A
A. An abbreviation for the word anode.
Absolute. Complete by itself. In quantities it refers to fixed units. A galvanometer gives absolute readings if it is graduated to read direct amperes or volts. An absolute vacuum is one in which all residual gases are exhausted; an absolute void is the theoretical consequent. The absolute unit of current is measured in one, two, three, or more amperes or volts.
A-C. An abbreviation expressing alternating current.
Acceleration. The rate of change in velocity.
The increase or decrease of motion when acted upon by the electric current.
Accumulator. A term applied to a secondary battery, commonly called a storage-battery.
Accumulator, Electrostatic. (See [Electrostatic Accumulator].)
Accumulator, Storage. A storage-battery.
Acid. A compound of hydrogen capable of uniting with a base to form salts.
Sour, resembling vinegar.
A sharp, biting fluid.
Acidometer. A hydrometer used to determine the gravity of acids. It is employed chiefly in running storage-batteries to determine when the charge is complete.
Adapter. A screw-coupling to engage with different size screws on either end, and used chiefly to connect incandescent lamps to gas-fixtures.
Adherence. The attraction between surfaces of iron due to electro-magnetic action. The term is used in connection with electric brakes—electro-magnetic adherence.
Adjustment. Any change in an apparatus rendering it more efficient and correct in its work.
Aerial Conductor. A wire or electric conductor carried over housetops or poles, or otherwise suspended in the air, as distinguished from underground or submarine conductors.
Affinity. The attraction of atoms and molecules for each other, due to chemical or electrical action.
Air-condenser. A static condenser whose dielectric is air.
Air-line Wire. In telegraphy that portion of the line-wire which is strung on poles and carried through the air.
Alarm, Burglar. A system of circuits with an alarm-bell, the wires of which extend over a house or building, connecting the windows and doors with the annunciator.
Alarm, Electric. An appliance for calling attention, generally through the ringing of a bell or the operating of a horn.
Alarm, Fire and Heat. An expansion apparatus that automatically closes a circuit and rings a bell.
Alive, or “Live.” A term applied to a wire or circuit that is charged with electricity. A “live” wire.
Active circuits or wires.
Alloy. Any mixture of two or more metals making a scientific compound. For example: copper and zinc to form brass; copper, tin, and zinc to form bronze; copper, nickel, and zinc to form German-silver.
Alternating Current. (See [Current, Alternating].)
Alternating Current-power. Electrical distribution employing the alternating current from dynamos or converters.
Alternation. A change in the direction of a current; to and fro. Alternations may take place with a frequency ranging from 500 to 10,000 or more vibrations per second.
Alternator. An electric generator-dynamo supplying an alternating current.
Amalgam. A combination of mercury with any other metal.
Amalgamation. The application of mercury to a metal, the surface of which has been cleansed with acid. Mercury will adhere to all metals, except iron and steel, and particularly to zinc, which is treated with mercury to retard the corrosive action of acid on its surface.
Amber. A fossil resin, valuable only in frictional electric experiments. Most of it is gathered on the shores of the Baltic Sea between Königsberg and Memel. It is also found in small quantities at Gay Head, Massachusetts, and in the New Jersey green sand. When rubbed with a cloth it becomes excited with negative electricity.
Ammeter. The commercial name for an ampere-meter. An instrument designed to show, by direct reading, the number of amperes of current which are passing through a circuit.
Ampere. The practical unit of electric current strength. It is the measure of the current produced by an electro-motive force of one volt through a resistance of one ohm.
Ampere-currents. The currents theoretically assumed to be the cause of magnetism.
Ampere-hour. The quantity of electricity passed by a current of one ampere in one hour. It is used by electric light and power companies as the unit of energy supplied by them, and on which they base their reckoning for measuring the charges for current consumed.
Ampere-ring. A conductor forming a ring or circle. Used in electric balances for measuring current.
Animal Electricity. A form of electricity of high tension generated in certain animal systems—the Torpedo, Gymnotus, and Célurus. The shocks given by these fish, and particularly the electric eel, are often very severe.
Annealing. The process of softening yellow metals by heating them to a cherry redness, then allowing them to cool gradually in the air.
Electric annealing is done by passing a current through the body to be annealed, and heating it to redness; then allowing it to cool gradually.
Annunciator. An apparatus for giving a call from one place to another, as from a living-room to a hotel office, or for designating a window or door that may have been opened when protected by a burglar-alarm.
Annunciator-drop. The little shutter which is dropped by some forms of annunciators, and whose fall discloses a number or letter, designating the location from which the call was sent.
Anode. The positive terminal in a broken, metallic, or true conducting circuit.
The terminal connected to the carbon-plate of a battery, or to its equivalent in any other form of electric generator, such as a dynamo or a voltaic pile.
The copper, nickel, gold, or silver plates hung in an electro-plating bath, and from which the metal is supplied to fill the deficiency made by the electro-deposition of metal on the kathode or negative object in the bath.
Anti-hum. A shackle inserted directly in a line-wire near a pole. It is provided with a washer or cushion of rubber to take up the vibrations of a wire. To continue the circuit a bridle, or curved piece of wire, is connected with the line-wires that are attached to the shackle.
Arc. A term applied to an electric current flowing from carbon to carbon, or from metals separated by a short gap, as in the arc street-lamps.
The original arc was produced by two vertical rods, through which the current passed up and down. When not in action the upper ends touched, but as the current flowed the ends were separated, so that the current, passing up one carbon across the gap and down the other, formed the segment of a circle in jumping from one tip to the other.
An arc of electric flame is of brilliant and dazzling whiteness. The voltaic arc is the source of the most intense heat and light yet produced by man. The light is due principally to the incandescence of the ends of carbon-pencils, when a current of sufficient strength is passing through them and jumping over the gap. Undoubtedly the transferred carbon particles have much to do with its formation. The conductivity of the intervening air and the intense heating to which it is subjected, together with its coefficient of resistance, are other factors in the brilliant light produced.
Arc-lamp. An electric lamp which derives its light from the voltaic arc, by means of carbon-pencils and a current jumping from one to the other.
Arc, Quiet. An arc free from the hissing sound so common in arc-lights.
Arc, Simple. A voltaic arc produced between only two electrodes.
Armature. A body of iron or other material susceptible to magnetization, and which is placed on or near the poles of a magnet.
That part of an electric mechanism which by magnetism is drawn to or repelled from a magnet.
The core of a dynamo or motor which revolves within the field magnets, and which is the active principle in the generation of current by mechanical means, or in the distribution of power through electrical influence. Armatures are sometimes made of steel, and are permanent magnets. These are used in magneto-generators, telegraph instruments, and other apparatus.
Armature-bar. An armature in a dynamo or motor whose winding is made up of conductors in the form of bars.
Armature-coil. The insulated wire wound around the core of the armature of an electric current-generator or motor.
Armature-core. The central mass of iron on which the insulated wire is wound; it is rotated in the field of an electric current-generator or motor.
Armored. Protected by armor; as cables may be surrounded by a proper sheathing to guard them from injury.
Astatic. Having no magnetic directive tendency, the latter being a general consequent of the earth’s magnetism.
Astatic Circuit. (See [Circuit, Astatic].)
Astatic Couple. (See [Couple, Astatic].)
Astatic Needle. A combination of two magnetic needles so adjusted as to have as slight directive tendency as possible. The combination is generally made up of two needles arranged one above the other with the poles in opposite directions—commonly called “Nobili’s Pair.” These needles require but a slight electro-force to turn them one way or the other, and are used in astatic galvanometers.
Atmospheric Electricity. (See [Electricity, Atmospheric].)
Atom. The ultimate particle or division of an elementary substance. Electricity is largely responsible for the presence of atoms in the atmosphere.
Atomic Attraction. The attraction of atoms for each other. Principally due to electric disturbance.
Attraction. The tendency to approach and adhere or cohere which is shown in all forms of matter. It includes gravitation, cohesion, adhesion, chemical affinity, electro-magnetic and dynamic attraction.
Aurora. A luminous electric display seen in the northern heavens. It is commonly thought to be the electric discharges of the earth into the atmosphere, due to revolution of the former and to the heat produced at the equator. As compared to the static machine for generating frictional electricity, the earth represents the revolving wheel gathering the current and discharging it at the poles.
Automatic Cut-out. An electro-magnetic switch introduced into a circuit, so as to break the circuit of the latter should it become overloaded with current; it also acts in the event of a mechanical interruption.
Automatic Regulation. A speed regulator worked by electricity so that a uniform flow of current may be secured automatically.
Ayrton’s Condenser. This is a pile of glass plates separated by small pieces of glass at the four comers, so that the plates cannot touch each other. Tin-foil is pasted on both sides of every plate, and the two coatings are connected. The tin-foil on each second plate is smaller in area than that on the others, and the plates are connected in two sets, negative and positive. In this construction it will be seen that the glass is not the dielectric proper, but acts only as the plane to which the tin-foil is pasted. One set of plates are connected to a binding-post by strips of tin-foil, and the other set are connected to another binding-post in a similar manner.