_Pump-cheeks._ A forked piece serving as a fulcrum for the handle of a pump. _Pump-well._ A compartment extending from a ship’s bottom to the lower or the upper deck, as the case may be, to contain the pump stocks, etc. The _bilge water_ collects in the _limbers_ and is discharged through a spout called the _pump-dale_. _Rain-gauge._ A vessel graduated to measure the fall of rain in a given period. [Illustration: REDUCING COUPLING.] _Reducing-coupling._ A fitting for connecting two sizes of threaded pipe. _Resistance._ The force that a pump has to work against, caused by gravity, friction, head of water, etc. _Right-hand Thread._ A screw thread in which, with the threaded end of the bolt towards you, _the top of the nut_ must revolve from left to right like the hands of a watch, in order to cause the nut to screw upon the bolt. [Illustration: OPEN. ROPE SOCKETS. CLOSED. ] _Rope-socket._ A device fastened to the end of a rope by means of which the rope may be attached to its load. The socket may be open or closed. _Rust-joint._ A joint which is made by being filled with sifted cast-iron borings, mixed with sal ammoniac, sulphur and water; this causes the cuttings to rust and form a solid cement. _Sea Injection._ The pipe and valve through which sea water is injected into the condenser of a marine engine. _Screw jack or lifting jack._ A screw working in a threaded base or stationary nut and turned by a lever inserted into holes near the top, of which there are usually four. A loose plate or swivel is placed on top of screw. [Illustration: SCREW JACKS.] _“Slams” and “Shocks.”_ Banging, clanking and jarring noises indicating a derangement of the action of a pump. [Illustration: SLEEVE COUPLING.] _Sleeve-coupling._ A threaded connection for uniting the two ends of pipes of equal size. “_Slippage._” The difference between the calculated and actual work performed by a pump. _Sluice._ A water-gate; a channel to run off waste water. _Slurry pump._ A special pump for handling a mixture of earth water. _Socket-wrench._ A wrench for turning nuts, having a socket in the end made to a special size and shape of the nut to be turned. _Spanner._ Is a wrench for turning round nuts having holes or slots. [Illustration: SPANNER.] _Spline or feather._ A key made fast in a shaft. _Split-pin or cutter._ An iron pin divided at the end which is to be spread apart after inserting in the hole. “_Spread._” A term used to indicate the distance from center to center of the cylinders of a duplex pump. _Spring-seat._ An elastic seat for a valve. _Steam thrown valves._ Valves moved by steam only. _Steam end of a pump._ The end operated by steam.