point ii can rest only in two positions, viz. 
when fJiP said center of gravity is exactly 
above or below the point of suspension. Si 
When the center of gravity is supported the 
whole body is kept from falling. 4. Because 
this point has a constant endeavour to de- 
scend to the center of the earth ; therefore, 
5. When the point is at liberty to descend 
the whole body must also descend, either 
by sliding, rolling, or tumbling down. 6. 
The center of gravity in regular uniform 
and homogeneal bodies, as squares, circles, 
&c. is the middle point in a line connecting 
^ any two opposite points or angles ; where- 
fore, if such a line be bisected the point of 
section will be the center of gravity. 
To find the center of gravity of a triangle. 
Let BG (Plate III. Miscell. fig. 1,) bisect the 
base A C of the triangle ABC, it will also 
bisect every other line D E drawn parallel 
to the base, consequently the eenter of gra- 
vity of the triangle will be found somewhere 
in the line B G. The area of the triangle 
may be considered as consisting of an in- 
finite number of indefinitely small parallelo- 
grams, D, E, h, a, each of which is to be con- 
sidered as a weight, and also as the fluxion 
of the area of the triangle, and so may be 
expressed by 2 y a;, (putting B F = a:, and 
F E = y) if tliis fluxionary weight be mul- 
tiplied by its velocity x, we shall have 2 yxx 
for its momentum. Now put B G = a and 
A C = i, then B G («) : A C (5) :: B F (x) .- 
D E = — = 2 y, tlierefore the fluxion of 
a ^ 
the weights 2 yx —— — ; and the fluxion 
* h X T' X 
of the momenta 2 y x a: = , whence 
•' a 
the fluent of the latter, viz. divided by 
i) 
tlie fluent of the former, viz. will give 
/O Oi 
a 
- X for the distance of the point from B in 
^ / 
the line B F, which has a velocity equal to 
the mean velocity of all the particles in the 
triangle D B E, and is therefore its qenter 
of gravity. Consequently the center of gra- 
vity of any triangle ABC, is distant from 
the vertex B f B G a right line drawn from 
tlie angle B bisecting the base AC. And 
since tlie section of a superficial or hollow 
cone is a triangle, and circles have the same 
ratio as their diameters, it follows that tlie 
circle whose plane passes through the center 
of gravity of the cone, is | of the length of 
the side distant from the vertex of the said 
cone. 
To find the center of gravity of a solid 
