Chit

An instrument formerly used for cleaving laths.

Chord

The right line which joins the two extremities of an arc. It is so called from its resemblance to a bow and string, the chord representing the string.

Circle

A figure bounded by one continued curved line, called the circumference, all parts of which are equidistant from a point called the centre. It is the most capacious of all plain figures. The circumference of any circle, divided by 3.1416, will give the diameter; or the diameter, multiplied by the same number, will give the circumference. In common practice, where great exactness is not required, it is usual to consider the diameter to the circumference as 22 to 7.

To find the area of any circle, multiply half the diameter by half the circumference; or, for a more accurate calculation, multiply the square of the diameter by .7854, or the square of the circumference by .07958. Squaring the circle, as it is termed, is the attempt to ascertain the exact contents of a circle in square measure, - a problem as yet unsolved.

Clamp

A piece of wood so fixed to another that the fibres or grain of one may cross those of the other, and thus prevent its-warping or twisting.

Clear

The clear or unmolested distance between any two surfaces or points. The net distance between a floor and ceiling is said to be the height of the story in the clear.

Clere-Story

A continuation of the nave, choir, and transepts of a church, above the roof of the aisles.

Cleaving

The act of separating, by force, one part of a piece of wood or other substance from another, in the direction of its fibres.

Clefts

Those cracks or fissures produced in wood when wrought too green; or when, in an unseasoned state, it is exposed to sudden heat. In thin stuff, as boards, etc, the clefts, being somewhat different from those in framing lumber, are usually termed shakes.

Cocking

A method of confining the tie-beams of a roof to the top of the wall-plates, or the joists of a floor to the girders and girts, by dove-tailing the parts together. Its design is to prevent the walls from spreading.

Collar-Beam

A beam used to prevent the bending or sagging of the rafters in a common roof, or the nearer approach of the tops of the rafters in one that is trussed.

Compasses

A mathematical instrument for describing circles and measuring distances. Common compasses need no description. Triangular compasses have, in addition to the two legs of common ones, another, made with a joint, and movable in any direction. Beam compasses are designed for describing large circles. (See description.) Proportional compasses have two pairs of legs, connected by a shifting centre sliding in a groove, and thereby regulating the proportion which the opening or distance between the joints at one end bears to that at the other. They are used to enlarge or diminish drawings to any given scale.

Compressibility

The quality of being compressible, or the capacity of being reduced to smaller dimensions. A post sustaining a heavy superincumbent weight, or the collar-beam or strut of a truss-roof, when in use, are said to be in a state of compression.

Concus

This term is doubtless derived from the Latin concutio, to shake or shatter. In carpentry, it properly denotes wood so rotten or decayed in some of its parts as to be shaky. Of late years, it is generally used to signify rotten or decayed knots; and boards or sticks of timber having such knots are termed concussed.

Cone

A solid body having a circle for its base, and terminating at its top in a point, or vertex.

Conical Roof

A roof whose exterior surface is formed like a cone.

Construction

The act of building, or of devising and forming. Among architects, the term more generally denotes the arranging and distributing of the parts of a building in such a manner as will insure durability to the structure, and economy in the use of its materials.

Constructive Carpentry

Practical or operative carpentry.

Contact

A touching or juncture of two bodies. Things are said to be in contact when parts of them are so near together that there is no sensible intervening space. The places where they touch are called the points of contact.

Contour

The outline bounding any figure.

Contraction

The act of drawing together or shortening, by causing the parts of a body to approach each other. Thus, in an iron rod, heat, by insinuating itself between the particles of the metal, causes the rod to become longer; and it is then said to be expanded. Cold, which is simply the absence of heat, causes or permits the particles to come nearer each other; and the rod in this state is said to be contracted.

Convergent Lines

Lines tending to one point, and which, if continued, would meet.

Counter-Sink

To sink a recess or cavity in any material, for the reception of a projection on the piece to be connected with it; as the head of a screw or bolt, or the plate of iron against which the nut or head of a bolt is fixed.

Cradling

The timber-ribs to which are nailed the laths or furrings of a vaulted ceiling.

Cramp

An iron instrument used by carpenters to draw or force mortises and tenons together. It is made of iron, with a movable shoulder at one end, and a screw at the other.

The term also denotes a piece of iron bent at the ends towards one side, and used to confine the larger timbers of a frame together.

Crane

A machine for raising great weights. It consists of a stout upright shaft or post, termed a puncheon, from which projects a strong arm, or piece of timber, furnished at the extremity with a tackle and pulley.

Cross-Beam

A large beam extending from wall to wall of a building, or the girder holding the sides of an edifice together.