=Combination-chuck.= A chuck in which the jaws may be moved simultaneously or independently.

=Comparator.= A machine for comparing measurements, for testing them and originating sub-divisions.

=Compa.s.s-calipers.= A pair of calipers having one bent leg and one leg with compa.s.s joint.

=Compa.s.ses.= A tool answering the same purpose as dividers, but with longer legs and a set screw to secure the position of the legs.

=Compa.s.s-plane.= A plane whose sole or bottom is curved in its length.

=Compound gears.= A train of gear wheels in which there are two wheels fixed on the same shaft but of different diameters so as to vary the velocity.

=Compound slide-rest.= A slide-rest having two slides, one above the other.

=Cone-bearing.= A bearing (for a journal) that contains a coned sleeve that may be moved endways to take up wear.

=Cone-mandrel.= A mandrel that holds hollow work by means of two cones.

=Cone-plate.= A device for steadying work in the lathe by supporting one end in a coned mouth.

=Cone-pulley.= A pulley having steps of different diameters.

=Cone-shaft.= The shaft for a cone-pulley.

=Cook's auger.= An auger rounded at the end for cutting end-grain wood.

=Cope-cutter.= A cutter for under-cutting the shoulder of a tenon on wood-work.

=Cope-head.= A head for a cope-cutter in a tenoning machine.

=Core.= A body of sand that produces a hole or cavity in a casting.

=Core-box.= The box in which a core is made.

=Cored.= Containing a hole or recess.

=Cotter= _or_ =cottar.= A term applied to small keys that are very broad in proportion to their thickness.

=Cotter-drill.= A drill used in cutting out keyways in a machine.

=Cotter-file.= A file thin in proportion to its length, for filing out keyways or slots.

=Counterbore.= 1. A parallel recess at the mouth of a hole. 2. A tool for producing such a recess.

=Countershaft.= A shaft with pulleys upon it, employed to permit a machine to be started and stopped without stopping and starting the line shaft, also, to afford means for varying the speed of a machine.

=Countersink.= A tool for cutting a coned mouth to a hole.

=Countersunk.= Having a coned mouth.

=Coupling.= A piece used to connect two pieces together.

=Covering-plate.= A plate used to cover the seams of a boiler.

=Cow-mouth chisel.= A machinist's chisel shaped at the cutting end like a carpenter's gouge.

=Crank.= An arm that is fast to a shaft and is used as a lever wherewith to revolve the shaft.

=Crank-shaft.= A shaft having a crank.

=Cross-cut.= A narrow machinist's chisel.

=Cross-cut saw.= A saw whose teeth are shaped to cut across the fibre or grain of wood.

=Cross-face.= A plate straightener's or saw maker's hammer, having one face at a right angle to the other.

=Cross-feed.= That feed of a lathe which runs across the bed.

=Cross-filing.= That cla.s.s of filing in which the file is pushed in the line of its length.

=Cross-head.= That part of an engine that connects the piston rod to the connecting rod.

=Cross-slide.= A slide that stands across a work-table.

=Crowning.= Highest in the middle when tested by a straight edge.

=Crown-wheel.= A gear wheel having its teeth upon its side face.

=Cup-chuck.= A chuck having a coned or cupped mouth.

=Cup-shape.= A crack of circular form in a piece of timber or a log.

=Cutter.= A tool that is held or carried in a stock bar or mandrel.

=Cutter-bar.= The bar or shaft that carries the cutting knives in a wood-planing machine.

=Cutter-grinder.= A machine for grinding cutters.

=Cutter-head.= 1. A head that carries cutters. 2. The head that carries the cutters in a wood-moulding machine.

=Cutting-off lathe.= A lathe used for cutting up rods into required lengths, and having a hollow spindle through which the rod pa.s.ses.

=Cutting-off saw.= A sawing machine designed for cropping the ends of work and cutting it to length.

=Cutting-off tool.= A tool for cutting up rods or bars, and used in the common lathe and in the cutting-off lathe.

=Cycloid= (si'kloid). A curve generated by a pencil fixed in the perimeter of a circle that is rolled upon another circle.

=Cylinder.= 1. That part of a steam-engine in which the steam is utilized to drive the piston. 2. The shaft that carries the knives in a wood-planing machine.