3 o C E N 
In medicine, it is the point in which its virtue refides. In' 
anatomy, the middle point of fome parts is fo named, as 
centrum nerveum , the middle or tendinous part of the 
diaphragm, See. 
The heav-ns themfelves, the planets, and this centre, 
Obferve degree, priority, and place. Sbakefpeare. 
CEN'TRE, f, with builders, the frame of wood or 
timber on which the brick or Hone of arches are turned, 
and from which they receive their form and curvature. 
See Architecture, vol. ii. p. 86, 133, See. 
To CEN'TRE, v. a. To place on a centre ; to fix as on 
a centre. 
One foot he centred, and the other turn’d 
Round through the vaft profundity obfeure. Milton. 
To collect to a point. 
By thy each look, and thought, and care, ’tis fhown. 
Thy joys are centred all in me alone. Pope. 
To CEN'TRE, v. n. To reft on ; to repofe on ; as bo¬ 
dies when they gain an equilibrium.—Where there is no 
vifible truth wherein to centre, error is as wide as men’s 
fancies, and may wander to eternity. Decay of Piety To 
be placed in the midlt or centre: 
As God in heav’n 
Is centre, yet extends to all; fo thou. 
Centring, receiv’ft from all thofe orbs. Milton. 
To be collefted to a point : 
What hopes you had in Diomede, lay down ; 
Our hopes muft centre on ourfelves alone. . Dryden. 
CEN'TRE of Attraction, or Gravitation, is 
the point to which bodies tend by gravity; or that point 
to which a revolving planet or comet is impelled or at¬ 
tracted, by the force or impetus of gravity. 
CEN'TRE of a Bastion, is a point* in the middle of 
the gorge, where the capital line commences-, and which 
is ufually at the angle of the inner polygon of the figure. 
Or it is the point where the two adjacent curtains produced 
interfeCl each other. 
CEN'TRE of a Circle, is the point in the middle of 
a circle, or circular figure, from which all lines drawn to 
the circumference are equal. 
CEN'TRE of a Conic Section, is the middle point 
of any diameter, or the point in which all the diameters 
interfect and hi left one another. In the ellipfe the centre 
is within the figure; but in the hyperbola it is without, 
or between the conjugate hyperbolas ; and in the parabola 
it is at an infinite diftance from the vertex. See Conic 
Sections. 
CEN'TRE of a Curve, of the higher kind, is the 
point where two diameters meet. When all the diame¬ 
ters meet in the fame point, it is called, by Sirlfaac New¬ 
ton, the general centre. 
CEN'TRE of an Ellipse, is the middle of any diame¬ 
ter, or the point where all the diameters interfeft. 
CENTRE of Friction, is that point in the bafe of a 
body on which it revolves, into which if the whole furface 
of the bafe and the mafs of the body were colle&ed, and 
made to revolve about the centre of the bafe of the given 
body, the angular velocity deftroyed by its fri&ion would 
be equal to the angular velocity deftroyed in the given 
body by its friftion in the fame time. See Friction. 
CEN'TRE of Gravity, is that point about which all 
the parts of a body do in any fituation exactly balance 
each other. Hence, by means of this property, if the bo¬ 
dy be fupported or fufpended by this point, the body will 
reft in any petition into which it is put; as alio that, if a 
plane pafs through the fame point, the fegments on each 
tide will be equiponderate, neither of them being able to 
move the other. SeeGRAViTY. 
CEN'TRE of Gv ration, is that point in which if the 
whole mafs be collected, the fame angular velocity will 
, c E N 
be generated in the fame time, by a given force afting at 
any place, as in the body or fyftem itfelf. This point dif¬ 
fers from the centre of ofcillation, in as much as hr this 
latter cafe the motion of the body is produced by the gra¬ 
vity of its own particles, but in the cafe of the centre of 
gyration the body is put in motion by fome other force act¬ 
ing at one place only. 
CEN'TRE of an Hyperbola, is the middle of the 
axis, or of any other diameter, being the point without 
the figure in which all the diameters interfeft one another; 
and it is common to all the four conjugate hyperbolas. 
CEN'TRE of Magnitude, is thepointwhich is equal¬ 
ly diftant from all the fimilar external parts of a body. 
This is the fame as the centre of gravity in homogeneal 
bodies that can be cut into like and equal parts according 
to their length, as in a cylinder, or any other prifm. 
CEN'TRE of Motion, is the point about which any 
body, or fyftem of bodies, moves, in a revolving motion. 
CEN'TRE of Oscillation, is that point in the axis 
or line of fufpenlion of a vibrating body, or fyftem of bo¬ 
dies, in which, if the whole matter or weight be collefted, 
the vibrations will ftill be performed in the fame time, 
and with the fame angular velocity, as before. Hence, 
in a compound pendulum, its diftance from the point of 
fufpenfion is equal to the length of a fimple pendulum 
whofe ofcillations are ifochronai with thole of the com¬ 
pound one. See Mechanics. 
CEN'TRE of Percussion, in a moving body, is that 
point where the perculfion or ftroke is the greateft, in. 
which the whole percutient force of the body is fuppofed 
to he colle&ed ; or about which the impetus of the parts 
is balanced on every fide, fo that it may be ftopt by an im¬ 
moveable obftacle at this point, and reft on it, without 
afting on the centre of fufpenfion. 
CEN'TRE of a Parallelogram, the point in which 
its diagonals interfeft. 
CEN'TRE of Pressure, of a fluid againft a plane, is 
that point againft which a force being applied equal and 
contrary to the whole prefibre, it; will juft fuftain it, fo as 
that the body prefied on will not incline to either fide. 
This is the fame as the centre of perculfion, fuppofing the 
axis of motion to be at the interfeftion of this plane with 
the furface of the fluid : and the centre of preflure upon 
a plane parallel to the horizon, or upon any plane where 
the preflure is uniform, is the fame as the centre of gravity 
of that plane. 
CEN'TRE of a Regular Polygon, or Regular 
Body, is the fame as that of the inferibed, or circum- 
Icribed circle or fphere. 
CEN'TRE of a Sphere, is the fame as that of its ge¬ 
nerating femicircle, or the middle point of the fphere, 
from whence all right lines drawn to the luperficies are 
equal. 
CENTREVIL'LE, the chief town of Queen Anne’s 
county, in North America, fituate on the ealt fide of Che- 
fapeak-bay in Maryland. It lies between the forks of 
Corfica-creek, which runs into Chefter-river, and has been 
but lately laid out. It is eighteen miles fouth of Chefter, 
thirty-four fouth-eaft by ealt of Baltimore, and ninety-five 
fouth-weft by fouth of Philadelphia. Lat. 39. 6. N. 
CENTRIC, aTj. Placed in the centre : 
Some, that have deeper digg’d in mine than I, 
Say where his centric happinefs doth lieT Donne. 
CENTRI’FUGAL, adj. [from centrum and/bgA, Lat.] 
Having the quality acquired by bodies in motion, of re¬ 
ceding from the centre. 
CENTRI'PETAL, adj. [from centrum and peto, Lat.] 
Having a tendency to the centre ; having gravity. Hence, 
in mechanics, centrifugal force, is that by which a body 
revolving about a centre, or about another body, endea¬ 
vours to recede from it. And centripetal force, is that by 
which a moving body is perpetually urged towards a cen¬ 
tre, and made to revolve in a curve, inftead of a right 
line. Therefore, when a body revolves in a circle, thefe 
two 
