Practical Mechanics for Boys Part 27

Refractory. Difficult to work, and not easily fused.

Recess. A hole, or a depression.

Rocking. A lever which rotates only part way and then moves in the opposite direction.

Rotate. A spindle which turns round. Compare revolve.

Rosin. Certain gums; particularly the sap of pine trees.

Roughing. The taking off of the first coating with a tool.

Saturated. A soluble substance which cannot be further dissolved by a liquid.

Scribe. To mark with a tool.

Screw plate. A tool which has within it means for adjusting different cutting tools.

Section lining. The marks made diagonally across drawings to indicate that the part is cut away.

Shaper. A large tool for surfacing off material, cutting grooves, and the like.

Shrinkage. The term applied to metals when cast, as all will be smaller when cold than when cast in the mold.

Slide rest. The part of the lathe which holds the tool post.

Sonorous. Having the quality of vibration.

Slotted. Grooved, or channeled.

Solvent. That which can be changed from a solid by liquids.

Spelter. A combination of zinc and copper. A hard solder.

Soldering. Uniting of two substances by a third, with heat.

Spindle. A small shaft.

Spur. The larger of two intermes.h.i.+ng gears.

Socket. A depression or hole.

Sprocket. Teeth in a wheel to receive a chain.

Spiral. A form wound like the threads of a screw.

Surface plate. A true surface made of metal, used as a means of determining evenness of the article made.

Sulphate. Any substance which is modified by sulphuric acid.

Subst.i.tute. An element or substance used for another.

Superposed. One placed above the other.

Swage. Tool for the purpose of changing the form in a material.

Swivel. A point on which another turns.

Surfacing. Taking off the outer coating or covering.

Tap. A small drill.

Tapering. An object with the sides out of parallel.

Tangential. A line from the periphery of a circle which projects out at an angle.

Tension. The exertion of a force.

Tenacity. The property of a material to hang together.

Tempering. Putting metal in such condition that it will be not only hard but tough as well.

Technical. Pertaining to the strict forms and terms of an art.

Texture. That of which the element or substance is composed.

Threads. The ridges, spiral in form, which run around a bolt.

Theoretically. The speculative form or belief in a subject.

Tinned. The term applied to the coating on a soldering iron with a fluxed metal.

Tines. Small blades.

Torsion. The force exerted around an object, like the action of a crank on a shaft.

Tommy. A lever to be inserted in a hole in a screw head for turning a screw.

Transmitting. Sending forth; to forward.

Trammel. A tool for the purpose of drawing ellipses.

Traction. Drawing; pulling power.

Tripping. A motion applied to a finger, which holds a pivoted arm, whereby the latter may be swung from its locked position.

Triangular. Having three sides and three angles.

Transverse. Across; at right angles to the long direction.