Simple Circuit. (See [Circuit, Simple].)
Simple Immersion. (See [Immersion, Simple].)
Simple Magnet. (See [Magnet, Simple].)
Single-trolley System. A trolley system employing only one overhead conducting wire, the track and ground serving as the return-circuit.
Single-wound Wire. Wire insulated by winding or overlaying with but a single layer of material.
Sliding-condenser. (See [Condenser, Sliding].)
Snap-switch. A switch so contrived as to give a quick break. A spiral spring is fastened between the handle and arm in such a manner that when the handle is drawn back the spring operates and quickly draws a knife-bar from the keeper, breaking the contact instantly and without the formation of an arc.
Socket. A receptacle for an incandescent lamp or plug.
Solenoid. A helical coil of wire of uniform diameter or cylindrical in shape. It is useful in experiments with electro-magnetism.
Solution. A fluid composed of dissolved salts; a mixture of liquids and fluids.