Resonator, An open-circuited conductor for electrically Electric. resounding or giving back a vibration, usually exhibited by means of a spark. Rheostat. A device which has an adjustable resistance, so arranged that while adjusting the same the circuit will not be open. Safety Fuse. A piece of fusible metal of such resistance that it breaks down at a certain current strength. Saturated. When a liquid has taken up a soluble material to the fullest extent it is then completely saturated. Secondary. One of the two coils in a transformer, or induction coil. Secondary Plates. The brown or deep red plates in a storage battery when charged. Self-excited. Producing electricity by its own current. Series. Arranged in regular order. From one to the other directly. If lamps, for instance, should be arranged in circuit on a single wire, they would be in series. Series, Multiple. When lamps are grouped in sets in parallel, and these sets are then connected up in series. Series Windings. A generator or motor wound in such a manner that one of the commutator brush connections is joined to the field magnet winding, and the other end of the magnet winding joined to the outer circuit. Shunt. Going around. Shunt Winding. A dynamo in which the field winding is parallel with the winding of the armature. Snap Switch. A switch so arranged that it will quickly make a break. Sounder. The apparatus at one end of a line actuated by a key at the other end of the line. Spark Coil. A coil, to make a spark from a low electro-motive force. Spark, Electric. The flash caused by drawing apart the ends of a conductor. Specific Gravity. The weight or density of a body. Static Electricity. Generated by friction. Also lightning. Any current generated by a high electro-motive force. Strength of Current. The quantity of electricity in a circuit. Synchronize. Operating together; acting in unison. Terminal. The end of any electric circuit or of a body or machine which has a current passing through it. Thermostat, Electric. An electric thermometer. Usually made with a metal coil which expands through the action of the electricity passing through it, and, in expanding, it makes a contact and closes a circuit. Transformer. The induction coil with a high initial E. M. F. changes into a low electro-motive force.