Part 8

_Carcel Lamp._—The French standard, equal to 9·4 candles.

_Capacity_ (K).—The powder of a surface to hold electricity as “static charge.” A coulomb divided by a volt. Its Unit is the Farad.

_Cathode._—The negative pole of a battery; the wire or plate connected with the zinc or positive element of the battery. The object on which a metallic deposit is to be formed. (_v._ Anode).

_Centimetre._—The hundredth part of a metre.

_Cell._—Each separate vessel in which a chemical action occurs, by which electricity is capable of being developed.

_Central-station._—A building containing plant for supplying electricity to the public.

_C. G. S._—The centimetre-gramme-second system.

_Circuit Conductive._—The wires which form the path for the passage of the current.

_Commutator._—A circuit changer, or switch. The collector of currents on a dynamo.

_Compound Winding._—A method of increasing or decreasing the energy developed in a dynamo in proportion to the demand.

_Conductivity._—Is the reciprocal to resistance, and applies to that property of any substance whereby the passage of electricity through it is effected with the least opposition.

_Conductors._—Substances which most freely permit electricity to pass.

_Connections._—Wires, &c., completing the circuit between different apparatus.

_Contact Breaker._—The electric lighting equivalent for a gas tap.

_Coulomb_ (Q).—The Unit of quantity, which passes in one second of an ampère current.

_Cut-out._—An instrument placed in the circuit which will open it automatically.

_Current_ (C).—The Unit is the Ampère. The supposed flow or passage of electricity or electrical force in the direction from + to -, or positive to negative.

_Current Reverse._—A current in the opposite direction to the normal current.

_Decimetre._—The tenth part of a metre.

_Deflection._—The angle or number of degrees through which the needle of a galvanometer moves when a current is passing through its coils.

_Diaphragm._—A porous division between two liquids through which electric current passes.

_Duplex Cut-out._—An instrument which enables a spare fuse to be immediately substituted for that melted.

_Duty._—A term used to denote the economy of any motor.

_Dynamo._—A name given to machines which produce electricity for commercial purposes.

_Dynamometer._—An instrument for ascertaining the horse-power absorbed by any machine.

_Dyne._—The Unit of force which gives a velocity of 1 centimetre per second to 1 gramme weight after acting for 1 second.

_Direct-Current Dynamo._—An electric generator producing currents passing in one direction.

_Earth._—A term for the return circuit, which for economy is formed through the earth in telegraph work. A return conductor common to many circuits is sometimes called “earth.”

_Electrodes._—A term for the poles or plates leading the current into and out of a cell.

_Electrolysis._—The act of decomposition by the electric current.

_Electrolyte._—The liquid in a cell.

_Electrometer._—An instrument for measuring electric potential.

_Electro-motive Force_ (_E. M. F._) (E).—The electric force tending to produce electric current. The Unit is the volt.

_Erg._—The C. G. S. Unit of energy. The work of moving a body through 1 centimetre against the force of a dyne.

_Extra Current._—The induced current of higher E. M. F., which appears in a wire wound in a helix when the current is broken.

_Farad._—The Unit of capacity: a coulomb divided by a volt.

_Field of Force._—The space between or around the poles of a magnet.

_Filament._—That part of an incandescent lamp which gives out the light.

_Field-Magnets._—In a dynamo the magnets between which the armature revolves.

_Foot Pound._—The British Unit of work, or 1 lb. raised 1 foot high.

_Galvanometer._—An instrument for measuring current.

_Generator._—Another term for a dynamo.

_Governor._—An apparatus for controlling the speed of any motor.

_Horse-Power_ (_HP._)—indicated HP.—The Unit is 33,000 lbs. lifted 1 foot high per minute. The nominal HP. of any motor is generally fixed considerably less than the indicated.

2(A P R S) Ind. HP. of any engine = ————————— 33,000

A = Area of piston in square inches. P = Average pressure of steam in lbs. per square inch. R = Number of revolutions per minute. S = Length of stroke in feet (if in inches, × 33,000 by 12).

The French “force cheval” represents 32,560 foot pounds.

_Horse-Power of Water._—Indian Government rule, 15 cube feet per second falling through 1 foot = 1 HP.

_Indicator Diagram._—The drawing produced by an instrument which is fixed to the cylinder of a steam-engine for the purpose of ascertaining its duty.

_Induction._—The name given to effects produced out of a force-exerting body or out of the circuit to which the force is directly applied. A current in a wire induces currents in other conductors parallel to it.

_Inertia._—The resistance to change of state of rest or motion.

_Insulators._—Bodies possessing high electrical resistance. All insulating substances, however, allow some electricity to pass.

_Intensity._—The old term for the properties now described as E. M. F. and potential.

_Joule_, also called _Joulad_ (W).—The Unit of heat or work, it has also been applied to the mechanical equivalent of heat, 772 foot lbs.

_Kilowatt._—One thousand watts.

_Knot._—The geographical and nautical mile.

_Leads._—Terms usually applied to copper conductors.

_Magnetism._—A condition which can be highly developed in iron and steel, by electric action or otherwise.

_Measurement._—See Units.

_Metre._—The French standard of length = 3·28 feet.

_Meg Ohm._—The prefix meg signifies a million.

_Millimetre._—The thousandth part of a metre.

_Milliampère._—The thousandth of an ampère.

_Mica-foil._—The fusible portion of a Hedges cut-out.

_Multiple Arc._—Galvanic cells or dynamos connected parallel, or lamps so arranged that each furnishes a separate path for the current.

_Negative._—In a machine the wire returning from the lamp. In a galvanic battery the copper, carbon, or platinum plate. Sign -.

_Nigger._—An American term used to denote an electrical fault.

_Ohm._—The Unit of resistance. A volt divided by an ampère.

_Ohm’s Laws._—Laws, investigated by Ohm, regulating electrical current magnitudes. Calling the current C, electro-motive force E, and resistance R: the expression is

Current E. M. F. Resistance. E E C = ——, amps. E = C × R, volts. R = —— ohms. R C (See Electrical Measurements.)

_Osmose._—The process of diffusion of liquids through a porous division.

_Paraffin._—An insulating substance much used in telegraphic work.

_Plummer Block._—The bearing on which a shaft revolves.

_Polarity._—The distinct features of the two separate poles of a magnet.

_Poles._—The two ends of a magnet. The wires, plates, &c., leading from a battery.

_Positive._—In a machine the wire proceeding to the lamp. In a battery the zinc plate. Sign +.

_Potential._—A word used to indicate a condition for work. Difference of potential is a difference of electrical condition. Potential of a battery means its E. M. F.

_Power_ (P).—The rate of doing work. When an ampère passes through an ohm, the unit power, called a watt, is required.

_Quantity_ (Q).—The Unit is the Coulomb.

_Relay._—An electro-magnet which, receiving its current from a distance, closes the circuit of a local battery so as to produce the required effect of strength.

_Resistance_ (R).—The opposition presented by the circuit to the development of the current. The Unit of resistance is the Ohm.

_Rheostat._—An instrument for inserting resistances. A valuable artificial resistance employed for measuring unknown resistances.

_Return Current._—The current in the wire leading to the machine.

_Rigger._—The pulley or wheel by which power is transmitted.

_Secondary Battery._—Wrongly termed an accumulator, is an appliance for storing energy in such a form that it shall be available for the reproduction of electric currents.

_Secondary Generator._—A transformer of a current of high potential into a current of less E. M. F.

_Series._—The plan of connecting lamps so that the current passes one after the other.

_Shunt._—A coil of wire arranged to take a certain proportion of any current.

_Solenoids._—Helices of wire which act like magnets.

_Switch._—An apparatus for changing one circuit on to another.

_Spectrum._—The elongated figure of the prismatic colours.

_Torque._—Term used to express the strain on a shaft due to electro-magnetic action.

_Units._—The various bases of any system of measurement.

_Volt._—The Unit of electro-motive force and potential. An ampère multiplied by an ohm. (See Electrical Measurements.)

_Voltameter._—An apparatus for measuring the current by its chemical action.

_Voltmeter._—An instrument used for measuring E. M. F.

_Watt._—The Unit of power. A volt-ampère. The horse-power electrical, taken as 746 B A watts, is equivalent to only 736 true watts. The horse-power electrical is equal to 756 B A watts, which is equal to 746 true watts. The “force de cheval,” or horse-power in use abroad, is defined as 75 kilogrammetres, and is, therefore, 736 true watts.

_Work_ (W.)—Is a volt multiplied by a coulomb, or (amp.² × sec × ohm) or (amp. × sec × volt). The Unit is the Joule.

_Yoke._—Is a term applied to the apparently neutral mass of iron which connects the poles of a horse-shoe magnet at the back.

APPENDIX I.—PRINCIPAL ELECTRIC LIGHTING STATIONS IN GREAT BRITAIN.

+--------------+-------------+-----------+-----------+ | Approximate | |Approximate| | |No. of Lights.| | length of | | Name of +--------+-----+ Systems | longest | Main | Station. | Incan- | | employed. | main | conductor | | descent| Arc.| | supply |overhead or| | or Glow| | | conductor |underground| | Lamps.| | | in miles. | | -----------+--------+-----+-------------+-----------+-----------+ Brighton | | |High-tension | | | Electric- | 1,800 | 40 | lamps in | 20 | Overhead | Light | | | multiple | | | Company | | |series Brush | | | | | | Dynamos | | | -----------+--------+-----+-------------+-----------+-----------+ Cadogan | | | | | | Electricity| | | Edmunds’ | | | Supply | · · | · · | system | 2 | Overhead | Company | | | of Battery | | | (New | | |Transformers | | | Company) | | | | | | -----------+--------+-----+-------------+-----------+-----------+ | | |Lowrie Hall | | 7 miles | Eastbourne | 1,700 | 30 |Transformers | 15 | under- | | | | | | ground | -----------+--------+-----+-------------+-----------+-----------+ | | |High-tension | | | Grosvenor | | |with Ferranti| 6 | | District | | |Transformers | circuits, | | Electrical | 20,000 | 40 | primary | total | | Supply | | | 2,400 volts,| about | Overhead | | | | secondary | 70 miles | | | | | 200 volts, | | | | | | Ferranti | | | | | | dynamos | | | -----------+--------+-----+-------------+-----------+-----------+ Kensington | | | Crompton | | | Court | 1600 | | 105 volts | | | Electric | to be | · · | low-tension,| ¼ |Underground| Lighting |extended| | constant | | | Company | to | | supply | | | | 10,000 | | by means of | | | | | |accumulators | | | -----------+--------+-----+-------------+-----------+-----------+ | | | Low-tension | | Overhead | Liverpool | 1,000 | · · | continuous | · · | and | | | | current | |Underground| | | | dynamos | | | -----------+--------+-----+-------------+-----------+-----------+ | | | Chamberlain | | | Leamington | 1,500 | · · | and Hookham | |Underground| | | |dynamos with | 1¼ | | | | |accumulators | | | -----------+--------+-----+-------------+-----------+-----------+ Paddington | 4,115 | 98 | E. M. F. | | | Electric |16 C. P.|3,000| 150 volts, | | | Lighting | lamps |C. P.| Gordon | 3 |Underground| | | |alternating | | | | | | current | | | | | | Dynamos | | | -----------+--------+-----+-------------+-----------+-----------+

+--------------+--------+--------+------------+ | | | | | | | | | Charges. | Name of | Approximate | | | | Station. | area of |Working |Hours of+------------+ | distribution.|Capital.|Supply. | | | | | | By Meter. | -----------+--------------+--------+--------+------------+ Brighton | | | | Meter | Electric- | About 3 | | | rent, | Light | square | £12,000|Constant|21_s._ 8_d._| Company | miles | | | per | | | | | annum | -----------+--------------+--------+--------+------------+ Cadogan | | | | | Electricity|Belgravia and | | | | Supply | Cadogan | | | | Company | Estate | £20,000| · · | · · | (New | | | | | Company) | | | | | -----------+--------------+--------+--------+------------+ | | | | | Eastbourne | · · | £20,000|Constant| · · | | | | | | -----------+--------------+--------+--------+------------+ |Very irregular| | | | Grosvenor | district, | | | 7½ per | District | a house is |£375,000| 8 A.M. | Board of | Electrical | lighted | | to | Trade | Supply | 2 miles | | 3 A.M. | unit | | station | | | | | from the | | | | | station | | | | | | | | | -----------+--------------+--------+--------+------------+ | The streets | | | | Kensington | adjoining | | | By meter | Court | the station, | | |and minimum | Electric | the mains to | £25,000|Constant| charge of | Lighting | be continued | | | 10_s._ per | Company | to another | | | light per | | station at | | | annum | |Knightsbridge | | | | -----------+--------------+--------+--------+------------+ | | | | | Liverpool | | | | By meter | | · · |£20,000 | · · | on sliding | | | | | scale | -----------+--------------+--------+--------+------------+ | | | | | | | | | | | | | | | Leamington | 183 | | | | | street | · · |Constant| | | lamps | | | meter | | | | | | -----------+--------------+--------+--------+------------+ Paddington | | | | | Electric | | | | | Lighting | 67 acres | · · |Constant| · · | | | | | | -----------+--------------+--------+--------+------------+

+---------------------------------+---------------------+ | | | | Charges. | | Name of | | | Station. |---------------------------------+ Remarks. | | | | | By yearly fixed amount. | | | | | -----------+---------------------------------+---------------------+ Brighton | Glow lamps, 1_s._ per unit, or | If consumption | Electric- | rather over ¾_d._ per lamp | is below | Light | per hour. Arc lamps, 4_s_. per | 100 units | Company | lamp per week including | quarterly, | | maintenance | 10¾_d._ discount. | -----------+---------------------------------+---------------------+ Cadogan | | | Electricity| | | Supply | | | Company | · · | · · | (New | | | Company) | | | -----------+---------------------------------+---------------------+ | According to consumption | A similar | Eastbourne | averaging about 6½_d._ | station | | per unit | at Hastings. | -----------+---------------------------------+---------------------+ | | | Grosvenor | | | District | | A station at | Electrical | · · | Deptford is | Supply | | under erection | | | to maintain | | | 200,000 lights. | | | | | | | -----------+---------------------------------+---------------------+ | | | Kensington |8_d._ per unit, equal to 0·56_d._| | Court | per 20 C.-P. lamp per hour, | District embraces | Electric | or 0·28_d._ per 10 C.-P. lamp. | residences, shops, | Lighting | Shops taken at £2 per annum | public hall, and | Company | per 20 C.-P. lamp minimum | church. | | of 10 lights | | | | | -----------+---------------------------------+---------------------+ | | Board of Trade | Liverpool | First 400 hours, 1_s._ per unit | license for six | | Second ” ” 8_d._ ” |years, hotels, shops,| | Afterwards 4_d._ ” | and residences. | -----------+---------------------------------+---------------------+ | Street lights £2 2_s._ per | | | annum for 2,860 hours, | | | including renewals. | | Leamington |1 to 40 units per quarter 8_d._ | | | per unit. 41 to 150 units per | · · | | quarter, 6_d._ per unit. 151 | | |units per quarter 4_d._ per unit | | -----------+---------------------------------+---------------------+ Paddington | |The district between | Electric | | Paddington and | Lighting | Worked by G. W. Railway | Westbourne Park is | | | lighted throughout. | -----------+---------------------------------+---------------------+