Biquadratic Equation, one in which the unknown quantity rises to

the 4th power.

Bisection, the division of a quantity into two equal parts.
Catenary, a curve line into which a chain or cord forms itself, by

hanging freely from two points of suspension. Catoptrics, that part of Optics which explains the laws and proper

ties of light reflected from Specula. Centre of Gravity, that point about which all the parts of a body in

any situation exactly balance each other. Characteristic, of a logarithm, the same as Index or Exponent. Chord, a right line, connecting the two extrems of an arc. Circumgyration, the revolving motion of any body about a centre. Coefficients in Algebra, numbers or given quantities usually prefixed

to letters or unknowr. quantities, by which they are multiplied. Combinations, the alterations or variations of any number of quan

tities, &c. in all possible ways. Commensurable quantities or magnitudes, such as have some com

mon aliquot part, or which may be measured or divided without

a remainder, by the same measure or divisor. Cominon, applied to an angle, line, measure, or the like, that be

longs to two or more figures, &c. Compasses, a Mathematical instrument for describing circles, mea

suring and dividing lines, &c. Complement, in general, what is wanting or necessary to complete

some certain quantity or thing. Composite number, one that is compounded of, or made up by the

multiplication of, two other numbers, greater than 1. Compound quantities, in Algebra, such as are connected together by

the sign + or -: Concavily, that side of a figure or body which is hollow. Concentric, having the same centre. Conchoid or Conchiles, the name of a curve, invented by Nico

medeg. Concreie numbers, are those that are applied to express, or denote

any particular subject, as 3 men, 2 pounds. Concurring or congruent figures, in Geometry, are such as, being

laid upon one another, do exactly coincide. Condensation, the compressing or reducing a body into less bulk, or

space, whereby it becomes more dense. Cone, a kind of round pyramid, or a solid body having a circle for

its base, and its sides formed by right lines drawn from the cir

cumference of the base to a point at top, being its vertex. Conic Sections, the figures made by cutting a cone by a plane. Conoid, a figure resembling a coné, except that the slant sides from

the base to the vertex are not straight lines, as in the cone, but

ourved. Consequent, the latter of the two terms of a ratio. Constant quantities, such as remain invariably the same, while others

Construction, in Geometry, the art or manner of drawing or describ

ing figures, the lines of a problem, &c. Contact, Angle of, the opening between a curve line and a tangent

to it, particularly the circle and its tangent. Continued Proportion, that in which the consequent of the first ratio

is the same with the antecedent of the second, &c. Converging lines, such as continually approximate until they meet. Coverging series, a series of terms that always decrease the further

they proceed, or which tend to a certain magnitude or limit. Convex, round or curved and protuberant on the surface. Coordinates, the general term used, when the abscissa and ordinates

of a curve are considered corresponding, whether they are at right angles with each other or not. Corollary, a consequence drawn from some proposition or principles

already advanced or demonstrated, without the aid of any other proposition. Cubature of a solid, the measuring of the space contained in it, or

finding the solid content of it. Cube, a regular solid body, enclosed by six equal sides or faces,

which are squares. Curve, a line whose several parts proceed bowing, or tend different

ways. Curvilinear Angle, figure, superficies, &c. such as are formed or

bounded by curves. Cycloid, a curve, conceived to be described by a point in the cir

cumference of a wheel, moving forward in a straight line. Cylinder, a solid having two equal circular ends, and every plane

section parallel to the ends, a circle equal to them also. Cylindroid, a solid resembling a cylinder, but differing from it, in

having ellipses for its ends or bases. Decagon, a plane geometrical figure of ten sides, and terangles. Declination, the distance of the sun, star, &c. from the Equinoctial,

either northward or southward. Liagonal, a right line drawn across a figure, from one angle to

another. Diagram, a scheme for the explanation or demonstration of any

figure or of its properties. Differential

, an indefinitely small quantity, part, or difference, called also an Infinitesimal. Differential method, a method of finding quantities by means of

their successive differences. Dimension, the extension of a body considered as measurable, also

used with regard to the power of quantities in equations. Diophantine problems, certain questions relating to square and eubic

numbers, and to right angled triangles. Dioptrics, that part of Optics, which explains the effects of light

as refracted by passing through different mediums. Directrix, a particular right line, perpendicular to the axis of a

Conic Section. Dirigent, a term expressing the line of motion, along which a dis

cribent line, or surface is carried in the genesis of any plane or

solid figure. Disc, the body or face of the sun or moon, such as it appears to us. Divergent or Diverging lines, those whose distance is continually

increasing Dodecagon, a regular polygon of twelve equal sides and angles. Duodecimals, a kind of multiplication in Arithinetic by which artifi

cers square their dimensions. Duplicate ratio, the square of a ratio, or the ratio of the squares

of two quantities. Dynamics, the science of moving powers. Elimination, in Algebra, that operation by which any number n of

equations, containing n unknown quantities, are reduced to one equation involving only one unknown quantity. Ellipse or Ellipsis, one of the Conic Sections, popularly called an

an oval. Elliptoid, an infinite or indefinite Ellipse. Epicycloid, a curve generated by the revolution of a point of the periphery of a circle, which rolls along or upon the circumference

of another circle. Equation, in Algebra, an expression of equality between two dif

ferent quantities. Equimultiples, the products of quantities equally multiplied. Excentric, a term applied to such figures, circles, &c. as have not

the same centre. Ercess, in Trigonometry, the excess of the sum of the three angles

of any spherical triangle, above two right angles. Exponent, the number of quantity expressing the degree or eleva

tion of the power. Expression, any Algebraical quantity, simple or compound. Extermination, the taking away of certain unknown quantities from

depending equations, so as to have only one equation and one

unknown quantity. Factors, a name given to two numbers that are multiplied together. Fluent, the variable quantity, in the doctrine of Fluxions, which is

considered as increasing or decreasing. Fluxion, the rate or proportion at which a flowing or varying quan

tity eucreases its magnitude or quantity. Fueus, a certain point in the Ellipse, Hyperbola, and Parabola, where

the rays reflected from all parts of these curves concur, or meet. Function, an Algebraical expression any how compounded of a cer

lain letter or quantity with other quantities or numbers, said to

be a function of that letter or quantity. Generating line or figure, that which by any kind of supposed mo

tion, may generate or produce some other figure, plane, or solid. Half-Tangents, the tangents of the half arcs. Heptagon, a figure of seven sides and angles. Hexagon, a figure of six sidles and angles. Homologous, in Geometry, applied to the correspondmg sides of

similar figures

Horopter, in Optics, a right line drawn through the point where

the two optic axes meet, parrallel to that which joins the centres

of the two eyes or pupils. Hyperbola, one of the Conic Sections, being that, made by a plane cutting a cone, through the base, not parallel to the opposite

side. Hypothenuse, in a right angled triangle, the side which subtends,

or is opposite to the right angle. Imaginary quantities, in Algebra, the even roots of negative quan

tities. Impact, the simple or single action of one body upon another to put

it in motion. Incidence or Line of Incidence, the direction or inclination in which

one body strikes or acts on another. Inclination, the mutual tendency of two lines, planes, or bodies,

towards each other. Inclined plane, a plane inclined to the horizon, or making an angle

with it. Incommensurable lines, or quantities, such as have no common

measure. Increment, the small increase of a variable quantity. Infinitesimals, certain infinitely or indefinitely small parts, also the

method of computing by them. Inscribed Hyperbola, one that lies wholly within the angle of its

asymptotes. Interscendent, a term applied to quantities, when the exponents of

their power are radical quantities ; as xv2. Intersection, the cutting off one line or plane by another. Isoperimetrical figures, such as have equal perimeters or circum

ferences. Lemniscale, the name of a curve in the form of the figure 8. Marimum, the greatest value of a variable quantity. Mulliplicand, one of the two factors in multiplication, being the

number to be multiplied. Negative, in Algebra, something maked with the sign Nodes, the two opposite points where the plane of the orbit of a

planet intersects the plane of the ecliptic. Nonagon, a figure having nine sides and angles. Oblate, flattened or shortened. Oblique, aslant, indirect, or deviating from the perpendicular. Opaque, not admitting a free passage to the rays of light. Orbit, the path of a planet or comet, being the curve line described

by its centre, in its proper motion in the heavens. Ordinates, right lines drawn parallel to each other, and cutting the

curve in a certain number of points. Oscillation, the vibration, or the ascent and descent of a pendulum. Osculatory circle, the same as the circle of curvature. Parabola, a figure arising from the section of a cone, by a plane

parallel to one of its sides,

Parallax, an arc of the heavens intercepted between the true place

of a star and its apparent place. Parameter, a certain constant right line, in each of the three conic

sections; called also latus rectum. Pentagon, a figure consisting of five sides and angles. Perimeter, the limit, or outer bounds of a plane rectilineal figure. Periphery, the circumference or bounding line of a curvilineal

figure. Polygon, a figure of many sides and angles. Polynomial, a quantity consisting of many terms, called a multinomial. Positive quantities, in Algebra, of a real, or additive nature. Prime numbers, those which may only be measured by unity. Prism, a solid, whose two ends are any plane figures, which are

parrallel, equal, and similar, and its sides connecting those ends

parallelograms. Pyramid, a solid having any plane figure for its base and its sides triangles, whose vertices all meet in a point at the top, called the

vertex. Quadratic Equations, those in which the unknown quantity is of

two dimensions. Quadralrir, a mechanical line by means of which right lines are

found equal to curves. Quindecagon, a plane figure of 15 sides. Radical sign, the sign or character denoting the root of a quantity. Radix or root, a certain finite expression or function, which being

evolved or expanded, according to the rules proper to its form,

produces a series. Rational, the quality of numbers, fractions, &c. when they can be

expressed by common numbers. Reciprocal, the quotient arising by dividing 1, by any number or

quantity. Refrangibility of Light, the disposition of the rays to be turned aside. Root, in Arithmetic and Algebra, denotes a quantity, which being

multiplied by itself produces some higher power. Series, a rank or progression of quantities or terms, which usually

proceed according to some certain law. Spheroid, a solid body approaching to the figure of a sphere with

one of its diameters longer than the other. Spiral, a curve line of the circular kind, which, in its progress, re

cedes always more and more from a point within called its centre, Terms of a product, of a ratio, &c. the several quantities employed

in forming or composing them. Variable, a term applied to such quantities as are considered in a

variable or changeable state, either encreasing or decreasing.