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O'Conor Slone - -Release Date: September 5, 2008 [EBook #26535] - -Language: English - -Character set encoding: ISO-8859-1 - -*** START OF THIS PROJECT GUTENBERG EBOOK THE STANDARD ELECTRICAL DICTIONARY *** - - - - -Produced by Don Kostuch - - - - - -</pre> - -<big><big>STANDARD ELECTRICAL DICTIONARY.<br> -<br> -</big></big><big><big><br> -[Transcriber's Notes]<br> -<br> -Obvious spelling errors have been corrected. I have not reconciled the<br> -variety of spellings of names and other words. Obvious factual errors,<br> -typographical errors, discoveries made after 1892, and contemporary<br> -(2008) theories and use of words are noted in the text within square<br> -brackets. I have not researched and checked every assertion by the<br> -author.<br> -<br> -This book was published 5 years before discovery of the electron. See<br> -the labored and completely inaccurate explanations of aurora and<br> -"energy, atomic". The author and his contemporaries were like fifteenth<br> -century sailors. They had a good idea of their latitude and direction<br> -(Ampere, Kirkoff, Maxwell, Gauss, Faraday, Edison, …), but only the<br> -vaguest notion of their longitude (nuclear structure, electrons, ions).<br> -Altitude (special relativity, quantum theory) was not even imagined.<br> -<br> -Some relevant dates:<br> -Franklin's Kite--1752<br> -Faraday's Law of Induction--1831<br> -Maxwell's Equations--1861<br> -Edison's Phonograph--1877<br> -Edison's light bulb--1879<br> -Edison's first DC power station--1882<br> -Michelson-Morley experiment disproving ether--1887<br> -Hertz demonstrates radio waves--1888<br> -Westinghouse first AC power station--1891<br> -This book--1892<br> -Discovery of the electron--1897<br> -Marconi radio signals cross the English Channel--1897<br> -First Vacuum Tube--1904<br> -Special Relativity, photo-electric effect explained with photons--1905<br> -General Relativity: space-time dilation and curvature--1915<br> -Confirmation of general relativity's prediction of the deflection<br> - of starlight by the Sun--1919<br> -Discovery of the proton--1920<br> -Quantum theory--1926<br> -Discovery of neutron--1932<br> -First transistor--1947<br> -Soviet satellite Luna measures solar wind--1959<br> -Edward M. Purcell explains magnetism with special relativity--1963<br> -<br> -Purcell's explanation of magnetism as a result of Lorentz contraction of<br> -space along the direction of a current is a welcome relief from the<br> -convoluted descriptions in this book.<br> -<br> -Mathematical notation is rendered using "programming" notation.<br> -^ Power--Exponential; A^3 means "A cubed"<br> -* Multiply<br> -/ Divide<br> -+ Add<br> -- Subtract<br> -( ) Precedence--Perform before enclosing -expression<br> -2E6 Scientific Notation (2,000,000)<br> -<br> -<br> - A<br> ----------------------<br> -4.452 X 10^12 X t<br> -<br> -is rendered as<br> -<br> -A / ( 4.452E12 * t )<br> -<br> -<br> -Where the rendering of a mathematical expression is in doubt, an image<br> -of the original text is included.<br> -<br> -<br> -Here are some definitions absent from the text.<br> -<br> -Foucault currents.<br> - Eddy currents.<br> -<br> -inspissate<br> - To thicken, as by evaporation.<br> -<br> -riband<br> - Ribbon.<br> -<br> -sapotaceous<br> - Order Sapotace[ae] of trees and shrubs, including the star -apple, the<br> - Lucuma, or natural marmalade tree, the gutta-percha tree -(Isonandra),<br> - and the India mahwa, as well as the sapodilla, or sapota, after -which<br> - the order is named.<br> -<br> -<br> -Don Kostuch, MS, Electrical Engineering.<br> -[End Transcriber's notes.]<br> -</big></big><br> -<br> -<br> -<big><big><br> -WORKS OF<br> -T. O'CONOR SLOANE, A.M., E.M., Ph.D.<br> -<br> -<br> -ARITHMETIC OF ELECTRICITY<br> -A MANUAL OF ELECTRICAL CALCULATIONS<br> -BY ARITHMETICAL METHODS.<br> -Third Edition. Illustrated. $1.00.<br> -It is very useful to that class of readers to whom Algebra is a<br> -comparatively unknown quantity, and will meet its wants<br> -admirably.--Electrical World.<br> -<br> -<br> -<br> -ELECTRICITY SIMPLIFIED.<br> -A POPULAR TREATMENT OF THE SUBJECT.<br> -Illustrated. $1. 00.<br> -We especially recommend it to those who would like to acquire a popular<br> -idea of the subject.--Electric Age.<br> -<br> -<br> -<br> -ELECTRIC TOY MAKING.<br> -FOR AMATEURS.<br> -INCLUDING BATTERIES, MAGNETS, MOTORS, MISCELLANEOUS TOYS,<br> -AND DYNAMO CONSTRUCTION.<br> -Fully Illustrated. $1.00.<br> -<br> -<br> -THE STANDARD ELECTRICAL DICTIONARY.<br> -<br> -A POPULAR DICTIONARY OF WORDS AND TERMS<br> -USED IN THE PRACTICE OF ELECTRICAL ENGINEERING.<br> -<br> -<br> -BY<br> -T. O'CONOR SLOANE, A.M., E.M., Ph.D.<br> -<br> -<br> -NEW YORK<br> -GEORGE D. HURST<br> -PUBLISHER<br> -<br> -<br> -<br> -Copyright 1892<br> -by<br> -NORMAN W. HENLEY & CO.<br> -<br> -<br> -<br> -PREFACE<br> -<br> -The purpose of this work is to present the public with a concise and<br> -practical book of reference, which it is believed will be appreciated in<br> -this age of electricity. The science has expanded so much that the<br> -limits of what may be termed strictly a dictionary of the present day<br> -would a few years ago have sufficed for an encyclopedia. It follows that<br> -an encyclopedia of electricity would be a work of great size. Yet a<br> -dictionary with adequate definitions, and kept within the closest limits<br> -by the statement of synonyms, and by the consigning of all the<br> -innumerable cross-references to a concise index will be far more than a<br> -mere dictionary in the ordinary sense of the term.<br> -<br> -Duplication of matter is to be avoided. This makes many definitions<br> -appear short. Yet, by the assistance of the reader's own general<br> -knowledge, and by referring to the very complete index, almost any<br> -subject can be found treated in all its aspects. There are exceptions to<br> -this statement. So much has been done in the way of mechanical detail,<br> -so many inventions in telegraphy and other branches have sprung into<br> -prominence only to disappear again, or to be modified out of<br> -recognition, that to embody descriptions of many ingenious and<br> -complicated apparatus has been absolutely impossible for want of space.<br> -<br> -A word as to the use of the book and the system of its construction may<br> -be given here. Each title or subject is defined once in the text. Where<br> -a title is synonymous with one or more others the definition is only<br> -given under one title, and the others appear at the foot of the article<br> -as synonyms. It may be that the reader is seeking the definition of one<br> -of these synonyms. If so a reference to the index shows him at once what<br> -page contains the information sought for. The use of an index in a work,<br> -necessarily of an encyclopedic form, will be appreciated by all users of<br> -this book.<br> -<br> -vi PREFACE.<br> -<br> -Where a title embraces several words, all orders of the words will be<br> -cited in the index. To make the operation of finding references easy<br> -this rule has been carried out very fully.<br> -<br> -It is customary to regard electricity as a growing science. It is<br> -unquestionably such, but the multiplication of terms and words is now<br> -not nearly so rapid as it has been, and the time for the compiling of a<br> -work of this character seems most propitious. It is hoped that the<br> -public will indulgently appreciate the labor it has entailed on all<br> -concerned in its production.<br> -<br> -<br> -SYMBOLS AND ABBREVIATIONS.<br> -<br> -</big></big> -<table style="width: 794px; height: 328px;" border="1" cellpadding="2" - cellspacing="2"> - <tbody> - <tr> - <td><big><big>adj.</big></big></td> - <td><big><big> Adjective.</big></big></td> - </tr> - <tr> - <td><big><big>v. </big></big></td> - <td><big><big>Verb.</big></big></td> - </tr> - <tr> - <td><big><big>q.v. </big></big></td> - <td><big><big> "Which see.'</big></big></td> - </tr> - <tr> - <td><big><big>/ </big></big></td> - <td><big><big>A mark of division, as A/B, meaning "A divided by -B."</big></big></td> - </tr> - <tr> - <td><big><big>./. </big></big></td> - <td><big><big>The same as above.</big></big></td> - </tr> - <tr> - <td><big><big><br> - </big></big></td> - <td><big><big> [Transcriber's note: / will be substituted for -this divide symbol.]</big></big></td> - </tr> - <tr> - <td><big><big>= </big></big></td> - <td><big><big> A mark of equality, meaning "is equal to."</big></big></td> - </tr> - <tr> - <td><big><big>X </big></big></td> - <td><big><big> A mark of multiplication, meaning "multiplied by."</big></big></td> - </tr> - <tr> - <td><big><big><br> - </big></big></td> - <td><big><big> [Transcriber's note: * will be substituted for -this divide symbol.]</big></big></td> - </tr> - </tbody> -</table> -<big><big><br> -<br> -Fractional exponents indicate the roots expressed by their denominators<br> -and the powers expressed by their numerators. Thus, A^1/2 means the<br> -"square root of A;" A^1/3 means the "cube root of A;" B^3/2 means the<br> -"square root of the cube or third power of B."<br> -<br> -The use of powers of ten, as 10^10, 10^11, as multipliers, will be found<br> -explained at length in the definition "Ten, Powers of."<br> -</big></big><br> -<br> -<big><big><br> -vii STANDARD ELECTRICAL DICTIONARY<br> -<br> -<span style="font-weight: bold;">A. </span><br> -Abbreviation for anode, employed in text relating to<br> -electro-therapeutics. It is sometimes written An.<br> -<br> -<br> -<span style="font-weight: bold;">Abscissa. </span><br> -In a system of plane co-ordinates (see Co-ordinates) the<br> -distance of any point from the axis of ordinates measured parallel to<br> -the axis of abscissas.<br> -<br> -In the cut the abscissa of the point a is the line or distance a c.<br> -<br> -<img style="width: 867px; height: 668px;" alt="" src="images/007F1.jpg"><br> -Fig. 1. AXES OF CO-ORDINATES.<br> -<br> -<br> -<span style="font-weight: bold;">Absolute.</span> adj.<br> -In quantities it may be defined as referring to fixed units of quantity,<br> -and it is opposed to "relative," which merely refers to the relation of<br> -several things to each other. Thus the relative resistance of one wire<br> -may be n times that of another; its absolute resistance might be 5 ohms,<br> -when the absolute resistance of the second wire would be 5/n ohms. A<br> -galvanometer gives absolute readings if it is graduated to read directly<br> -amperes or volts; if not so graduated, it may by "calibration" q. v. be<br> -made to do practically the same thing.<br> -<br> -8 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Absolute Measurement.</span><br> -Measurement based upon the centimeter, gram, and second. (See<br> -Centimeter-Gram-Second System.)<br> -<br> -<br> -<span style="font-weight: bold;">Absolute Temperature.</span><br> -Temperature reckoned from absolute zero (see "Zero, Absolute"). It is<br> -obtained by adding for the centigrade scale 273, and for the Fahrenheit<br> -scale 459, to the degree readings of the regular scale.<br> -<br> -<br> -<span style="font-weight: bold;">Absorption, Electric.</span><br> -A property of the static charge. When a Leyden jar is being charged it<br> -dilates a little and the capacity increases, so that it can take a<br> -little more charge for a given potential difference existing between its<br> -two coatings. This phenomenon occurs with other static condensers,<br> -varying in degree with the dielectric. With shellac, paraffin, sulphur<br> -and resin, for instance, the absorption is very slight; with<br> -gutta-percha, stearine, and glass, the absorption is relatively great.<br> -The term is due to Faraday. Iceland spar seems almost or quite destitute<br> -of electric absorption.<br> -<br> -<br> -<span style="font-weight: bold;">A. C. C.</span><br> -Symbol of or abbreviation for "anodic closure contraction" q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Acceleration.</span><br> -The rate of change of velocity. If of increase of velocity it is<br> -positive; if of decrease, it is negative. It can only be brought about<br> -by the exercise of force and is used as the measure of or as determining<br> -the unit of force. It is equal to velocity (L/T) imparted, divided by<br> -time (T); its dimensions therefore are L/(T^2). The c. g. s. unit of<br> -acceleration is one centimeter in one second.<br> -<br> -[Transcriber's note: The unit of acceleration is "centimeters per second<br> -per second."]<br> -<br> -<br> -<span style="font-weight: bold;">Accumulator.</span><br> -(a) A term sometimes applied to the secondary or storage battery. (See<br> -Battery, Secondary.)<br> -(b) See Accumulator, Electrostatic<br> -(c) See Accumulator, Water Dropping.<br> -(d) See Wheel, Barlow's<br> -<br> -<br> -<span style="font-weight: bold;">Accumulator, Electrostatic.</span><br> -Two conducting surfaces oppositely placed, and separated by a<br> -dielectric and arranged for the opposite charging of the two surfaces,<br> -constitute an accumulator, sometimes termed a condenser. As this<br> -arrangement introduces the element of a bound and of a binding charge,<br> -the electrostatic capacity of such is greater than that of either or of<br> -both of its component surfaces. The thinner the dielectric which<br> -separates the conducting surfaces, and the larger the surfaces the<br> -greater is the capacity; or the less will be the potential difference<br> -which a given charge will establish between its two coatings. The nature<br> -of the dielectric also determines its capacity. (See Capacity, Specific<br> -Inductive.)<br> -<br> -<br> -9 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 885px; height: 795px;" alt="" src="images/009F2.jpg"><br> -Fig. 2. SIR WILLIAM THOMSON'S WATER-DROPPING ACCUMULATOR.<br> -<br> -<br> -<span style="font-weight: bold;">Accumulator, Water Dropping.</span><br> -This is also known as Sir William Thomson's Water-Gravity Electric<br> -Machine. It is an apparatus for converting the potential energy of<br> -falling water drops, due to gravity, into electric energy. Referring to<br> -the illustration, G represents a bifurcated water pipe whose two faucets<br> -are adjusted to permit a series of drops to fall from each. C and F are<br> -two metallic tubes connected by a conductor; E and D are the same. Two<br> -Leyden jars, A and B, have their inner coatings represented by strong<br> -sulphuric acid, connected each to its own pair of cylinders, B to D and<br> -E, and A to F and C. The outer coatings are connected to earth, as is<br> -also the water supply. One of the jars, say A, is charged interiorily<br> -with positive electricity. This charge, C and F, share with it, being in<br> -electric contact therewith. Just before the drops break off from the jet<br> -leading into C, they are inductively charged with negative electricity,<br> -the positive going to earth. Thus a series of negatively excited drops<br> -fall into the metal tube D, with its interior funnel or drop arrester,<br> -charging it, the Leyden jar B, and the tube E with negative electricity.<br> -This excitation causes the other stream of drops to work in the converse<br> -way, raising the positive potential of F and C and A, thus causing the<br> -left-hand drops to acquire a higher potential. This again raises the<br> -potential of the right-hand drops, so that a constant accumulating<br> -action is kept up. The outer coatings of the Leyden jars are connected<br> -to earth to make it possible to raise the potential of their inner<br> -coatings. In each case the drops are drawn by gravity into contact with<br> -objects similarly excited in opposition to the electric repulsion. This<br> -overcoming of the electric repulsion is the work done by gravity, and<br> -which results in the development of electric energy.<br> -<br> -<br> -10 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Acidometer.</span><br> -A hydrometer or areometer used to determine the specific gravity of<br> -acid. They are employed in running storage batteries, to determine when<br> -the charging is completed. (See Areometer.)<br> -<br> -<br> -<span style="font-weight: bold;">Aclinic Line.</span><br> -A terrestrial element; the locus on the earth's surface of no<br> -inclination of the magnetic needle; the magnetic equator. (See Magnetic<br> -Elements.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Acoustic Telegraphy.</span><br> -The system of sound-reading in telegraphy, universally used in the Morse<br> -system. The direct stroke of the armature of the electro-magnet and its<br> -"back stroke" disclose to the ear the long and short strokes, dots and<br> -lines, and long and short spaces as produced by the dispatcher of the<br> -message. In the Morse system a special magnet and armature is used to<br> -produce the sound called the "sounder;" in other systems, e. g.,<br> -Steinheil's and Bright's apparatus, bells are used. (See Alphabets,<br> -Telegraphic.)<br> -<br> -<br> -<span style="font-weight: bold;">Acoutemeter.</span><br> -A Hughes audiometer or sonometer applied to determining the quality of a<br> -person's hearing (See Hughes' Induction Balance,--Audiometer). The<br> -central coil by means of a tuning fork and microphone with battery<br> -receives a rapidly varying current tending to induce currents in the<br> -other two coils. Telephones are put in circuit with the latter and pick<br> -up sound from them. The telephones are applied to the ears of the person<br> -whose hearing is to be tested. By sliding the outer coils back and forth<br> -the intensity of induction and consequent loudness of the sounds in the<br> -telephones is varied. The position when the sounds grow so faint as to<br> -be no longer audible, gives the degree of delicacy of the person's<br> -hearing. By using a single telephone the same apparatus affords a means<br> -of testing the relative capacity of the right and left ears.<br> -<br> -<br> -11 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Actinic Rays.</span><br> -The rays of light at the violet end of the spectrum; also the invisible<br> -rays beyond such end, or the ether waves of short periods which most<br> -strongly induce chemical change.<br> -<br> -<br> -<span style="font-weight: bold;">Actinism.</span><br> -The power possessed by ether waves of inducing chemical change, either<br> -of decomposition or of combination. The violet and ultra-violet end of<br> -the spectrum of white light, generally speaking, represent the most<br> -highly actinic rays.<br> -<br> -<br> -<span style="font-weight: bold;">Actinometer, Electric.</span><br> -Properly an apparatus for measuring the intensity of light by its action<br> -upon the resistance of selenium. A current produced by fixed<br> -electro-motive force passing through the selenium affects a galvanometer<br> -more or less according to the intensity of the light. It is more<br> -properly an electric photometer. The term has also been applied to a<br> -combination of a thermo-electric pile and galvanometer, the light<br> -falling on the pile affecting the motions of the galvanometer.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Action, Local.</span><br> -(a) The wasteful oxydation of the zinc in a galvanic battery due to<br> -local impurities and variations in the composition of the zinc. These<br> -act to constitute local galvanic couples which cause the zinc to<br> -dissolve or oxydize, without any useful result. Amalgamation of the zinc<br> -prevents local action. Chemically pure zinc is also exempt from local<br> -action, and can be used in an acid battery without amalgamation. (See<br> -Amalgamation.)<br> -<br> -(b) The same term has been employed to indicate the eddy or foucault<br> -currents in dynamo electric machines. (Sec Current, Foucault.)<br> -<br> -<br> -<span style="font-weight: bold;">Activity.</span><br> -The rate of doing work; the work done per second by any expenditure of<br> -energy. The activity of a horse-power is 550 foot lbs. per second, or<br> -746 volt-coulombs per second. The practical electric unit is the<br> -volt-ampere, often called the watt. (Sec Energy, Electric.)<br> -<br> -<br> -<span style="font-weight: bold;">Adapter.</span><br> -A screw coupling to engage with a different sized screw on each end; one<br> -of the uses is to connect incandescent lamps to gas-fixtures.<br> -<br> -<br> -<span style="font-weight: bold;">A. D. C.</span><br> -Abbreviation for Anodic Duration Contraction, q. v.; a term in<br> -electro-therapeutics.<br> -<br> -<br> -<span style="font-weight: bold;">Adherence, Electro-magnetic.</span><br> -The adherence between surfaces of iron due to elcctro-magnetic<br> -attraction. It has been applied to the driving-wheels of an engine and<br> -rail, whose grip is increased by such action. In one method a deep<br> -groove was cut around the wheel which was wound with a magnetizing coil.<br> -Thus one rim becomes a north and the other a south pole, and the rail<br> -completing the circuit acts as the armature. Such an arrangement<br> -prevents a wheel from sliding. Electro-magnetic adherence has also been<br> -employed to drive friction gear wheels. In one arrangement the two<br> -wheels are surrounded by a magnetizing coil, under whose induction each<br> -attracts the other, developing high adherence between their peripheries.<br> -<br> -<br> -12 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 430px; height: 615px;" alt="" src="images/012F3.JPG"><br> -Fig. 3. ELECTRO-MAGNETIC CAR WHEEL.<br> -<br> -<br> -<img style="width: 510px; height: 688px;" alt="" src="images/012F4.JPG"><br> -Fig. 4. ELECTRO-MAGNETIC FRICTION GEAR.<br> -<br> -<br> -<span style="font-weight: bold;">Admiralty Rule of Heating.</span><br> -The British Admiralty specifications for the permissible heating of<br> -dynamos. It holds that at the end of a run of six hours no part of the<br> -dynamo under trial shall show a rise of temperature greater than -11º C.<br> -(20º F.) above the temperature of the air surrounding it. This is<br> -thought to be a very stringent and unnecessarily high requirement.<br> -<br> -<br> -<span style="font-weight: bold;">Aerial Conductor.</span><br> -An electric conductor carried from housetops, poles, or otherwise so as<br> -to be suspended in the air, as distinguished from an underground or<br> -submarine conductor.<br> -<br> -<br> -<span style="font-weight: bold;">Affinity.</span><br> -The attraction of atoms and in some cases perhaps of molecules for each<br> -other by the force of chemical attraction. When the affinity is allowed<br> -to act or is carried out, a chemical change, as distinguished from a<br> -physical or mechanical change, ensues. Thus if sulphur and iron are each<br> -finely powdered and are mixed the change and mixture are mechanical. If<br> -slightly heated the sulphur will melt, which is a physical change. If<br> -heated to redness the iron will combine with the sulphur forming a new<br> -substance, ferric sulphide, of new properties, and especially<br> -characterized by unvarying and invariable ratios of sulphur to iron.<br> -Such change is a chemical one, is due to chemical affinity, is due to a<br> -combination of the atoms, and the product is a chemical compound.<br> -<br> -<br> -13 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Agir Motor.</span><br> -The Anderson and Girdlestone motor. The term "agir" is made up from the<br> -first portions of each name.<br> -<br> -<br> -<span style="font-weight: bold;">Agonic Line.</span><br> -The locus of points on the earth's surface where the magnetic needle<br> -points to the true north; an imaginary line determined by connecting<br> -points on the earth's surface where the needle lies in the true<br> -geographical meridian. Such a line at present, starting from the north<br> -pole goes through the west of Hudson's Bay, leaves the east coast of<br> -America near Philadelphia, passes along the eastern West Indies, cuts<br> -off the eastern projection of Brazil and goes through the South Atlantic<br> -to the south pole. Thence it passes through the west of Australia, the<br> -Indian Ocean, Arabia, the Caspian sea, Russia and the White sea to the<br> -North Pole. It crosses the equator at 70° W. and 55° E. -approximately.<br> -(See Magnetic Elements.)<br> -<br> -Synonym--Agone.<br> -<br> -<br> -<img style="width: 700px; height: 615px;" alt="" - src="images/309_Declination_1590_1990.gif"><br> -[Transcriber's note: The file Earth_Declination_1590_1990.gif provided<br> -by the U.S. Geological Survey (http://www.usgs.gov) is an animation of<br> -the declination of the entire earth.]<br> -<br> -<br> -<span style="font-weight: bold;">Air.</span><br> -Air is a dielectric whose specific inductive capacity at atmosphere<br> -pressure is taken as 1. It is practically of exactly the same<br> -composition in all places and hence can be taken as a standard. When dry<br> -it has high resistance, between that of caoutchouc and dry paper.<br> -Dampness increases its conductivity.<br> -<br> -It is a mixture of oxygen and nitrogen, with a little carbonic acid gas<br> -and other impurities. Its essential composition is:<br> -<small><br> -</small></big></big><big><big><small><span - style="font-family: monospace;">Oxygen: (by weight) -23.14 (by volume) 21 </span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Nitrogen: - 76.86 - 79</span></small><br> -<br> -The specific inductive capacity varies for different pressures thus:<br> -<br> -</big></big><big style="font-family: monospace;">Approximate -</big><big style="font-family: monospace;"> (.001 mm., .0004 inch) - 0.94 (Ayrton) <br> -</big><big style="font-family: monospace;">Vacuum </big><small - style="font-family: monospace;"><br> -</small><big style="font-family: monospace;"> - </big><big - style="font-family: monospace;">( 5 mm. , .2 inches ) </big><big><big><small - style="font-family: monospace;"> 0.9985 (Ayrton)<br> - - 0.99941 (Boltzman.)</small><br> -<br> -The specific gravity of air under standard conditions 15.5° C -(60° F.)<br> -and 760 mm. barometric pressure (30 inches) is taken as unity as a<br> -standard for gases.<br> -<br> -[Transcriber's note: Argon accounts for 0.9340%. It was discovered in<br> -1894, two years after this book.]<br> -<br> -<br> -<span style="font-weight: bold;">Air-Blast.</span><br> -(a) In the Thomson-Houston dynamo an air-blast is used to blow away the<br> -arc-producing spark liable to form between the brushes and commutator.<br> -It is the invention of Prof. Elihu Thomson. The air is supplied by a<br> -positive action rotary blower connected to the main shaft, and driven<br> -thereby. The wearing of the commutator by destructive sparking is thus<br> -prevented.<br> -<br> -A drum H H is rotated, being mounted on the axis X of the dynamo. As it<br> -rotates the three vanes are thrown out against the irregular shaped<br> -periphery of the outer case T T. The arrow shows the direction of<br> -rotation. The air is thus sent out by the apertures a a. O is the<br> -oil-cup.<br> -<br> -(b) The air-blast has also been used by Prof. Thomson in experiments<br> -with high frequency currents of high potential. By directing a blast of<br> -air against a spark discharge between ball terminals of an alternating<br> -current, the nature of the current was changed and it became capable of<br> -producing most extraordinary effects by induction.<br> -<br> -<br> -14 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 527px; height: 629px;" alt="" src="images/014F5.jpg"><br> -Fig. 5. AIR BLOWER FOR THOMSON'S DYNAMO.<br> -<br> -<br> -<span style="font-weight: bold;">Air Condenser.</span><br> -A static condenser whose dielectric is air. The capacity of an air<br> -condenser in farads is equal to<br> - A / ( 4.452E12 * t )<br> -in which A is the area of one sheet or sum of the areas of one set of<br> -connected sheets in square inches and t is the thickness of the layer of<br> -air separating them.<br> -<br> -A convenient construction given by Ayrton consists in a pile of glass<br> -plates P separated by little bits of glass F of known thickness, three<br> -for each piece. Tin-foil T is pasted on both sides of each piece of<br> -glass and the two coatings are connected. The tin-foil on each second<br> -plate is smaller in area than that on the others. The plates are<br> -connected in two sets, each set comprising every second plate. For A in<br> -the formula the area of the set of smaller sheets of tin-foil is taken.<br> -By this construction it will be seen that the glass does not act as the<br> -dielectric, but only as a plane surface for attachment of the tin-foil.<br> -Posts E E keep all in position. One set of sheets connects with the<br> -binding post A, the other with B.<br> -<br> -The capacity of any condenser with a dielectric of specific inductive<br> -capacity i is given by the formula:<br> - ( i *A^1 ) / ( 4.452E12 * t1 )<br> -<br> -The air condenser is used for determining the value of i for different<br> -dielectrics.<br> -<br> -<br> -<img style="width: 496px; height: 513px;" alt="" src="images/015F6.jpg"><br> -Fig. 6. AIR CONDENSER.<br> -<br> -<br> -15 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Air Gaps.</span><br> -In a dynamo or motor the space intervening between the poles of the<br> -field magnet and the armature. They should be of as small thickness, and<br> -of as extended area as possible. Their effect is to increase the<br> -magnetic reluctance of the circuit, thereby exacting the expenditure of<br> -more energy upon the field. They also, by crowding back the potential<br> -difference of the two limbs, increase the leakage of lines of force from<br> -limb to limb of the magnet.<br> -<br> -<br> -<span style="font-weight: bold;">Air Line Wire.</span><br> -In telegraphy the portion of the line wire which is strung on poles and<br> -carried through the air.<br> -<br> -<br> -<span style="font-weight: bold;">Air Pump, Heated.</span><br> -It has been proposed to heat portions of a mercurial air pump to secure<br> -more perfect vacua, or to hasten the action. Heating expands the air and<br> -thus produces the above effects.<br> -<br> -<br> -16 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Air Pump, Mercurial.</span><br> -An air pump operated by mercury. The mercury acts virtually as the<br> -piston, and the actuating force is the weight of the column of mercury,<br> -which must exceed thirty inches in height. There are many types.<br> -Mercurial air pumps are largely used for exhausting incandescent lamp<br> -chambers. (See Geissler Air Pump,--Sprengel Air Pump.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Air Pumps, Short Fall.</span><br> -A mercurial air pump in which the fall of mercury or the height of the<br> -active column is comparatively small. It is effected by using several<br> -columns, one acting after the other. A height of ten inches for each<br> -column suffices in some forms. Enough columns must be used in succession<br> -to make up an aggregate height exceeding 30 inches.<br> -<br> -<br> -<img style="width: 525px; height: 212px;" alt="" src="images/016F7.jpg"><br> -Fig. 7. BURGLAR ALARM SWITCH OR CIRCUIT BREAKER.<br> -<br> -<br> -<img style="width: 440px; height: 325px;" alt="" src="images/016F8.jpg"><br> -Fig. 8. BURGLAR ALARM SWITCH OR CIRCUIT BREAKER.<br> -<br> -<br> -<span style="font-weight: bold;">Alarm, Burglar.</span><br> -A system of circuits with alarm bell extending over a house or<br> -apartments designed to give notice of the opening of a window or door.<br> -As adjuncts to the system the treads of the stairs are sometimes<br> -arranged to ring the bell, by completing a circuit when trod on. Door<br> -mats are also arranged to close circuits in like manner.<br> -<br> -<br> -17 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -For doors and windows switches are provided which are open as long as<br> -the door or window is closed, but which, on being released by opening<br> -the door or windows, automatically close the circuit. The circuit<br> -includes an alarm bell and battery, and the latter begins to ring and<br> -continues until stopped, either by the closing of the door or by a<br> -switch being turned. The connections are sometimes so contrived that the<br> -reclosing of the door or window will not stop the bell from ringing.<br> -<br> -The cuts show various switches for attachment to doors and windows. It<br> -will be seen that they normally keep the circuit closed, and that it is<br> -only open when pressure, as from a closed door, is brought upon them. In<br> -the case of a door a usual place for them is upon the jamb on the hinge<br> -side, where they are set into the wood, with the striking pin<br> -projecting, so that as the door is closed the pin is pressed in, thus<br> -breaking the circuit.<br> -<br> -Sometimes the connections are arranged so as to switch on the electric<br> -lights if the house is entered. Special annunciators showing where the<br> -house has been entered are a part of the system. A clock which turns the<br> -alarm on and off at predetermined hours is also sometimes used.<br> -<br> -The circuits may be carried to a central station or police station. One<br> -form of burglar alarm device is the Yale lock switch. This is a contact<br> -attached to a Yale lock which will be closed if the wrong key is used,<br> -completing a circuit and ringing a bell.<br> -<br> -<br> -<img style="width: 746px; height: 253px;" alt="" src="images/017F9.jpg"><br> -Fig. 9. BURGLAR ALARM SWITCH OR CIRCUIT BREAKER.<br> -<br> -<br> -<span style="font-weight: bold;">Alarm, Electric. </span><br> -An appliance for calling attention, generally by <br> -ringing a bell. It is used to notify of water-level in boilers or -tanks, <br> -of entrance of a house, or of other things as desired. It is evident <br> -that any number of alarms could be contrived.<br> -<br> -<br> -18 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Alarm, Fire and Heat.</span><br> -An alarm for giving notice of the existence of a conflagration. Such are<br> -sometimes operated by a compound bar thermostat (see Thermostat), which<br> -on a given elevation of temperature closes a circuit and rings an<br> -electric bell. Sometimes the expansion of a column of mercury when<br> -heated is used. This, by coming in contact with one or two platinum<br> -points, completes a circuit, and rings the bell.<br> -<br> -The identical apparatus may be used in living rooms, greenhouses.<br> -factories and elsewhere, to give an alarm when the temperature rises or<br> -falls beyond predetermined limits.<br> -<br> -<br> -<span style="font-weight: bold;">Alarm, Overflow.</span><br> -An alarm to indicate an overflow of water has been suggested on the<br> -lines of a contact completed by water, or of the elements of a battery<br> -which would be made active by water. Thus two sheets of metal might be<br> -separated by bibulous paper charged with salt. If these sheets were<br> -terminals of a circuit including a bell and battery, when water reached<br> -them the circuit would be closed and the bell would ring. It was also<br> -proposed to use one copper and one zinc sheet so as to constitute a<br> -battery in itself, to be thrown into action by moisture. These contacts<br> -or inactive batteries could be distributed where water from an overflow<br> -would be most likely to reach them.<br> -<br> -<br> -<span style="font-weight: bold;">Alarm, Water Level.</span><br> -An alarm operated by a change of water level in a tank or boiler. By a<br> -float a contact is made as it rises with the water. Another float may be<br> -arranged to fall and close a contact as the level falls. The closing of<br> -the contacts rings an electric bell to notify the attendant in charge.<br> -<br> -<br> -<span style="font-weight: bold;">Alcohol, Electrical Rectification of.</span><br> -A current of electricity passed through impure alcohol between zinc<br> -electrodes is found to improve its quality. This it does by decomposing<br> -the water present. The nascent hydrogen combines with the aldehydes,<br> -converting them into alcohols while the oxygen combines with the zinc<br> -electrode.<br> -<br> -<br> -<span style="font-weight: bold;">Alignment.</span><br> -The placing in or occupying of the same straight line. The bearings of a<br> -shaft in dynamos, engines, and other machinery have to be in accurate<br> -alignment.<br> -<br> -<br> -<span style="font-weight: bold;">Allotropy.</span><br> -The power of existing in several modifications possessed by some<br> -substances, notably by chemical elements. Instances of the allotropic<br> -state are found in carbon which exists as charcoal, as graphite<br> -(plumbago or black lead), and as the diamond. All three are the same<br> -elemental substance, although differing in every physical and electrical<br> -property.<br> -<br> -<br> -19 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Alloy.</span><br> -A mixture, produced almost universally by fusion, of two or more metals.<br> -Sometimes alloys seem to be chemical compounds, as shown by their having<br> -generally a melting point lower than the average of those of their<br> -constituents. An alloy of a metal with mercury is termed an amalgam. An<br> -important application in electricity is the use of fusible alloys for<br> -fire alarms or for safety fuses. German silver is also of importance for<br> -resistance coils, and palladium alloys are used for unmagnetizable<br> -watches. An alloy of wrought iron with manganese is almost<br> -unmagnetizable, and has been proposed for use in ship building to avoid<br> -errors of the compass.<br> -<br> -Alloys or what are practically such can be deposited by electrolysis in<br> -the electro- plater's bath. We give the composition of some alloys<br> -interesting to the electrician.<br> -<small><br> - <span style="font-family: monospace;">Solder: -Lead 1 part -Tin 2 parts</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -" " -" 1 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -" " -" 2 "</span></small> -<br> -<br> -German Silver: Copper, 2 parts; Nickel, 1 part;<br> - -Zinc, 1 part (used for resistances).<br> -<br> -Platinum, Silver Alloys: Platinum, 1 part;<br> - -silver, 2 parts (used for resistances.)<br> -<br> -Palladium alloys for watch springs. (See Palladium.)<br> -<br> -<br> -<span style="font-weight: bold;">Alphabet, Telegraphic.</span><br> -The combinations of sounds, of dots and dashes marked on paper, of<br> -right-hand and left-hand deflections of a needle, of bells of different<br> -notes, or of other symbols by which a fixed combination is expressed for<br> -each character of the alphabet, for numerals, and for punctuation. While<br> -the code is designed for telegraphic uses it can be used not only for<br> -the conveyance of signals and messages by the electrical telegraphs, but<br> -also by any semaphoric or visual system, as by flashes of light,<br> -movements of a flag or even of the arms of the person signalling.<br> -<br> -In the English and continental needle telegraphy in which the message is<br> -transmitted by the movements of an index normally vertical, but<br> -oscillating to one side or the other under the influence of the current,<br> -the latter being controlled by the transmitter of the message, the left<br> -hand swings of the needle are interpreted as dots, the right hand as<br> -dashes.<br> -<br> -This system enables one alphabet to be translated into the other, or<br> -virtually one alphabet answers for both Morse and needle transmitters.<br> -<br> -There are two principal telegraphic alphabets, the American Morse and<br> -the International codes. They are very similar, their essential<br> -distinction being that spaces are used in the American code, while they<br> -are excluded from the International code.<br> -<br> -In the American Morse system the message is now universally received by<br> -sound. (See Sounder--Sound Reading.)<br> -<br> -<br> -20 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The two codes or telegraphic alphabets are given here.<br> -<br> -THE INTERNATIONAL ALPHABET.<br> - -<span style="font-family: monospace;">Parenthesis, -- . - - . -</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Understand, -... - .</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> I don't -understand, ..-- ....--..</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -Wait, -.-. . .</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Erase, -... ... ...</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Call -signal, --.-.-.-</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> End of -message, .-.-.-.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Cleared out all -right, .-..-..-.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> A -.- L .-.. W .--</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> B -... M --- X -..-</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> C -.-. N --. Y -.--</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> D -.. -O --- Z --..</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> E -. P .--.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> F ..-. Q ---.- Ch ----</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> G --. -R .-. Ä .-.-</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> H .... S -... Ö ---.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> I -.. T - -Ü ..--</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> J .--- U -..- É ..-..</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> K -.- -V ...- Ñ --.--</span><br - style="font-family: monospace;"> -<br style="font-family: monospace;"> -<span style="font-family: monospace;">NUMERALS</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> 1 .---- -4 ....- 8 ---..</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> 2 ..--- -5 ..... 9 ----.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> 3 ...-- -6 -.... 0 -----</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -7 --...</span><br> -<br> -<br> -[Transcriber's note: The original image of the dot/dash pattern is -somewhat<br> -ambiguous. Since there may be differences from contemporary -specifications,<br> -the original image is included.]<br> -<br> -<img style="width: 640px; height: 1019px;" alt="" - src="images/020Pic.jpg"><br> -[Image of page 20: THE INTERNATIONAL ALPHABET.]<br> -<br> -<br> -21 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-family: monospace;">PUNCTUATION, ETC.,</span><br - style="font-family: monospace;"> -<br style="font-family: monospace;"> -<span style="font-family: monospace;"> Period -(.) -... ...</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Comma -(,) -.-.-.-</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Query(?) -..--..</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Exclamation -(!) --..--</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Apostrophe -(') .----.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Hyphen -(-) -....-</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Fresh -paragraph, .-.-..</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Inverted -commas, -..-.</span><br style="font-family: monospace;"> -<br style="font-family: monospace;"> -<span style="font-family: monospace;">THE AMERICAN ALPHABET.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> A -.- L -----(Continuous) W .--</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> B --... M --- -X .-..</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> C -..s. N --. -Y ..s..</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> D --.. O -.s. -Z ….</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> E -. P .....</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> F -.-. Q -..-. -Ch ----</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> G ---. R -.s.. -Ä .-.-</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> H -.... S -... -Ö ---.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> I -.. T -- -Ü ..--</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> J - . - . -U -..- -É ..-..</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> K --.- V -...- -Ñ --.--</span><br style="font-family: monospace;"> -<br style="font-family: monospace;"> -<span style="font-family: monospace;">NUMERALS</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> 1 -.--. 4 -....- 8 -....</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> 2 ..-.. -5 ---- 9 -..-</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> 3 ...-. -6 ... ... 0 ------(Continuous)</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -7 --..</span><br> -<br> -[Transcriber's Note: The "s" in the American Code indicates a "space". -I <br> -leave the following to the reader's imagination. See the original <br> -image.]<br> -<br> -<span style="font-family: monospace;">Comma (,)</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Semicolon (;)</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Colon (:)</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Colon Dash (:~)</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Period (.)</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Interrogation (?)</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Exclamation (!)</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Dash (-)</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Hyphen (-)</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Pound Sterling (£)</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Shilling Mark ( )</span><br> -<br> -<br> -<img style="width: 624px; height: 1052px;" alt="" - src="images/021Pic.jpg"><br> -[Image of page 21: THE AMERICAN ALPHABET.]<br> -<br> -<br> -22 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -[Transcriber's Note: I leave these to the reader's imagination. See the -<br> -following original image.]<br> -<br> -Dollars ($)<br> -Decimal Point (.)<br> -Cents (c)<br> -Paragraph ()<br> -Pence (d.)<br> -Fractional Mark (--)<br> -Capitalized Letter<br> -Italics or Underline<br> -Colon followed by Quotation :"<br> -Parenthesis ( )<br> -Brackets [ ]<br> -Quotation Marks " "<br> -Quotation within a Quotation " ' ' "<br> -<br> -<br> -<img style="width: 677px; height: 341px;" alt="" src="images/022Pic.jpg"><br> -[Image of page 22: THE AMERICAN ALPHABET.]<br> -<br> -<br> -The principal differences in the two codes are the use of spaces in the<br> -American code, such being excluded from the International code. This<br> -affects the letters C, R, Y, & Z.<br> -<br> -The following diagram, due to Commandant Perian, enables the letter<br> -corresponding to an International code sign to be rapidly found with the<br> -exception of R.<br> -<small><br> - -<span style="font-family: monospace;"><- -dot -start dash --></span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -/ -\</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -E -T</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -/ -\ -/ -\</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -I -A -N -M</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -/ -\ -/ \ -/ \ -/ \</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -S -U -R W -D K -G O</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> / \ -/ \ / -\ / \ / -\ / \ / -\ / \</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">H V -F U L -A P J B X -C Y Z Q Ô -CH</span><br> -</small> -<br> -Fig. 10. Diagram for translating the Morse Alphabet.<br> -<br> -In order to find what letter corresponds to a given sign, starting from<br> -the top of the diagram, each line is traced down to a bifurcation,<br> -taking the right hand line of each bifurcation for a dash, and the left<br> -hand line for a dot, and stopping when the dots and dashes are used up.<br> -Thus, for example,<br> -<br> -the signal -.- - leads us to the letter d,<br> -<br> -the signal - - - - to the letter j and so on.<br> -<br> -<br> -23 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Alternating. adj. </span><br> -Term descriptive of a current changing periodically in<br> -direction. (See Current, Alternating.)<br> -<br> -Synonyms--Oscillatory--periodic--undulatory--harmonic.<br> -<br> -<span style="font-weight: bold;">Alternating Current Arc.</span><br> -The arc produced by the alternating current. It presents several<br> -peculiarities. With an insufficient number of alternations per second it<br> -goes out. As the carbons wear away equally it is adopted for such lamps<br> -as the Jablochkoff candle, (see Candle, Jablochkoff). As no crater is<br> -formed the light is disseminated equally both up and down. For this<br> -reason to get full downward illumination a reflector is recommended.<br> -<br> -<br> -<span style="font-weight: bold;">Alternating Current System.</span><br> -A system of electric distribution employing the alternating current. For<br> -transmission in the open air or in conduits a high potential circuit is<br> -used, from 1,000 to 10,000 volts being maintained at the central<br> -station. Two leads unconnected at the end lead from the station. Where<br> -current is desired a converter or transformer (see Converter) is placed,<br> -whose primary is connected to the two leads bridging the interval<br> -between them. From the secondary the house leads are taken with an<br> -initial potential in some cases of 50 volts. The converters are thus all<br> -placed in parallel. By law or insurance rules the converters are<br> -generally kept outside of buildings. Where no secondary current is taken<br> -from the converters very little primary current passes them on account<br> -of their counter-electromotive force. As more secondary current is taken<br> -the primary increases and this accommodation of one to the other is one<br> -of the interesting and valuable features. Street lamps are sometimes<br> -connected in series. Each lamp in such case is in parallel with a small<br> -coil with iron core. While the lamp is intact little current passes<br> -through the coil. If the lamp is broken, then the converter impedes the<br> -current by its spurious resistance, q. v., just enough to represent and<br> -replace the resistance of the extinguished and broken lamp filament.<br> -(See Meter, Alternating Current; Motor, Alternating Current.)<br> -<br> -<br> -<span style="font-weight: bold;">Alternation.</span><br> -The change in direction of a current. The number of such changes is<br> -expressed as number of alternations; thus a current may have a frequency<br> -of 500 or 20,000 alternations per second.<br> -<br> -[Transcriber's note: One alternation per second is now called one -hertz.]<br> -<br> -<br> -<span style="font-weight: bold;">Alternation, Complete. </span><br> -A double alternation; a change from one direction<br> -to the other and back again to the original phase. A symbol derived from<br> -its graphic representation by a sine curve is used to indicate it. The<br> -symbol is ~<br> -<br> -<br> -24 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Alternative Path.</span> <br> -A second path for a current appearing as a disruptive<br> -discharge. Where two paths are offered the discharge, as it is of<br> -alternating or oscillatory type, selects the path of least<br> -self-induction. Thus a thick bar of copper, with no air gap, may be<br> -abandoned by the current in favor of a small iron wire with an air gap,<br> -but which has less self-induction.<br> -<br> -The lightning arresters, q. v., for the protection of telegraph offices<br> -are sometimes based on these principles. A path of very high resistance<br> -but of small self-induction is offered between the line and the earth.<br> -This the lightning discharge selects in preference to the instruments<br> -with their iron cores, as the latter are of very high self-induction.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Alternator. </span><br> -A dynamo electric generator supplying an alternating current. (See<br> -Dynamo, Alternating Current.)<br> -<br> -Synonym--Alternating current generator or dynamo.<br> -<br> -<br> -<span style="font-weight: bold;">Alternator, Constant Current.</span><br> -An alternating current dynamo supplying a current of unvarying virtual<br> -amperage. Alternators of this type are constructed with an armature of<br> -high self-induction. Sometimes fine winding contained in deep peripheral<br> -notches in the core-discs is employed to magnify the self-induction.<br> -Such generators are employed for series lighting, especially<br> -arc-lighting.<br> -<br> -<br> -<span style="font-weight: bold;">Aluminum.</span><br> -A metal; one of the elements; symbol: Al.<br> -Atomic weight: 27.4. Equivalent: 9.13. Valency: 3.<br> -Specific gravity: 2.6. It is a conductor of electricity.<br> -Relative resistance annealed, (Silver = 1) 1.935<br> -Specific resistance at 0ºC (32°F.) 2.912 -microhms<br> -<br> -<small><span style="font-family: monospace;">Resistance of a wire at -0ºC (32°F.)</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">a) 1 foot long, weighing 1 -grain, 0.1074 ohms.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">b) 1 foot long, 1/1000 inch -thick, -17.53 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">c) 1 meter long, weighing 1 -gram, -0.0749 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">d) 1 meter long, 1 millimeter -thick 0.03710 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Resistance of a 1-inch cube at -0ºC (32°F.) 1.147 microhms</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Electro-chemical -equivalent. .0958 (hydrogen == .0105)</span></small><br> -<br> -<br> -25 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Amalgam.</span><br> -(a) A combination or alloy in which one of the constituents is mercury.<br> -Usually the term is applied to an alloy of a single metal with mercury.<br> -Some metals readily form amalgams; such metals are: Gold, zinc, silver,<br> -lead and others; some, such as platinum and iron, form amalgams only<br> -under exceptional circumstances.<br> -<br> -(b) The word is also applied to compositions for application to the<br> -cushions of frictional electric machine in which cases it is often a<br> -misnomer. True amalgams used for this purpose are made as follows:<br> -<br> -(a) Tin, 1 part; Zinc, 1 part; Mercury, 2 parts (Kienmayer).<br> -(b) Tin, 2 parts; Zinc, 3 parts.<br> -(c) Tin, 3 parts; Zinc, 5 parts; Mercury, 4 parts.<br> -(d) Zinc, 1 part: Mercury, 4 parts; Mercury, 9 parts. [sic]<br> -<br> -The tin, if such is used, (formula a, b and c) is first melted, the zinc<br> -is added in successive portions. The mercury, which must be heated, is<br> -slowly poured into the melted alloy after removal of the latter from the<br> -fire, and the mixture, while making, is constantly stirred. It is kept<br> -stirred or rubbed in a mortar until cold. Sometimes it is poured into<br> -water and kept in constant agitation until cold. It is thus obtained in<br> -a granular condition, and is pounded in a mortar until reduced to<br> -powder. It must be dried and kept in tightly stopped bottles and is<br> -applied to the cushions after they have been greased. It is to be<br> -noticed that it is said that alloy (d) requires no pulverization beyond<br> -constant rubbing in a mortar as it cools. Sometimes the amalgam is<br> -shaken about in a wooden tray with chalk while cooling. The action of<br> -amalgams is not very clearly understood. Some claim that there is a<br> -chemical action, others that they simply act as conductors, others that<br> -they are more highly negative to the glass than the leather of the<br> -cushions.<br> -<br> -Graphite or sulphide of tin (mosaic gold) are sometimes used to coat the<br> -cushions; it is these that are sometimes incorrectly called amalgams.<br> -<br> -<br> -<span style="font-weight: bold;">Amalgamation.</span><br> -The application of mercury to a metal with which it forms an amalgam, or<br> -with which it amalgamates. Battery zincs are amalgamated in two ways. In<br> -the immersion method, the plate is dipped into an acid solution of<br> -mercuric chloride or nitrate. The latter is best. In the direct<br> -application method the plate is first wet all over with dilute acid and<br> -a little mercury is dropped upon it and is rubbed over the surface with<br> -a rag or, what is better, with a piece of galvanized iron. A very little<br> -mercury answers the purpose. The whole surface of the plate should be<br> -left as bright as silver. (See Action, Local.)<br> -<br> -<br> -<span style="font-weight: bold;">Amber.</span><br> -Amber is a fossil resin, supposed to be a product of the extinct Pinites<br> -Succinifer and other coniferous trees. Most of it is gathered on the<br> -shores of the Baltic between Koenigsberg and Memel. It is also found in<br> -small pieces at Gay Head, Mass., and in New Jersey green sand. It is<br> -found among the prehistoric remains of the Swiss Lake dwellers. When<br> -rubbed with a cloth it becomes excited with negative electricity. The<br> -Greek word for it is electron, which gave the name electricity to the<br> -modern science. Thales of Miletus, 600 B. C., and Theophrastus, about<br> -300 B. C., both mention its electric properties or power of attracting<br> -small objects when rubbed.<br> -<br> -<br> -26 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Ammeter.</span> <br> -The commercial name for an ampere-meter, an instrument designed<br> -to show by direct reading the number of amperes of current which are<br> -passing through a circuit.<br> -<br> -A great variety of ammeters have been invented, based on different<br> -principles. The definitions following this one give some idea of the<br> -lines of construction followed.<br> -<br> -Synonym--Ampere meter.<br> -<br> -<br> -<span style="font-weight: bold;">Ammeter, Ayrton's.</span><br> -A direct reading instrument for measuring current intensity.<br> -<br> -A solenoid receives the current. In the axis of the solenoid an iron<br> -tube is suspended by a long spiral spring that passes down within it,<br> -and the upper end of which spring is fastened to the glass top of the<br> -instrument. The tube is provided with proper guides so as to maintain a<br> -vertical position, and is free to rotate. Its upper end carries an<br> -index.<br> -<br> -The whole operates as a magnifying device. A slight longitudinal<br> -displacement of the tube causes it to rotate through a considerable<br> -angle by the action of the spring. By properly proportioning the parts,<br> -the angle of displacement of the index is directly proportional to the<br> -current between 15º and 270º angular displacement.<br> -<br> -The same instrument is wound for use as a volt-meter.<br> -<br> -Its principal fault is its restricted range.<br> -<br> -<br> -<span style="font-weight: bold;">Ammeter, Commutator.</span><br> -A commutator ammeter is one whose windings consist of separate strands,<br> -each of any desired number of turns, and provided with a commutating<br> -attachment for throwing them into series or into parallel as desired.<br> -The essential condition is that all the wires shall be of equal<br> -resistance and of equal number of turns. Such an instrument can be used<br> -for heavy or light currents. Two sets of graduations are marked on its<br> -scale if it is a calibrated instrument. (See Calibration.) Commutator<br> -volt-meters are constructed on the same principle.<br> -<br> -<br> -<span style="font-weight: bold;">Ammeter, Cunynghame's.</span><br> -A modification of the Siemens' electro-dynamometer. (See<br> -Electro-dynamometer, Siemens'.) An electro-magnet with very massive core<br> -is excited by the current. As the core is of small reluctance the<br> -strength of the magnet is nearly proportional to the current strength.<br> -Between the poles of the magnet a soft iron armature or induced magnet<br> -is pivoted. It carries a pointer so adjusted that when the axis of the<br> -soft iron magnet is at an angle of about 30º with the line joining -the<br> -poles of the electro-magnet the pointer will indicate zero.<br> -<br> -The soft iron armature is so massive that the magnetism induced in it is<br> -proportional to the strength of the electro-magnet. Hence the couple<br> -exerted by the electro-magnet on the pivoted armature will be<br> -proportional to the square of the current.<br> -<br> -The armature is retained in place by a spiral spring lying in line with<br> -its axis of rotation. The instrument is operated as a zero reading<br> -instrument. The current is passed through it. The needle is deflected;<br> -it is brought back to zero by turning a milled head which twists the<br> -spring. The current will be proportional to the square root of the angle<br> -of displacement of the milled head. A scale with index is provided,<br> -giving directly the square roots of the angle over which the pointer is<br> -moved.<br> -<br> -The same instrument is wound for use as a volt-meter.<br> -<br> -<br> -27 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Ammeter, Eccentric Iron Disc.</span><br> -This ammeter comprises a cylindrical electro-magnet excited by the<br> -current to be measured. A disc of iron free to rotate is suspended on<br> -pivots below it. A piece is cut off the disc at one part of its<br> -periphery so as to give more metal to one side than to the other. In its<br> -zero position this portion of the disc swings towards the magnet. As the<br> -latter is more and more excited the other or more projecting portion of<br> -the disc turns towards it, being attracted like an armature, and moves<br> -against the force of gravity, the disc rotating. An index attached to<br> -the disc swings over the face of a graduated scale. The disc is so<br> -counterpoised that in its natural position the index points to zero.<br> -<br> -<br> -<span style="font-weight: bold;">Ammeter, Electro-magnetic.</span><br> -An ammeter depending for its working upon the action of an<br> -electro-magnet, which is excited by the current to be measured.<br> -<br> -<span style="font-weight: bold;">Ammeter, Gravity.</span><br> -An ammeter whose hand or index is drawn into the zero position by<br> -gravity, and whose displacement therefrom is produced by the action of<br> -the current to be measured.<br> -<br> -<br> -<img style="width: 517px; height: 810px;" alt="" src="images/027F11.jpg"><br> -Fig. 11. GRAVITY SOLENOID AMMETER.<br> -<br> -<br> -<span style="font-weight: bold;">Ammeter, Magnetic Vane.</span><br> -A fixed plate of soft iron is placed within a coil. Facing it is a<br> -second disc free to move or swing on an axis. When the field is excited<br> -the two repel each other because like polarity is induced in each, and<br> -the motion of the movable disc indicates the strength of the current.<br> -The same instrument is wound for high resistance and constitutes a<br> -Magnetic Vane Voltmeter.<br> -<br> -<br> -28 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Ammeter, Magnifying Spring.</span><br> -A solenoid ammeter in which a spiral spring is used to convert the<br> -longitudinal motion of the armature or movable core into a rotary motion<br> -(see Ammeter, Ayrton's) and magnify the apparent range of motion.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Ammeter, Permanent Magnet.</span><br> -An ammeter with a magnetic field produced by a permanent magnet.<br> -<br> -<br> -<span style="font-weight: bold;">Ammeter, Solenoid.</span><br> -An ammeter in which the attraction, when a current is passing through<br> -it, exerted by a hollow coil of wire upon an iron bar or tube in line<br> -with its axis, is utilized to indicate the strength of current. The bar<br> -is drawn into the coil to different extents proportional to the<br> -attraction. As an example see Ammeter, Ayrton's, and cut of Gravity<br> -Ammeter.<br> -<br> -<br> -<span style="font-weight: bold;">Ammeter, Spring.</span><br> -An ammeter in which the part moved by the current is controlled or<br> -brought to the zero position by a spring.<br> -<br> -<br> -<span style="font-weight: bold;">Ammeter, Steel Yard.</span><br> -A solenoid ammeter in which the solenoid core is suspended vertically<br> -from the short end of a steel yard fitted with a sliding weight. The<br> -current passes through the solenoid coil and attracts or draws downwards<br> -the coil. A sliding weight is moved in and out on the long steel-yard<br> -arm which is graduated for amperes. In use the weight is slid out until<br> -the arm is in equipose; the divisions give the amperes.<br> -<br> -<br> -<img style="width: 638px; height: 387px;" alt="" src="images/028F12.jpg"><br> -Fig. 12. STEEL YARD AMMETER.<br> -<br> -<br> -29 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Ammunition Hoist, Electric.</span><br> -An apparatus for use on ships for hoisting ammunition to the guns by an<br> -electric elevator. The characteristic feature of it is that a constant<br> -motion of the switch or handle is required to keep it in action. If the<br> -operator is shot so as to be incapacitated from taking charge of the<br> -switch, the hoist stops until another is assigned to it.<br> -<br> -<br> -<span style="font-weight: bold;">Amperage.</span><br> -Current intensity expressed in amperes, as an amperage of ten amperes.<br> -<br> -<br> -<span style="font-weight: bold;">Ampere.</span><br> -The practical unit of electric current strength. It is the measure of<br> -the current produced by an electro-motive force of one volt through a<br> -resistance of one ohm. In electric quantity it is the rate of one<br> -coulomb per second. It is one-tenth the absolute C. G. S. unit of<br> -current strength. Its best analogy is derived from water. Assuming the<br> -electric current to be represented by a current of water, the pressure,<br> -head, or descent producing such current would be the electro-motive<br> -force. The current might be measured in gallons (or other unit) passed<br> -per second. In the analogy these gallons would be coulombs. But it might<br> -be measured by reference to a standard stream, as for instance, the<br> -stream which would pass through a hole an inch square under a given<br> -head, say six inches of water. This unit is the miner's inch, and is the<br> -exact analogy of the ampere. A current of water may flow at the rate of<br> -so many miner's inches, just as a current of electricity may flow at the<br> -rate of so many amperes. In neither case it will be noted is there any<br> -reference to time. "An ampere per second" is a redundant expression, and<br> -means no more than "an ampere"; an "ampere-second," on the other hand,<br> -is a coulomb. The number of coulombs passed per second gives the amperes<br> -of current.<br> -<br> -For value of ampere, see Coulomb.<br> -<br> -[Transcriber's note: The SI definition of an ampere: A current in two<br> -straight parallel conductors of infinite length and negligible<br> -cross-section, 1 metre apart in vacuum, would produce a force equal to<br> -2E-7 newton per metre of length.]<br> -<br> -<br> -<img style="width: 644px; height: 450px;" alt="" src="images/029F13.jpg"><br> -Fig. 13. THE MINER'S INCH AS AN ANALOGY FOR THE AMPERE.<br> -<br> -<br> -30 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Ampere, Arc.</span><br> -A conductor bent into the arc of a circle, and employed in measuring the<br> -electric current by the electric balance.<br> -<br> -<br> -<span style="font-weight: bold;">Ampere-currents.</span><br> -The currents assumed to be the cause of magnetism. (See Magnetism,<br> -Ampere's Theory of.)<br> -<br> -<br> -<span style="font-weight: bold;">Ampere-feet.</span><br> -The product of amperes of current by the length, in feet, of a conductor<br> -passing such current. It may be in empiric calculations of dynamo or<br> -motor construction, but is little used. One ampere-foot is a current of<br> -one ampere passing through one foot length of a conductor, or one-tenth<br> -ampere through ten feet, and so on.<br> -<br> -<br> -<span style="font-weight: bold;">Ampere-hour.</span><br> -The quantity of electricity passed by a current of one ampere in one<br> -hour. It is used by electric power and lighting companies as the unit of<br> -energy supplied by them, because they maintain a constant potential<br> -difference in their leads, so that only the amperes and hours need<br> -measuring or recording to give the energy, viz. : volt-ampere-hours.<br> -The same unit is applied to batteries to indicate their potential<br> -energy, because they also are assumed to be of constant voltage or<br> -electro-motive force.<br> -<br> -<br> -<span style="font-weight: bold;">Ampere-meters.</span><br> -The product of amperes of current by the length, in meters, of a<br> -conductor carrying such current. One ampere-meter is a current of one<br> -ampere passing through one meter of a conductor.<br> -<br> -The term must not be confused with the identically spelled Ampere-meter,<br> -a synonym for Ammeter.<br> -<br> -<br> -<span style="font-weight: bold;">Ampere-minute.</span><br> -The quantity of electricity passed by a current of one ampere in one<br> -minute; sixty coulombs.<br> -<br> -<br> -<span style="font-weight: bold;">Ampere Ring.</span><br> -A conductor forming a ring or circle used in electric balances for<br> -measuring currents. (See Balance, Ampere.)<br> -<br> -<br> -<span style="font-weight: bold;">Ampere-second.</span><br> -The quantity of electricity passed by a current of one ampere in one<br> -second; the coulomb, q. v.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Amperes, Lost.</span><br> -In a shunt or compound-wound dynamo, part of the total amperes of<br> -current produced in the armature coils go through the shunt, and hence,<br> -do not appear in the outer circuit. S. P. Thompson has proposed the term<br> -"lost amperes" for this portion of the current.<br> -<br> -<br> -<span style="font-weight: bold;">Ampere's Memoria Technica.</span><br> -An expression of the effect of a current on a magnetic needle. If we<br> -imagine the observer in the line of the current and facing the magnetic<br> -needle, the current entering by his feet and leaving by his head, the<br> -north pole is deflected to his left.<br> -<br> -<br> -31 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Ampere-turns.</span><br> -The amperes of current supplied to a magnet coil multiplied by the<br> -number of turns the current makes in the coil. If the coil is wound two<br> -or three in parallel, the virtual turns by which the amperes are<br> -multiplied are one-half or one-third the actual turns of wire.<br> -<br> -Synonym--Ampere Windings.<br> -<br> -<br> -<span style="font-weight: bold;">Ampere-turns, Primary.</span><br> -The ampere-turns in the primary coil of an induction coil or<br> -transformer.<br> -<br> -<br> -<span style="font-weight: bold;">Ampere-turns, Secondary.</span><br> -The ampere-turns in the secondary coil of an induction coil or<br> -transformer.<br> -<br> -<br> -<span style="font-weight: bold;">Amplitude of Waves.</span><br> -Waves are distinguished by length and amplitude. The latter, in the case<br> -of transverse waves, such as those of water and of the ether, correspond<br> -with and measure the height from lowest to highest point, or from valley<br> -to summit of the waves in question. In the case of longitudinal waves,<br> -such as those of the air, due to sounding bodies, the ratio of degree of<br> -rarefaction to degree of condensation existing in the system is the<br> -amplitude. The latter can be graphically represented by a sinuous line,<br> -such as would represent the section of a transverse wave. Ether waves<br> -are produced by heated bodies and by electro-magnetic impulses, as in<br> -the discharge of the Leyden jar.<br> -<br> -The amplitude of a wave, other things being equal, is the measure of its<br> -intensity. Thus, the louder a sound the greater is the amplitude of the<br> -system of waves to which it is due. The same applies to ether waves,<br> -whether they are perceived in the electro-magnetic, light, or<br> -heat-giving modification. As the amplitude of ether waves cannot be<br> -accurately known, amplitude is a relative term and is not stated<br> -generally in any absolute unit.<br> -<br> -<br> -<span style="font-weight: bold;">Analogous Pole.</span><br> -One of the elements of a pyro-electric crystalline substance, such as<br> -tourmaline. When heated, such bodies acquire electrical properties. If<br> -of such crystalline form that they are differently modified at the ends<br> -of their crystalline axis, by hemihedral modifications, the ends may be<br> -differently affected. One end may show positive electricity when the<br> -temperature is rising, and negative when falling. Such end is then<br> -called the analogous pole. The opposite end presents, in such cases, the<br> -opposite phenomena; becoming negative when the temperature is rising,<br> -and becoming positive when it is falling; such end is called the<br> -antilogous pole.<br> -<br> -<br> -<span style="font-weight: bold;">Analysis.</span><br> -The determination of the elements of a case. It may be chemical, and<br> -consist in finding what a substance consists of; it may be mathematical,<br> -and consist in determining the unknown quantities in a problem; or it<br> -may belong to other branches of science. The term has a very extended<br> -application. Where the constituents are only determined in kind it is<br> -called qualitative analysis; where their quantity or percentage is<br> -ascertained it is called quantitative analysis.<br> -<br> -<br> -32 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Analysis, Electric.</span><br> -Chemical analysis by electrolytic methods. (See Electrolytic -Analysis.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Analyzer, Electric.</span><br> -An apparatus used in investigations on electric ether waves. It consists<br> -of a series of parallel metallic wires. When the electric waves have<br> -been polarized, the analyzer will only permit them to go through it<br> -intact, when the plane of vibration of the waves is parallel to its<br> -wires.<br> -<br> -<br> -<span style="font-weight: bold;">Anelectrics.</span><br> -(a) Bodies which do not become electrified by friction; a term<br> -introduced by Gilbert, now little used, as all bodies develop<br> -electricity under proper conditions by contact action; the reverse of<br> -idioelectrtics.<br> -<br> -(b) Also a conductor of electricity, the reverse of a dielectric, q. v.<br> -(See Conductor.)<br> -<br> -It will be seen that Gilbert's anelectrics were, after all, the same as<br> -the modern anelectrics, i.e., conductors.<br> -<br> -<br> -<span style="font-weight: bold;">Anelectrotonus.</span><br> -A term used in medical electricity or electro-therapeutics to indicate<br> -the deceased functional activity induced in a nerve by the proximity of<br> -the anode of an active electric circuit completed through the nerve. The<br> -converse of Kathelectrotonus.<br> -<br> -<br> -<span style="font-weight: bold;">Angle of Declination.</span><br> -The angle of error of the magnetic needle or compass, measuring the<br> -extent of its deviation from the meridian in any locality. It is the<br> -angle between the plane of the magnetic axis of a magnetic needle free<br> -to take its natural position, and the geographical meridian, the needle<br> -being counterpoised if necessary, so as to hold an absolutely horizontal<br> -position. The deviation is expressed as being east or west, referring<br> -always to the north pole. (See Magnetic Elements.)<br> -<br> -Synonym--Variation of the Compass.<br> -<br> -[Transcriber's note: See Agonic Line.]<br> -<br> -<br> -<span style="font-weight: bold;">Angle of the Polar Span.</span><br> -In a dynamo or motor the angle subtended by the portion of a pole piece<br> -facing the armature, such angle being referred to the centre of the<br> -cross-section of the armature as its centre.<br> -<br> -<br> -33 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Angular Velocity.</span><br> -The velocity of a body moving in a circular path, measured with<br> -reference to the angle it passes over in one second multiplied by the<br> -radius and divided by the time. A unit angle is taken (57°.29578 =<br> -57° 17' 44".8 nearly) such that it is subtended by a portion of the<br> -circumference equal in length to the radius. Hence, the circumference,<br> -which is 360°, is equal to 2*PI*unit angle, PI being equal to -3.1416--.<br> -"Unit angular velocity" is such as would in a circle of radius = 1<br> -represent a path = 1, traversed in unit time = 1 second. If the radius<br> -is r and the angle passed over is theta, the distance is proportional to<br> -r*theta; if this distance is traversed in t seconds the angular velocity<br> -is theta / t. The angular velocity, if it is multiplied by r, theta<br> -expressing a distance, will give the linear velocity. The dimensions of<br> -angular velocity are an angle (= arc / radius) / a Time = (L/L)/T =<br> -(T^-1).<br> -<br> -The velocity expressed by the rate of an arc of a circle of unit radius,<br> -which arc subtends an angle of 57° 17' 44".8, such arc being -traversed<br> -in unit time, is unit angular velocity.<br> -<br> -<br> -<span style="font-weight: bold;">Animal Electricity.</span><br> -Electricity, notably of high tension, generated in the animal system, in<br> -the Torpedo, Gymnotus and Silurus. The shocks given by these fish are<br> -sometimes very severe. The gymnotus, or electric eel, was elaborately<br> -investigated by Faraday. It has the power of voluntarily effecting this<br> -discharge. There is undoubtedly some electricity in all animals. The<br> -contact of the spinal column of a recently killed frog with the lumbar<br> -muscles produces contraction, showing electric excitement. Currents can<br> -be obtained from nerve and muscle, or from muscle sides and muscle cut<br> -transversely, in each case one thing representing positive and the other<br> -negative elements of a couple.<br> -<br> -<br> -<span style="font-weight: bold;">Angle of Inclination or Dip.</span><br> -The angle which the magnetic axis of a magnet, which magnet is free to<br> -move in the vertical plane of the magnetic meridian, makes with a<br> -horizontal line intersecting such axis. To observe it a special<br> -instrument, the dipping compass, inclination compass, dipping needle, or<br> -dipping circle, as it is called, is used. (See Elements, Magnetic,<br> ---Dipping Needle,--Compass, Inclination.)<br> -<br> -<br> -<span style="font-weight: bold;">Angle of Lag.</span><br> -The angle expressing the displacement of the magnetic axis of the<br> -armature core of a dynamo in the direction of its rotation. (See Lag.)<br> -Lag is due to the motion of the armature core.<br> -<br> -<br> -<span style="font-weight: bold;">Angle of Lead.</span><br> -The angle expressing the displacement in the direction of rotation of<br> -the armature of a dynamo which has to be given the brushes to compensate<br> -for the lag. (See Lag.) This is positive lead. In a motor the brushes<br> -are set the other way, giving a negative angle of lead or angle of<br> -negative lead.<br> -<br> -<br> -<span style="font-weight: bold;">Anion.</span><br> -The electro-negative element or radical of a molecule, such as oxygen,<br> -chlorine or the radical sulphion. (See Ions.) It is the portion which<br> -goes to the anode, q.v., in electrolytic decomposition.<br> -<br> -<br> -34 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Anisotropic. (adj.)</span><br> -Unequal in physical properties, as in conduction and specific inductive<br> -capacity, along various axes or directions. An anisotropic conductor is<br> -one whose conductivity varies according to the direction of the current,<br> -each axis of crystallization in a crystalline body marking a direction<br> -of different conductivity. An anisotropic medium is one varying in like<br> -manner with regard to its specific inductive capacity. In magnetism an<br> -anisotropic substance is one having different susceptibilities to<br> -magnetism in different directions. The term is applicable to other than<br> -electric or magnetic subjects.<br> -<br> -Synonym--AEolotropic.<br> -<br> -<br> -<span style="font-weight: bold;">Annealing, Electric.</span><br> -Annealing by the heat produced by the passage of the electric current<br> -through the body to be annealed. The object is clamped or otherwise<br> -brought into a circuit, and a current strong enough to heat it to<br> -redness, or to the desired temperature is passed through it.<br> -<br> -<br> -<span style="font-weight: bold;">Annunciator.</span><br> -An apparatus for announcing a call from any place to another, as from a<br> -living-room to an office in a hotel, or for announcing the entering of<br> -any given room or window in a building protected by a burglar alarm.<br> -<br> -A usual system comprises for each annunciator an electro-magnet. Its<br> -armature is normally held away from its poles by a spring, and when in<br> -that position a latch connected to the armature holds a little shutter.<br> -When by a push-button or other device a current is sent through a<br> -circuit which includes the electro-magnet the armature is attracted,<br> -this releases the latch and the shutter drops. In dropping it displays a<br> -number, letter or inscription which indicates the locality of the<br> -push-button or other circuit-closing device. Often annunciators are<br> -connected in circuit with a bell.<br> -<br> -<br> -<img style="width: 581px; height: 617px;" alt="" src="images/034F14.jpg"><br> -Fig. 14. ANNUNCIATOR.<br> -<br> -<br> -35 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Annunciator Clock.</span><br> -A clock operating an annunciator by making contact at determined times.<br> -<br> -<span style="font-weight: bold;">Annunciator Drop.</span><br> -The little shutter which is dropped by some forms of annunciators, and<br> -whose fall discloses a number, character or inscription, indicating<br> -whence the call was sent.<br> -<br> -<br> -<img style="width: 576px; height: 702px;" alt="" src="images/035F15.jpg"><br> -Fig. 15. DROP ANNUNCIATOR.<br> -<br> -<br> -<img style="width: 665px; height: 418px;" alt="" src="images/035F16.jpg"><br> -Fig. 16. ANNUNCIATOR DETACHING MECHANISM.<br> -<br> -<br> -<span style="font-weight: bold;">Annunciator, Gravity Drop.</span><br> -An annunciator whose operations release shutters which fall by gravity.<br> -<br> -<br> -<span style="font-weight: bold;">Annunciator, Needle.</span><br> -A needle annunciator is one whose indications are given by the movements<br> -of needles, of which there is usually a separate one for each place of<br> -calling.<br> -<br> -<br> -<span style="font-weight: bold;">Annunciator, Swinging or Pendulum.</span><br> -An annunciator which gives its indications by displacing from its<br> -vertical position a pendulum or vertically suspended arm.<br> -<br> -<br> -36 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Anodal Diffusion.</span><br> -A term in electro-therapeutics; the introduction of a medicine into the<br> -animal system by using a sponge-anode saturated with the solution of the<br> -drug in question. On passing a current the desired result is secured by<br> -cataphoresis, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Anode.</span><br> -The positive terminal in a broken metallic or true conducting circuit;<br> -the terminal connected to the carbon plate of a galvanic battery or to<br> -its equivalent in case of any other generator. In general practice it is<br> -restricted to the positive terminal in a decomposition or electrolytic<br> -cell, such as the nickel anode in a nickel-plating bath or the anode of<br> -platinum in a gas voltameter. It is the terminal out of or from which<br> -the current is supposed to flow through the decomposition cell. In<br> -electro-therapeutics the term is used simply to indicate the positive<br> -terminal. In an electrolytic cell the electro-negative substance or<br> -anion goes to the anode. Hence, it is the one dissolved, if either are<br> -attacked. The nickel, copper or silver anodes of the electroplater<br> -dissolve in use and keep up the strength of the bath. The platinum anode<br> -in a gas voltameter is unattacked because the anion cannot act upon it<br> -chemically.<br> -<br> -<br> -<span style="font-weight: bold;">Anodic Closure Contraction.</span><br> -A physiological change in a living subject produced by the closing of<br> -the electric current; the muscular contraction which takes place beneath<br> -the anode applied to the surface of the body when the circuit is closed,<br> -the kathode being applied elsewhere; it is due, presumably, to direct<br> -action on the motor nerve. It is a term in electro-therapeutics. It is<br> -the converse of anodic opening contraction, q. v. An abbreviation A. C.<br> -C. is often used to designate it.<br> -<br> -<br> -<span style="font-weight: bold;">Anodic Duration Contraction.</span><br> -A term in electro-therapeutics. On the opening or closing of an electric<br> -circuit, the anode of which is placed over a muscle, a contraction is<br> -observed (see Anodic Closure Contraction--Anodic Opening Contraction).<br> -The above term is used to designate the duration of such contraction. An<br> -abbreviation A. D. C. is often used to designate it.<br> -<br> -<br> -<span style="font-weight: bold;">Anodic Opening Contraction.</span><br> -The converse of Anodic Closure Contraction, q. v.; it is the contraction<br> -of living muscle beneath or near the anode where the circuit, including<br> -such anode and the body in its course, is closed; a physiological<br> -phenomenon observed in electro-therapeutics to which branch of science<br> -the term belongs. An abbreviation A. O. C. is often used to designate<br> -it.<br> -<br> -<br> -<span style="font-weight: bold;">Anodic Reactions.</span><br> -A term in electro-therapeutics; the diagnosis of disease by the actions<br> -of the tissue near the anode of a circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Anti-Induction Conductor.</span><br> -A conductor constructed to avoid induction effects in the conducting<br> -element. Many kinds have been made. A tubular metal shield or envelope<br> -which may be grounded will protect an enclosed conductor to some extent.<br> -Or the conductor may be a double wire twisted around itself, one branch<br> -being used for the regular and the other for the return circuit, thus<br> -constituting a closed metallic circuit. The inductive effects are due to<br> -interrupted or varying currents in neighboring wires and circuits. Many<br> -anti-induction conductors have been invented and patented.<br> -<br> -<br> -37 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Anti-magnetic Shield.</span><br> -In general terms a hollow screen of soft iron designed to protect any<br> -mass of steel behind or enclosed by it from magnetization by any magnet<br> -near it, such as a dynamo field magnet. This it does by concentrating<br> -the lines of force within its own mass, so that the space within it or<br> -enclosed by it is comparatively free from lines of force. It is often<br> -applied to watches, and is virtually an iron case in which they are<br> -enclosed.<br> -<br> -<span style="font-weight: bold;">Antimony.</span><br> -A metal, one of the elements, atomic weight, 122:<br> -equivalent, 40.6 and 24.4; valency, 3 and 5;<br> -specific gravity, 6.8.<br> -It is a conductor of electricity.<br> -<small><span style="font-family: monospace;">Relative resistance, -compressed (silver = 1), 23.60</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Specific resistance, -35.50 microhms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Resistance of a wire,</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">(a) 1 foot long, weighing 1 -grain, -3.418 ohms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">(b) 1 foot long, 1/1000 inch -thick, -213.6 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">(c) 1 meter long, weighing 1 -gram, -2.384 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">(d) 1 meter long. 1 millimeter -thick, 0.4521 "</span></small><br> -<br> -Resistance of a 1-inch cube, 13.98 microhms.<br> -<br> -Approximate percentage resistance per degree C.<br> -(1.8º F. at 20º C. 88º F.) 0.389 per cent.<br> -<br> -Elcctro-chemical equivalent (hydrogen = .0105) .2560<br> -(See Thermo-Electric Series.)<br> -<br> -<br> -<span style="font-weight: bold;">Anvil.</span><br> -An intermittent contact, or "make and break" of the current is sometimes<br> -produced by directly pressing a key down upon a metallic surface, the<br> -two being terminals of the circuit. The surface or stud on which such<br> -pressure is produced is called the anvil. The ordinary telegraph key,<br> -which makes a contact by the pressure of the operator's fingers does it<br> -by making a contact between a contact piece upon the front end of the<br> -key and the anvil. In the induction coil the anvil is also found. Thus<br> -in the cut representing the end of an induction coil and its circuit<br> -breaker in which O and O' and P and P' represent the secondary circuit<br> -terminal connections A is the core of soft iron wires, h is the anvil;<br> -the hammer when resting upon it so as to be in contact closes the<br> -circuit. When the current coming from the primary to the post i, passes<br> -through the hammer and anvil h, and emerges by m, it magnetizes the<br> -core; this attracts the hammer, which is made of or is armed with a mass<br> -of iron. This breaks the circuit. The hammer falls at once on the anvil,<br> -again making the circuit, and the action is repeated with great<br> -rapidity. Hammer and anvil or key and anvil connections should be made<br> -of platinum.<br> -<br> -<br> -<img style="width: 619px; height: 507px;" alt="" src="images/038F17.jpg"><br> -Fig. 17. INDUCTION COIL CIRCUIT BREAKER.<br> -<br> -<br> -38 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">A. O. C.</span><br> -Abbreviation for Anodic Opening Contraction, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Aperiodic. adj.</span><br> -In an oscillating apparatus, or in the oscillating member of apparatus,<br> -the fact of having no reference to time of vibration; dead-beat.<br> -<br> -Synonym. Dead-beat.<br> -<br> -<br> -39 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 627px; height: 429px;" alt="" src="images/038F18.jpg"><br> -Fig. 18. ARAGO'S DISC.<br> -<br> -<br> -<span style="font-weight: bold;">Arago's Disc.</span><br> -An apparatus consisting of a disc of copper mounted horizontally, or on<br> -a vertical spindle, and so arranged as to be susceptible of rapid<br> -rotation. Immediately over it, and best with a pane of glass<br> -intervening, a magnetic needle is mounted on a pivot directly over the<br> -axis of the disc. If the disc is rotated the lines of force of the<br> -magnet are cut by it, and consequently currents are produced in the<br> -copper. These currents act upon the needle and cause it to rotate,<br> -although quite disconnected. It is advisable for the needle to be strong<br> -and close to the disc, which should rotate rapidly.<br> -<br> -<br> -<span style="font-weight: bold;">Arc v.</span><br> -To form a voltaic arc.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Arc, Compound.</span><br> -A voltaic arc springing across between more than two electrodes.<br> -<br> -<br> -<span style="font-weight: bold;">Arc, Metallic.</span><br> -The voltaic arc produced between terminals or electrodes of metal. The<br> -characteristics of such arc as contrasted with the more usual arc<br> -between carbon electrodes are its greater length for the same<br> -expenditure of energy, its flaming character and characteristic colors<br> -due to the metals employed. It is sometimes, for the latter reason, used<br> -in spectroscopic investigations.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Arc Micrometer.</span><br> -A micrometer for measuring the distance between the electrodes of a<br> -voltaic arc.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Arc, Simple.</span><br> -A voltaic arc produced, as usual, between only two electrodes.<br> -<br> -<br> -40 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Arc, Voltaic.</span><br> -The voltaic arc is the arc between two carbon electrodes slightly<br> -separated, which is produced by a current of sufficient strength and<br> -involving sufficient potential difference. The pencils of carbon are<br> -made terminals in a circuit. They are first placed in contact and after<br> -the current is established they are separated a little. The current now<br> -seems to jump across the interval in what sometimes appears an arch of<br> -light. At the same time the carbon ends become incandescent. As regards<br> -the distance of separation with a strong current and high electro-motive<br> -force, the arc may be several inches long.<br> -<br> -The voltaic arc is the source of the most intense heat and brightest<br> -light producible by man. The light is due principally to the<br> -incandescence of the ends of the carbon pencils. These are differently<br> -affected. The positive carbon wears away and becomes roughly cupped or<br> -hollowed; the negative also wears away, but in some cases seems to have<br> -additions made to it by carbon from the positive pole. All this is best<br> -seen when the rods are slender compared to the length of the arc.<br> -<br> -It is undoubtedly the transferred carbon dust which has much to do with<br> -its formation. The conductivity of the intervening air is due partly,<br> -perhaps, to this, but undoubtedly in great measure to the intense<br> -heating to which it is subject. But the coefficient of resistance of the<br> -intervening air is so much higher than that of any other part of the<br> -circuit that an intense localization of resistance occurs with<br> -corresponding localization of heating effect. This is the cause of the<br> -intense light. Thus if the carbons are but 1/32 of an inch apart as in a<br> -commercial lamp the resistance may be 1.5 ohms. The poor thermal<br> -conductivity of the carbon favors the concentration of heat also. The<br> -apparent resistance is too great to be accounted for by the ohmic<br> -resistance of the interposed air. A kind of thermoelectric effect is<br> -produced. The positive carbon has a temperature of about 4,000° C.<br> -(7,232° F.), the negative from 3,000° C. (5,432° F.) to -3,500° C.<br> -(6,322° F.). This difference of temperature produces a<br> -counter-electro-motive force which acts to virtually increase the<br> -resistance of the arc. The carbon ends of an arc can be projected with<br> -the lantern. Globules are seen upon them due to melted silica from the<br> -arc of the carbon.<br> -<br> -<br> -</big></big><big><big><img style="width: 708px; height: 655px;" alt="" - src="images/040F19.jpg"></big></big><br> -<big><big>Fig. 19. EXPERIMENTAL APPARATUS FOR PRODUCING THE VOLTAIC ARC.<br> -<br> -<br> -41 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Areometer.</span><br> -An instrument for determining the specific gravity of a fluid. It<br> -consists of an elongated body ballasted so as to float vertically and<br> -provided with a mark or a scale. It floats deeper in a light than in a<br> -heavy liquid. If it carries but one mark weights are added until that<br> -mark is reached, when the weights required give the specific gravity. Or<br> -the scale may give the reading directly based upon the depth to which it<br> -sinks. Areometers are often made of glass, ballasted with shot or<br> -mercury enclosed in their bottom bulb as shown. They are used in<br> -regulating battery solutions, and in watching the charging and<br> -discharging of storage batteries.<br> -<br> -<br> -<img style="width: 103px; height: 629px;" alt="" src="images/041F20.jpg"><br> -Fig. 20. AREOMETER<br> -<br> -<br> -<img style="width: 86px; height: 621px;" alt="" src="images/041F21.jpg"><br> -Fig. 21. BEAD AREOMETER<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Areometer, Bead.</span><br> -A tube of glass containing beads of different specific gravities. It has<br> -apertures at top and bottom. When immersed in a liquid, the same fills<br> -it, and the specific gravity within certain limits, depending on the<br> -factors of the beads, is shown by the beads which float and those which<br> -sink. It is used for storage batteries and other purposes where acids<br> -and solutions have to be tested.<br> -<br> -<br> -<span style="font-weight: bold;">Argyrometry.</span><br> -The method of ascertaining the weight and inferentially the thickness of<br> -an electroplater's deposit of silver. It is done by weighing the article<br> -before and after plating.<br> -<br> -<br> -<span style="font-weight: bold;">Arm.</span><br> -The four members of a Wheatstone bridge, q. v., are termed its arms.<br> -Referring to the diagram of a bridge, P, Q, R, S, are the arms.<br> -<br> -<br> -<img style="width: 454px; height: 594px;" alt="" src="images/041F22.jpg"><br> -Fig. 22. DIAGRAM OF WHEATSTONE'S BRIDGE.<br> -<br> -<br> -<span style="font-weight: bold;">Armature.</span><br> -(a.) A mass or piece of iron or steel, or a collection of pieces of iron<br> -designed to be acted on by a magnet. While nickel or cobalt might be<br> -used, they rarely or never are except in experimental apparatus. The<br> -armature of a permanent horse shoe magnet is simply a little bar of soft<br> -iron. When the magnet is not in use it is kept in contact with the poles<br> -with the idea of retaining its magnetism. It is then said to be used as<br> -a keeper. A bar magnet does not generally have an armature. The armature<br> -is also used to exhibit the attraction of the magnet.<br> -<br> -Sometimes an armature is made of steel and is permanently magnetized.<br> -Such an armature, termed a polarized armature, is repelled when its like<br> -poles are opposed to like poles of the magnet and otherwise is attracted<br> -with force due to the sums of the magnetism. If the magnet is<br> -sufficiently powerful depolarization of the armature may ensue when like<br> -poles are opposed to like poles. Polarized armatures are used in various<br> -appliances, magneto generators, telegraphic instruments and others.<br> -<br> -(b) In a dynamo or Motor the mass of laminated iron or of wire which<br> -carries the coils of insulated wires which are caused to rotate in the<br> -field of force of the field magnets in order to establish and maintain<br> -potential difference with its accompanying current, or which rotates<br> -under the effects of a current in a motor. (See Dynamo Electric<br> -Generator.)<br> -<br> -The work of the armature core is twofold. It acts as a portion of the<br> -magnetic circuit, conducting the lines of force, and by virtue of its<br> -high permeability or multiplying power concentrating a number of the<br> -lines of force through its own substance. To enable it to act with<br> -efficiency in this direction it should be made of iron of the highest<br> -permeability, and should approach as closely as possible to the armature<br> -cores consistent with leaving space for the wire winding. It next acts<br> -as a support for the wires which are to be swept through the field of<br> -force. Thus it acts both to establish a strong field and then acts as a<br> -carrier for the wires which are to be cut by the wires in question. In<br> -connection with this subject the different definitions under Armature,<br> -Dynamo, Commutator, Induction and similar topics may be consulted.<br> -<br> -(c) See Armature of Influence Machine.<br> -<br> -(d) See Armature of Leyden Jar or Static Condenser.<br> -<br> -<br> -42 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Bar.</span><br> -An armature in a dynamo or motor whose winding is made up of conductors<br> -in the form of bars, round, rectangular and of other sections. This type<br> -of armature conductor is objectionable as Foucault currents are produced<br> -in it. It is found best to laminate or subdivide low resistance armature<br> -windings.<br> -<br> -[Transcriber's Note: Foucault currents are also called eddy currents.]<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Bipolar.</span><br> -An armature in which two poles are induced by the field. A bipolar field<br> -magnet produces a bipolar armature.<br> -<br> -<br> -<span style="font-weight: bold;">Armature Bore.</span><br> -The cylindrical space defined by the pole pieces of a dynamo or motor<br> -within which the armature rotates.<br> -<br> -Synonym--Armature Chamber.<br> -<br> -<br> -43 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Armature, Closed Coil.</span><br> -An armature for a motor or dynamo, the ends of all of whose coils are<br> -united, so as to be in one closed circuit all the way around.<br> -<br> -<br> -<img style="width: 607px; height: 377px;" alt="" src="images/043F23.jpg"><br> -Fig. 23. CLOSED COIL GRAMME RING ARMATURE.<br> -<br> -<br> -<span style="font-weight: bold;">Armature Coil, or Coils.</span><br> -The insulated wire wound around the core of the armature of an electric<br> -current generator or motor.<br> -<br> -<br> -<span style="font-weight: bold;">Armature Core.</span><br> -The central mass of iron on which the insulated wire, to be rotated in<br> -the field of an electric current generator or motor, is wound. (See<br> -Dynamo-electric Machine and Motor, Electric.)<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Cylinder.</span><br> -An armature of the Gramme ring type, but longer in the axial direction,<br> -so that its core resembles a long hollow cylinder, the wire being wound<br> -inside and outside as in the Gramme ring. (See Gramme Ring.)<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Disc.</span><br> -(a) An armature of a dynamo electric machine or motor in which the coils<br> -are wound so as to be flat and are carried on the face of a disc forming<br> -the core or part of the core of the armature. S. P. Thompson treats it<br> -as a modified drum armature extended radially, the outer periphery<br> -corresponding to the back end of the drum. The poles of the field are<br> -generally placed to face the side or sides of the disc.<br> -<br> -(b) Another type of disc armature has its wire wound on bobbins arranged<br> -around the periphery of a disc.<br> -<br> -In disc armatures there is often no iron core, their thinness enabling<br> -this to be dispensed with.<br> -<br> -<br> -44 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 676px; height: 746px;" alt="" src="images/044F24.jpg"><br> -Fig. 24. DISC ARMATURE OF FRITSCHE MACHINE.<br> -<br> -<br> -<img style="width: 772px; height: 728px;" alt="" src="images/044F25.jpg"><br> -Fig. 25. PLAN OF WINDING PACINOTTI'S DISC ARMATURE.<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Discoidal Ring.</span><br> -In a dynamo an armature of the shape of a ring of considerable radial<br> -depth of section as compared to its axial depth. It is generally made of<br> -iron ribbon or thin band wound to the proper size.<br> -<br> -Synonym--Flat Ring Armature.<br> -<br> -<br> -45 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Drum.</span><br> -An armature for a dynamo or motor, consisting of a cylinder of iron<br> -preferably made up of discs insulated from each other by thin shellacked<br> -paper, or simply by their oxidized surfaces, and wound with wire<br> -parallel to the axis where it lies on the cylindrical periphery and<br> -crossing the heads approximately parallel to the diameter. It operates<br> -practically on the same principle as a Gramme Ring Armature. (See Gramme<br> -Ring.)<br> -<br> -Synonym--Cylindrical Armature.<br> -<br> -<br> -<span style="font-weight: bold;">Armature Factor.</span><br> -The number of conductors on an armature, counted or enumerated all<br> -around its external periphery.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Armature, Hinged.</span><br> -An armature pivoted to the end of one of the legs of an electro-magnet<br> -so as to be free to swing and bring its other end down upon the other<br> -pole.<br> -<br> -<br> -<img style="width: 664px; height: 383px;" alt="" src="images/045F26.jpg"><br> -Fig. 26. HINGED ARMATURES OF CLUB-FOOT ELECTRO MAGNETS.<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Hole.</span><br> -An armature whose core is perforated to secure cooling.<br> -<br> -Synonym--perforated Armature.<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Intensity.</span><br> -An armature wound for high electro-motive force. A term little used at<br> -the present time.<br> -<br> -<br> -<span style="font-weight: bold;">Armature Interference.</span><br> -A limit to the ampere turns permissible on a given armature is found in<br> -the increase of cross magnetizing effect, q. v., the increased lead<br> -necessitated, and the growth of the demagnetizing power. All such<br> -perturbing effects are sometimes expressed as armature interference.<br> -<br> -<br> -46 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Load of.</span><br> -The circumflux, q. v., of the armature, or the ampere turns of the same.<br> -The maximum load which can be carried by an armature without sparking is<br> -directly proportional to the radial depth of core and to the length of<br> -the gap, and inversely proportional to the breadth of the polar span.<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Multipolar.</span><br> -An armature in which a number of poles greater than two is determined by<br> -the field. A multipolar field is employed for its production.<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Neutral.</span><br> -An armature of a magnet or telegraph relay which is not polarized or<br> -magnetized.<br> -<br> -Synonym--Non-polarized Armature--Neutral Relay Armature.<br> -<br> -<br> -<span style="font-weight: bold;">Armature of Influence Machine.</span><br> -Pieces of paper pasted on the stationary plate of an electric machine of<br> -the Holtz type.<br> -<br> -<br> -<span style="font-weight: bold;">Armature of Leyden Jar or Static -Condenser.</span><br> -The inner and outer tin-foil coatings of a Leyden jar or other<br> -condenser.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Armature, Open Coil.</span><br> -An armature of a dynamo or motor on which the coils are not joined in<br> -one closed circuit, but have their ends or some of them separated, and<br> -connected each to its own commutator bar or each set to their own bar.<br> -<br> -<br> -<img style="width: 517px; height: 401px;" alt="" src="images/046F27.jpg"><br> -Fig. 27. OPEN COIL RING ARMATURE.<br> -<br> -<br> -47 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Pivoted.</span><br> -An armature for an electro-magnet mounted on a pivot, which is at right<br> -angles to the yoke or parallel with the legs of the magnet, so as to be<br> -free to rotate. When the magnet is excited the armature is drawn into<br> -line or approximately so with its base or yoke. The system is used in<br> -some telegraph apparatus.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Armature Pockets.</span><br> -Spaces or recesses in armatures provided for the reception of the coils.<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Polarized.</span><br> -An armature made of steel or having a steel core to which permanent<br> -magnetism has been imparted. Such are used in some forms of magneto<br> -current generators, and in telegraphic instruments. (See Relay,<br> -Polarized.)<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Pole.</span><br> -An armature having coils wound on separate poles projecting radially all<br> -around the periphery of its central hub or disc, or projecting<br> -internally from a ring-like frame, their ends facing the field magnet.<br> -<br> -Synonym--Radial Armature.<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Quantity.</span><br> -An armature of a dynamo or motor wound for current of large quantity.<br> -The term is now but little used.<br> -<br> -<br> -<span style="font-weight: bold;">Armature-Reactions.</span><br> -When an armature is running in an active dynamo a series of<br> -reactions is established, the more important of which are:<br> -I. A tendency to cross-magnetize the armature.<br> -II. A tendency to spark at the brushes.<br> -III. A tendency for the armature current to demagnetize on account of<br> -the lead which has to be given to the brushes.<br> -IV. Variations in the neutral points as more or less current is taken<br> -from the machine.<br> -V. Heating of armature, both core and conductors, and of pole pieces,<br> -which heating is due to Foucault currents.<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Revolving, Page's.</span><br> -An early form of motor. The field is produced by a permanent magnet.<br> -Above its poles is a soft iron armature wound with a coil of insulated<br> -wire. A two-part commutator with contact springs conveys the current to<br> -the coil. The whole is so arranged that the polarity of the armature, as<br> -induced by the coil, through which a current is passed, is reversed as<br> -its ends sweep by the poles of the magnet. Then it is repelled from the<br> -poles and swings through 180° to have its polarity reversed and to -go<br> -through the next 180°, and so on. Thus it rotates at a very high -rate of<br> -speed.<br> -<br> -In the cut showing the elevation A, B, is the armature; f, g, the<br> -springs or brushes; h, the commutator with its sections o, i. In the<br> -section of the commutator W, W, designate the springs or brushes, A, the<br> -vertical spindle carrying the armature and commutator, and S, S, the<br> -commutator sections.<br> -<br> -<br> -48 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 516px; height: 718px;" alt="" - src="images/048F28_29.jpg"><br> -Fig. 28. PAGE'S REVOLVING ARMATURE.<br> -<br> -Fig. 29. SECTION OF COMMUTATOR OF PAGE'S REVOLVING ARMATURE.<br> -W, W, Brushes; A, Spindle; S, S, Armature Segments.<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Ring.</span><br> -An armature whose core is in the shape of a ring, as the Gramme Ring<br> -Armature. (See Figs. 23 & 27.)<br> -<br> -<br> -49 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Rolling.</span><br> -(a) An armature for a permanent horseshoe magnet consisting of a<br> -straight cylinder of soft iron on which a heavy wheel is mounted. When<br> -the legs of the magnet are inclined downward and the bar is laid across<br> -them it rolls down to the poles, across their ends, and back up the<br> -under side. It is merely a magnetic toy or illustrative experiment.<br> -<br> -Synonym--Wheel Armature.<br> -<br> -(b) Another form consists of little bars of iron with brass discs<br> -attached to the ends. On placing two of these together and bringing the<br> -poles of a magnet near them, as shown, they become magnetized with like<br> -polarity by induction and repel each other, rolling away in opposite<br> -directions.<br> -<br> -<br> -<img style="width: 328px; height: 756px;" alt="" src="images/049F30.jpg"><br> -Fig. 30. ROLLING OR WHEEL ARMATURE.<br> -<br> -<br> -<img style="width: 358px; height: 582px;" alt="" src="images/049F31.jpg"><br> -Fig. 31. ROLLING ARMATURES.<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Shuttle.</span><br> -The original Siemens' armature, now discarded. The core was long and<br> -narrow, and its cross section was nearly of the section of an H. The<br> -grooves were wound full of wire, so that the whole formed almost a<br> -perfect cylinder, long and narrow comparatively. (See Winding Shuttle.)<br> -<br> -Synonym--Siemens' Old Armature--Girder Armature--H Armature.<br> -<br> -<br> -<img style="width: 679px; height: 171px;" alt="" src="images/049F32.jpg"><br> -Fig. 32. SHUTTLE OR H ARMATURE.<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Spherical.</span><br> -An armature of a dynamo which is wound on a spherical core, so as to be<br> -almost a sphere. It is employed in the Thomson-Houston dynamo, being<br> -enclosed in a cavity nearly fitting it, formed by the pole pieces.<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Stranded Conductor.</span><br> -A substitute for bar-armatures in which stranded copper wire conductors<br> -are substituted for the solid bar conductors, to avoid Foucault<br> -currents. (See Armature, Bar.)<br> -<br> -<br> -50 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Armature, Unipolar.</span><br> -An armature of a unipolar dynamo. (See Dynamo Unipolar.)<br> -<br> -<br> -<span style="font-weight: bold;">Armor of Cable.</span><br> -The metal covering, often of heavy wire, surrounding a telegraph or<br> -electric cable subjected to severe usage, as in submarine cables.<br> -<br> -Synonym--Armature of Cable.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Arm, Rocker.</span><br> -An arm extending from a rocker of a dynamo or motor, to which arm one of<br> -the brushes is attached. (See Rocker.) Ordinarily there are two arms,<br> -one for each brush.<br> -<br> -<br> -<span style="font-weight: bold;">Articulate Speech.</span><br> -Speech involving the sounds of words. It is a definition which has<br> -acquired importance in the Bell telephone litigations, one contention,<br> -concerning the Bell telephone patent, holding that the patentee did not<br> -intend his telephone to transmit articulations, but only sound and<br> -music.<br> -<br> -<br> -<span style="font-weight: bold;">Astatic. adj.</span><br> -Having no magnetic directive tendency due to the earth's magnetism.<br> -Examples are given under Astatic Needle; Circuit, Astatic; and<br> -Galvanometer Astatic.<br> -<br> -<br> -<img style="width: 579px; height: 515px;" alt="" src="images/050F33.jpg"><br> -Fig. 33. NOBILI'S PAIR.<br> -<br> -<br> -<img style="width: 407px; height: 390px;" alt="" src="images/051F34.jpg"><br> -FIG. 34. VERTICAL PAIR ASTATIC COMBINATION.<br> -<br> -<br> -<span style="font-weight: bold;">Astatic Needle. </span><br> -A combination of two magnetic needles so adjusted as to<br> -have as slight directive tendency as possible. Such a pair of needles<br> -when poised or suspended will hardly tend to turn more to one point of<br> -the compass than another. The combination is generally made up of two<br> -needles arranged one above the other, with their poles in opposite<br> -directions. This combination is usually called Nobili's pair. If of<br> -equal strength and with parallel magnetic axes of equal length they<br> -would be astatic. In practice this is very rarely the case. A resultant<br> -axis is generally to be found which may even be at right angles to the<br> -long axis of the magnets, causing them to point east and west. Such a<br> -compound needle requires very little force to turn it one way or the<br> -other. If one of the needles is placed within a coil of insulated wire a<br> -feeble current will act almost as strongly to deflect the system as if<br> -the other was absent, and the deflection will only be resisted by the<br> -slight directive tendency of the pair of needles. This is the basis of<br> -construction of the astatic galvanometer. Sometimes coils wound in<br> -opposite directions and connected in series, or one following the other,<br> -surround both needles, thus producing a still greater effect of<br> -deflection.<br> -<br> -Other astatic needles are shown in the cuts below. [Figures 33 to 35.]<br> -<br> -<br> -51 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 314px; height: 519px;" alt="" src="images/051F35.jpg"><br> -FIG. 35. SIMPLE ASTATIC NEEDLE.<br> -<br> -<br> -<span style="font-weight: bold;">Asymptote</span>.<br> -A line continuously approached by a curve, but which the curve, owing to<br> -its construction or nature of curvature, can never touch, be tangent to,<br> -or intersect.<br> -<br> -<br> -<span style="font-weight: bold;">Atmosphere.</span><br> -(a) A term applied to the atmospheric pressure as a practical unit of<br> -pressure equal to 15 lbs. to the square inch as generally taken. It is<br> -really about 14.7 lbs. per square inch, or 1,033 grams per square<br> -centimeter.<br> -<br> -(b) Air, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Atmosphere Residual.</span><br> -The atmosphere left in a vessel after exhaustion. The term may be<br> -applied to any gas. In an incandescent lamp after flashing the residual<br> -atmosphere consists of hydro-carbons.<br> -<br> -<br> -<span style="font-weight: bold;">Atmospheric Electricity.</span><br> -The electricity of the atmosphere, rarely absent, but often changing in<br> -amount and sign. Benjamin Franklin, in a memoir published in 1749,<br> -indicated the method of drawing electricity from the clouds by pointed<br> -conductors. In June, 1752, he flew a kite and by its moistened cord drew<br> -an electric spark from the clouds, confirming his hypothesis that<br> -lightning was identical with the disruptive discharge of electricity. To<br> -observe electricity in fine weather a gold-leaf or other electroscope<br> -may be connected to the end of a long pointed insulated conductor. The<br> -electricity during thunderstorms can be shown by a similar arrangement,<br> -or burning alcohol or tinder gives an ascending current of warm air that<br> -acts as a conductor. Quite elaborate apparatus for observing and<br> -recording it have been devised. Atmospheric electricity is usually<br> -positive, but occasionally negative. When the sky is cloudless it is<br> -always positive, increasing with the elevation and isolation of the<br> -place. In houses, streets, and under trees no positive electricity can<br> -be found. In the Isle of Arran, Scotland, a rise of 24 to 48 volts per<br> -foot of increase in elevation was found by Sir William Thomson. At<br> -sunrise the electrification of the air is feeble, it increases towards<br> -noon and decreases again to reach a second maximum a few hours after<br> -sunset. It increases with the barometric pressure generally. In cloudy<br> -weather it is sometimes negative and the sign often changes several<br> -times in the same day. In a thunderstorm the changes in sign and<br> -potential are very rapid. The cause of atmospheric electricity is far<br> -from clear. Tait attributes it to a contact effect between air and water<br> -vapor, Solmeke to friction of water vesicles against ice particles in<br> -the upper atmosphere, he first showing that the two may coexist. The<br> -cause of the enormous increase of potential producing lightning is<br> -attributed to the decreased capacity due to the change of water from<br> -cloud vesicles to drops, thus diminishing the electrostatic capacity of<br> -the water in question. (See Lightning.)<br> -<br> -<br> -52 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Atom.</span><br> -The ultimate particle or division of an elementary substance; the<br> -smallest part that can exist in combination, and one which cannot exist<br> -alone. An elementary substance is composed of molecules just as truly as<br> -a compound one, but the atoms in the molecule of an elementary substance<br> -are all precisely alike. Hence atoms are the units of chemistry, they<br> -have to do with combinations, but the physical unit, the smallest<br> -particle of matter that can have an independent existence, is the<br> -molecule. The two are often confounded, especially by writers of a few<br> -years ago, so that by "atom" the molecule is often meant. There is<br> -nothing to be said of their size or mass. All such calculations refer to<br> -the molecule, q. v., often spoken of and called the atom.<br> -<br> -[Transcriber's note: Yet to be discovered: electron--1897 (5 years),<br> -proton--1920 (28 years), neutron--1932 (30 years), quark--1961 (69 -years).]<br> -<br> -<br> -<span style="font-weight: bold;">Atomic Attraction.</span><br> -The attraction of atoms for each other, in virtue of which they combine<br> -into molecules; chemical affinity, q. v., treats principally of this,<br> -although molecular attraction also plays a part in it.<br> -<br> -<br> -<span style="font-weight: bold;">Atomic Heat.</span><br> -The product of the atomic weight of a substance by its specific heat.<br> -This product is approximately the same, 6.4; this approximation is so<br> -close that it is of use in determining the valency and atomic weights of<br> -substances. The atomic weight of a substance therefore represents the<br> -approximate number of gram-calories required to raise one gram-atom, q.<br> -v., of such substance through 1° C. (1.8° F.)<br> -<br> -<br> -<span style="font-weight: bold;">Atomicity.</span><br> -The quantivalence or valency of the atoms; the number of combination<br> -bonds, or bonds of affinity, possessed by the atoms of any substance.<br> -Thus two atoms of hydrogen combine with one atom of oxygen, and three of<br> -oxygen with one of sulphur, forming saturated compounds. Therefore,<br> -taking hydrogen as of single atomicity or a monad, oxygen is of double<br> -atomicity or a dyad, and sulphur is of six-fold atomicity, or a hexad.<br> -The elements are thus classified into seven orders of atomicities, thus:<br> -<br> - <span style="font-family: monospace;">1, Monads or Univalent -elements, Hydrogen, etc.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> 2, Dyads or -Bivalent -" Oxygen, etc.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> 3, Triads or -Trivalent -" Nitrogen, etc.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> 4, Tetrads or -Quadrivalent " -Lead, etc.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> 5, Pentads or Quinquivalent -" -Phosphorous, etc.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> 6, Hexads or -Sexivalent -" Chromium, etc.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> 7, Heptads or -Septivalent -" Chromium, etc.</span><br> -<br> -The same element often possesses several atomicities. Barium is<br> -generally a dyad, sometimes a tetrad; nitrogen acts as a monad, dyad,<br> -triad, tetrad and pentad. The familiar electrolysis of water, giving two<br> -volumes of hydrogen to one of oxygen, is one of the illustrations of the<br> -theory indicating that two atoms of hydrogen are combined with one of<br> -oxygen.<br> -<br> -<br> -53 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Atomic Weight.</span><br> -The number expressing the relative weight of the atom of any substance,<br> -that of hydrogen being generally taken as unity. This is the universal<br> -system, although any other element might be taken as the basis of the<br> -system. The whole theory of atomic weights is based on the<br> -indivisibility of the atom and on the theory of atomicity, q. v. (See<br> -Equivalents.)<br> -<br> -[Transcriber's note: The standard is now the isotope carbon-12 as<br> -exactly 12.]<br> -<br> -<br> -<span style="font-weight: bold;">Attraction.</span><br> -The tendency to approach and adhere or cohere, shown by all forms of<br> -matter. It includes gravitation, cohesion, adhesion, chemical affinity<br> -and other forms, and is opposed by repulsion, and is sometimes overcome<br> -by it, although it may be assumed to be always present. See the<br> -different kinds of attractions under their titles: Atomic Attraction,<br> -Electro-magnetic Attraction and Repulsion, Electro Static Attraction and<br> -Repulsion, Electro-dynamic Attraction and Repulsion; Magnetic Attraction<br> -and Repulsion; Molar Attraction.<br> -<br> -<br> -<span style="font-weight: bold;">Audiometer.</span><br> -An apparatus for obtaining a balance of induction from two coils acting<br> -upon a third. The third is placed between the other two and is free to<br> -move towards either. A scale is provided to show the extent of its<br> -movement. A varying or interrupted current being passed through the two<br> -outer coils, the preponderating current will produce the most induction<br> -if the central coil is equidistant. It can always be moved to such a<br> -point that there will be no inductive effect, one counteracting the<br> -other. Thus its position measures the relative induction. A telephone is<br> -in circuit with the intermediate coil and is used to determine when its<br> -position is such that no current is induced in it. It is sometimes used<br> -as a direct test of hearing. (See Hughes' Induction Balance.)<br> -<br> -Synonym--Acoutemeter.<br> -<br> -<br> -<span style="font-weight: bold;">Aura, Electrical.</span><br> -The blast of air produced at highly electrified points.<br> -<br> -<br> -<span style="font-weight: bold;">Aurora.</span><br> -A luminous display seen in the northern heavens in the northern<br> -hemisphere, where it is the Aurora Borealis, and seen in the southern<br> -heavens in the southern hemisphere, where it is called Aurora Australis,<br> -or indifferently for either, the Aurora Polaris. It takes the form of<br> -pale luminous bands, rays and curtains varying in color. Near the poles<br> -they are very numerous. A French commission observed 150 auroras in 200<br> -days. Their height is variously estimated at from 90 to 460 miles; they<br> -are most frequent at the equinoxes and least so at the solstices. There<br> -is a secular variation also, they attain a maximum of occurrence every<br> -11 years together with sun spots, with a minimum 5 or 6 years after the<br> -maximum. There is also a period of 60 years, coincident with<br> -disturbances in the earth's magnetism. Various attempts have been made<br> -to account for them. They have a constant direction of arc with<br> -reference to the magnetic meridian (q. v.) and act upon the magnetic<br> -needle; in high latitudes they affect telegraph circuits violently.<br> -There is a strong probability that they represent electric currents or<br> -discharges. De la Rive considers them due to electric discharges between<br> -the earth and atmosphere, which electricities are separated by the<br> -action of the sun in equatorial regions. According to Balfour Stewart,<br> -auroras and earth currents.(q. v.) may be regarded as secondary currents<br> -due to small but rapid changes in the earth's magnetism. The subject is<br> -very obscure. Stewart treats the earth as representing the magnetic core<br> -of an induction coil, the lower air is the dielectric, and the upper<br> -rarefied and therefore conducting atmosphere is the secondary coil. This<br> -makes the aurora a phenomenon of induced currents. Then the sun may be<br> -regarded as the instigator of the primary changes in the earth's lines<br> -of force representing the primary of an induction coil.<br> -<br> -[Transcriber's note: Solar wind, streams of electrons and protons,<br> -interacting with the earth's magnetic field causes aurora. Neither<br> -electrons (1897) nor protons (1920) were known in 1892. The Soviet<br> -satellite Luna first measured the solar wind in 1959. Even today<br> -increased understanding of solar and auroral phenomenon continues.]<br> -<br> -<br> -54 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Austral Pole.</span><br> -The north pole of the magnet is thus called sometimes in France; the<br> -austral pole of a magnet is the one which points towards the north polar<br> -regions As unlike magnetic poles attract each other, it is but rational<br> -to call the north-seeking pole of the magnet the south or Austral Pole.<br> -In the same nomenclature the south pole of a magnet, or the<br> -south-seeking pole, is called the Boreal Pole.<br> -<br> -<br> -<span style="font-weight: bold;">A. W. G.</span><br> -Abbreviation for American Wire Gauge, q. v.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Axis, Electric.</span><br> -The electric axis of a pyroelectric crystal, such as a tourmaline<br> -crystal; the line connecting the points of greatest pyroelectric<br> -excitability.<br> -<br> -<br> -<span style="font-weight: bold;">Axis of Abscissa.</span><br> -In a system of rectilinear, or right angle co-ordinates, the horizontal<br> -axis. (See Co-ordinates.)<br> -<br> -Synonym--Axis of X.<br> -<br> -<br> -<span style="font-weight: bold;">Axis of Ordinates.</span><br> -In a system of rectilinear right angle co-ordinates, the vertical axis.<br> -(See Co-ordinates.)<br> -<br> -Synonym--Axis of Y.<br> -<br> -<br> -<span style="font-weight: bold;">Azimuth.</span><br> -The angle between the plane of the meridian and the plane of an azimuth<br> -circle, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Azimuth Circle.</span><br> -A great circle, whose plane passes through the zenith or point of the<br> -heavens directly overhead; any great circle in whose plane the vertical<br> -at the point of observation is included.<br> -<br> -Each celestial body has or determines an azimuth circle.<br> -<span style="text-decoration: underline;"><br> -</span></big></big><big><big><br> -55 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">B.</span><br> -(a) Abbreviation for Baumé, a hydrometer scale. (See -Baumé.) Thus 10º B.<br> -means "ten degrees Baumé."<br> -<br> -(b) Symbol for the coefficient of induced magnetization, or the number<br> -of lines per square centimeter induced in a magnetic circuit or in any<br> -specified part of it.<br> -<br> -<br> -<span style="font-weight: bold;">B. A.</span><br> -Abbreviation for British Association. It is prefixed to standards fixed<br> -by the committee of the British Association for the Advancement of<br> -Science. Thus the B. A. ohm means the British Association ohm, a measure<br> -of resistance which is equal to the resistance of a column of mercury<br> -104.9 centimeters long and one square millimeter area of cross-section.<br> -(See Ohm.)<br> -<br> -<br> -<span style="font-weight: bold;">Back Induction.</span><br> -A demagnetizing force produced in a dynamo armature when a lead is given<br> -the brushes. The windings by such setting of the brushes are virtually<br> -divided into two sets, one a direct magnetizing set, the other a cross<br> -magnetizing set. The latter have a component due to the obliqueness of<br> -the neutral line, which component is demagnetizing in its action.<br> -<br> -<br> -<span style="font-weight: bold;">Back Shock or Stroke of Lightning.</span><br> -A lightning stroke received after the main discharge of the lightning,<br> -and caused by a charge induced in neighboring surfaces by the main<br> -discharge. The discharge affects the evenness of distribution of<br> -surrounding surfaces so that a species of secondary discharge is<br> -required to make even the distribution, or to supply charge where needed<br> -to bind an opposite one. The effects are much lese severe as a rule than<br> -those of the main charge, although the back stroke has caused death. The<br> -back stroke is sometimes felt a considerable distance from the place of<br> -the original lightning stroke.<br> -<br> -Synonym--Return Stroke.<br> -<br> -<br> -<span style="font-weight: bold;">Back Stroke.</span><br> -(a) In telegraphy the return stroke of the lever in a telegraph sounder,<br> -striking the end of the regulating screw with a sound distinct from that<br> -which it produces on the forward stroke as it approaches the magnet<br> -poles. It is an important factor in receiving by ear or sound reading.<br> -<br> -(b) See Back Shock or Stroke of Lightning.<br> -<br> -<br> -<span style="font-weight: bold;">Balance.</span><br> -(a) Wheatstone's Bridge, q. v., is sometimes termed the Electric<br> -Balance.<br> -<br> -(b) A suspension or torsion balance is one which includes a filament or<br> -pair of filaments to whose lower end or ends are attached a horizontal<br> -indicator often called a needle, or a magnetic needle. (See Torsion<br> -Balance.)<br> -<br> -(c) See Induction Balance, Hughes'.<br> -<br> -(d) For Thermic Balance, see Bolometer.<br> -<br> -(e) See Balance, Ampere.<br> -<br> -<br> -56 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Balance, Ampere.</span><br> -A class of electrical measuring instruments due to Sir William Thomson<br> -may be grouped under this head.<br> -<br> -The instrument is a true balance or scales such as used for weighing. It<br> -is supported by a torsional wire support in place of knife edges. At<br> -each end it carries a circle of wire through which the current to be<br> -tested is passed. The torsional wire support enables the current to be<br> -carried to these wire rings. Above and below each of these rings are two<br> -similar rings, also connected so as to receive the current. They are so<br> -connected that the current shall go through them in opposite senses.<br> -When a current passes, therefore, one of these rings repels and one<br> -attracts the balanced ring.<br> -<br> -The extent of this action measures the intensity of the current. A<br> -sliding weight moving along a graduated scale on the balance is used to<br> -bring the balance beam into equilibrium when the current is passing. The<br> -degree of displacement of this weight gives the strength of the current<br> -in amperes.<br> -<br> -These balances are made for different currents. Thus there is a<br> -centi-ampere balance, deka-ampere balance and others, as well as an<br> -ampere balance.<br> -<br> -<br> -<span style="font-weight: bold;">Balata.</span><br> -A gum used as an insulating material. It is the inspissated juice of a<br> -sapotaceous tree, the bullet tree, Mimusops globosa, of tropical<br> -America, from the Antilles to Guiana. It is intermediate in character<br> -between caoutchouc and gutta percha. It is superior to gutta percha in<br> -some respects, being very slightly acted on by light.<br> -<br> -Synonym--Chicle.<br> -<br> -<br> -B. & S.. W. G.<br> -Abbreviation for Brown & Sharpe Wire Gauge; the regular American -Wire<br> -Gauge. (See Wire Gauge, American.)<br> -<br> -<br> -<span style="font-weight: bold;">Barad.</span><br> -An absolute or fundamental unit of pressure, equal to one dyne per<br> -square centimeter.<br> -<br> -<br> -<span style="font-weight: bold;">Barometer.</span><br> -An apparatus for measuring the pressure exerted by the atmosphere. It<br> -consists, in the mercurial form, of a glass tube, over 31 inches long,<br> -closed at one end, filled with mercury and inverted, with its open end<br> -immersed in a cistern of mercury. The column falls to a height<br> -proportional to the pressure of the atmosphere from 30 to 31 inches at<br> -the sea level. The "standard barometer" is a height of the mercury or of<br> -the "barometric column" of 30 inches or 760 centimeters, measured from<br> -the surface of the mercury in the cistern.<br> -<br> -The column of mercury is termed the barometric column. Above it in the<br> -tube is the Torricellian vacuum.<br> -<br> -[Transcriber's note: More accurately, 29.92 inches of mercury or 14.696<br> -PSI.]<br> -<br> -<br> -<span style="font-weight: bold;">Bars of Commutators.</span><br> -The metal segments of a commutator of a dynamo or motor. They are made<br> -of bars of copper, brass or bronze insulated from one another. (See<br> -Commutator.)<br> -<br> -Synonyms--Segments, Commutator Segments, Commutator Bars.<br> -<br> -<br> -57 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Bath.</span><br> -(a) In electro-plating the solution used for depositing metal as<br> -contained in a vat or tank; as a silver, copper, or nickel bath used for<br> -plating articles with silver, copper, or nickel respectively.<br> -<br> -(b) In electro-therapeutics a bath with suitable arrangements,<br> -electrodes and connections for treating patients with electricity. It is<br> -termed an electric bath or electro-therapeutic bath.<br> -<br> -<br> -<span style="font-weight: bold;">Bath, Bipolar Electric.</span><br> -In electro-therapeutics a bath in which the electrodes are both immersed<br> -in the water. The patient placed between them receives part of the<br> -discharge. The electrodes are large copper plates, termed shovel<br> -electrodes.<br> -<br> -<br> -<span style="font-weight: bold;">Bath, Electric Shower.</span><br> -An electro-medical shower bath. The patient is placed on a metallic<br> -stove or support connected to one of the electric terminals. Water<br> -slightly alkaline is showered upon him. The other electrode is in<br> -connection with the water. The rain of drops and streamlets is the<br> -conductor of the current or discharge.<br> -<br> -<br> -<span style="font-weight: bold;">Bath, Multipolar Electric.</span><br> -An electro-medical bath with a number of electrodes instead of two.<br> -<br> -<br> -<span style="font-weight: bold;">Bath, Stripping.</span><br> -In electro-plating a solution used for dissolving and thus removing the<br> -plating from any object. The stripping bath is of the same general type<br> -as the plating bath for the same metal as the one to be dissolved. The<br> -object to be "stripped" is made the anode of a plating circuit, and as<br> -the current acts the old plating is attacked and dissolves, leaving the<br> -body of the article bare. It is simply the operation of plating<br> -reversed. The same term is applied to baths acting by simple solution.<br> -Stripping baths are described under the different metals as Silver Bath,<br> -Stripping--Gold Bath, Stripping.<br> -<br> -<br> -<span style="font-weight: bold;">Bath, Unipolar Electric.</span><br> -An electro-medical bath, in which only one electrode connects with the<br> -water of the bath. The second electrode is supported above the bath. The<br> -patient touches this while in the water whenever electric action is<br> -desired.<br> -<br> -<br> -<img style="width: 509px; height: 327px;" alt="" src="images/057F36.jpg"><br> -FIG. 36. THREE WIRE MOULDING OR BATTEN.<br> -<br> -<br> -<img style="width: 486px; height: 302px;" alt="" src="images/057F37.jpg"><br> -FIG. 37. TWO WIRE MOULDING OR BATTEN.<br> -<br> -<br> -58 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Batten.</span><br> -A strip of wood grooved longitudinally for holding wires in wiring<br> -apartments for electric light or power. In use they are fastened to the<br> -wall, grooves inward, or else grooves outward, with the wires lying in<br> -the grooves and covered with the covering strip. For two wire work each<br> -batten contains two grooves; for the three wire system it contains three<br> -grooves.<br> -<br> -Synonym--Moulding.<br> -<br> -<br> -<span style="font-weight: bold;">Battery.</span><br> -A combination of parts or elements for the production of electrical<br> -action. The term is principally applied to voltaic batteries, but there<br> -are also magnetic batteries, batteries of Leyden jars, and other<br> -combinations, described in their places, which come under this category.<br> -<br> -[Transcriber's note: A group of similar items such as questions,<br> -machines, parts, guns, or electric cells.]<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Acetic Acid.</span><br> -A battery whose active solution or excitant is acetic acid or vinegar.<br> -This acid has been used by Pulvermacher in his medical battery, as being<br> -a substance found in every household in the form of vinegar. It is now<br> -but little used.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Alum.</span><br> -A battery using as excitant a solution of alum. This battery has had<br> -some application for electric clocks, but only to a limited extent.<br> -<br> -<br> -<img style="width: 421px; height: 513px;" alt="" src="images/058F38.jpg"><br> -Fig. 38. BALLOON OR FLASK BATTERY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Aluminum.</span><br> -A battery in which aluminum is the negative plate and aluminum sulphate<br> -the excitant. It is mounted like the gravity battery. Its electro-motive<br> -force is 0.2 volt.<br> -<br> -<br> -59 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Bagration.</span><br> -A battery with zinc and carbon electrodes immersed in earth sprinkled<br> -with sal ammoniac (ammonium chloride). The copper is preferably first<br> -immersed in sal ammoniac solution and dried, until a green layer is<br> -formed on its surface.<br> -<br> -The battery is highly praised for its constancy by De la Rive, but may<br> -be regarded as obsolete.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Balloon.</span><br> -A form of gravity battery into whose centre a globular flask, B, is<br> -inverted, which is filled before inversion with copper sulphate, of<br> -which 2 lbs. are used, and water, so as to remain full. This acts as a<br> -reservoir of copper sulphate, which it constantly supplies. The glass<br> -jar is closed with a perforated wooden cover.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Banked.</span><br> -(a) A battery arranged to feed a number of separate circuits.<br> -<br> -(b) A battery connected in parallel or in multiple arc.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Bichromate.</span><br> -A battery with amalgamated zinc and carbon plates, with an exciting<br> -fluid composed of sulphuric acid, water, and potassium bichromate. For<br> -formula of such solutions see Electropoion Fluid--Kookogey's<br> -Solution--Poggendorff's Solution--Trouvé's Solution--Delaurier's<br> -Solution, and others. (See Index.)<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Bunsen.</span><br> -A two fluid porous cell battery. The negative plate is carbon, the<br> -positive plate, amalgamated zinc. The depolarizer is nitric acid or<br> -electropoion fluid, q.v., in which the carbon is immersed. The last<br> -named depolarizer or some equivalent chromic acid depolarizing mixture<br> -is now universally used. The excitant is a dilute solution of -sulphuric<br> -acid. Originally the carbon was made cylindrical in shape and surrounded<br> -the porous cups, in which the zinc was placed. This disposition is now<br> -generally reversed. The electro-motive force is 1.9 volts. The<br> -depolarizing solution is placed in the compartment with the carbon. The<br> -excitant surrounds the zinc.<br> -<br> -<br> -<img style="width: 576px; height: 600px;" alt="" src="images/059F39.jpg"><br> -Fig. 39. BUNSEN'S BATTERY.<br> -<br> -<br> -60 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Cadmium.</span><br> -A battery in which cadmium is the negative plate, sulphate of cadmium<br> -solution the excitant and depolarizer, and zinc the positive plate.<br> -Electro-motive force, .31 volt or about one third of a Daniell cell. It<br> -is mounted like a gravity battery.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Callan.</span><br> -A modification of Grove's battery. Platinized lead is used for the<br> -negative plate, and as a depolarizer a mixture of 4 parts concentrated<br> -sulphuric acid, 2 parts of nitric acid, and 2 parts of a saturated<br> -solution of potassium nitrate. (See Battery, Grove's.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Battery, Camacho's.</span><br> -A battery with carbon negative and amalgamated zinc positive electrodes.<br> -The carbon is contained in a porous cup, packed with loose carbon.<br> -Electropoion or other fluid of that type serves as excitant and<br> -depolarizer, and is delivered as shown from cell to cell by syphons.<br> -<br> -<br> -<img style="width: 628px; height: 444px;" alt="" src="images/060F40.jpg"><br> -Fig. 40. CAMACHO'S BATTERY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Carré's.</span><br> -A Daniell battery for whose porous cup a vessel or species of sack made<br> -of parchment paper is substituted. The battery has been used for<br> -electric light, and has been run for 200 successive hours, by replacing<br> -every 24 hours part of the zinc sulphate solution by water.<br> -<br> -<br> -61 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Cautery.</span><br> -A battery used for heating a platinum wire or other conductor used for<br> -cauterization in electro-therapeutics. The term is descriptive, not<br> -generic.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Chloric Acid.</span><br> -A battery of the Bunsen type in which an acidulated solution of<br> -potassium chlorate is used as depolarizer.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Chloride of Lime.</span><br> -A battery in which bleaching powder is the excitant. The zinc electrode<br> -is immersed in a strong solution of salt, the carbon in a porous vessel<br> -is surrounded with fragments of carbon and is packed with chloride of<br> -lime (bleaching powder). There is no action on open circuit. It has to<br> -be hermetically sealed on account of the odor. Its electro-motive force<br> -is--initial, 1.65 volts; regular, 1.5 volts.<br> -<br> -Synonym--Niaudet's Battery.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Chromic Acid.</span><br> -Properly a battery in which chromic acid is used as a depolarizer. It<br> -includes the bichromate battery. (See Battery, Bichromate.)<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Closed Circuit.</span><br> -A battery adapted by its construction to maintain a current on a closed<br> -circuit for a long time without sensible polarization. The term is<br> -merely one of degree, for any battery becomes exhausted sooner or later.<br> -As examples the Grove, Bunsen or Daniell batteries may be cited.<br> -<br> -<br> -62 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 591px; height: 485px;" alt="" src="images/061F41.jpg"><br> -Fig. 41. COLUMN BATTERY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Column.</span><br> -The original Volta's pile. It consists of a series of compound circular<br> -plates, the upper or lower half, A, copper; the other, Z, of zinc.<br> -Between each pair of plates some flannel or cloth, u, u, is laid, which<br> -is saturated with dilute acid. As shown in the cut, the parts are laid<br> -up in two piles, connected at the top with a bar, c, c, and with vessels<br> -of acidulated water, b, b, as electrodes. The great point in setting it<br> -up is to be sure that no acid runs from one disc of flannel to the next<br> -over the outside of the plates, as this would create a short circuit.<br> -The plates are best compound, being made up of a zinc and a copper plate<br> -soldered together. They may, however, be separate, and merely laid one<br> -on the other. In such case great care must be taken to admit no acid<br> -between them.<br> -<br> -Volta's pile is no longer used, except occasionally. Trouvé's -blotting<br> -paper battery (see Battery, Trouvé's) is a relic of it, and the -same is<br> -to be said for Zamboni's dry pile.<br> -<br> -It rapidly polarizes, the flannel retains but little acid, so that it is<br> -soon spent, and it is very troublesome to set up. Great care must be<br> -taken to have the cloth discs thoroughly saturated, and wrung out to<br> -avoid short circuiting by squeezing out of the acid.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, D'Arsonval's.</span><br> -A battery of the Bunsen type, differing therefrom in the solutions. As<br> -excitant in which the zinc electrode is immersed, the following solution<br> -is used:<br> -<br> -Water, 20 volumes;<br> -Sulphuric Acid (purified by shaking with a little olive or similar oil),<br> -1 volume;<br> -hydrochloric acid, 1 volume.<br> -<br> -As polarizer in which the carbon is immersed the following is used:<br> -<br> -Nitric acid, 1 volume;<br> -hydrochloric acid, 1 volume;<br> -water acidulated with 1/20th sulphuric acid, 2 volumes.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, de la Rue.</span><br> -A battery with zinc positive and silver negative electrode; the<br> -depolarizer is silver chloride; the excitant common salt or ammonium<br> -chloride. The cut shows one of its forms of construction.<br> -<br> -The right hand portion of the cut, Fig. 42, shows the zinc perforated at<br> -C for the connection from the next silver plate. The next to it is the<br> -negative electrode of silver around which a mass of silver chloride is<br> -cast in cylindrical form. A is a parchment paper cylinder with two holes<br> -near its top, through which the silver wire of the negative electrode is<br> -threaded, as shown in B. A solution of 23 parts ammonium chloride in<br> -1,000 parts of water is the approved excitant. Its electro-motive force<br> -is 1.03 volts.<br> -<br> -The jars are closed with paraffin.<br> -<br> -<br> -<img style="width: 598px; height: 382px;" alt="" src="images/062F42.jpg"><br> -Fig. 42. DE LA RUE'S BATTERY.<br> -<br> -<br> -63 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Dry.</span><br> -(a) A form of open circuit battery in which the solutions by a mass of<br> -zinc oxychloride, gypsum, or by a gelatinous mass such as gelatinous<br> -silica, or glue jelly, are made practically solid. Numbers of such have<br> -been patented, and have met with considerable success.<br> -<br> -(b) Zamboni's dry pile, q. v., is sometimes termed a dry battery.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Element of.</span><br> -A term applied sometimes to a single plate, sometimes to the pair of<br> -plates, positive and negative, of the single couple.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Faradic.</span><br> -A term applied, not very correctly however, to apparatus for producing<br> -medical faradic currents. It may be an induction coil with battery, or a<br> -magneto-generator worked by hand.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Ferric Chloride.</span><br> -A battery of the Bunsen type, in which a solution of perchloride of iron<br> -(ferric chloride) is used for the depolarizing agent. A little bromine<br> -is added with advantage. The depolarizing agent recuperates on standing,<br> -by oxidation from the oxygen of the air.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Fuller's.</span><br> -A battery of the Bunsen type. The zinc plate is short and conical, and<br> -rests in the porous jar into which some mercury is poured. An insulated<br> -copper wire connects with the zinc. A plate of carbon is in the outer<br> -jar. The solutions are used as in the Bunsen battery.<br> -<br> -Synonym--Mercury Bichromate Battery.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Gas.</span><br> -(a) A battery whose action depends on the oxidation of hydrogen as its<br> -generating factor. It was invented by Grove. Plates of platinum are<br> -immersed in cups of dilute acid, arranged as if they were plates of zinc<br> -and carbon, in an ordinary battery. Each plate is surrounded by a glass<br> -tube sealed at the top. The plates are filled with acid to the tops.<br> -Through the top the connection is made. A current from another battery<br> -is then passed through it, decomposing the water and surrounding the<br> -upper part of one set of plates with an atmosphere of oxygen and of the<br> -other with hydrogen. Considerable quantities of these gasses are also<br> -occluded by the plates. On now connecting the terminals of the battery,<br> -it gives a current in the reverse direction of that of the charging<br> -current.<br> -<br> -This battery, which is experimental only, is interesting as being the<br> -first of the storage batteries.<br> -<br> -(b) Upward's Chlorine Battery and any battery of that type (see Battery,<br> -Upward's,) is sometimes termed a gas battery.<br> -<br> -<br> -64 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery Gauge.</span><br> -A pocket or portable galvanometer for use in testing batteries and<br> -connections.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Gravity.</span><br> -A battery of the Daniell type, in which the porous cup is suppressed and<br> -the separation of the fluids is secured by their difference in specific<br> -gravity. A great many forms have been devised, varying only in details.<br> -The copper plate, which is sometimes disc shaped, but in any case of<br> -inconsiderable height, rests at the bottom of the jar. Near the top the<br> -zinc plate, also flat or of slight depth, is supported. As exciting<br> -liquid a strong solution of copper sulphate lies at the bottom of the<br> -jar. This is overlaid by a solution of zinc sulphate, or sodium<br> -sulphate, which must be of considerably less specific gravity than that<br> -of the copper sulphate solution. In charging the jar one-tenth of a<br> -saturated solution of zinc sulphate mixed with water is sometimes used<br> -as the upper fluid. This may be first added so as to half fill the jar.<br> -The strong solution of copper sulphate may then be added with a syphon<br> -or syringe underneath the other so as to raise it up. From time to time<br> -copper sulphate in crystals are dropped into the jar. They sink to the<br> -bottom and maintain the copper sulphate solution in a state of<br> -saturation.<br> -<br> -<br> -<img style="width: 651px; height: 347px;" alt="" src="images/064F43.jpg"><br> -Fig. 43. GRAVITY BATTERY OF THE TROUVÉ-CALLAUD TYPE.<br> -<br> -<br> -If the battery is left on open circuit the liquids diffuse, and metallic<br> -copper precipitates upon the zincs. This impairs its efficiency and<br> -creates local action. As long as the battery is kept at work on closed<br> -circuit work but little deposition, comparatively speaking, occurs.<br> -<br> -From time to time, in any case, the zinc plates are removed and scraped,<br> -so as to remove the copper which inevitably forms on their surface. Care<br> -must be taken that the zinc sulphate solution, which is constantly<br> -increasing in strength, does not get so strong as to become of as high<br> -specific gravity as the copper sulphate solution. From time to time some<br> -of the upper solution is therefore removed with a syphon or syringe and<br> -replaced with water. An areometer is useful in running this battery.<br> -<br> -<br> -65 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Grenet.</span><br> -A plunge battery with zinc positive and carbon negative electrodes.<br> -Electropoion or other chromic acid or bichromate solution is used as<br> -depolarizer and excitant. The zinc plate alone is plunged into and<br> -withdrawn from the solution.<br> -<br> -<br> -<img style="width: 390px; height: 608px;" alt="" src="images/065F44.jpg"><br> -Fig. 44. GRENET'S BATTERY.<br> -<br> -<br> -<img style="width: 462px; height: 583px;" alt="" src="images/065F45.jpg"><br> -Fig. 45. GROVE'S BATTERY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Grove's.</span><br> -A two fluid galvanic battery. A porous cup has within it a riband of<br> -platinum, which is the negative plate; amalgamated zinc in the outer jar<br> -is the positive plate. Dilute sulphuric acid (10 per cent. solution) is<br> -placed in the outer jar, and strong nitric acid (40° B.) as a<br> -depolarizer in the porous cups. Its E. M. F. is 1.96 volts.<br> -<br> -It is objectionable, as it gives off corrosive nitrous fumes. These are<br> -produced by the oxidation of the nascent hydrogen by the nitric acid, by<br> -the following reaction:<br> -<br> -3 H + H N O3 = 2 H2 O + N O. There are other reactions, one of which<br> -results in the formation of ammonia by the reduction of the nitric acid<br> -radical by the hydrogen. Ammonium can be detected in the spent liquids.<br> -<br> -<br> -66 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Hydrochloric Acid.</span><br> -A battery in which hydrochloric acid is used as the excitant. Many<br> -attempts have been made to use this acid in batteries, but the volatile<br> -nature of the acid causes the production of so much odor with corrosive<br> -fumes that it has never come into use.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Lead Chloride.</span><br> -A battery of the lead sulphate type in which lead chloride is the<br> -depolarizer. It has had no extended use.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Lead Sulphate.</span><br> -A battery similar to Marié Davy's battery or the gravity -battery, but<br> -using lead sulphate as depolarizer and excitant. Lead, copper or tin is<br> -the material of the negative plate. Becquerel used the lead sulphate as<br> -a solid cylindrical mass surrounding a lead rod 1/5 to 1/4 inch in<br> -diameter. One part of common salt may be mixed with 5 parts of the lead<br> -sulphate. The electro-motive force is about 0.5 volt. The resistance is<br> -very high.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Battery, Leclanché.</span><br> -An open circuit battery with porous cup. In the outer jar is a zinc rod;<br> -a carbon plate is placed in the porous cup. The latter is packed with a<br> -mixture of clean powdered manganese binoxide as depolarizer, and<br> -graphite in equal volumes. A strong solution of ammonium chloride (sal<br> -ammoniac) is placed in the outer jar. It is only used on open circuit<br> -work. Its electromotive force is 1.48 volts, when not polarized.<br> -<br> -The reaction is supposed to be about the following:<br> -<br> -2 N H4 Cl + 2 Mn O2 + Zn = Zn Cl2 + 2 N H3 + H2 0 + M2 O3<br> -<br> -The battery rapidly weakens on open circuit, but quickly recuperates.<br> -There is another form of this battery, termed the agglomerate battery.<br> -(See Battery, Leclanché Agglomerate.)<br> -<br> -<br> -<img style="width: 380px; height: 583px;" alt="" src="images/067F46.jpg"><br> -Fig. 46. LECLANCHÉ BATTERY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Leclanché Agglomerate.</span><br> -A form of the Leclanché in which the porous jar is suppressed. -Cakes<br> -made of a mixture of carbon, 52 parts; manganese binoxide, 40 parts; gum<br> -lac, 5 parts; potassium bisulphate, 3 parts, compressed at 300<br> -atmospheres, at a temperature of 100° C. (212° F.), are -fastened by<br> -India rubber bands or otherwise against the carbon plate. These<br> -constitute the depolarizer. Various shapes are given the carbon and<br> -depolarizing agglomerates.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Local.</span><br> -A battery supplying a local circuit (see Circuit. Local). The current is<br> -governed by the relay situated on the main line and operated by its<br> -current.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Main.</span><br> -The battery used in operating the main line. It is usually applied to<br> -telegraphy. Its function is then to supply current for working relays,<br> -which in turn actuate the local circuits.<br> -<br> -Main and local circuits and batteries are also used in the automatic<br> -block system of railroad signalling.<br> -<br> -<br> -67 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Marié Davy's.</span><br> -A two fluid porous cup battery with carbon negative plate, zinc positive<br> -plate, and mercury sulphate, a nearly insoluble salt, as depolarizer and<br> -excitant. Mercurous or mercuric sulphates have been used in it. Its<br> -electromotive force is 1.5 volts. The local action and waste, owing to<br> -the slight solubility of the mercury compounds, is very slight. If used<br> -on close circuit it becomes polarized. It is also subject under extreme<br> -circumstances to reversal of polarity, zinc becoming deposited upon the<br> -carbon, and there forming a positive electrode.<br> -<br> -In using the cells in series the level of liquid in all must be the<br> -same, otherwise the cell in which it is lowest will become polarized and<br> -exhausted.<br> -<br> -Modifications of this battery on the lines of the gravity battery have<br> -been constructed.<br> -<br> -Synonym--Sulphate of Mercury Battery.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Maynooth's.</span><br> -A battery of the Bunsen type, with cast iron negative plate. The iron<br> -takes the passive form and is not attacked.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Medical.</span><br> -A term applied very indiscriminately to medical current generators, and<br> -to medical induction coils, or to any source of electricity, static or<br> -current, for medical application.<br> -<br> -<br> -68 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Meidinger's.</span><br> -A variety of Daniell cell of the gravity type. The plates are<br> -cylindrical. The zinc plate lies against the upper walls of the vessel.<br> -The copper plate of smaller diameter rests on the bottom. A large tube,<br> -with an aperture in its bottom, is supported in the centre and is<br> -charged with copper sulphate crystals. The cup is filled with a dilute<br> -solution of Epsom salts (magnesium sulphate) or with dilute sulphuric<br> -acid.<br> -<br> -<br> -<span style="font-weight: bold;">Battery Mud.</span><br> -A deposit of mud-like character which forms in gravity batteries and<br> -which consists of metallic copper precipitated by the zinc. It indicates<br> -wasteful action.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Battery, Multiple-connected.</span><br> -A battery connected in parallel, all the positive plates being connected<br> -to one electrode, and all the negative to another.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Battery, Nitric Acid.</span><br> -A battery in which nitric acid is used as the excitant. Owing to its<br> -cost and volatility this acid has been but little used in batteries,<br> -other than as a depolarizer. In Grove's battery (see Battery, Grove's)<br> -it has been thus used.<br> -<br> -<br> -<span style="font-weight: bold;">Battery of Dynamos.</span><br> -A number of dynamos may be arranged to supply the same circuit. They are<br> -then sometimes termed as above, a Dynamo Battery. They may be arranged<br> -in series or in parallel or otherwise combined.<br> -<br> -<br> -<span style="font-weight: bold;">Battery of Leyden Jars.</span><br> -To produce the quantity effect of a single large Leyden jar with a<br> -number of small ones they are often connected in parallel and termed a<br> -battery. In such case the inner coatings are all connected by regular<br> -bar conductors, and the outside coatings are also all in connection.<br> -They are conveniently placed in a box or deep tray whose inner surface<br> -is lined with tinfoil, with an outside connection for grounding, etc.<br> -The cascade, q. v., arrangement is not so generally termed a battery.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Open Circuit.</span><br> -A battery adapted for use in open circuit work. Its main requirement is<br> -that it shall not run down, or exhaust itself when left on open circuit.<br> -The Leclanché battery is very extensively used for this work. -Its action<br> -is typical of that of most open circuit batteries. It is without any<br> -action on open circuit. It is very quickly exhausted on closed circuit,<br> -but recuperates or depolarizes quite soon when on open circuit. It is<br> -always in condition for a momentary connection, but useless for steady<br> -work.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Oxide of Copper.</span><br> -A battery with zinc positive and iron negative electrodes. The excitant<br> -is a 30 or 40 per cent. solution of sodium or potassium hydrate (caustic<br> -soda or caustic potash). The depolarizer is copper oxide. In action the<br> -copper is gradually reduced to the metallic state. The iron element is<br> -often the containing vessel. The battery is practically inactive on open<br> -circuit.<br> -<br> -Its electro-motive force varies from .75 to .90 volt. To prevent the<br> -formation of sodium or potassium carbonate the cell should be closed, or<br> -else the liquid should be covered with mineral oil.<br> -<br> -Synonyms--Lalande & Chaperon Battery--Lalande-Edison Battery.<br> -<br> -<br> -69 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Peroxide of Lead.</span><br> -A battery in which peroxide of lead (lead binoxide) is the depolarizer.<br> -It is a sort of predecessor of the present secondary battery.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Platinized Carbon.</span><br> -A modification of Smee's battery, in which platinized carbon is used for<br> -the negative plates. Before polarization the E. M. F. is equal to that<br> -of Smee's battery. Polarization reduces its electro-motive force<br> -one-half.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Plunge.</span><br> -A battery whose plates are mounted so as to be immersed in the battery<br> -cups or cells, when the battery is to be used, and withdrawn and<br> -supported out of the cups when not in use. The object is to prevent<br> -wasting of the plates by standing in the solution. It is a construction<br> -generally used with sulphuric acid--chromic acid solution and<br> -amalgamated zinc and carbon plates.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Pneumatic.</span><br> -A battery arranged to have air blown through the solution to assist<br> -diffusion and depolarization. It is a construction applied to chromic<br> -acid or bichromate batteries.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Primary.</span><br> -A battery in which the current is supplied by the solution of one of the<br> -plates by the solution. The term distinguishes it from a secondary or<br> -storage battery.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Battery, Pulvermacher's -Electro-Medical.</span><br> -In this battery, the electrodes were zinc and copper wires wound upon<br> -small pieces of wood. Dilute vinegar was used as the excitant, because<br> -it could be found in every household. Formerly the battery had great<br> -success. It is now little used.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Sal Ammoniac.</span><br> -Batteries in which a solution of ammonium chloride is the excitant; they<br> -are very extensively used on open circuit work. (See Battery,<br> -Leclanché.)<br> -<br> -The crystals formed in these batteries have been analyzed and found to<br> -consist of ammonium zinc chloride, 3 Zn Cl2, 8 N H3, 4 H20.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Salt, or Sea Salt.</span><br> -Batteries in which a solution of sodium chloride or common salt is the<br> -excitant, have been largely used, especially for telegraphic purposes.<br> -The Swiss telegraphs use a carbon-zinc combination with salt and water<br> -as the excitant. The batteries are sometimes mounted as plunge<br> -batteries. They are exhausted by short circuiting after some hours, but<br> -recuperate on standing. The zinc is not amalgamated.<br> -<br> -<br> -70 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Sand.</span><br> -A battery whose cells are charged with sand saturated with dilute acid.<br> -It prevents spilling of acid. It is now practically obsolete.<br> -<br> -<br> -<img style="width: 530px; height: 709px;" alt="" src="images/070F47.jpg"><br> -Fig. 47. SECONDARY BATTERY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Secondary.</span><br> -A voltaic battery whose positive and negative electrodes are formed or<br> -deposited by a current from a separate source of electricity by<br> -electrolysis. On disconnection the battery is ready to yield a current,<br> -in the reverse direction of that of the charging current. The usual type<br> -has lead plates on one of which lead binoxide and on the other of which<br> -spongy lead is formed. The lead binoxide seems to be the negative<br> -element, and it also acts as the depolarizer. The spongy lead is the<br> -positive electrode. The solution is dilute sulphuric acid of specific<br> -gravity 1.17. The action consists first in the oxidation of the spongy<br> -lead. The hydrogen set free by the reaction, and which by electrolytic<br> -transfer goes to the other plate, reduces the lead binoxide to<br> -protoxide. The sulphuric acid then attacks the oxides and converts the<br> -oxides into sulphates.<br> -<br> -The charging process consists in sending a current in the reverse <br> -direction through the battery. If there are several cells they are <br> -arranged in series, so that each one receives the same intensity of <br> -current. An electrolytic decomposition takes place, the lead sulphate -on <br> -one plate is reduced to metallic lead, and that on the other plate is <br> -oxidized to lead binoxide. It is then ready for use.<br> -<br> -<br> -71 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The plates in a lead plate battery are of very large area per cell, and<br> -are placed close together. Sometimes, as in Planté's battery, -large flat<br> -plates are laid together with a separating insulator between them, and<br> -are then rolled into a spiral. Sometimes, the most usual arrangement,<br> -the plates are in sets, the positive and negative ones alternating, and<br> -each cell containing a number of plates.<br> -<br> -To secure a good quantity of active material, the plates are sometimes<br> -perforated, and the perforations are filled with oxide of lead. This<br> -gives a good depth of material for the charging current to act on, and<br> -avoids the necessity for a tedious "forming," q. v.<br> -<br> -The electro-motive force of such a battery per cell is 2 volts. Its<br> -resistance may only be one or two-hundredths of an ohm. An intense<br> -current of many amperes can be supplied by it, but to avoid injuring the<br> -cell a current far less than the maximum is taken from it.<br> -<br> -To charge it, a slightly greater electro-motive force, the excess being<br> -termed spurious voltage, is required.<br> -<br> -<br> -<img style="width: 573px; height: 703px;" alt="" src="images/071F48.jpg"><br> -Fig. 48. SIEMENS' AND HALSKE'S PAPER PULP BATTERY.<br> -<br> -<br> -72 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<span style="font-weight: bold;">Battery, Secondary, Plante's.</span><br> -Plante's secondary battery is one of the earlier forms of storage<br> -battery, but has had much success. Two lead plates, large in area and<br> -close together but not touching, are "formed," by exposure to an<br> -electrolyzing current of electricity in one direction, while they are<br> -immersed in dilute sulphuric acid. This converts the surface of one<br> -plate into binoxide. The cell is then allowed to discharge itself almost<br> -completely, when the charging current is again turned on. This process<br> -is repeated over and over again, until the surfaces of the plates are<br> -considerably attacked, one plate, however, being maintained in a state<br> -of oxidation. After a few days of this operation a period of rest is<br> -allowed between the reversals, which sets up a local action on the<br> -oxidized plate, between the metallic lead of the plate, and its coating<br> -of binoxide. This causes the lead to be attacked, under the influence of<br> -the local couple, and sulphate of lead is formed, which, ultimately, by<br> -the charging current is converted into peroxide. These operations<br> -produce an exceedingly good battery. The process described is termed<br> -forming.<br> -<br> -The plates separated by strips of insulating material are generally<br> -wound into a double spiral.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Siemens' and Halske's.</span><br> -A Daniell battery of peculiar shape. The copper, C, is at the bottom of<br> -the glass jar, A. The inner jar, K, has the form of a bell, and supports<br> -a mass of paper pulp, which is dampened with sulphuric acid. The zinc,<br> -Z, rests on top of the mass of pulp. The battery is very durable, but of<br> -high resistance.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Sir William Thomson's.</span><br> -A form of Daniell battery, of the gravity type. The receptacles are<br> -shallow wooden trays lined with lead. A thin plate of copper rests on<br> -the bottom. The zinc plate is of gridiron shape, and rests on wooden<br> -blocks which support it in a horizontal position above the copper. One<br> -tray is placed on top of the other, the upper tray resting on the<br> -corners of the zinc plate which rise above the level of the top of the<br> -flat vessel. Thus connection is assured without wires or binding posts.<br> -It is charged like a gravity battery. The density of the zinc sulphate<br> -solution should be between 1.10 and 1.30. The circuit must be kept<br> -closed to prevent deposition of metallic copper on the zinc. The entire<br> -disposition of the battery is designed to reduce resistance.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Skrivanow.</span><br> -A pocket battery of the De la Rue type, with a solution of 75 parts<br> -caustic potash in 100 parts of water as the excitant. The silver<br> -chloride is contained in a parchment paper receptacle. Its<br> -electro-motive force is 1.45 to 1.5 volts.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Smee's.</span><br> -A single fluid combination, with zinc positive plate, and a plate of<br> -silver, coated with platinum black, for the negative plate. The finely<br> -divided platinum affords a surface from which the hydrogen bubbles<br> -instantly detach themselves, thus preventing polarization. The liquid is<br> -a mixture of one part sulphuric acid to seven parts of water. For the<br> -negative plate silver-plated copper, coated with platinum black, is<br> -used. Electromotive force, .47 volt.<br> -<br> -<br> -<img style="width: 349px; height: 608px;" alt="" src="images/072F49.jpg"><br> -Fig. 49. SMEE'S BATTERY.<br> -<br> -<br> -73 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 493px; height: 712px;" alt="" src="images/073F50.jpg"><br> -Fig. 50. SPIRAL BATTERY, OR HARE'S DEFLAGRATOR.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Spiral.</span><br> -A battery whose plates of thin zinc and copper are wound into a spiral<br> -so as to be very close, but not touching. Dilute sulphuric acid is the<br> -excitant. It is now practically obsolete.<br> -<br> -Synonyms--Calorimeter--Hare's Deflagrator.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Split.</span><br> -A battery of a number of voltaic cells, connected in series, with their<br> -central portion grounded or connected to earth. This gives the ends of<br> -opposite potentials from the earth, and of difference therefrom equal to<br> -the product of one-half of the number of cells employed, multiplied by<br> -their individual voltage.<br> -<br> -<br> -<span style="font-weight: bold;">Battery Solutions, Chromic Acid.</span><br> -A number of formulae have been proposed for these solutions. (See<br> -Electropoion Fluid--Kookogey's Solution--Poggendorff's Solution--<br> -Trouvé's Solution--Delaurier's Solution--Chutaux's -Solution--Dronier's<br> -Salt--Tissandier's Solution.)<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Trough.</span><br> -A battery whose elements are contained in a trough, which is divided by<br> -cross-partitions so as to represent cups. A favorite wood for the trough<br> -is teak, which is divided by glass or slate partitions. Marine glue or<br> -other form of cement is used to make the joints tight. For porous cup<br> -divisions plates of porous porcelain or pottery are placed across,<br> -alternating with the impervious slate partitions.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Trouvé's Blotting -Paper.</span><br> -A battery of the Daniell type in which the solutions are retained by<br> -blotting paper. A considerable thickness of blotting paper lies between<br> -the two plates. The upper half of the thickness of the blotting paper is<br> -saturated with a solution of zinc sulphate, on which the zinc plate<br> -rests.<br> -<br> -The lower half of the paper is saturated with copper sulphate solution,<br> -and this rests upon the copper plate.<br> -<br> -<br> -<img style="width: 696px; height: 512px;" alt="" src="images/074F51.jpg"><br> -Fig. 51. TROUVÉ'S BLOTTING PAPER BATTERY.<br> -<br> -<br> -74 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Tyer's.</span><br> -A modification, as regards the positive element, of Smee's battery, q.<br> -v. The bottom of the battery jar contains a quantity of mercury in which<br> -pieces of zinc are thrown, and this constitutes the positive element.<br> -<br> -A ball of zinc at the end of an insulated copper wire affords the<br> -connection with the zinc and mercury. Its great advantage is that the<br> -smallest scraps of zinc can be used in it, by being dropped into the<br> -mercury. The negative plate is platinized silver; the exciting liquid,<br> -dilute sulphuric acid.<br> -<br> -<br> -<img style="width: 642px; height: 585px;" alt="" src="images/074F52.jpg"><br> -Fig. 52. TYER'S BATTERY.<br> -<br> -<br> -75 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 452px; height: 702px;" alt="" src="images/075F53.jpg"><br> -Fig. 53. SECTION OF UPWARD'S BATTERY.<br> -<br> -<br> -<img style="width: 566px; height: 676px;" alt="" src="images/075F54.jpg"><br> -Fig. 54. ELEVATION OF UPWARD'S BATTERY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Upward's.</span><br> -A primary voltaic cell, the invention of A. Renée Upward. -Referring to<br> -the cuts, the positive plate. Z, is of cast zinc; it is immersed in<br> -water, in a porous cup, B. Outside of the porous cup and contained in<br> -the battery jar are two carbon plates, C, C, connected together. The<br> -rest of the space between the porous cup and battery jar is packed with<br> -crushed carbon, and the top is cemented. Chlorine gas is led by a pipe,<br> -D, into the outer cell. It diffuses through the fine carbon, dissolves<br> -in the water, and so finds its way to the zinc, which it attacks,<br> -directly combining therewith, and forming zinc chloride (Zn + 2 Cl = Zn<br> -Cl 2). Such of the chlorine as is not absorbed finds its way by an -outlet<br> -tube, E, to the next cell. Arrangements are provided for generating<br> -chlorine gas as required. The high specific gravity of the gas is<br> -utilized in regulating its distribution through the cells. The<br> -electro-motive force of the cell is 2.1 volts. A cell 11.5 by 5.5 inches<br> -and 12.5 inches deep has a resistance of 0.2 ohm.<br> -<br> -An overflow pipe, F, with faucet, T, is supplied to withdraw the<br> -solution of zinc chloride as it accumulates.<br> -<br> -<br> -76 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Varley's.</span><br> -A Daniell battery of the Siemens' and Halske's type (see Battery,<br> -Siemens' and Halske's), in which zinc oxide is substituted for the paper<br> -pulp of the other battery. It has been very little used.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Battery, Volta's.</span><br> -The original acid battery. It has a negative electrode of copper, a<br> -positive electrode of zinc; the excitant is sulphuric acid diluted with<br> -sixteen times its volume of water. It rapidly polarizes, and is very<br> -little used.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Voltaic or Galvanic.</span><br> -An apparatus for converting chemical energy directly into electric<br> -energy. This is as broad a definition as can well be given. The general<br> -conception of a battery includes the action of electrolysis, a solution<br> -in the battery acting upon one of two conducting electrodes immersed in<br> -such fluid, which dissolves one of them only, or one more than the<br> -other. The best way to obtain a fundamental idea of a battery is to<br> -start with the simplest. Dilute sulphuric acid dissolves neither pure<br> -zinc nor copper. But it has a far stronger affinity for the first named<br> -metal. If now we immerse in dilute acid two plates, one of pure zinc,<br> -and one of copper, no action will be discernible. But if the plates are<br> -brought in contact with each other a stream of bubbles of hydrogen gas<br> -will escape from the surface of the copper and the zinc will dissolve.<br> -By applying proper tests and deductions it will be found that the copper<br> -and zinc are being constantly charged with opposite electricities, and<br> -that these are constantly recombining. This recombination produces what<br> -is known as an electric current.<br> -<br> -To constitute a battery the zinc and copper plates must be connected<br> -outside of the solution. This connection need not be immediate. Any<br> -conductor which touches both plates will bring about the action, and the<br> -current will pass through it.<br> -<br> -The easiest way to picture the action of a battery is to accept the<br> -doctrine of contact action. In the battery the molecules of water are<br> -pulled apart. The hydrogen molecules go to the copper, the oxygen<br> -molecules go to the zinc, each one, leaving its contact with the other,<br> -comes off charged with opposite electricity. This charges the plates,<br> -and the continuous supply of charge and its continuous discharge<br> -establishes the current.<br> -<br> -The accumulation of hydrogen acts to stop the action by polarization.<br> -Its own affinity for oxygen acts against or in opposition to the<br> -affinity of the zinc for the same element, and so cuts down the action.<br> -A depolarizer of some kind is used in acid batteries for this reason. As<br> -such depolarizer has only to act upon one plate, in most batteries it is<br> -usual to surround such plate only, as far as it is possible, with the<br> -depolarizer. The solution which dissolves the zinc is termed the<br> -excitant or exciting solution.<br> -<br> -To this concrete notion of a voltaic battery the different modifications<br> -described here may be referred. Zinc, it will be seen, forms the almost<br> -universally used dissolved plate; carbon or copper forms the most usual<br> -undissolved plate; sulphuric acid in one form or another is the most<br> -usual excitant.<br> -<br> -The solution in a voltaic battery is electrolyzed (see Electrolysis).<br> -Hence the solutions must be electrolytes. The sulphuric acid and other<br> -ingredients play a secondary role as imparting to the battery fluids<br> -this characteristic.<br> -<br> -It is not necessary to have electrodes of different substances, the same<br> -metal maybe used for both if they are immersed in different solutions<br> -which act differentially upon them, or which act with more energy on one<br> -than on the other. Such are only of theoretical interest.<br> -<br> -<br> -77 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Water.</span><br> -A voltaic battery, whose exciting fluid is water. They are used for<br> -charging quadrant electrometer needles and similar purposes. They<br> -polarize very quickly and are of high resistance. Hence very small<br> -plates in large number can be used without impairing their advantage.<br> -<br> -Rowland's water battery dispenses with cups and uses capillarity<br> -instead. The zinc and platinum or copper plates of a couple are placed<br> -very close together, while the couples are more distant. On dipping into<br> -water each couple picks up and retains by capillarity a little water<br> -between its plates, which forms the exciting fluid. Many hundred couples<br> -can be mounted on a board, and the whole is charged by dipping into<br> -water and at once removing therefrom. It then develops its full<br> -potential difference.<br> -<br> -<br> -<img style="width: 583px; height: 622px;" alt="" src="images/077F55.jpg"><br> -Fig. 55. SECTION OF WOLLASTON BATTERY.<br> -<br> -<br> -<img style="width: 370px; height: 623px;" alt="" src="images/077F56.jpg"><br> -Fig. 56. PLATES OF WOLLASTON'S BATTERY.<br> -<br> -<br> -78 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Battery, Wollaston.</span><br> -The original plunge battery is attributed to Wollaston. He also invented<br> -the battery known by his name, having the disposition shown in the cut,<br> -of zinc Z, surrounded by a thin sheet of copper C; o, o', o", are the<br> -terminals and B, B, the battery jars. Dilute sulphuric acid is used for<br> -exciting fluid.<br> -<br> -<br> -<span style="font-weight: bold;">B. A. U.</span><br> -Abbreviation for British Association unit, referring generally to the B.<br> -A. unit of resistance.<br> -<br> -<br> -<span style="font-weight: bold;">B. A. Unit of Resistance.</span><br> -The original ohm used under that name previous to 1884. The Paris<br> -committee of that year recommended as a practical unit what is known as<br> -the legal ohm. (See Ohm, Legal.)<br> - 1 Legal -Ohm -= 1.0112 B. A. Units of Resistance.<br> - 1 B. A. Unit of Resistance = -.9889 Legal Ohms.<br> - 1 B. A. Unit of Resistance = -.98651E9 C. G. S. units.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">B. E. adj.</span><br> -British Engineering, a qualification of a set of units, the B. E. units,<br> -having for base the foot and pound. The term is but little used.<br> -<br> -<br> -<span style="font-weight: bold;">Beaumé Hydrometer.</span><br> -A hydrometer graduated on the following principle:<br> -<br> -The zero point corresponds to the specific gravity of water for liquids<br> -heavier than water. A solution of 15 parts of salt in 85 parts of water<br> -corresponds in specific gravity to 15° B., and between that and zero<br> -fifteen equal degrees are laid out. The degrees are carried down below<br> -this point.<br> -<br> -The zero points for liquids lighter than water correspond to the<br> -specific gravity of a solution of 10 parts of salt in 90 parts of water.<br> -The specific gravity of water is taken as 10° B. This gives ten -degrees<br> -which are continued up the scale.<br> -<br> -<br> -<span style="font-weight: bold;">Becquerel's Laws of Thermoelectricity.</span><br> -These are stated under the heads, Law of Intermediate Metals and Law of<br> -Successive Temperatures, q. v.<br> -<br> -<br> -Bed Piece.<br> -In a dynamo or motor the frame carrying it, including often the<br> -standards in which the armature shaft is journaled, and often the yoke<br> -or even entire field magnet core.<br> -<br> -<br> -<span style="font-weight: bold;">Bell, Automatic Electric.</span><br> -A bell which rings as long as the circuit is closed, having a circuit<br> -breaker operated by its own motion. (See Bell, Electric.)<br> -<br> -Synonyms--Trembling Bell--Vibrating Bell.<br> -<br> -<br> -<span style="font-weight: bold;">Bell, Call.</span><br> -A bell operated by electricity, designed to call attention, as to a<br> -telephone or telegraphic receiver. (See Bell, Electric.)<br> -<br> -<br> -79 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Bell Call.</span><br> -A calling device for attracting the attention of any one, consisting of<br> -some type of electric bell.<br> -<br> -<br> -<span style="font-weight: bold;">Bell, Circular.</span><br> -A gong-shaped bell, whose clapper and general mechanism is within its<br> -cavity or behind it.<br> -<br> -<br> -<span style="font-weight: bold;">Bell, Differentially Wound.</span><br> -An electric bell, whose magnet is wound differentially so as to prevent<br> -sparking.<br> -<br> -<br> -<img style="width: 308px; height: 598px;" alt="" src="images/079F57.jpg"><br> -Fig. 57. AUTOMATIC ELECTRIC BELL.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Bell, Electric.</span><br> -A bell rung by electricity. Generally it is worked by a current exciting<br> -an electro-magnet, attracting or releasing an armature which is attached<br> -to the vibrating or pivoted tongue of the bell. It may be worked by a<br> -distant switch or press-button, q. v., ringing once for each movement of<br> -the distant switch, etc., or it may be of the vibrating bell type as<br> -shown in the cut. When the current is turned on in this case it attracts<br> -the armature. As this moves towards the poles of the magnet it breaks<br> -the circuit by drawing the contact spring, q. v., away from the contact<br> -point, q. v. This opens the circuit, to whose continuity the contact of<br> -these two parts is essential. The hammer, however, by its momentum<br> -strikes the bell and at once springs back. This again makes the contact<br> -and the hammer is reattracted. This action continues as long as the<br> -circuit is closed at any distant point to which it may be carried. The<br> -ordinary vibrating bell is a typical automatic circuit breaker, q. v.,<br> -this type keeping up the ringing as long as the circuit is closed. Other<br> -bells have no electric contact and simply ring once every time the<br> -circuit is closed. Others worked by an alternating current ring once for<br> -each change of direction of current.<br> -<br> -<br> -80 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Bell, Electro-mechanical.</span><br> -A bell which has its striking train operated by a spring or descending<br> -weight, and which train is thrown into action by the release of a detent<br> -or equivalent action by the closing of an electric circuit. It rings for<br> -any given time after being started.<br> -<br> -<br> -<span style="font-weight: bold;">Bell, Indicating.</span><br> -A bell which by drop-shutter or other indicator connected in circuit<br> -with it, indicates its number or other designation of its call.<br> -<br> -<br> -<span style="font-weight: bold;">Bell, Magneto.</span><br> -An electric bell operated by the alternating current from a magneto<br> -generator. It has a polarized armature and no circuit breaker. The<br> -armature is attracted first in one direction and then in the other, as<br> -the current alternates and reverses the polarity of the electro-magnet.<br> -<br> -<br> -<span style="font-weight: bold;">Bell, Relay.</span><br> -A bell operated by a relay circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Bias.</span><br> -In polarized relay the adjustment of the tongue to lie normally against<br> -one or the other contact. (See Relay, Polarized.)<br> -<br> -<br> -81 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 661px; height: 374px;" alt="" src="images/080F58.jpg"><br> -Fig. 58. RESISTANCE COILS SHOWING BIFILAR WINDING.<br> -<br> -<br> -<span style="font-weight: bold;">Bifilar Winding.</span><br> -The method followed in winding resistance coils to prevent them from<br> -creating fields of force. The wire is doubled, and the doubled wire<br> -starting with the bend or bight is wound into a coil. The current going<br> -in opposite senses in the two lays of the winding produces no field of<br> -force.<br> -<br> -<br> -<span style="font-weight: bold;">Binary Compound.</span><br> -A chemical compound whose molecule contains only two elements, such as<br> -water (H2 0), lead oxide (Pb 0), and many others.<br> -<br> -<br> -<span style="font-weight: bold;">Binding.</span><br> -In a dynamo or motor armature the wire wound around the coils to secure<br> -them in place and prevent their disturbance by centrifugal action.<br> -<br> -<br> -<img style="width: 458px; height: 565px;" alt="" src="images/081F59.jpg"><br> -Fig. 59. DOUBLE BINDING POST.<br> -<br> -<br> -<img style="width: 298px; height: 586px;" alt="" src="images/081F60.jpg"><br> -Fig. 60. BINDING POST, ENGLISH PATTERN.<br> -<br> -<br> -<img style="width: 227px; height: 622px;" alt="" src="images/081F61.jpg"><br> -FIG. 61. WOOD SCREW BINDING POST.<br> -<br> -<br> -<span style="font-weight: bold;">Binding Posts or Screws.</span><br> -Arrangements for receiving the loose end of a wire of an electric<br> -circuit, and securing such end by a screw. Several constructions are<br> -used, as shown here. Sometimes the wire is passed through a hole, and a<br> -screw tapped in at right angles to the hole is screwed down upon the<br> -wire. Sometimes the wire is clamped between two shoulders, one on the<br> -screw, the other on the post. The screw is often a flat-headed thumb<br> -screw or has a milled edge. Sometimes the screw has a slot and is turned<br> -by a screw-driver.<br> -<br> -Several openings are often provided in the same post for different<br> -wires.<br> -<br> -<br> -<span style="font-weight: bold;">Binnacle.</span><br> -The case containing a mariner's compass on shipboard. It is enclosed<br> -completely; it has a glass side or window through which the compass can<br> -be seen, and is provided with one or two lamps arranged to light the<br> -card, while showing as little light as possible outside.<br> -<br> -<br> -82 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Bioscopy, Electric.</span><br> -The diagnosis of life and death by the action of the animal system when<br> -subjected to an electric current or electrification.<br> -<br> -<br> -<span style="font-weight: bold;">Bismuth.</span><br> -A metal, one of the elements, atomic weight, 210 ; equivalent, 70;<br> -valency, 3; specific gravity, 9.9. It is a conductor of electricity.<br> -Relative Resistance, compressed, (silver = 1) 87.23<br> -Specific Resistance, 131.2 microhms<br> -Resistance of a wire<br> - (a) 1 foot long, weighing 1 grain, -18.44 ohms<br> - (b) 1 foot long, 1/1000 inch thick, -789.3 "<br> - (c) 1 meter long, weighing 1 gram, -12.88 "<br> - (d) 1 meter long, 1 millimeter thick, -1.670 "<br> -Resistance of a 1-inch cube 51.65 microhms<br> -Electro chemical equivalent, .7350 (Hydrogen = .0105)<br> -(See Thermo-electric Series.)<br> -<br> -<br> -<img style="width: 470px; height: 646px;" alt="" - src="images/082F62_63.jpg"><br> -Figs. 62, 63. INCANDESCENT WIRE FUSE. ABEL'S PATENT.<br> -<br> -<br> -<img style="width: 560px; height: 742px;" alt="" src="images/082F64.jpg"><br> -Fig. 64. VON EBNER'S FRICTIONAL ELECTRIC MACHINE FOR<br> -EXPLODING ELECTRIC FUSES OR DETONATORS.<br> -<br> -<br> -<span style="font-weight: bold;">Bi-telephone.</span><br> -A pair of telephones arranged with a curved connecting arm or spring, so<br> -that they can be simultaneously applied to both ears. They are<br> -self-retaining, staying in position without the use of the hands.<br> -<br> -<br> -83 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Blasting, Electric.</span><br> -The ignition of blasting charges of powder or high explosives by the<br> -electric spark, or by the ignition to incandescence (red or white heat)<br> -of a thin wire immersed in or surrounded by powder. Special influence or<br> -frictional electric machines or induction coils are used to produce<br> -sparks, if that method of ignition is employed. For the incandescent<br> -wire a hand magneto is very generally employed. (See Fuse, Electric.)<br> -<br> -The cuts, Figs. 62 and 63, show one form of incandescent wire fuse. The<br> -large wires are secured to the capsule, so that no strand can come upon<br> -the small wire within the cavity.<br> -<br> -The cut, Fig. 64, shows a frictional electric machine for igniting spark<br> -fuses.<br> -<br> -<br> -<span style="font-weight: bold;">Bleaching, Electric.</span><br> -Bleaching by agents produced or made available by the direct action of<br> -electricity. Thus if a current under proper conditions is sent through a<br> -solution of common salt (sodium chloride), the electrodes being close<br> -together, the salt is decomposed, chlorine going to one pole and sodium<br> -hydrate to the other. The two substances react upon each other and<br> -combine, forming sodium hypochlorite, which bleaches the tissue immersed<br> -in its solution.<br> -<br> -<br> -<span style="font-weight: bold;">Block System.</span><br> -A system of signalling on railroads. The essence of the system consists<br> -in having signal posts or stations all along the road at distances<br> -depending on the traffic. The space between each two signal posts is<br> -termed a block. From the signal posts the trains in day time are<br> -signalled by wooden arms termed semaphores, and at night by lanterns.<br> -The arms may be moved by hand or by automatic mechanism depending in<br> -part on electricity for carrying out its functions. Thus in the<br> -Westinghouse system the semaphores are moved by pneumatic cylinders and<br> -pistons, whose air valves are opened and shut by the action of solenoid<br> -magnets, q. v. The current of these magnets is short circuited by<br> -passing trains, so as to let the valves close as the train passes the<br> -signal post. The block system causes the semaphore to be set at "danger"<br> -or "caution," as the train enters the next block. Then the following<br> -train is not allowed to enter the block until the safety signal is<br> -shown. The Westinghouse system provides for two semaphores on a post,<br> -one indicating "danger" as long as the train is on the next block; the<br> -other indicating "caution" as long as the train is on the next two<br> -blocks. The rails form part of the circuit, their joints being bridged<br> -by copper wire throughout the block, and being insulated where the<br> -blocks meet.<br> -<br> -<br> -<span style="font-weight: bold;">Block Wire.</span><br> -In the block system a wire connecting adjacent block-signal towers or<br> -semaphore poles.<br> -<br> -<br> -<span style="font-weight: bold;">Blow-pipe.</span><br> -A name sometimes given to an electric experiment illustrating the<br> -repulsion of electrified air particles from a point held at high<br> -relative potential. A metallic point, placed on the prime conductor of<br> -an electric friction or influence machine, becomes highly electrified,<br> -and the air becoming excited is repelled and acts upon the candle flame.<br> -If the candle is placed on the conductor and a point held towards it the<br> -repulsion is still away from the point.<br> -<br> -<br> -84 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Blow-pipe, Electric Arc.</span><br> -A name sometimes given to devices for using the voltaic arc to produce<br> -local heating effects. The directive action of the magnet may be used to<br> -force out the arc like a blow-pipe flame, or a blast of air may be<br> -directly applied for the same purpose.<br> -<br> -<br> -<span style="font-weight: bold;">Blue-stone.</span><br> -A trade name for crystallized copper sulphate, used in Daniell's and<br> -gravity batteries.<br> -<br> -<br> -<span style="font-weight: bold;">Boat, Electric.</span><br> -A boat propelled by electricity. The electricity drives a motor which<br> -actuates a screw propeller. The current is generally supplied by a<br> -storage battery. When used on rivers charging stations are established<br> -at proper places. When the boat is used as a tender or launch for a<br> -steam ship, such as a war-vessel, the battery is charged by a plant on<br> -board the ship. From their noiselessness electric boats are peculiarly<br> -available for nocturnal torpedo operations, and the universal equipment<br> -of modern war-ships with electric lightning and power plants makes their<br> -use possible at all points. This type is often termed an electric<br> -launch, and most or all electric boats fall under this category.<br> -<br> -<br> -<span style="font-weight: bold;">Bobbins.</span><br> -A spool of wood or other material wound with insulated wire. In a<br> -tangent galvanometer the bobbin becomes a ring, with a channel to<br> -receive the winding. As the ring is not infinitely large compared to the<br> -needle the tangent law is not absolutely fulfilled. It is most<br> -accurately fulfilled (S. P. Thomson) when the depth of the groove or<br> -channel in the radial direction bears to the breadth in the axial<br> -direction the ratio of square root of 3 to the square root of 2 or<br> -approximately 11 : 9<br> -<br> -<br> -<span style="font-weight: bold;">Body Protector.</span><br> -A metallic short circuit connected with the wrists and lower legs of the<br> -human body, so that if by accident an active circuit is grounded by the<br> -hands and body of the workman wearing it, most of the current will pass<br> -through the wire conductors, thus avoiding the vital organs of the body.<br> -<br> -<br> -<span style="font-weight: bold;">Boiler Feed, Electric.</span><br> -An apparatus by which an electric current acting on an electro-magnet,<br> -or other equivalent device, opens the water supply when the water level<br> -in a boiler sinks too low, and cuts off the water supply as the water<br> -level rises.<br> -<br> -<br> -<span style="font-weight: bold;">Boiling.</span><br> -In secondary batteries the escape of hydrogen and oxygen gas when the<br> -battery is charged. The bubbling of the escaping gases produces the<br> -effect of boiling.<br> -<br> -<br> -85 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Boll.</span><br> -An absolute, or c. g. s., unit of momentum; a gram moving at the rate of<br> -one centimeter per second; a gram-kine (see Kine); a unit proposed by<br> -the British Association.<br> -<br> -<br> -<span style="font-weight: bold;">Bolometer.</span><br> -An apparatus for detecting small amounts of radiant energy (radiant<br> -heat, so called). A coil suspended by a fine wire or filament so as to<br> -be free to rotate under the effect of force is made up of two parallel<br> -and equal wires, insulated from each other, but connected so that<br> -parallel currents sent through them go in opposite direction through<br> -each. This coil is hung in a strong electro-magnetic field produced by a<br> -large coil surrounding it. When a current passes through the suspended<br> -coil no effect will follow, because the oppositely wound portions<br> -counteract each other exactly. In the circuit with one half of the<br> -suspended coil is an exceedingly thin strip of platinum wire. The other<br> -half of the coil has no strips. Both halves unite after leaving the<br> -coil. If now the strip of platinum is heated its conductivity is<br> -affected and its half of the coil receives less current than the other<br> -half. This disturbs the balance and the coil swings through a small arc.<br> -This apparatus may be made very sensitive, so that an increase of<br> -temperature of 1/1400º F., 9/70000°C. (1/14000º F.) will -be perceptible.<br> -Another construction takes the form of a Wheatstone Bridge, q. v., in<br> -whose arms are introduced resistances consisting of bands of iron, .5<br> -Millimeter wide (.02 inches), .004 millimeter (.00016 inch) thick, and<br> -folded on themselves 14 times so as to make a rectangular grating, 17 x<br> -12 millimeters (.68 x .48 inch). The least difference of heat applied to<br> -the grating affects the galvanometer.<br> -<br> -Synonym-Thermic Balance.<br> -<br> -<br> -<span style="font-weight: bold;">Boreal Pole.</span><br> -The south pointing pole of the magnet. (See Austral Pole.)<br> -<br> -<br> -<span style="font-weight: bold;">Bot.</span><br> -A colloquial expression for the English Board of Trade unit of<br> -Electrical Supply. It is formed of the initials of the words "Board of<br> -Trade." (See Unit, Board of Trade.)<br> -<br> -<br> -<span style="font-weight: bold;">Box Bridge.</span><br> -A constriction of Wheatstone's Bridge in which the necessary resistance<br> -coils are contained in a single box with plugs for throwing the coils in<br> -and out of circuit, and connections to bring the coils into the<br> -different arms of the system. The cut shows a box bridge. Connections<br> -for the galvanometer, battery wires, and terminals of the unknown<br> -resistance are provided, by which its resistances and the connections<br> -are brought into the exact relations indicated in the conventional<br> -diagram of Wheatstone's bridge. (See Wheatstone's Bridge.)<br> -<br> -Referring to the cut, the battery wire, say from the zinc plate,<br> -connects at A1, thereby reaching A, its true connecting point. To B1 one<br> -end of the galvanometer circuit or lead is attached, thereby reaching B,<br> -its true connecting point. To C are connected the other end from the<br> -galvanometer and one end of the unknown resistance. The other end of the<br> -unknown resistance, and the other end of the battery wire, in this case<br> -from the carbon plate, connect to D. At G is an infinity plug, as it is<br> -called. When out it breaks the circuit.<br> -<br> -In use after the connections are made the key is depressed and the<br> -galvanometer observed. The resistance is changed until no action of the<br> -galvanometer is produced by closing the circuit when the ratio of the<br> -resistances of the arms gives the proportion for calculating the unknown<br> -resistances.<br> -<br> -Synonym--Commercial Wheatstone Bridge, or commercial form of same.<br> -<br> -<br> -<img style="width: 592px; height: 443px;" alt="" src="images/086F65.jpg"><br> -Fig. 65. TOP OF BOX BRIDGE.<br> -<br> -<br> -86 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Boxing the Compass.</span><br> -Naming the thirty-two points of the compass in order, and in sequence to<br> -any point called out at random. There are many exercises in the relative<br> -sailing points and bearings that come under the same head. Thus the<br> -direction of two given points being given by names of the compass<br> -points, it may be required to state the number of points intervening.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Brake, Electro-magnetic.</span><br> -A brake to stop a wheel from rotating. It comprises a shoe, or sometimes<br> -a ring, which by electro-magnetic attraction is drawn against the<br> -rotating wheel, thus preventing it from turning, or tending to bring it<br> -to rest. (See Electro-magnet, Annular.)<br> -<br> -<br> -<img style="width: 625px; height: 449px;" alt="" src="images/087F66.jpg"><br> -Fig. 66. ELECTRIC BRAKE.<br> -<br> -<br> -87 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Branch.</span><br> -A conductor branching from a main line. Sometimes the term is restricted<br> -to a principal conductor, from which current is distributed.<br> -<br> -<br> -<span style="font-weight: bold;">Branch Block.</span><br> -In electric wiring of buildings, a block of porcelain or other material<br> -with grooves, holes and screws for the connection of branch wires to a<br> -main wire. Its functions are not only to afford a basis for connecting<br> -the wires, but also to contain safety fuses. As when a branch wire is<br> -taken off, fuses have to be put in its line, the branch block carries<br> -these also. One end of each fuse connects with a main wire, the other<br> -end connects with one of the wires of the branch leader or wire.<br> -<br> -Porcelain is a favorite material for them, as the fusing or "blowing<br> -out" of the safety fuses cannot set it on fire.<br> -<br> -<br> -<span style="font-weight: bold;">Branch Conductor.</span><br> -A parallel or shunt conductor.<br> -<br> -<br> -<span style="font-weight: bold;">Brazing, Electric.</span><br> -Brazing in which the spelter is melted by means of electricity; either<br> -current incandescence or the voltaic arc may be used. It is identical in<br> -general with electric welding. (See Welding, Electric.)<br> -<br> -<br> -<span style="font-weight: bold;">Branding, Electric.</span><br> -A system of branding in which the heat of electrically ignited or<br> -incandescent conductors is used to produce or burn in the marks upon the<br> -surface. For the alternating current a small transformer is connected to<br> -or forms part of the tool.<br> -<br> -<br> -88 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Brassing.</span><br> -The deposition of a coating of brass by electrolysis. The plating bath<br> -contains both copper and zinc. As anode a plate of brass is used. The<br> -operation must be constantly watched. The deposition of both metals goes<br> -on simultaneously, so that a virtual alloy is deposited. By -changing<br> -the depth of immersion of the anode the color of the deposit is varied.<br> -<br> -As a formula for a brassing bath the following are typical. They are<br> -expressed in parts by weight.<br> -<br> -(a) For iron and steel.<br> -<span style="font-family: monospace;">I.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Sodium -Bisulphate, -200</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Potassium Cyanide, 70 per -cent., 500</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Sodium -Carbonate, -1,000</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Water, -8,000</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">II.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Copper -Acetate, -125</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Zinc -Chloride, -100</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Water, -2,000</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Add the second solution to the -first.</span><br style="font-family: monospace;"> -<br style="font-family: monospace;"> -<span style="font-family: monospace;">(b) For zinc.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">I.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Sodium -Bisulphate, -700</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Potassium Cyanide, 70 per -cent., 1,000</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Water, -20,000</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">II.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Copper -Acetate, -350</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Zinc -Chloride, -350</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Aqua -Ammoniae, -400</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Water, -5,000</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Add the second solution to the -first.</span><br> -<br> -Use a brass anode; add more zinc to produce a greenish color; more<br> -copper for a red color. A weak current gives a red color; a strong<br> -current lightens the color. The battery power can be altered, a larger<br> -or smaller anode can be used, or a copper or zinc anode can be used to<br> -change the color of the deposit. The bath may vary from 1.036 to 1.100<br> -sp. gr., without harm.<br> -<br> -<br> -<span style="font-weight: bold;">Break.</span><br> -A point where an electric conductor is cut, broken, or opened by a<br> -switch or other device, or simply by discontinuity of the wires.<br> -<br> -<br> -<span style="font-weight: bold;">Break-down Switch.</span><br> -A switch used in the three-wire system to provide for the discontinuance<br> -of the running of one of the dynamos.<br> -<br> -By connecting the positive and negative bus wires to one terminal of the<br> -active dynamo, and the neutral bus wire to the other terminal, one<br> -dynamo will supply the current and the system operates like a two-wire<br> -system, but can only be used for half its normal capacity.<br> -<br> -<br> -<span style="font-weight: bold;">Breaking Weight.</span><br> -The weight which, applied in tension, will break a prism or cylinder, as<br> -an electric current conductor.<br> -<br> -<br> -89 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Breath Figures, Electric.</span><br> -If a conductor is electrified and placed upon a piece of glass, it will<br> -electrify the glass in contact with it by conduction or discharge. On<br> -removing the conductor the glass remains electrified. The localized<br> -electrification is shown by breathing gently on the glass, when a<br> -species of image of the conductor is produced by the condensed moisture.<br> -A coin is often used for conductor.<br> -<br> -<br> -<span style="font-weight: bold;">Breeze, Electric.</span><br> -A term in medical electricity, used to designate the silent or brush<br> -discharge of high tension electricity. As an instance of its employment,<br> -the electric head bath (see Bath, Electric Head,) may be cited. The<br> -patient forming one electrode, being insulated and connected to one of<br> -the conductors, the other conductor, on being brought near his person,<br> -discharges into his body.<br> -<br> -<br> -<span style="font-weight: bold;">Bridge.</span><br> -(a) A special bar of copper connecting the dynamos to the bus wire, q. -v.,<br> -in electric lighting or power stations.<br> -<br> -(b) Wheatstone's bridge, q. v., and its many modifications, all of which<br> -may be consulted throughout these pages.<br> -<br> -<br> -<span style="font-weight: bold;">British Association Bridge.</span><br> -The type of Wheatstone bridge used by the committee of the association<br> -in determining the B. A. ohm; the meter bridge, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Broadside Method.</span><br> -A method of determining the magnetic moment of a magnet. The magnet, n,<br> -s, under examination is fixed so that it is at right angles to the<br> -magnetic meridian, M, R, which passes through its own center and that of<br> -a compass needle. From the deflection of the latter the moment is<br> -calculated.<br> -<br> -<br> -<img style="width: 229px; height: 646px;" alt="" src="images/089F67.jpg"><br> -Fig. 67. BROADSIDE METHOD.<br> -<br> -<br> -<span style="font-weight: bold;">Bronzing.</span><br> -In electro-plating the deposition of a mixture or virtual alloy of<br> -copper and tin. In general manipulation it resembles the operation of<br> -depositing gold and silver alloy, or of brassing.<br> -<br> -For bronzing the following bath is recommended:<br> -<br> -Prepare each by itself (a) a solution of copper phosphate and (b) a<br> -solution of stannous chloride in a solution of sodium pyrophosphate. For<br> -a, dissolve recently precipitated copper phosphate in concentrated<br> -solution of sodium pyrophosphate. For b, add to a saturated solution of<br> -sodium pyrophosphate solution of stannous chloride as long as the<br> -precipitate which is formed dissolves. Of these two solutions add to a<br> -solution of sodium pyrophosphate which contains about 1.75 oz. of the<br> -salt to the quart, until the precipitate appears quickly and of the<br> -desired color. For anodes use cast bronze plates. Sodium phosphate must<br> -be added from time to time; if the deposit is too light add copper<br> -solution, if too dark add tin solution. (W. T. Brannt.)<br> -<br> -<br> -90 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Brush.</span><br> -In electric current generators and motors, the pieces of copper or other<br> -material that bear against the cylindrical surface of the commutator are<br> -thus termed. Many different constructions have been employed. Some have<br> -employed little wheels or discs bearing against and rotating on the<br> -surface of the commutator. A bundle of copper strips is often employed,<br> -placed flatwise. Sometimes the same are used, but are placed edgewise.<br> -Wire in bundles, soldered together at their distant ends have been<br> -employed. Carbon brushes, which are simply rods or slabs of carbon, are<br> -used with much success.<br> -<br> -Synonym--Collecting Brush.<br> -<br> -<br> -<span style="font-weight: bold;">Brush, Carbon.</span><br> -A brush for a dynamo or motor, which consists of a plate or rod of<br> -carbon, held in a brush holder and pressed against the commutator<br> -surface.<br> -<br> -<br> -<span style="font-weight: bold;">Brushes, Adjustment of.</span><br> -In electric current generators and motors, the brushes which bear upon<br> -the commutator when the machine is in action need occasional adjustment.<br> -This is effected by shifting them until sparking between them and the<br> -commutator is nearly or quite suppressed.<br> -<br> -<br> -<img src="images/090F68.jpg" alt="" style="width: 629px; height: 532px;"><br> -Fig. 68. BRUSH HOLDER.<br> -<br> -<br> -<span style="font-weight: bold;">Brushes, Lead of.</span><br> -In a dynamo electric generator, the lead or displacement in advance of<br> -or beyond the position at right angles to the line connecting the poles<br> -of the field magnet, which is given the brushes. In a motor the brushes<br> -are set back of the right angle position, or are given a negative lead.<br> -(See Lag.)<br> -<br> -<br> -91 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Brush Holders.</span><br> -The adjustable (generally) clutch or clamps for holding the commutator<br> -brushes of a dynamo, which keep them in contact with the commutator, and<br> -admit of adjustment by shifting backward and forward of the brushes to<br> -compensate for wear. They are connected to and form part of the rocker,<br> -q. v. By rotating the latter the brush-holders and brushes are carried<br> -in one direction or other around the commutator, so as to vary the lead<br> -as required.<br> -<br> -<br> -<span style="font-weight: bold;">Brush, Pilot.</span><br> -A third brush, used for application to different parts of a revolving<br> -armature commutator to determine the distribution of potential<br> -difference between its different members. (See Curve of Distribution of<br> -Potential in Armature.) One terminal of a volt-meter is connected to one<br> -of the regular brushes, A, of a dynamo; the other to a third brush, p,<br> -which is pressed against different portions of the commutator of the<br> -dynamo. The readings of the volt-meter are plotted in a curve of<br> -distribution of potential.<br> -<br> -<br> -<img style="width: 637px; height: 536px;" alt="" src="images/091F69.jpg"><br> -Fig. 69. PILOT BRUSH.<br> -<br> -<br> -<span style="font-weight: bold;">Brush, Rotating.</span><br> -Brushes for taking off the current from dynamo commutators, or giving<br> -current connection to motors, whose ends are in the form of rollers<br> -which rotate like little wheels, and press against the commutator<br> -surface.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Brush, Third.</span><br> -A third brush is sometimes provided in a dynamo for regulating purposes.<br> -Applied to a series machine it adjoins one of the regular brushes and<br> -delivers its current to a resistance, to whose further end the regular<br> -circuit is connected. By a sliding connection the resistance is divided<br> -between the third brush circuit and the regular circuit, and by varying<br> -the position of this contact regulation is obtained.<br> -<br> -It is to be distinguished from the pilot brush used for determining the<br> -characteristic of the commutator, although based on the same general<br> -principles.<br> -<br> -<br> -<img style="width: 641px; height: 622px;" alt="" src="images/092F70.jpg"><br> -Fig. 70. THIRD BRUSH REGULATION.<br> -<br> -<br> -92 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Brush, Wire Gauze.</span><br> -A collecting or commutator brush for a dynamo or motor, which brush is<br> -made of wire gauze rolled up and compressed into shape.<br> -<br> -<br> -<span style="font-weight: bold;">Buckling.</span><br> -The bending up and distortion of secondary battery plates. It is largely<br> -due to over-exhausting the batteries. Where the E. M. F. is never<br> -allowed to fall below 1.90 volt it is far less liable to occur.<br> -<br> -<br> -<span style="font-weight: bold;">Bug.</span><br> -Any fault or trouble in the connections or working of electric<br> -apparatus.<br> -<br> -<br> -<span style="font-weight: bold;">Bug Trap.</span><br> -A connection or arrangement for overcoming a "bug." It is said that the<br> -terms "bug" and "bug trap" originated in quadruplex telegraphy.<br> -<br> -<br> -<span style="font-weight: bold;">Bunsen Disc.</span><br> -In photometry, the Bunsen Disc is a piece of paper upon whose centre a<br> -spot is saturated with melted paraffin, or a ring of paraffined surface<br> -surrounds an untouched central spot. If placed in such a position that<br> -it receives an equal illumination on each side, the spot almost<br> -disappears. It is used on the bar photometer. (See Photometer, Bar.)<br> -<br> -Synonym--Grease Spot.<br> -<br> -<br> -93 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Buoy, Electric.</span><br> -A buoy for use to indicate channels or dangers in harbors and elsewhere,<br> -which carries an electric light, whose current is supplied by cable from<br> -shore. It has been proposed to use glass tubes exhausted of air and<br> -containing mercury, which, as moved by the waves, would produce a<br> -luminous effect. A fifty-candle power incandescent lamp is an approved<br> -source of light.<br> -<br> -<br> -<span style="font-weight: bold;">Burner, Electric Gas.</span><br> -A gas burner arranged for the flame to be lighted by electricity. It<br> -takes a great variety of forms. In some cases a pair of terminals are<br> -arranged near the flame or a single terminal is placed near the metal<br> -tip, the latter forming one of the terminals. The spark is generally<br> -produced by an induction coil, or a spark coil. The gas may first be<br> -turned on and the spark then passed. Sometimes the turning of the gas<br> -cock of an individual burner makes and breaks a contact as it turns, and<br> -thereby produces simultaneously with the turning on of the gas a spark<br> -which lights it.<br> -<br> -Another form is wholly automatic. A pair of electro-magnets are attached<br> -below the base of the burner, one of which, when excited, turns on the<br> -gas, and the other one when it is excited turns it off. At the same time<br> -a spark is produced with the turning on of the gas so that it is<br> -lighted. Thus, by use of a automatic burner, a distant gas burner can be<br> -lighted by turning an electric switch. An out-door lamp may be lighted<br> -from within a house.<br> -<br> -The increasing use of electric incandescent lamps, lighted by the<br> -turning of a switch, tends to displace electric gas burners. The latter<br> -have been classified into a number of types depending on their<br> -construction.<br> -<br> -Burners are sometimes connected in series with leads from an induction<br> -coil. Then the gas is turned on all at once, and a succession of sparks<br> -passed until the gas is all lighted. The ignition is practically<br> -instantaneous.<br> -<br> -<br> -<span style="font-weight: bold;">Button, Push.</span><br> -A species of switch which is actuated by the pressure of a button. In<br> -its normal position the button is pressed outwards by a spring, and the<br> -circuit is open. When pressed inwards, it closes the circuit. When<br> -released it springs backward and opens the circuit again.<br> -<br> -They are principally used for ringing bells. If the latter are of the<br> -automatic type, they ring as long as the button is pressed.<br> -<br> -For door-bells and room-bells, the button often occupies the center of a<br> -rosette of wood or bronze or other ornamental piece. Sometimes, as shown<br> -in the cut, they are constructed for use on floors to be pressed by the<br> -foot. The general principle of their construction is shown, although the<br> -method of making the contact varies.<br> -<br> -Synonym--Press Button.<br> -<br> -<br> -<img style="width: 388px; height: 479px;" alt="" src="images/093F71.jpg"><br> -Fig. 71. FLOOR PUSH BUTTON.<br> -<br> -<br> -94 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Burning.</span><br> -(a) In a dynamo, the production of shifting and temporary arcs between<br> -the commutator and brushes, which arcs produce heat enough to injure the<br> -parts in question.<br> -<br> -(b) In electro-plating, a defect due to too strong a current in<br> -proportion to the strength of solution and area of electrodes. This<br> -gives a black or badly-colored deposit.<br> -<br> -<br> -<span style="font-weight: bold;">Bus Rod.</span><br> -A copper conductor used in electric lighting or power stations, to<br> -receive the current from all the dynamos. The distributing leads are<br> -connected to the bus wires.<br> -<br> -In the three-wire system there are three; in the two-wire system there<br> -are two bus wires.<br> -<br> -The name is undoubtedly derived from "omnibus."<br> -<br> -The bus wires may be divided into positive, negative, and, in the<br> -three-wire system, neutral bus wires.<br> -<br> -Synonyms--Omnibus Rod, Wire, or Bar--Bus Bar, or Wire.<br> -<br> -<br> -<span style="font-weight: bold;">Buzzer.</span><br> -An electric alarm or call produced by a rapid vibration of electric make<br> -and break mechanism, which is often magnified by enclosure in a<br> -resonating chamber, resembling a bell, but which is not struck or<br> -touched by the vibrating parts. Sometimes a square wooden box is used as<br> -resonator.<br> -<br> -<br> -<img style="width: 716px; height: 592px;" alt="" src="images/094F72.jpg"><br> -Fig. 72. BUZZER.<br> -<br> -<br> -95 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">B. W. G.</span><br> -Abbreviation for Birmingham Wire Gauge. (See Wire Gauge, Birmingham.)<br> -</big></big><br> -<big><big><span style="text-decoration: underline;"></span></big></big><big><big><span - style="font-weight: bold;"><br> -<br> -C.</span><br> -(a) Abbreviation for Centigrade, as 100 C., meaning 100 Centigrade. (See<br> -Centigrade Scale.)<br> -<br> -(b) A symbol of current or of current strength. Thus in the expression<br> -of Ohm's law C = E/R. C indicates current strength or intensity, not in<br> -any fixed unit, but only in a unit of the same order in which E and R<br> -are expressed; E Indicating electro-motive force and R resistance.<br> -<br> -<br> -<span style="font-weight: bold;">Cable.</span><br> -(a) Abbreviation for Cablegram, q. v.<br> -<br> -(b) v. It is also used as a verb, meaning to transmit a message by<br> -submarine cable.<br> -<br> -(c). An insulated electric conductor, of large diameter. It often is<br> -protected by armor or metallic sheathing and may be designed for use as<br> -an aerial, submarine, subterranean or conduit cable. A cable often<br> -contains a large number of separately insulated conductors, so as to<br> -supply a large number of circuits.<br> -<br> -<br> -<span style="font-weight: bold;">Cable, Aerial.</span><br> -A cable usually containing a large number of separately insulated wires,<br> -and itself insulated. It is suspended in the air. As its weight is<br> -sometimes so great that it could not well sustain it, a suspending wire<br> -is in such cases carried along with it, to which it is suspended by<br> -cable hangers, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Cable Box.</span><br> -A box for receiving underground cable ends and connecting the separate<br> -wires of the cable to air-line wires. It is often mounted on a pole,<br> -which forms the starting point of the air-line portion of the system.<br> -<br> -<br> -<span style="font-weight: bold;">Cable, Bunched.</span><br> -A cable containing a number of separate and individual conductors. In<br> -some forms it consists virtually of two or more small cables laid<br> -tangent to each other and there secured. Thus each in section represents<br> -two or more tangent circles with the interstice solidly filled with the<br> -metal sheathing.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Cable, Capacity of.</span><br> -The electrostatic capacity of a cable. A cable represents a Leyden jar<br> -or static condenser. The outer sheathing or armor, or even the more or<br> -less moist coating, if it is unarmored, represents one coating. The wire<br> -conductors represent the other coating, and the insulator is the<br> -dielectric.<br> -<br> -The capacity of a cable interferes with its efficiency as a conductor of<br> -broken or interrupted currents, such as are used in telegraphy or<br> -telephoning. As each impulse or momentary current is sent into the line,<br> -it has to charge the cable to at least a certain extent before the<br> -effects of the current are perceptible at the other end. Then the cable<br> -has to discharge itself. All this creates a drag or retardation.<br> -<br> -The capacity of a cable is used to determine the locality of breaks in<br> -the continuity of the conductors. The capacity per unit of length being<br> -accurately known, it is obvious that, if the conductor breaks without<br> -disturbance of the insulator, the distance of the break from the end can<br> -be ascertained by determining the capacity of the cable from one end.<br> -This capacity will be in proportion to the capacity of a mile, a knot or<br> -any fixed unit, as the distance to the break is to the length used as<br> -standard.<br> -<br> -<br> -96 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Cable Core.</span><br> -The conductors of a cable. They are generally copper wire. In a<br> -telephone cable they may be very numerous and insulated from each other.<br> -In ocean cables they may be a group of bare wires twisted or laid<br> -together. Sometimes the conductors are arranged for metallic circuits,<br> -each pair being distinguished by special colored windings.<br> -<br> -<br> -<span style="font-weight: bold;">Cable, Duplex.</span><br> -A cable containing two wires, each with separate insulation, so as to be<br> -virtually two cables, laid and secured parallel and side by side.<br> -<br> -<br> -<span style="font-weight: bold;">Cable, Flat.</span><br> -A cable, flat in shape, so as to lie closely against a wall or ceiling.<br> -<br> -<br> -<span style="font-weight: bold;">Cablegram.</span><br> -A message which has been transmitted or is to be transmitted by a<br> -submarine cable. It is sometimes called a cable.<br> -<br> -<br> -<span style="font-weight: bold;">Cable Grip.</span><br> -A grip for holding the end of a cable, when the cable is to be drawn<br> -into a conduit in a subway. It is an attachment to provide the cable<br> -with an eye or loop. Its end is a split socket and embraces the end of<br> -the cable, and is secured thereto by bolts driven through the cable end.<br> -In drawing a cable into a conduit a capstan and rope are often used, and<br> -the rope is secured to the cable end by the grip.<br> -<br> -<br> -<img style="width: 589px; height: 425px;" alt="" src="images/096F73.jpg"><br> -Fig. 73. CABLE HANGER, CABLE, AND SUSPENDING WIRE.<br> -<br> -<br> -<img style="width: 339px; height: 510px;" alt="" src="images/096F74.jpg"><br> -Fig. 74. CABLE HANGER, OPEN.<br> -<br> -<br> -<span style="font-weight: bold;">Cable Hanger.</span><br> -When a heavy electric cable is suspended from poles it often would be<br> -unsafe to trust to its longitudinal strength to support or sustain its<br> -own weight unless the poles were very near together. In such case an<br> -auxiliary or sustaining wire is run along with it, and by clips or<br> -hangers the cable is connected thereto at as frequent intervals as seem<br> -desirable. The contrivance may take the form of a strip of metal<br> -surrounding the cable and carrying a hook or eye through which the<br> -supporting wire passes.<br> -<br> -Synonym--Cable Clip.<br> -<br> -<br> -97 STANDARD ELECTRICAL DICTIONARY<br> -<br> -<br> -<span style="font-weight: bold;">Cable Hanger Tongs.</span><br> -Tongs for attaching cable hangers, q.v. They have long handles so as to<br> -be worked from the ground at the middle of a span.<br> -<br> -<br> -<span style="font-weight: bold;">Cable, Suspending Wire of.</span><br> -A wire by which an aerial cable is in part or entirely suspended. The<br> -cable, being incapable of sustaining its own weight, is secured by clips<br> -or hangers to a wire, strong from pole to pole immediately above it.<br> -(See Cable Hanger.)<br> -<br> -<br> -<span style="font-weight: bold;">Cable Tank.</span><br> -A tank in which a submarine cable is coiled away on board a cable-laying<br> -ship, or in the factory on shore for the purpose of testing or<br> -watching its insulation. Sometimes, in order to test it under pressures<br> -approximating to those it will be subjected to in practice, the tank is<br> -closed and the portion of cable within it is subjected to hydraulic<br> -pressure. This represents the pressure it will be exposed to in deep<br> -water.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Calamine.</span><br> -A mineral; zinc silicate; formula Zn2 Si 03, crystalline system,<br> -Orthorhombic; specific gravity, 3.16-3.9.<br> -<br> -The crystals often show strong pyroelectric properties.<br> -<br> -<br> -<span style="font-weight: bold;">Calibration.</span><br> -The determination by experiment or calculation of the value of the<br> -readings of an instrument, such as a galvanometer or eudiometer. Thus if<br> -a tangent galvanometer has its circle graduated in degrees, a table of<br> -the value of tangents corresponding to every reading occurring in<br> -practice would represent a calibration by calculation. A determination<br> -of the current required to produce each deflection would be a<br> -calibration in the more usual sense. Calibration is generally absolute,<br> -as referring to some fixed unit, but it may be relative, as between two<br> -things both of unknown absolute value.<br> -<br> -<br> -<span style="font-weight: bold;">Calibration, Absolute.</span><br> -The determination of the absolute value of currents producing given<br> -deflections in a galvanometer, or in other instruments the determination<br> -of corresponding values, as the instrument may be a magnetometer,<br> -quadrant electrometer, or other apparatus.<br> -<br> -<br> -<span style="font-weight: bold;">Calibration, Invariable.</span><br> -Calibration applicable to specially constructed galvanometers, which is<br> -unaffected by the proximity of masses of iron or field magnets. Such<br> -galvanometers must have a constant controlling field. Such is given by a<br> -powerful permanent magnet, whose field is practically unaffected by the<br> -causes named. Or else, in place of a controlling field, a spring maybe<br> -used to which the needle is attached, and which tends to hold it in one<br> -position.<br> -<br> -<br> -98 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Calibration, Relative.</span><br> -The determination of the law connecting the various indications of an<br> -instrument, such as the deflections of the needle of a galvanometer,<br> -with the relative causes; in the case of a galvanometer, the strength of<br> -the currents or the electro-motive forces producing them directly or<br> -indirectly.<br> -<br> -<br> -<span style="font-weight: bold;">Call Bell.</span><br> -A bell rung by pressing a button or otherwise to call the attention of a<br> -person in a distant place. They can be classified into a great variety<br> -of types according to their uses or construction.<br> -<br> -<br> -<span style="font-weight: bold;">Call Button.</span><br> -A push button used for ringing a call bell, sounding a buzzer, working<br> -an annunciator and for similar purposes. (See Push Button.)<br> -<br> -Synonym--Push Button.<br> -<br> -<br> -<span style="font-weight: bold;">Calling Drop.</span><br> -In a telephone exchange or telegraph office a drop shutter annunciator,<br> -which falls to call the attention of the operator, notifying him that<br> -the line connected to such drop is to be connected to some other<br> -circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Calorie or Calory.</span><br> -A practical unit of heat. There are two calories, respectively called<br> -the great and the small calorie, or the kilogram and the gram calorie.<br> -The first is the quantity of heat required to raise the temperature of<br> -one kilogram of water one degree centigrade. The second is the quantity<br> -of heat required to raise the temperature of one gram of water one<br> -degree centigrade.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Calorimeter.</span><br> -An apparatus for measuring the quantity of heat evolved or produced by<br> -or under different conditions. Dulong's water calorimeter consists of a<br> -water jacket, and by the increase of temperature of the water and<br> -enclosing vessels the amount of heat produced by anything in the inner<br> -vessels is determined. The amount of ice a heated body will melt is<br> -sometimes made the basis of a calorimeter. The expansion of a fluid, as<br> -water, may be used. In the calorimeter shown in the cut the heat<br> -produced in a conductor by the passage of an electric current is caused<br> -to heat water whose temperature is shown by a thermometer immersed<br> -therein. The increase of temperature and the weight of the water give<br> -the basis for a determination of the heat produced by the current.<br> -Knowing the resistance of the conductor immersed, the watts can be<br> -calculated. This gives the bases for the determination of the<br> -heat-equivalent of electric energy. This is but an imperfect<br> -calorimeter, as it constantly would lose heat by the surrounding<br> -atmosphere, and would cease to operate as a calorimeter when the water<br> -was as hot as the wire normally would be, for then it would not absorb<br> -all the heat.<br> -<br> -<br> -<img style="width: 451px; height: 621px;" alt="" src="images/098F75.jpg"><br> -Fig. 75. CALORIMETER.<br> -<br> -<br> -99 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Candle</span>. <br> -The generally accepted unit of illuminating power; there are<br> -three kinds in use as standards. (See Candle, Decimal--Candle, German<br> -Standard--Candle, Standard.)<br> -<br> -<br> -<span style="font-weight: bold;">Candle, Concentric.</span><br> -An electric candle of the Jablochkoff type, having a small solid carbon<br> -inside of an outside tubular carbon, the space between being filled with<br> -refractory material corresponding to the colombin, q. v., of the<br> -ordinary type. The arc springs across from one carbon to the other.<br> -<br> -<br> -<span style="font-weight: bold;">Candle, Debrun.</span><br> -An arc lamp with approximately parallel carbons. A transverse priming<br> -connects their bases, and the arc starting there at once flies out to<br> -the end.<br> -<br> -<br> -<span style="font-weight: bold;">Candle, Decimal.</span><br> -A standard of illuminating power, proposed to the Congress of<br> -Electricians of 1889 by Picou. It is one-twentieth of a Viole, or almost<br> -exactly one standard candle. (See Viole's Standard of Illuminating<br> -Power.)<br> -<br> -<span style="font-weight: bold;">Candle, Electric.</span><br> -An arc lamp regulated by simple gravity, or without any feed of the<br> -carbons or special feeding apparatus, generally for the production of an<br> -arc light of low intensity. This definition may be considered too<br> -elastic, and the word may be restricted to parallel carbon lamps in<br> -which the arc springs across from carbon to carbon. For the latter class<br> -an alternating current is used to keep the carbons of equal length. They<br> -are but little used now. Various kinds have been invented, some of which<br> -are given here.<br> -<br> -<br> -<span style="font-weight: bold;">Candle, German Standard.</span><br> -A standard of illuminating power used in Germany. It is a paraffin<br> -candle, 6 to the pound, 20 millimeters diameter; flame, 56 millimeters<br> -high; rate of consumption, 7.7 grams per hour. Its value is about two<br> -per cent. lower than the English standard candle.<br> -<br> -<br> -100 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Candle Holder.</span><br> -A clamp for holding electric candles of the Jablochkoff type. The ones<br> -shown in the cut designed for Jablochkoff candles comprise a pair -of<br> -metallic clamps, each member insulated from the other, and connected as<br> -terminals of the circuit. When the candle is placed in position the<br> -metal pieces press against the carbons of the candle and thus convey the<br> -current. Below each member of the clamps is a binding screw for the line<br> -wire terminals.<br> -<br> -<br> -<img style="width: 546px; height: 520px;" alt="" src="images/100F76.jpg"><br> -Fig. 76. JABLOCHKOFF CANDLE HOLDERS.<br> -<br> -<br> -<img style="width: 417px; height: 526px;" alt="" src="images/100F77.jpg"><br> -Fig. 77. JABLOCHKOFF CANDLE.<br> -<br> -<br> -<span style="font-weight: bold;">Candle, Jablochkoff.</span><br> -An arc lamp without regulating mechanism, producing an arc between the<br> -ends of parallel carbons. It consists of two parallel rods of carbon,<br> -between which is an insulating layer of non-combustible material called<br> -the colombin. Kaolin was originally employed for this part; later, as<br> -the fusion of this material was found to short- circuit the arc, a<br> -mixture of two parts of calcium sulphate and one of barium sulphate was<br> -used. The carbons are 4 millimeters (.16 inch) thick, and the colombin<br> -is 3 millimeters (.12 inch) wide and two-thirds as thick. A little slip<br> -of carbon is placed across the top, touching both carbons to start the<br> -arc. Once started the candle burns to the end, and cannot be restarted<br> -after ignition, except by placing a short conductor across the ends, as<br> -at first. The Jablochkoff candle may now be considered as virtually<br> -extinct in this country. In France at one time a great number were in<br> -use.<br> -<br> -To keep the carbons of equal length an alternating current must always<br> -be used with them. Special alternating combinations were employed in<br> -some cases where a direct current had to be drawn upon.<br> -<br> -<br> -<span style="font-weight: bold;">Candle, Jamin.</span><br> -An arc lamp with approximately parallel carbons, one of which oscillates<br> -and is controlled by an electro-magnet and armature. A coil of wire is<br> -carried around the carbons to keep the arc steady and in place. The<br> -frame and wire coils have been found unsatisfactory, as causing a<br> -shadow.<br> -<br> -<br> -<span style="font-weight: bold;">Candle Power.</span><br> -The amount of light given by the standard candle. The legal English and<br> -standard American candle is a sperm candle burning two grains a minute.<br> -It should have burned some ten minutes before use, and the wick should<br> -be bent over and have a red tip. Otherwise its readings or indications<br> -are useless. A sixteen candle power lamp means a lamp giving the light<br> -of sixteen candles. The candle power is a universal unit of illuminating<br> -power.<br> -<br> -<br> -101 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Candle Power, Rated.</span><br> -The candle power of arc lamps is always stated in excess of the truth,<br> -and this may be termed as above. A 2000 candle power lamp really gives<br> -about 800 candles illumination.<br> -<br> -Synonym--Nominal Candle Power.<br> -<br> -<br> -<span style="font-weight: bold;">Candle Power, Spherical.</span><br> -The average candle power of a source of light in all directions. An arc<br> -lamp and an incandescent lamp vary greatly in the intensity of light<br> -emitted by them in different directions. The average of a number of<br> -determinations at various angles, the lamp being moved about into<br> -different positions, is taken for the spherical candle power.<br> -<br> -<br> -<span style="font-weight: bold;">Candle, Standard.</span><br> -A standard of illuminating power. Unless otherwise expressed the English<br> -standard sperm candle is indicated by this term. (See Candle Power.)<br> -<br> -<br> -<span style="font-weight: bold;">Candle, Wilde.</span><br> -An arc lamp with approximately parallel carbons. One of the carbons can<br> -rotate through a small arc being pivoted at its base. This oscillation<br> -is regulated by an electro-magnet at its base, and the carbons touch<br> -when no current is passing. They separate a little when the current<br> -passes, establishing an arc. The regulation is comparable to that of a<br> -regular arc lamp.<br> -<br> -<br> -<img style="width: 410px; height: 562px;" alt="" src="images/101F78.jpg"><br> -Fig. 78. WILDE CANDLE.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Caoutchouc.</span><br> -India rubber; a substance existing in an emulsion or solution in the<br> -juice of certain trees and vines of the tropics, whence it is obtained<br> -by coagulation and drying. The name "rubber" is due to the fact that one<br> -of its earliest uses was for erasing pencil marks by rubbing. It has a<br> -very high value as an insulator. The unworked crude rubber is called<br> -virgin gum; after working over by kneading, it is termed masticated or<br> -pure gum rubber; after mixture with sulphur and heating, it is termed<br> -vulcanized rubber. If enough sulphur is added it becomes hard, and if<br> -black, is termed ebonite; if vermilion or other pigment is also added to<br> -produce a reddish color, it is termed vulcanite. The masticated gum<br> -dissolves more or less completely in naphtha (sp. gr., .850) benzole,<br> -turpentine, chloroform, ether and other similar liquids.. The resistance<br> -per centimeter cube of "Hooper's" vulcanized India rubber, such as is<br> -used in submarine cables is 1.5E16 ohms. The specific inductive capacity<br> -of pure India rubber is 2.34--of vulcanized 2.94 (Schiller).<br> -<br> -Synonyms--India Rubber--Rubber.<br> -<br> -<br> -102 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Capacity, Dielectric.</span><br> -The capacity of a dielectric in retaining an electrostatic charge; the<br> -same as Specific Inductive Capacity. 'The number expressing it is<br> -sometimes called the dielectric constant. (See Capacity, Specific<br> -Inductive.)<br> -<br> -<br> -<span style="font-weight: bold;">Capacity, Electric, or Electrostatic.</span><br> -The relative capacity of a conductor or system to retain a charge of<br> -electricity with the production of a given difference of potential. The<br> -greater the charge for a given change of potential, or the less the<br> -change of potential for a given charge the greater the capacity. The<br> -measure of its capacity is the amount of electricity required to raise<br> -the potential to a stated amount. The unit of capacity is the farad, q.<br> -v. Electric capacity is comparable to the capacity of a bottle for air.<br> -A given amount of air will raise the pressure more or less, and the<br> -amount required to raise its pressure a stated amount might be taken as<br> -the measure of capacity, and would be strictly comparable to<br> -electrostatic charge and potential change. The capacity, K, is obviously<br> -proportional to the quantity, Q, of the charge at a given potential, E,<br> -and inversely proportional to the potential, E, for a given quantity, Q,<br> -or,<br> - (1) K == Q/E<br> - and<br> - (2) Q = K * E,<br> -or, the quantity required to raise a conductor by a given potential is<br> -equal to the capacity of the conductor or system multiplied by the rise<br> -of potential. The capacity of a conductor depends upon its environments,<br> -such as the nature of the dielectric surrounding it, the proximity of<br> -oppositely charged bodies and other similar factors. (See<br> -Dielectric-Condenser-Leyden jar.)<br> -<br> -The dimensions of capacity are found by dividing a quantity of<br> -electricity by the potential produced in the conductor by such<br> -quantity.<br> -<br> -Quantity ( ((M^.5)*(L^1.5)) / T ) / potential ( ((M^.5)*(L^.5)) / T ) = -L.<br> -<br> -<br> -<span style="font-weight: bold;">Capacity, Instantaneous.</span><br> -The capacity of a condenser when connected only for an instant to a<br> -source of electricity. This is in contrast to electric absorption (see<br> -Absorption, Electric), and is capacity without such absorption taking<br> -part in the action.<br> -<br> -<br> -103 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Capacity of a Telegraph Conductor.</span><br> -The electric capacity of a telegraphic conductor is identical in quality<br> -with that of any other conductor. It varies in quantity, not only for<br> -different wires, but for the same wire under different environments, as<br> -the wire reacting through the surrounding air or other dielectric upon<br> -the earth, represents one element of a condenser, the earth, in general,<br> -representing the other. Hence, a wire placed near the earth has greater<br> -capacity than one strung upon high poles, although the wires may be<br> -identical in length, material and diameter. The effect of high capacity<br> -is to retard the transmission of intermitting signals. Thus, when--as in<br> -the Morse system--a key is depressed, closing a long telegraph current<br> -and sending a signal into a line, it is at least very probable that a<br> -portion of the electricity travels to the end of the wire with the<br> -velocity of light. But as the wire has to be charged, enough current to<br> -move the relay may not reach the end for some seconds.<br> -<br> -<br> -<span style="font-weight: bold;">Capacity of Polarization of a Voltaic -Cell.</span><br> -The relative resistance to polarization of a voltaic cell, measured by<br> -the quantity of electricity it can supply before polarization. A<br> -counter-electromotive force may be developed, or the acid or other<br> -solution may become exhausted. The quantity of electricity delivered<br> -before this happens depends on the size and type of cell and other<br> -factors.<br> -<br> -<br> -C<span style="font-weight: bold;">apacity, Residual.</span><br> -When two insulated conductors are separated by a dielectric, and are<br> -discharged disruptively by being connected or nearly connected<br> -electrically, on removing the discharger it is found that a slight<br> -charge is present after a short interval. This is the residual charge.<br> -(See Charge, Residual.) Shaking or jarring the dielectric facilitates<br> -the complete discharge. This retaining of a charge is a phenomenon of<br> -the dielectric, and as such, is termed residual capacity. It varies<br> -greatly in different substances. In quartz it is one-ninth what it is in<br> -air. Iceland spar (crystalline calcite) seems to have no residual<br> -capacity. The action of shaking and jarring in facilitating a discharge<br> -indicates a mechanical stress into which the electrostatic polarization<br> -of the conductor has thrown the intervening dielectric.<br> -<br> -<br> -<span style="font-weight: bold;">Capacity, Specific Inductive.</span><br> -The ratio of the capacity of a condenser when its plates are separated<br> -by any substance to the capacity of the same condenser when its plates<br> -are separated by air.<br> -<br> -A static accumulator consists of two conducting surfaces separated by an<br> -insulator. It is found that the capacity of an accumulator for an<br> -electric charge, which varies with or may be rated by the potential<br> -difference to which its conductors will be brought by the given charge,<br> -varies with the nature of the interposed dielectric, and is proportional<br> -to a constant special to each substance. This constant is the specific<br> -inductive capacity of the dielectric.<br> -<br> -The same condenser will have a higher capacity as the dielectric is<br> -thinner, other things being equal. But different dielectrics having<br> -different specific inductive capacities, the constant may be determined<br> -by ascertaining the relative thicknesses of layers having the same total<br> -inductive capacity. The thicker the layer, the higher is its specific<br> -inductive capacity.<br> -<br> -Thus it is found that 3.2 units thickness of sulphur have the same total<br> -inductive capacity as 1 unit thickness of air. In other words, if<br> -sulphur is interposed between two conducting plates, they may be<br> -separated to over three times the distance that would be requisite to<br> -retain the same capacity in air. Hence, sulphur is the better<br> -dielectric, and air being taken as unity, the specific inductive<br> -capacity of sulphur is 3.2.<br> -<br> -<br> -104 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The specific inductive capacity of a dielectric varies with the time and<br> -temperature. That of glass rises 2.5 per cent. between 12° C. -(53.6° F.)<br> -and 83° C. (181.4° F.). If a condenser is discharged -disruptively, it<br> -retains a small residual charge which it can part with later. If a<br> -metallic connection is made between the plates, the discharge is not<br> -instantaneous. Vibration shaking and jarring facilitate the complete<br> -discharge. All this shows that the charge is a phase of the dielectric<br> -itself, and indicates a strained state into which it is brought.<br> -<br> -The following table gives the specific inductive capacity of various<br> -substances:<br> -<br> - <span - style="font-family: monospace;"> -<small>Specific Inductive Capacity.</small></span><small><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Substance -Specific</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Inductive Authority</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -Capacity.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Vacuum, air at about 0.001 -millimeters pressure 0.94 -about Ayrton</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Vacuum, air at about 5 -millimeters -0.9985 Ayrton</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -0.99941 Boltzmann</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Hydrogen at about 760 millimeters -pressure -0.9997 Boltzmann</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -0.9998 Ayrton</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Air at about 760 millimeters -pressure -1.0 Taken as the</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -standard</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Carbon Dioxide at about 760 -millimeters pressure -1.000356 Boltzmann</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -1.0008 Ayrton</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Olefiant Gas at about 760 -millimeters pressure -1.000722 Boltzmann</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Sulphur Dioxide at about 760 -millimeters pressure -1.0037 Ayrton</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Paraffin Wax, -Clear -1.92 Schiller</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -1.96 Wüllner</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -1.977 Gibson and Barclay</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -2.32 Boltzmann</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Paraffin Wax, -Milky -2.47 Schiller</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">India Rubber, -Pure -2.34 Schiller</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">India Rubber, -Vulcanized -2.94 Schiller</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Resin -2.55 Boltzmann</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Ebonite -2.56 Wüllner</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -2.76 Schiller</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -3.15 Boltzmann</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Sulphur -2.88 to 3.21 Wüllner</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -3.84 Boltzmann</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Shellac -2.95 to 3.73 Wüllner</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Gutta -percha -4.2</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Mica -5</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Flint Glass, Very -light -6.57 J. Hopkinson</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Flint Glass, -Light -6.85 J. Hopkinson</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Flint Glass, -Dense -7.4 J. Hopkinson</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Flint Glass, Double extra -dense -10.1 J. Hopkinson</span></small><br> -<br> -<br> -105 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Capacity, Unit of.</span><br> -The unit of capacity is the capacity of a surface which a unit quantity<br> -will raise to a unit potential. The practical unit is the surface which<br> -a coulomb will raise to one volt, and is called the farad, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Capacity, Storage.</span><br> -In secondary batteries the quantity of electrical current which they can<br> -supply when charged, without undue exhaustion. It is expressed in<br> -ampere-hours. The potential varies so little during the discharge that<br> -it is assumed to be constant.<br> -<br> -<br> -<span style="font-weight: bold;">Capillarity.</span><br> -The reaction between liquid surfaces of different kinds or between<br> -liquid and solid surfaces due to surface tension. Its phenomena are<br> -greatly modified by electric charging, which alters the surface tension.<br> -Capillarity is the cause of solutions "creeping," as it is termed. Thus<br> -in gravity batteries a crust of zinc sulphate often formed over the edge<br> -of the jar due to the solution creeping and evaporating. As a liquid<br> -withdraws from a surface which it does not wet, creeping as above is<br> -prevented by coating the edge with paraffin wax, something which water<br> -does not moisten. It also causes the liquids of a battery cell to reach<br> -the connections and injure them by oxidation. The solutions creep up in<br> -the pores of the carbons of a battery and oxidize the clamps. To give<br> -good connections a disc of platinum or of lead is used for the contact<br> -as not being attacked. Another way is to dip the upper ends of the dry<br> -and warm carbons into melted paraffin wax, or to apply the wax to the<br> -hot carbons at the top, and melt it in with a hot iron.<br> -<br> -<br> -106 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Carbon.</span><br> -(a) One of the elements; atomic weight, 12. It exists in three<br> -allotropic modifications, charcoal, graphite and diamond. In the<br> -graphitic form it is used as an electric current conductor, as in<br> -batteries and for arc lamp, electrodes and incandescent lamp filaments.<br> -It is the only substance which conducts electricity and which cannot be<br> -melted with comparative ease by increase of current. (See Resistance.)<br> -<br> -(b) The carbon plate of a battery or rod of an arc lamp. To secure<br> -greater conductivity in lamp carbons, they are sometimes plated with<br> -nickel or with copper.<br> -<br> -(c) v. To place carbons in arc lamps. This has generally to be done once<br> -in twenty-four hours, unless the period of burning is very short.<br> -<br> -<br> -<span style="font-weight: bold;">Carbon, Artificial.</span><br> -For lamps, carbons and battery plates carbons are made by igniting,<br> -while protected from the action of the air, a mixture of carbon dust and<br> -a cementing and carbonizable substance. Lamp black may be added also.<br> -Powdered coke or gas carbon is mixed with molasses, coal tar, syrup, or<br> -some similar carbonaceous liquid. It is moulded into shape. For lamp<br> -carbons the mixture is forced from a vessel through a round aperture or<br> -die, by heavy pressure, and is cut into suitable lengths. For battery<br> -plates it may be simply pressed into moulds. The carbons are ignited in<br> -covered vessels and also covered with charcoal dust, lamp black or its<br> -equivalent. They are heated to full redness for some hours. After<br> -removal and cooling they are sometimes dipped again into the liquid used<br> -for cementing and reignited. Great care in securing pure carbon is<br> -sometimes necessary, especially for lamps. Fine bituminous coal is<br> -sometimes used, originally by Robert Bunsen, in 1838 or 1840;<br> -purification by different processes has since been applied; carbon from<br> -destructive distillation of coal tar has been used. The famous -Carré<br> -carbons are made, it is said, from 15 parts very pure coke dust, five<br> -parts calcined lamp-black, and seven or eight parts sugar--syrup mixed<br> -with a little gum. Five hours heating, with subsequent treatment with<br> -boiling caramel and reignition are applied. The latter treatment is<br> -termed "nourishing." Napoli used three parts of coke to one of tar.<br> -Sometimes a core of different carbon than the surrounding tube is<br> -employed.<br> -<br> -<br> -107 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The following are the resistances of Carré's carbons per meter -(39.37<br> -inches):<br> -<br> -<span style="font-family: monospace;">Diameter -in Diameter in Resistance in -Ohms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Millimeters. -Inches. @ -20° C. (98° F.)</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -1 -.039 50.000</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -2 -.078 12.5</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -3 -.117 -5.55</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -4 -.156 -3.125</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -5 -.195 -2.000</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -6 -.234 -1.390</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -8 -.312 -.781</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -10 -.390 -.5</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -12 -.468 -.348</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -15 -.585 -.222</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -18 -.702 -.154</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -20 -.780 -.125</span><br> -<br> -At high temperatures the resistance is about one-third these amounts. A<br> -layer of copper may increase the conductivity one hundred times and<br> -prolong the duration 14 per cent. Thus a layer of copper 1/695<br> -millimeter (1/17300 inch) thick increases the conductivity 4.5 times; a<br> -coating 1/60 millimeter (1/1500 inch) thick increases the conductivity<br> -one hundred and eleven times.<br> -<br> -<br> -<span style="font-weight: bold;">Carbon, Cored.</span><br> -A carbon for arc lamps with a central core of softer carbon than the<br> -exterior zone. It fixes the position of the arc, and is supposed to give<br> -a steadier light.<br> -<br> -Synonym--Concentric Carbon.<br> -<br> -<br> -<span style="font-weight: bold;">Carbon Holders.</span><br> -In arc lamps, the fixed clamps for holding the ends of the carbons.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Carbonization.</span><br> -The igniting in a closed vessel, protected from air, of an organic<br> -substance so as to expel from it all the constituents except part of<br> -the carbon; destructive distillation. (See Carbonized Cloth.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Carbonized Cloth.</span><br> -Cloth cut in discs and heated in vessels protected from the air, until<br> -reduced to carbon. The heating is sometimes conducted in vacuo. They are<br> -placed in a pile in a glass or other insulating tube, and offer a<br> -resistance which can be varied by pressure. The greater the pressure the<br> -less will be the resistance, and vice versa.<br> -<br> -Carbon Dioxide.<br> -A compound gas, CO2. It is composed of<br> - Carbon, 12 parts by weight.<br> - Oxygen. 32 "<br> - Specific gravity, 1.524 (Dulong and Berzelins).<br> - Molecular weight, 44.<br> -<br> -It is a dielectric of about the resistance of air. Its specific<br> -inductive capacity at atmospheric pressures is<br> - 1.000356 (Boltzmann).<br> - 1.0008 (Ayrton).<br> -<br> -Synonyms--Carbonic Acid--Carbonic Acid Gas.<br> -<br> -<br> -108 STANDARD ELECTRICAL DICTIONARY<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Carbon, Volatilization of.</span><br> -In arc lamps the heat is so intense that it is believed that part of the<br> -carbon is volatilized as vapor before being burned or oxidized by the<br> -oxygen of the air. The same volatilization may take place in<br> -incandescent lamps which are overheated.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Carcel.</span><br> -The standard of artificial illumination used in France. It is the light<br> -yielded by a standard lamp burning 42 grams (648 grains) of colza oil<br> -per hour, with a flame 40 millimeters (1.57 inch) in height. One carcel<br> -is equal to 9.5 to 9.6 candles.<br> -<br> -<br> -<span style="font-weight: bold;">Carcel Lamp.</span><br> -The lamp giving the standard of illuminating power. The wick is<br> -cylindrical, giving an Argand or central draft flame. It is woven with<br> -75 strands, and weighs 3.6 grams (55.5 grains) per decimeter (3.9<br> -inches) of length. The chimney is 29 centimeters (11.3 inches) high, 47<br> -millimeters (1.88 inch) in diameter at the bottom, contracting just<br> -above the wick to 34 millimeters (1.36 inch).<br> -<br> -<br> -<span style="font-weight: bold;">Carcel Gas Jet.</span><br> -A standard Argand gas burner, made with proper rating to give the light<br> -of a definite number of carcels illuminating power. Cognizance must be<br> -taken of the quality of the gas as well as of the burner used.<br> -<br> -<br> -<span style="font-weight: bold;">Carrying Capacity.</span><br> -In a current conductor, its capacity for carrying a current without<br> -becoming unduly heated. It is expressed in amperes. (See Wire Gauge,<br> -American.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Cascade.</span><br> -The arrangement of Leyden jars in series on insulating supports, as<br> -described below.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Cascade, Charging and Discharging -Leyden Jars In.</span><br> -An arrangement of Leyden jars in series for the purpose of charging and<br> -discharging. They are placed on insulating supports, the inner coating<br> -of one connected with the outer coating of the next one all through the<br> -series. The actual charge received by such a series, the outer coating<br> -of one end jar being grounded, and the inner coating of the other being<br> -connected to a source of high potential, or else the same being<br> -connected to electrodes of opposite potentials is no greater than that<br> -of a single jar, but a much higher potential difference can be developed<br> -without risk of perforating the glass of a jar. The difference of<br> -potential in each jar of the series is equal to the total potential<br> -difference divided by the number of jars. The energy of discharge is<br> -equal to the same fraction of the energy of a single jar charged with<br> -the same quantity.<br> -<br> -[Transcriber's note: The equal distribution of potential assumes all the<br> -jars have the same capacity. The charge on all jars is the same since<br> -they are in series.]<br> -<br> -<br> -109 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Case-hardening, Electric.</span><br> -The conversion of the surface of iron into steel by applying a proper<br> -carbonaceous material to it while it is heated by an electric current.<br> -It is a superficial cementation process.<br> -<br> -<br> -<span style="font-weight: bold;">Cataphoresis.</span><br> -Electric osmore; the transfer of substances in solution through porous<br> -membranes under the influence probably of electrolysis, but without<br> -themselves being decomposed.<br> -<br> -<br> -<span style="font-weight: bold;">Cautery, Electric.</span><br> -An electro-surgical appliance for removing diseased parts, or arresting<br> -hemorrhages, taking the place of the knife or other cutting instrument.<br> -The cautery is a platinum wire heated to whiteness by an electric<br> -current, and when in that condition used to cut off tumors, stop the<br> -flow of blood and parallel operations. The application is painful, but<br> -by the use of anaesthetics pain is avoided, and the healing after the<br> -operation is greatly accelerated.<br> -<br> -The heated wire of the cautery can be used for cutting operations in<br> -many cases where excision by a knife would be almost impracticable.<br> -<br> -Synonyms--Galvano-cautery--Galvano-caustry--Galvano-electric,<br> -do.--Galvano-thermal, do.<br> -<br> -<br> -<span style="font-weight: bold;">C. C.</span><br> -A contraction of cubic centimeter. It is often written in small letters,<br> -as 100 c.c., meaning 100 cubic centimeters.<br> -<br> -<br> -<span style="font-weight: bold;">Cell, Constant.</span><br> -A cell which yields a constant and uniform current under unvarying<br> -conditions. This implies that neither the electro-motive force or the<br> -resistance of the cell shall vary, or else that as the electro-motive<br> -forces run down the resistance shall diminish in proper proportion to<br> -maintain a constant current. There is really no constant cell. The<br> -constancy is greatest when the external resistance is high in proportion<br> -to the internal resistance.<br> -<br> -<br> -<span style="font-weight: bold;">Cell, Electrolytic.</span><br> -A vessel containing the electrolyte, a liquid decomposable by the<br> -current, and electrodes, arranged for the passage of a decomposing<br> -current. The voltameter, q. v., is an example.<br> -<br> -<br> -<span style="font-weight: bold;">Cell, Standard Voltaic.</span><br> -A cell designed to be a standard of electro-motive force; one in which<br> -the same elements shall always be present under the same conditions, so<br> -as to develop the same electro-motive force. In use the circuit is<br> -closed only for a very short time, so that it shall not become altered<br> -by polarization or exhaustion.<br> -<br> -<br> -<span style="font-weight: bold;">Cell, Standard Voltaic, Daniell's. </span><br> -A zinc-copper-copper sulphate couple.<br> -Many forms are used. Sometimes a number of pieces of blotting paper are<br> -interposed between two plates, one of copper--the other of zinc. The<br> -paper next the copper is soaked in copper sulphate solution, and those<br> -next the zinc in zinc sulphate solution, of course before being put<br> -together. Sometimes the ordinary porous cup combination is employed. The<br> -cut shows a modification due to Dr. Fleming (Phil. Mag. S. 5, vol. xx,<br> -p. 126), which explains itself. The U tube is 3/4-inch diameter, and 8<br> -inches long. Starting with it empty the tap A is opened, and the whole U<br> -tube filled with zinc sulphate solution, and the tap A is closed. The<br> -zinc rod usually kept in the tube L is put in place, tightly corking up<br> -its end of the U tube. The cock C is opened, which lowers the level of<br> -the solution in the right-hand limb of the U tube only. The tap B is<br> -opened and the copper sulphate solution is run in, preserving the line<br> -of separation of the two solutions. The copper rod is taken out of its<br> -tube M, and is put in place. India rubber corks are used for both rods.<br> -As the liquids begin to mix the mixture can be drawn off at C and the<br> -sharp line of demarcation re-established. In Dr. Sloane's standard cell<br> -two test tubes are employed for the solutions and a syphon is used to<br> -connect them.<br> -<br> -Oxidation of the zinc lowers the E. M. F.; oxidation of the copper<br> -raises it. With solutions of equal sp. gr. the E. M. F. is 1.104 volts.<br> -If the copper sulphate solution is 1.100 sp. gr. and the zinc sulphate<br> -solution 1.400 sp. gr., both at 15° C. (59°F.), the E. M. F. -will be<br> -1.074 volt. Clean pure zinc and freshly electrolyzed copper should be<br> -used.<br> -<br> -<br> -<img style="width: 308px; height: 598px;" alt="" src="images/079F57.jpg"><br> -Fig. 79 STANDARD DANIELL CELL--FLEMING'S FORM.<br> -<br> -<br> -110 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Cell, Standard Voltaic, Latimer -Clark's. </span><br> -A mercury and zinc electrode couple with <br> -mercurous sulphate as excitant and depolarizer. The positive<br> -element is an amalgam of zinc, the negative is pure mercury. Each<br> -element, in a representative form, the H form, is contained in a<br> -separate vessel which communicate by a tube. Over the pure mercury some<br> -mercurous sulphate is placed. Both vessels are filled to above the level<br> -of the connecting tube with zinc sulphate solution, and kept saturated.<br> -It is tightly closed or corked. The E. M. F. at 15° C (59° F.) -is 1.438.<br> -Temperature correction<br> -<br> -(1 - (.00077 *(t - 15° C) ) )<br> -<br> -t being expressed in degrees centigrade (Rayleigh). A diminution in<br> -specific gravity of the zinc solution increases the E. M. F. The cell<br> -polarizes rapidly and the temperature coefficient is considered too<br> -high.<br> -<br> -<br> -<img style="width: 580px; height: 690px;" alt="" src="images/111F80.jpg"><br> -Fig. 80. LATIMER CLARK'S STANDARD CELL.<br> -<br> -<br> -111 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Cements, Electrical.</span><br> -A few cements find their use in electrical work. Marine glue,<br> -Chatterton's compound, and sealing wax may be cited.<br> -<br> -<br> -<span style="font-weight: bold;">Centi-.</span><br> -Employed as a prefix to indicate one-hundredth, as centimeter, the<br> -one-hundredth of a meter; centi-ampere, the one-hundredth of an ampere.<br> -<br> -<br> -<span style="font-weight: bold;">Centigrade-scale.</span><br> -A thermometer scale in use by scientists of all countries and in general<br> -use in many. The temperature of melting ice is 0º; the temperature -of<br> -condensing steam is 100° ; the degrees are all of equal length. To<br> -reduce to Fahrenheit degrees multiply by 9 and divide by 5, and add 32<br> -algebraically, treating all readings below 0º as minus quantities. -For<br> -its relations to the Reamur scale, see Reamur Scale. Its abbreviation is<br> -C., as 10º C., meaning ten degrees centigrade.<br> -<br> -<br> -<span style="font-weight: bold;">Centimeter.</span><br> -A metric system unit of length; one-hundredth of a meter; 0.3937 inch.<br> -The absolute or c. g. s. unit of length.<br> -<br> -<br> -<span style="font-weight: bold;">Centimeter-gram-second System.</span><br> -The accepted fundamental or absolute system of units, called the C. G.<br> -S. system. It embraces units of size, weight, time, in mechanics,<br> -physics, electricity and other branches. It is also called the absolute<br> -system of units. It admits of the formation of new units as required by<br> -increased scope or classification. The following are basic units of the<br> -system :<br> -<br> -Of length, centimeter;<br> -of mass, gram;<br> -of time, second:<br> -of force, dyne:<br> -of work or energy, erg.<br> -<br> -See Dyne, Erg., and other units in general.<br> -<br> -<br> -112 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Central Station Distribution or Supply.</span><br> -The system of supplying electric energy in current form from a main<br> -generating plant to a district of a number of houses, factories, etc. It<br> -is in contrast with the isolated plant system in which each house or<br> -factory has its own separate generating installment, batteries or<br> -dynamos.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Centre of Gravity. </span><br> -A point so situated with respect to any particular body, that the <br> -resultant of the parallel attracting forces between the earth and the <br> -several molecules of the body always passes through it. These are <br> -resultants of the relative moments of the molecules. If a body is <br> -suspended, as by a string, the centre of gravity always lies vertically -<br> -under its point of suspension. By two trials the point of intersection <br> -of plumb lines from the point of suspension being determined the centre -<br> -of gravity is known. The vertical from the point of support coincides <br> -with the line of direction.<br> -<br> -<br> -<span style="font-weight: bold;">Centre of Gyration.</span><br> -The centre of gyration with respect to the axis of a rotating body is a<br> -point at which if the entire mass of the body were concentrated its<br> -moment of inertia would remain unchanged. The distance of this point<br> -from the axis is the radius of gyration.<br> -<br> -<br> -<span style="font-weight: bold;">Centre of Oscillation.</span><br> -The point referred to in a body, suspended or mounted to swing like a<br> -pendulum, at which if all the mass were concentrated, 1t would complete<br> -its oscillations in the same time. The distance from the axis of support<br> -to this point gives the virtual length of the pendulum which the body<br> -represents.<br> -<br> -<br> -<span style="font-weight: bold;">Centre of Percussion.</span><br> -The point in a suspended body, one free to swing like a pendulum, at<br> -which an impulse may be applied, perpendicular to the plane through the<br> -axis of the body and through the axis of support without shock to the<br> -axis. It is identical with the centre of oscillation, q. v., when such<br> -lies within the body.<br> -<br> -<br> -<span style="font-weight: bold;">Centrifugal Force.</span><br> -The force which draws a body constrained to move in a curved path away<br> -from the centre of rotation. It is really due to a tangential impulse<br> -and by some physicists is called the centrifugal component of tangential<br> -velocity. It has to be provided against in generator and motor<br> -armatures, by winding them with wire or bands to prevent the coils of<br> -wire from spreading or leaving their bed upon the core.<br> -<br> -<br> -113 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Centrifugal Governor.</span><br> -The usual type of steam-engine governor. The motion of the engine<br> -rotates a system of weights, which are forced outward by centrifugal<br> -force, and are drawn inwards by gravity or by springs. Moving outwards<br> -they shut off steam, and moving inwards they admit it, thus keeping the<br> -engine at approximately a constant speed. The connections between them<br> -and the steam supply and the general construction vary widely in<br> -different governors.<br> -<br> -<br> -<span style="font-weight: bold;">C. G. S.</span><br> -Abbreviation or symbol for Centimeter-gram-second, as the C. G. S.<br> -system. (See Centimeter-gram-second System.) It is sometimes expressed<br> -in capitals, as above, and sometimes in small letters, as the c. g. s.<br> -unit of resistance.<br> -<br> -<br> -<span style="font-weight: bold;">Chamber of Incandescent Lamp.</span><br> -The interior of the bulb of an incandescent lamp. (See Lamp,<br> -Incandescent.)<br> -<br> -<br> -<img style="width: 487px; height: 676px;" alt="" src="images/113F81.jpg"><br> -Fig. 81. CHARACTERISTIC CURVE OF A DYNAMO.<br> -<br> -<br> -<img style="width: 442px; height: 641px;" alt="" src="images/113F82.jpg"><br> -FIG. 82. DROOPING CHARACTERISTIC.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Characteristic Curve.</span><br> -A curve indicating the variations in electro-motive force developed<br> -during the rotations of the armature of a dynamo or other generator of<br> -E. M. F. The term as used in the electrical sense is thus applied,<br> -although the indicator diagram of a steam engine may be termed its<br> -characteristic curve, and so in many other cases. As the amperes taken<br> -from a series generator are increased in number, the E. M. F. rises, it<br> -may be very rapidly up to a certain point, and thereafter more slowly.<br> -To construct the curve coordinates, q. v., are employed. The resistance<br> -of the dynamo and of the outer circuit being known, the current<br> -intensity is measured. To obtain variations in electro-motive force the<br> -external resistance is changed. Thus a number of ampere readings with<br> -varying known resistance are obtained, and for each one an<br> -electro-motive force is calculated by Ohm's law. From these data a curve<br> -is plotted, usually with volts laid off on the ordinate and amperes on<br> -the abscissa.<br> -<br> -By other methods other characteristic curves may be obtained, for which<br> -the titles under Curve may be consulted.<br> -<br> -<br> -114 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Characteristic, Drooping.</span><br> -A characteristic curve of a dynamo which indicates a fall in voltage<br> -when an excessive current is taken from the dynamo in question. It is<br> -shown strongly in some Brush machines, and is partly due to the<br> -arrangements for cutting out two of the coils as they approach the<br> -neutral line. It is an advantage, as it protects from overheating on<br> -short circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Characteristic, External.</span><br> -In a dynamo the characteristic curve in which the relations of volts<br> -between terminals to amperes in the outer circuit are plotted. (See<br> -Curve, External Characteristic.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Characteristic, Internal.</span><br> -A characteristic curve of a shunt dynamo, in which the relations of<br> -volts to amperes in the shunt circuit is plotted.<br> -<br> -<br> -<span style="font-weight: bold;">Characteristics of Sound. </span><br> -Of interest, electrically, as affecting the telephone, they comprise:<br> -<br> -(1) Pitch, due to frequency of vibrations.<br> -<br> -(2) Intensity or loudness, due to amplitude of waves of sound.<br> -<br> -(3) Quality or timbre, the distinguishing characteristics of any<br> -specific sound due to overtones, discords, etc., by which the sound is<br> -recognizable from others. The telephone is held by the U. S. courts to<br> -be capable of reproducing the voice by means of the undulatory current.<br> -(See Current, Undulatory.)<br> -<br> -<br> -<span style="font-weight: bold;">Charge.</span><br> -The quantity of electricity that is present on the surface of a body or<br> -conductor. If no electricity is supplied, and the conductor is connected<br> -to the earth, it is quickly discharged. A charge is measured by the<br> -units of quantity, such as the coulomb. The charge that a conductor can<br> -retain at a given rise of potential gives its capacity, expressible in<br> -units of capacity, such as the farad. A charge implies the stretching or<br> -straining between the surface of the charged body, and some<br> -complimentary charged surface or surfaces, near or far, of large or<br> -small area, of even or uneven distribution.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Charge. v.</span><br> -(a) To introduce an electrostatic charge, as to charge a condenser.<br> -<br> -(b) To decompose the elements of a secondary battery, q. v., so as to<br> -render it capable of producing a current. Thus, a spent battery is<br> -charged or recharged to enable it to do more work.<br> -<br> -Synonyms--Renovate--Revivify--Recharge.<br> -<br> -<br> -115 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Charge, Bound.</span><br> -A charge of electricity borne by the surface of a body so situated with<br> -reference to another oppositely charged body, that the charge is<br> -imperceptible to ordinary test, will not affect an electroscope nor<br> -leave the surface if the latter is connected to the earth. To discharge<br> -such a body it must be connected to its complimentarily charged body.<br> -The bound charge was formerly called dissimulated or latent electricity.<br> -(See Charge, Free.)<br> -<br> -The charge or portion of a charge of a surface which is neutralized<br> -inductively by a neighboring charge of opposite kind. The degree of<br> -neutralization or of binding will depend on the distance of the two<br> -charged surfaces from one another and on the electro-static nature of<br> -the medium intervening, which must of necessity be a dielectric. A<br> -charge not so held or neutralized is termed a free charge. Thus a<br> -surface may be charged and by the approach of a surface less highly<br> -charged may have part of its charge bound. Then if connected to earth.<br> -it will part with its unbound or free charge, but will retain the other<br> -until the binding surface is removed, or until the electricity of such<br> -surface is itself bound, or discharged, or until connection is made<br> -between the two surfaces. Thus a body may have both a bound and a free<br> -charge at the same time.<br> -<br> -<br> -<span style="font-weight: bold;">Charge, Density of.</span><br> -The relative quantity of electricity upon a given surface. Thus a<br> -charged surface may have an evenly distributed charge or one of even<br> -density, or an unevenly distributed charge or one of uneven density. In<br> -a thunderstorm the earth has a denser charge under the clouds than<br> -elsewhere.<br> -<br> -Synonym--Electrical Density.<br> -<br> -<br> -<span style="font-weight: bold;">Charge, Dissipation of.</span><br> -As every body known conducts electricity, it is impossible so to<br> -insulate a surface that it will not lose its charge by leakage. An<br> -absolute vacuum might answer, and Crookes in a high vacuum has retained<br> -a charge against dissipation for years. The gradual loss is termed as<br> -above.<br> -<br> -<br> -<span style="font-weight: bold;">Charge, Distribution of.</span><br> -The relation of densities of charge on different parts of a charged<br> -body. On a spherical conductor the charge is normally of even<br> -distribution; on other conductors it is unevenly distributed, being of<br> -greatest density at points, edges, and parts of smallest radius of<br> -curvature. Even distribution can also be disturbed by local induction,<br> -due to the presence of oppositely charged bodies.<br> -<br> -<br> -116 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Charge, Free.</span><br> -The charge borne by an insulated body, independent of surrounding<br> -objects. Theoretically it is an impossibility. A charge always has its<br> -compliment somewhere in surrounding objects. As a matter of convenience<br> -and convention, where the complimentary charge is so distributed that<br> -its influence is not perceptible the charge is called a free charge. If<br> -connected to earth the free charge will leave the body. If the body is<br> -connected with an electroscope the free charge will affect the same.<br> -(See Charge, Bound.)<br> -<br> -<br> -<span style="font-weight: bold;">Charge, Residual.</span><br> -When a Leyden jar or other condenser is discharged by the ordinary<br> -method, after a few minutes standing a second discharge of less amount<br> -can be obtained from it. This is due to what is known as the residual<br> -charge. It seems to be connected in some way with the mechanical or<br> -molecular distortion of the dielectric. The jarring of the dielectric<br> -after discharge favors the rapidity of the action, diminishing the time<br> -required for the appearance of the residual charge. The phenomenon, it<br> -will be seen, is analogous to residual magnetism. This charge is the<br> -reciprocal of electric absorption and depends for its amount upon the<br> -nature of the dielectric. (See Absorption, Electric, and Capacity,<br> -Residual.)<br> -<br> -Synonym--Electric Residue.<br> -<br> -<br> -<span style="font-weight: bold;">Chatterton's Compound.</span><br> -A cement used for cementing together layers or sheets of gutta percha,<br> -and for similar purposes in splicing telegraph cables. Its formula is:<br> - Stockholm Tar, 1 part.<br> - -Resin, 1 -part.<br> - Gutta Percha, 3 parts.<br> -All parts by weight.<br> -<br> -<br> -<span style="font-weight: bold;">Chemical Change.</span><br> -When bodies unite in the ratio of their chemical equivalents, so as to<br> -represent the satisfying of affinity or the setting free of thermal or<br> -other energy, which uniting is generally accompanied by sensible heat<br> -and often by light, as in the ignition of a match, burning of a candle,<br> -and, when the new compound exhibits new properties distinct from those<br> -of its components, a chemical combination is indicated. More definitely<br> -it is a change of relation of the atoms. Another form of chemical change<br> -is decomposition, the reverse of combination, and requiring or absorbing<br> -energy and producing several bodies of properties distinct from those of<br> -the original compound. Thus in a voltaic battery chemical combination<br> -and decomposition take place, with evolution of electric instead of<br> -thermal energy.<br> -<br> -<br> -<span style="font-weight: bold;">Chemical Equivalent.</span><br> -The quotient obtained by dividing the atomic weight, q. v., of an<br> -element by its valency, q. v. Thus the atomic weight of oxygen is 16,<br> -its valency is 2. its chemical equivalent is 8. It is the weight of the<br> -element corresponding to a unit weight of hydrogen, either as replacing<br> -it, or combining with it. In electro-chemical calculations the chemical<br> -equivalent is often conveniently used to avoid the necessity of dividing<br> -by the valency when atomic weights are used. The latter is really the<br> -better practice. The atomic weights in the old system of chemical<br> -nomenclature were chemical equivalents.<br> -<br> -<br> -117 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Chemical Recorder.</span><br> -A form of telegraphic recorder in which the characters, often of the<br> -Morse alphabet or some similar one, are inscribed on chemically prepared<br> -paper by decomposition affecting the compound with which the paper is<br> -charged. In the original chemical recorder of Bain, the instrument was<br> -somewhat similar to the Morse recorder, except that the motionless<br> -stylus, S, always pressing against the paper was incapable of making any<br> -mark, but being of iron, and the paper strip being impregnated with<br> -potassium ferrocyanide, on the passage of a current a stain of Prussian<br> -blue was produced where the stylus touched the paper. The current passes<br> -from the line by way of the iron stylus, through the paper, and by way<br> -of a brass surface, M, against which the paper is held and is pressed by<br> -the stylus, to the earth. This recorder is extremely simple and has no<br> -part to be moved by the current. The solution in which the paper is<br> -dipped contains a mixture of potassium ferrocyanide and ammonium<br> -nitrate. The object of the latter is to keep the paper moist. In recent<br> -recorders a solution of potassium iodide has been used, which gives a<br> -brown stain of free iodine, when the current passes. This stain<br> -disappears in a few days.<br> -<br> -<br> -<img style="width: 744px; height: 458px;" alt="" src="images/117F83.jpg"><br> -Fig. 83. BAIN'S TELEGRAPH EMPLOYING CHEMICAL RECORDER.<br> -<br> -<br> -In the cut, R is the roll of paper, B is a tank of solution with roll,<br> -W1, for moistening the paper; M is the brass surface against which the<br> -stylus, S, presses the paper, P P; W, W are feed rollers; T is the<br> -transmitting key, and zk the battery; Pl, Pl are earth plates. The<br> -apparatus is shown duplicated for each end.<br> -<br> -<br> -118 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Chemistry.</span><br> -The science treating of atomic and molecular relations of the elements<br> -and of chemical compounds of the same.<br> -<br> -<br> -<span style="font-weight: bold;">Chimes, Electric.</span><br> -An apparatus employed to illustrate the principles of the electrostatic<br> -charge, involving the ringing of bells by electrostatic attraction and<br> -repulsion. It is used in connection with a frictional, or influence<br> -electric machine. Two bells are employed with a button or clapper<br> -suspended between them. One bell is connected to one of the prime<br> -conductors, q. v., of the machine. The other insulated therefrom is<br> -connected to earth, or if an influence machine is used, to the other<br> -prime conductor. The clappers are hung by a silk thread, so as to be<br> -entirely insulated. On working the machine the bells become oppositely<br> -excited. A clapper is attracted to one, then when charged is repelled<br> -and attracted to the other, it gives up its charge and becoming charged<br> -with similar electricity to that of the bell it touches, is repelled and<br> -attracted to the other, and this action is kept up as long as the<br> -excitement continues, the bells ringing continuously.<br> -<br> -<br> -<img style="width: 563px; height: 504px;" alt="" src="images/118F84.jpg"><br> -Fig. 84. ELECTRIC CHIMES.<br> -<br> -<br> -<span style="font-weight: bold;">Chronograph, Electric.</span><br> -An apparatus for indicating electrically, and thereby measuring, the<br> -lapse of time. The periods measured may be exceedingly short, such as<br> -the time a photographic shutter takes to close, the time required by a<br> -projectile to go a certain distance, and similar periods.<br> -<br> -A drum rotated with even and known velocity may be marked by a stylus<br> -pressed upon it by the action of an electro-magnet when a key is<br> -touched, or other disturbance. Then the space between two marks would<br> -give the period elapsing between the two disturbances of the circuit. As<br> -it is practically impossible to secure even rotation of a drum, it is<br> -necessary to constantly measure its rate of rotation. This is effected<br> -by causing a tuning-fork of known rate of vibration to be maintained in<br> -vibration electrically. A fine point or bristle attached to one of its<br> -arms, marks a sinuous line upon the smoked surface of the cylinder. This<br> -gives the basis for most accurately determining the smallest intervals.<br> -Each wave drawn by the fork corresponds to a known fraction of a second.<br> -<br> -For projectiles, the cutting of a wire opens a circuit, and the opening<br> -is recorded instead of the closing. By firing so as to cut two wires at<br> -a known distance apart the rate is obtained by the chronograph.<br> -<br> -Synonym--Chronoscope.<br> -<br> -<br> -119 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Chutaux's Solution.</span><br> -A solution for bichromate batteries. It is composed as follows:<br> -<span style="font-family: monospace;"> -Water, -1,500 parts</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Potassium -bichromate, 100 parts</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> mercury -bisulphate, 100 parts</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> 66° sulphuric -acid, 50 parts.</span><br> -<br> -Circle, Galvanic or Voltaic.<br> -A term for the voltaic circuit; obsolete.<br> -<br> -<br> -<img style="width: 546px; height: 779px;" alt="" src="images/119F85.jpg"><br> -Fig. 85. MAGIC CIRCLE.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Circle, Magic.</span><br> -A form of electro-magnet. It is a thick circle of round iron and is used<br> -in connection with a magnetizing coil, as shown, to illustrate<br> -electro-magnetic attraction.<br> -<br> -<br> -120 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit.</span><br> -A conducting path for electric currents properly forming a complete path<br> -with ends joined and including generally a generating device of some<br> -kind. Part of the conduction may be true and part electrolytic. (See<br> -Electrolytic Conduction.) The term has become extended, so that the term<br> -is often applied to any portion of a circuit conveniently considered by<br> -itself. The simplest example of a complete circuit would be a circular<br> -conductor. If rotated in the earth's field so as to cut its lines of<br> -force a current would go through it, and it would be an electric<br> -circuit. Another example is a galvanic battery with its ends connected<br> -by a wire. Here the battery generates the current which, by electrolytic<br> -conduction, goes through the battery and by true conduction through the<br> -wire. For an example of a portion of a circuit spoken of as "a circuit"<br> -see Circuit, Astatic.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit, Astatic.</span><br> -A circuit so wound with reference to the direction of the currents<br> -passing through it that the terrestrial or other lines of force have no<br> -directive effect upon it, one member counteracting the other. It may be<br> -produced by making the wire lie in two closed curves, A and B, each<br> -enclosing an equal area, one of identical shape and disposition with the<br> -other, and with the current circulating in opposite directions in each<br> -one. Thus each circuit represents a magnetizing turn of opposite<br> -polarity and counteracting each other's directive tendency exhibited in<br> -a field of force with reference to an axis a c. Another form of astatic<br> -circuit is shown in Fig. 86. The portions C, D, lying on opposite sides<br> -of the axis of rotation a c, are oppositely acted on by the earth's<br> -directive force as regards the direction of their rotation.<br> -<br> -<br> -<img style="width: 638px; height: 401px;" alt="" - src="images/120F86_87.jpg"><br> -Figs. 86 and 87. ASTATIC CIRCUITS.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit, Branch.</span><br> -A circuit dividing into two or more parts in parallel with each other.<br> -<br> -<br> -121 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit Breaker.</span><br> -Any apparatus for opening and closing a circuit is thus termed, but it<br> -is generally applied to automatic apparatus. A typical circuit breaker<br> -is the hammer and anvil of the induction coil. (See Induction Coil;<br> -Anvil.) Again a pendulum connected to one terminal of a circuit may<br> -swing so as to carry a point on its lower end through a globule of<br> -mercury as it swings, which globule is connected to the other terminal.<br> -A great many arrangements of this character have been devised.<br> -<br> -Synonym.--Contact Breaker.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit Breaker, Automatic.</span><br> -A circuit breaker worked by the apparatus to which it is attached, or<br> -otherwise automatically. (See Induction Coil; Anvil; Bell, Electric.)<br> -<br> -<br> -<span style="font-weight: bold;">Circuit Breaker, File.</span><br> -A coarsely cut file, forms one terminal of an electric circuit, with a<br> -straight piece of copper or steel for the other terminal. The latter<br> -terminal drawn along the teeth makes and breaks the contact once for<br> -every tooth. The movable piece should have an insulated handle.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Circuit Breaker, Mercury.</span><br> -A circuit breaker which may be identical in principle, with the<br> -automatic circuit breaker of an induction coil, but in which in place of<br> -the anvil, q. v., a mercury cup is used, into which the end of a wire<br> -dips and emerges as it is actuated by the impulses of the current. Each<br> -dip makes the contact, which is broken as the wire springs back. The<br> -mercury should be covered with alcohol to protect it from oxidation.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Circuit Breaker, Pendulum.</span><br> -A circuit breaker in which a pendulum in its swing makes and breaks a<br> -contact. It may be kept in motion by clockwork, or by an electro-magnet,<br> -attracting intermittently an armature attached to its rod, the<br> -magnet circuit being opened and closed by the pendulum or circuit<br> -breaker itself. A mercury contact may be used with it.<br> -<br> -<br> -<img style="width: 302px; height: 764px;" alt="" src="images/121F88.jpg"><br> -Fig. 88. PENDULUM CIRCUIT BREAKER.<br> -<br> -<br> -122 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Circuit Breaker, Tuning Fork.</span><br> -A circuit breaker in which a tuning fork makes and breaks the circuit.<br> -Each vibration of one of the prongs in one direction makes a contact,<br> -and the reverse vibration breaks a contact. The adjustment is<br> -necessarily delicate, owing to the limited amplitude of the motion of<br> -the fork. The fork is kept in vibration sometimes by an electro-magnet,<br> -which is excited as the circuit is closed by the fork. One leg of the<br> -fork acts as the armature of the magnet, and is attracted according to<br> -its own natural period.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit Breaker, Wheel.</span><br> -A toothed wheel with a spring bearing against its teeth. One terminal of<br> -a circuit connects with the wheel through its axle, the other connects<br> -with the spring. When the wheel is turned the circuit is opened and<br> -closed once for each tooth. The interstices between teeth on such a<br> -wheel may be filled with insulating material, giving a cylindrical<br> -surface for the contact spring to rub on.<br> -<br> -<br> -<img style="width: 608px; height: 514px;" alt="" src="images/122F89.jpg"><br> -Fig. 89--TOOTHED WHEEL CIRCUIT BREAKER.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Circuit, Closed.</span><br> -A circuit whose electric continuity is complete; to make an open circuit<br> -complete by closing a switch or otherwise is to close, complete, or make<br> -a circuit.<br> -<br> -Synonyms--Completed Circuit--Made Circuit.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Circuit, Compound.</span><br> -A circuit characterized by compounding of generating or receiving<br> -devices, as including several separate batteries, or several motors, or<br> -other receiving devices. It is sometimes used to indicate a circuit<br> -having its battery arranged in series. It should be restricted to the<br> -first definition.<br> -<br> -<br> -123 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit, Derived.</span><br> -A partial circuit connected to two points of another circuit, so as to<br> -be in parallel with the portion thereof between such two points; a shunt<br> -circuit.<br> -<br> -Synonyms--Shunt Circuit--Derivative Circuit--Parallel Circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit, Electric, Active.</span><br> -A circuit through which a current passes. The circuit itself need only<br> -be a conducting ring, or endless wire. Generally it includes, as part of<br> -the circuit, a generator of electro-motive force, and through which<br> -generator by conduction, ordinary or electrolytic, the same current goes<br> -that passes through the rest of the circuit. One and the same current<br> -passes through all parts of a series circuit when such current is<br> -constant.<br> -<br> -A current being produced by electro-motive force, and electromotive<br> -force disappearing in its production in an active circuit, there must be<br> -some source of energy which will maintain electromotive force against<br> -the drain made upon it by the current.<br> -<br> -The simplest conception of an active electric circuit is a ring or<br> -endless conductor swept through a field of force so as to cut lines of<br> -force. A simple ring dropped over a magnet pole represents the<br> -simplification of this process. In such a ring a current, exceedingly<br> -slight, of course, will be produced. In this case there is no generator<br> -in the circuit. An earth coil (see Coil, Earth,) represents such a<br> -circuit, with the addition, when experimented with, of a galvanometer in<br> -the circuit.<br> -<br> -In practice, a circuit includes a generator such as a battery or dynamo,<br> -and by conductors is led through a continuous path. Electric lamps,<br> -electrolytic cells, motors and the like may be included in it.<br> -<br> -The term "circuit" is also applied to portions of a true circuit, as the<br> -internal circuit, or external circuit. A certain amount of elasticity is<br> -allowed in its use. It by no means necessarily indicates a complete<br> -through circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit, Electrostatic.</span><br> -(a) A circuit through which an electrostatic or high tension discharge<br> -takes place. It is virtually an electric circuit.<br> -<br> -(b) The term is applied also to the closed paths of electrostatic lines<br> -of force.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Circuit, External.</span><br> -The portion of a circuit not included within the generator.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit, Grounded.</span><br> -A circuit, one of whose members, the return circuit, is represented by<br> -the earth, so that the earth completes the circuit. In telegraphy each<br> -end of the line is grounded or connected to an earth-plate, q. v., or to<br> -the water or gas-pipes, and the current is assumed to go through the<br> -earth on its return. It really amounts to a discharging at one end, and<br> -charging at the other end of the line. The resistance of the earth is<br> -zero, but the resistance of the grounding or connection with the earth<br> -may be considerable.<br> -<br> -Synonyms--Ground Circuit--Earth Circuit--Single Wire Circuit.<br> -<br> -[Transcriber's note: The resistance of the earth is high enough that<br> -large power system return currents may produce dangerous voltage<br> -gradients when a power line is shorted to the ground. Don't walk near<br> -downed lines!]<br> -<br> -<br> -124 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit Indicator.</span><br> -A pocket compass, decomposition apparatus, galvanometer or other device<br> -for indicating the condition of a wire, whether carrying a current or<br> -not, and, if carrying one, its direction, and sometimes roughly<br> -indicating its strength.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit, Internal.</span><br> -The portion of an electric circuit included within the generator.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit, Line.</span><br> -The portion of a circuit embracing the main line or conductor, as in a<br> -telegraph circuit the line carried on the poles; distinguished from the<br> -local circuit (see Circuit, Local,) in telegraphy.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit, Local.</span><br> -In telegraphy, a short circuit with local generator or battery included,<br> -contained within the limits of the office or station and operated by a<br> -relay, q. v. This was the original local circuit; the term is applicable<br> -to any similar arrangement in other systems. Referring to the cut, the<br> -main line circuit includes the main battery, E, Key, P, Relay, R, ground<br> -plates, G, G1. The relay magnet opens and closes the local circuit with<br> -its local battery, L, and sounder magnet, H, with its armature, B. The<br> -minor parts, such as switches, are omitted.<br> -<br> -<br> -<img style="width: 656px; height: 446px;" alt="" src="images/124F90.jpg"><br> -Fig. 90. LOCAL CIRCUIT OF TELEGRAPH SYSTEM.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Circuit, Local Battery.</span><br> -A local circuit worked by and including a local battery in its course.<br> -<br> -<br> -125 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Circuit, Loop.</span><br> -A minor circuit introduced in series into another circuit by a cut-out,<br> -or other device, so as to become a portion of the main circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit Loop Break.</span><br> -A supporter or bracket with two arms for carrying insulators. Its use is<br> -to enable a loop connection to be introduced into a line which is cut,<br> -so as to enable the connection of the ends of the loop to be made, one<br> -to each end of the through wire, which ends are attached, one to each of<br> -the two insulators.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit, Main.</span><br> -The circuit including the main line and apparatus supplied by the main<br> -battery, as distinguished from the local circuit. (See Circuit, Local.)<br> -<br> -<br> -<span style="font-weight: bold;">Circuit, Main Battery.</span><br> -The main circuit, including the main or principal battery in its course.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit, Metallic.</span><br> -A circuit in which the current outside the generator, or similar parts,<br> -is carried on a metallic conductor; a circuit without any ground<br> -circuit. The including of a galvanic battery or electro plating bath<br> -would not prevent the application of the term; its essential meaning is<br> -the omission of the earth as the return circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit, Negative Side of.</span><br> -The side of a circuit opposite to the positive side. (See Circuit,<br> -Positive Side of) It is defined as the half of a circuit leading to the<br> -positive terminal of the generator.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Circuit, Open.</span><br> -A circuit with its continuity broken, as by disconnecting a wire from<br> -the battery, or opening a switch; a broken circuit is its synonym. To<br> -open a switch or disconnect or cut the wire is termed opening or<br> -breaking the circuit.<br> -<br> -Synonyms--Incomplete Circuit--Broken Circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit, Positive Side of.</span><br> -This side is such that an observer standing girdled by the current with<br> -his head in the positive side or region, would see the current pass<br> -around him from his right toward his left hand. It is also defined as<br> -the half of the circuit leading to the negative terminal of the<br> -generator.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Circuit, Recoil.</span><br> -The portion of a parallel circuit presenting an alternative path, q. v.,<br> -for a disruptive discharge.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Circuit, Return.</span><br> -(a) The part of a circuit extending from the generator to the extreme<br> -point in general, upon which no apparatus is placed. In telegraph<br> -systems the ground generally forms the return circuit. The distinction<br> -of return and working circuit cannot always be made.<br> -<br> -(b) It may also be defined as the portion of a circuit leading to the<br> -negative terminal of the generator.<br> -<br> -<br> -126 STANDARD ELECTRICAL DICTIONARY<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Circuits, Forked.</span><br> -Circuits starting in different paths or directions from one and the same<br> -point.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit, Simple.</span><br> -A circuit containing a single generator, and single receiver of any<br> -kind, such as a motor or sounder, with a single connecting conductor. It<br> -is also used to indicate arrangement in multiple arc, but not generally,<br> -or with approval.<br> -<br> -<br> -<span style="font-weight: bold;">Circuits, Parallel.</span><br> -Two or more conductors starting from a common point and ending at<br> -another common point are termed, parallel circuits, although really but<br> -parts of circuits. If of equal resistance their joint resistance is<br> -obtained by dividing the resistance of one by the number of parallel<br> -circuits. If of unequal resistance r, r', r" , etc., the formula for<br> -joint resistance, R, of two is<br> -<br> -R = ( r * r' ) / ( r + r' )<br> -<br> -This resistance may then be combined with a third one by the same<br> -formula, and thus any number may be calculated.<br> -<br> -Synonym--Shunt Circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Circuit, Voltaic.</span><br> -Properly a circuit including a conductor and voltaic couple.<br> -<br> -It is also applied to the electric circuit, q. v., or to any circuit<br> -considered as a bearer of current electricity.<br> -<br> -<br> -<span style="font-weight: bold;">Circular Units</span>.<br> -Units of area, usually applied to cross sectional area of conductors, by<br> -whose use area is expressed in terms of circle of unit diameter,<br> -usually a circular mil, which is the area of a circle of one-thousandth<br> -of an inch diameter, or a circular millimeter, which is the area of a<br> -circle of one millimeter diameter. Thus a wire one-quarter of an inch<br> -in diameter has an area of 250 circular mils; a bar one centimeter in<br> -diameter has an area of ten circular millimeters.<br> -<br> -[Transcriber's Note: Area is the diameter squared. A 1/4 inch wire has<br> -62500 circular mils of area. A one centimeter (10 millimeter) wire has<br> -100 circular millimeters of area. Actual area = circular mils * (PI/4).]<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Circumflux.</span><br> -The product of the total number of conductor turns on the armature of a<br> -dynamo or motor, into the current carried thereby. For two pole machines<br> -it is equal to twice the armature ampere-turns; for four pole machines<br> -to four times such quantity, and so on.<br> -<br> -<br> -<span style="font-weight: bold;">Clamp.</span><br> -The appliance for grasping and retaining the end of the rod that holds a<br> -carbon in the arc lamp.<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Clark's Compound.</span><br> -A cement used for the outside of the sheath of telegraph cables.<br> -Its formula is:<br> - Mineral Pitch, 65 parts.<br> - Silica, 30 -parts.<br> - -Tar, -5 parts.<br> -All parts by weight.<br> -<br> -<br> -127 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Cleats.<br> -A support; a short block of wood, grooved transversely, for holding<br> -electric wires against a wall. For the three wire system three grooves<br> -are used. The entire wiring of apartments is sometimes done by the<br> -"cleat system," using cleats instead of battens, q. v., or mouldings.<br> -The cleats are secured against the wall with the grooves facing it, and<br> -the wires are introduced therein.<br> -<br> -<br> -<img style="width: 584px; height: 237px;" alt="" src="images/127F91.jpg"><br> -Fig. 91. TWO WIRE CLEAT.<br> -<br> -<br> -<img style="width: 553px; height: 121px;" alt="" src="images/127F92.jpg"><br> -Fig. 92. THREE WIRE CLEAT.<br> -<br> -<br> -<span style="font-weight: bold;">Cleat, Crossing.</span><br> -A cleat with grooves or apertures to support wires which cross each<br> -other. Two or three grooves are transverse, and on the under side, as<br> -above; one groove is longitudinal and on the upper side.<br> -<br> -<br> -<span style="font-weight: bold;">Cleavage, Electrification by.</span><br> -If a mass of mica is rapidly split in the dark a slight flash is<br> -perceived. Becquerel found that in such separation the two pieces came<br> -away oppositely charged with electricity. The splitting of mica is its<br> -cleavage.<br> -<br> -<br> -<span style="font-weight: bold;">Clock, Controlled.</span><br> -In a system of electric clocks, the clocks whose movements are<br> -controlled by the current, regulated by the master or controlling clock.<br> -<br> -Synonym--Secondary Clock.<br> -<br> -<br> -<span style="font-weight: bold;">Clock, Controlling.</span><br> -In a system of electric clocks the master clock which controls the<br> -movements of the others, by regulating the current.<br> -<br> -Synonym--Master Clock.<br> -<br> -<br> -<span style="font-weight: bold;">Clock, Electric Annunciator.</span><br> -A clock operating any form of electric annunciator, as dropping<br> -shutters, ringing bells, and the like. It operates by the machinery<br> -closing circuits as required at any desired hour or intervals.<br> -<br> -<br> -128 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Clock, Electrolytic.</span><br> -A clock worked by the electrolytic deposition and resolution of a<br> -deposit of metal upon a disc. It is the invention of Nikola Tesla. A<br> -metallic disc is mounted on a transverse axis, so as to readily rotate.<br> -It is immersed in a vessel of copper sulphate. A current is passed<br> -through the bath, the terminals or electrodes being near to and facing<br> -the opposite edges of the disc, so that the line connecting the<br> -electrodes lies in the plane of the disc. If a current is passed through<br> -the solution by the electrodes, copper is deposited on one side of the<br> -disc, and as it rotates under the influence of the weight thus<br> -accumulated on one side, the same metal as it is brought to the other<br> -side of the disc is redissolved. Thus a continuous rotation is<br> -maintained. The cause of the deposition and solution is the position of<br> -the disc; one-half becomes negative and the other positive in their<br> -mutual relations.<br> -<br> -<br> -<span style="font-weight: bold;">Clock, Self-winding Electric.</span><br> -A clock which is wound periodically by an electric motor and battery.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Clockwork, Feed.</span><br> -In arc-lamps the system of feeding the carbon or carbons by clockwork<br> -whose movements are controlled by the resistance of the arc. This system<br> -is employed in the Serrin, and in the Gramme regulators, among others.<br> -The carbons, if they approach, move clockwork. The movement of this is<br> -stopped or freed by an electro-magnet placed in shunt around the arc<br> -and carbons.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Cloisons.</span><br> -Partitions or divisions; applied to the winding of electro-magnets and<br> -coils where the winding is put on to the full depth, over single<br> -sections of the core, one section at a time, until the whole core is<br> -filled up.<br> -<br> -<br> -<span style="font-weight: bold;">Closure.</span><br> -The closing or completion of a circuit by depressing a key or moving a<br> -switch.<br> -<br> -<br> -<span style="font-weight: bold;">Clutch.</span><br> -In arc lamps a device for the feed of the upper carbons. In its simplest<br> -form it is simply a plate or bar pierced with a hole through which the<br> -carbon passes loosely. The action of the mechanism raises or lowers one<br> -end of the plate or bar. As it rises it binds and clutches the carbon,<br> -and if the action continues it lifts it a little. When the same end is<br> -lowered the carbon and clutch descend together until the opposite end of<br> -the clutch being prevented from further descent, the clutch approaches<br> -the horizontal position and the rod drops bodily through the aperture.<br> -The cut shows the clutches of the Brush double carbon lamp. In practice<br> -the lifting and releasing as regulated by an electro-magnet are so very<br> -slight that practically an almost absolutely steady feed is secured. A<br> -similar clutch is used in the Weston lamp.<br> -<br> -<br> -129 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Clutch, Electro-magnetic.</span><br> -A clutch or appliance for connecting a shaft to a source of rotary<br> -motion while the latter is in action. In one form a disc, in whose face<br> -a groove has been formed, which groove is filled with a coil of wire, is<br> -attached to the loose wheel, while the shaft carries a flat plate to act<br> -as armature. On turning on the current the flat plate is attached,<br> -adheres, and causes its wheel to partake of the motion of the shaft.<br> -Contact is made by brushes and collecting rings.<br> -<br> -In the cut, A A is the attracted disc; the brushes, B B, take current to<br> -the collecting rings, C. The magnetizing coil is embedded in the body of<br> -the pulley, as shown.<br> -<br> -<br> -<img style="width: 535px; height: 336px;" alt="" src="images/129F93.jpg"><br> -Fig. 93. CLUTCH OF BRUSH LAMP.<br> -<br> -<br> -<img style="width: 536px; height: 709px;" alt="" src="images/129F94.jpg"><br> -Fig. 94. ELECTRO-MAGNETIC CLUTCH.<br> -<br> -<br> -130 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Coatings of a Condenser or Prime -Conductor.</span><br> -The thin conducting coatings of tinfoil, gold leaf or other conducting<br> -substance, enabling the surface to receive and part with the electric<br> -charge readily. Without such a coating the charge and discharge would be<br> -very slow, and would operate by degrees only, as one part of a<br> -non-conducting surface might be densely charged and another part be<br> -quite devoid of sensible charge.<br> -<br> -<br> -<span style="font-weight: bold;">Code, Cipher.</span><br> -A code of arbitrary words to designate prearranged or predetermined<br> -words, figures or sentences. The systems used in commerce have single<br> -words to represent whole sentences or a number of words of a sentence.<br> -This not only imparts a degree of secrecy, but makes the messages much<br> -shorter. Codes are used a great deal in cable transmission.<br> -<br> -<br> -<span style="font-weight: bold;">Code, Telegraphic.</span><br> -A telegraphic alphabet. (See Alphabets, Telegraphic.)<br> -<br> -<br> -<span style="font-weight: bold;">Coefficient.</span><br> -In algebra, the numerical multiplier of a symbol, as in the expression<br> -"5x," 5 is the coefficient. In physics, generally a number expressing<br> -the ratio or relation between quantities, one of which is often unity,<br> -as a standard or base of the set of coefficients. Thus the coefficient<br> -of expansion by heat of any substance is obtained by dividing its volume<br> -for a given degree of temperature by its volume at the standard<br> -temperature as 0º C., or 32º F. This gives a fraction by -which if any<br> -volume of a substance, taken at 0º C., or at whatever may be taken -as<br> -the basic temperature, is multiplied, the expanded volume for the given<br> -change of temperature will be obtained as the product. A coefficient<br> -always in some form implies the idea of a multiplier. Thus the<br> -coefficient of an inch referred to a foot would be 1/12 or .833+,<br> -because any number of inches multiplied by that fraction would give the<br> -corresponding number of feet.<br> -<br> -[Transcriber's note: 1/12 is 0.0833+]<br> -<br> -<br> -<span style="font-weight: bold;">Coefficient, Economic.</span><br> -In machinery, electric generators, prime motors and similar structures,<br> -the number expressing the ratio between energy absorbed by the device,<br> -and useful, not necessarily available, work obtained from it. It is<br> -equal to work obtained divided by energy absorbed, and is necessarily a<br> -fraction. If it exceeded unity the doctrine of the conservation of<br> -energy would not be true. The economic coefficient expresses the<br> -efficiency, q. v., of any machine, and of efficiencies there are several<br> -kinds, to express any one of which the economic coefficient may be used.<br> -Thus, let W--energy absorbed, and w = work produced ; then w/W is the<br> -economic coefficient, and for each case would be expressed numerically.<br> -(See Efficiency, Commercial--Efficiency, Electrical--Efficiency of<br> -Conversion.)<br> -<br> -The distinction between useful and available work in a dynamo is as<br> -follows: The useful work would include the work expended by the field,<br> -and the work taken from the armature by the belt or other mechanical<br> -connection. Only the latter would be the available work.<br> -<br> -<br> -131 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Coercive or Coercitive Force.</span><br> -The property of steel or hard iron, in virtue of which it slowly takes<br> -up or parts with magnetic force, is thus termed ("traditionally";<br> -Daniell). It seems to have to do with the positions of the molecules, as<br> -jarring a bar of steel facilitates its magnetization or accelerates its<br> -parting, when not in a magnetic field, with its permanent or residual<br> -magnetism. For this reason a permanent magnet should never be jarred,<br> -and permitting the armature to be suddenly attracted and to strike<br> -against it with a jar injures its attracting power.<br> -<br> -Coercive force is defined also as the amount of negative magnetizing<br> -force required to reduce remnant magnetism to zero.<br> -<br> -By some authorities the term is entirely rejected, as the phenomenon<br> -does not seem directly a manifestation of force.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Coil and Coil Plunger.</span><br> -A device resembling the coil and plunge, q. v., except that for the<br> -plunger of iron there is substituted a coil of wire of such diameter as<br> -to enter the axial aperture of the other, and wound or excited in the<br> -same or in the opposite sense, according to whether attraction or<br> -repulsion is desired.<br> -<br> -<br> -<span style="font-weight: bold;">Coil and Plunger.</span><br> -A coil provided with a core which is free to enter or leave the central<br> -aperture. When the coil is excited, the core is drawn into it. Various<br> -forms of this device have been used in arc lamp regulators.<br> -<br> -Synonym--Sucking coil.<br> -<br> -<br> -<img style="width: 190px; height: 632px;" alt="" src="images/131F95.jpg"><br> -Fig. 95. COIL AND COIL PLUNGER OF MENGIES ARC LAMP.<br> -<br> -<br> -<img style="width: 228px; height: 660px;" alt="" src="images/131F96.jpg"><br> -Fig. 96. COIL AND PLUNGER EXPERIMENT.<br> -<br> -<br> -132 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Coil and Plunger, Differential.</span><br> -An arrangement of coil and plunger in which two plungers or one plunger<br> -are acted on by two coils, wound so as to act oppositely or<br> -differentially on the plunger or plungers. Thus one coil may be in<br> -parallel with the other, and the action on the plunger will then depend<br> -on the relative currents passing through the coils.<br> -<br> -<br> -<span style="font-weight: bold;">Coil, Choking.</span><br> -A coil of high self-induction, used to resist the intensity of or<br> -"choke" alternating currents. Any coil of insulated wire wound around<br> -upon a laminated or divided iron core forms a choking coil. The iron<br> -coil is usually so shaped as to afford a closed magnetic circuit.<br> -<br> -A converter or transformer acts as a choking coil as long as its<br> -secondary is left open. In alternating current work special choking<br> -coils are used. Thus for theatrical work, a choking coil with a movable<br> -iron core is used to change the intensity of the lights. It is in<br> -circuit with the lamp leads. By thrusting in the core the self-induction<br> -is increased and the current diminishes, lowering the lamps; by<br> -withdrawing it the self-induction diminishes, and the current increases.<br> -Thus the lamps can be made to gradually vary in illuminating power like<br> -gas lights, when turned up or down.<br> -<br> -Synonyms--Kicking Coil--Reaction Coil.<br> -<br> -<br> -<img style="width: 392px; height: 766px;" alt="" src="images/132F97.jpg"><br> -Fig. 97. DIFFERENTIAL COILS AND PLUNGERS.<br> -<br> -<br> -<img style="width: 531px; height: 300px;" alt="" src="images/132F98.jpg"><br> -Fig. 98. BISECTED COILS.<br> -<br> -<br> -133 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Coils, Bisected.</span><br> -Resistance coils with connections at their centers, as shown in the<br> -diagram. They are used for comparing the resistances of two conductors.<br> -The connections are arranged as shown in the coil, each coil being<br> -bisected. For the wires, movable knife-edge contacts are employed. The<br> -principle of the Wheatstone bridge is used in the method and<br> -calculations.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Coil, Earth.</span><br> -A coil of wire mounted with commutator to be rotated so as to cut the<br> -lines of force of the earth's magnetic field, thereby generating<br> -potential difference. The axis of rotation may be horizontal, when the<br> -potential will be due to the vertical component of the earth's field, or<br> -the axis may be horizontal, when the potential will be due to the<br> -vertical component, or it may be set at an intermediate angle.<br> -<br> -Synonym--Delezenne's Circle.<br> -<br> -<br> -<img style="width: 610px; height: 430px;" alt="" src="images/133F99.jpg"><br> -Fig. 99. DELEZENNE'S CIRCLE OR EARTH COIL.<br> -<br> -<br> -<span style="font-weight: bold;">Coil, Electric.</span><br> -A coil of wire used to establish a magnetic field by passing a current<br> -through it. The wire is either insulated, or so spaced that its<br> -convolutions do not touch.<br> -<br> -<br> -<span style="font-weight: bold;">Coil, Flat.</span><br> -A coil whose windings all lie in one plane, making a sort of disc, or an<br> -incomplete or perforated disc.<br> -<br> -<br> -<span style="font-weight: bold;">Coil, Induction.</span><br> -A coil in which by mutual induction the electromotive force of a portion<br> -of a circuit is made to produce higher or lower electro-motive force, in<br> -an adjoining circuit, or in a circuit, part of which adjoins the<br> -original circuit, or adjoins part of it.<br> -<br> -An induction coil comprises three principal parts, the core, the primary<br> -coil and the secondary coil. If it is to be operated by a steady<br> -current, means must be provided for varying it or opening and closing<br> -the primary circuit. A typical coil will be described.<br> -<br> -<br> -134 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The core is a mass of soft iron preferably divided to prevent extensive<br> -Foucault currents. A cylindrical bundle of soft iron wires is generally<br> -used. Upon this the primary coil of reasonably heavy wire, and of one or<br> -two layers in depth, is wrapped, all being carefully insulated with<br> -shellac and paper where necessary. The secondary coil is wrapped upon or<br> -over the primary. It consists of very fine wire; No. 30 to 36 is about<br> -the ordinary range. A great many turns of this are made. In general<br> -terms the electro-motive force developed by the secondary stands to that<br> -of the primary terminals in the ratio of the windings. This is only<br> -approximate.<br> -<br> -The greatest care is required in the insulating. The secondary is<br> -sometimes wound in sections so as to keep those parts differing greatly<br> -in potential far from each other. This prevents sparking, which would<br> -destroy the insulation.<br> -<br> -A make and break, often of the hammer and anvil type, is operated by the<br> -coil. (See Circuit Breaker, Automatic.) As the current passes through<br> -the primary it magnetizes the core. This attracts a little hammer which<br> -normally resting on an anvil completes the circuit. The hammer as<br> -attracted is lifted from the anvil and breaks the circuit. The soft iron<br> -core at once parts with its magnetism and the hammer falls upon the<br> -anvil again completing the circuit. This operation goes on rapidly, the<br> -circuit being opened and closed in quick succession.<br> -<br> -Every closing of the primary circuit tends to produce a reverse current<br> -in the secondary, and every opening of the primary circuit tends to<br> -produce a direct current in the secondary. Both are of extremely short<br> -duration, and the potential difference of the two terminals of the<br> -secondary may be very high if there are many times more turns in the<br> -secondary than in the primary.<br> -<br> -The extra currents interfere with the action of an induction coil. To<br> -avoid their interference a condenser is used. This consists of two<br> -series of sheets of tin foil. Leaves of paper alternate with the sheets<br> -of tin-foil, the whole being built up into a little book. Each sheet of<br> -tin-foil connects electrically with the sheet next but one to it. Thus<br> -each leaf of a set is in connection with all others of the same set, but<br> -is insulated from the others. One set of leaves of tin-foil connects<br> -with the hammer, the other with the anvil. In large coils there may be<br> -75 square feet of tin-foil in the condenser.<br> -<br> -The action of the condenser is to dispose of the direct extra current.<br> -When the primary circuit is opened this current passes into the<br> -condenser, which at once discharges itself in the other direction<br> -through the coil. This demagnetizes the core, and the action intensifies<br> -and shortens the induced current. The condenser prevents sparking, and<br> -in general improves the action of the coil.<br> -<br> -Many details enter into the construction of coils, and many variations<br> -in their construction obtain. Thus a mercury cup into which a plunger<br> -dips often replaces the anvil and hammer.<br> -<br> -<br> -135 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The induction coil produces a rapid succession of sparks, which may<br> -spring across an interval of forty inches. The secondary generally ends<br> -in special terminals or electrodes between which the sparking takes<br> -place. A plate of glass, two inches in thickness, can be pierced by<br> -them. In the great Spottiswoode coil there are 280 miles of wire in the<br> -secondary, and the wire is about No. 36 A.W.G.<br> -<br> -<br> -<img style="width: 542px; height: 407px;" alt="" - src="images/135F100.jpg"><br> -Fig. 100. VERTICAL SECTION OF INDUCTION COIL.<br> -<br> -<br> -<img style="width: 534px; height: 290px;" alt="" - src="images/135F101.jpg"><br> -Fig. l01. PLAN OF INDUCTION COIL CONNECTIONS.<br> -<br> -<br> -Induction coils have quite extended use in electrical work. They are<br> -used in telephone transmitters, their primary being in circuit with the<br> -microphone, and their secondary with the line and receiving telephone.<br> -In electric welding, and in the alternating current system they have<br> -extended application. In all these cases they have no automatic circuit<br> -breaker, the actuating current being of intermittent or alternating<br> -type.<br> -<br> -<br> -136 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -In the cuts the general construction of an induction coil is shown. In<br> -the sectional elevation, Fig. 100, A, is the iron core; B is the primary<br> -of coarse wire; C is a separating tube, which may be of pasteboard; D is<br> -the secondary of fine wire; E, E are the binding posts connected to the<br> -secondary; H, H are the heads or standards; K, K are the terminals of<br> -the primary; F is the vibrating contact spring; G, a standard carrying<br> -the contact screw; J is the condenser with wires, L, M, leading to it.<br> -<br> -Referring to the plan, Fig. 101, H represents the primary coil; B and A<br> -are two of the separate sheets of the condenser, each sheet with<br> -projecting ears; G, G are the heads of the coil; the dark lines are<br> -connections to the condenser. One set of sheets connects with the<br> -primary coil at C, and also with the vibrating spring shown in plan and<br> -in the elevation at F. The other set of sheets connects with the post,<br> -carrying the contact screw. The other terminal of the primary runs to a<br> -binding post E. F, in the plan is a binding post in connection with the<br> -standard and contact screw.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Coil, Induction, Inverted.</span><br> -An induction coil arranged to have a lower electro-motive force in the<br> -secondary than in the primary. This is effected by having more<br> -convolutions in the primary wire than in the secondary. Such coils in<br> -practice are used with the alternating current and then do not include a<br> -circuit breaker or condenser. They are employed in alternating current<br> -system and in electric welding. (See Welding, Electric--Converter.)<br> -<br> -In the cut an inverted coil, as constructed for electric welding is<br> -shown. In it the primary coil is marked P; the secondary, merely a bar<br> -of metal, is marked E, with terminals S, S; the heavy coils, I, of iron<br> -wire are the core; K is a screw for regulating the clamps; J, Z is a<br> -second one for the same purpose, while between D and D' the heat is<br> -produced for welding the bars, B, B', held in the clamps, C, C'. It will<br> -be seen how great may be the difference in turns between the single<br> -circle of heavy copper rod or bar which is the secondary of the coil,<br> -and the long coil of wire forming the primary.<br> -<br> -<br> -<img style="width: 420px; height: 715px;" alt="" - src="images/136F102.jpg"><br> -Fig. 102. INVERTED INDUCTION COIL FOR ELECTRIC WELDING.<br> -<br> -<br> -137 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Coil, Induction, Telephone.</span><br> -An induction coil used in telephone circuits. It is placed in the box or<br> -case near the transmitter. The primary is in circuit with the<br> -microphone. The secondary is in circuit with the line and receiving<br> -telephone. In the Bell telephone apparatus the primary of the induction<br> -coil is wound with No. 18 to 24 A. W. G. wire to a resistance of 1/2<br> -ohm; the secondary, with No. 36 wire to a resistance of 80 ohms. The<br> -Edison telephone induction coil was wound with similar wires to a<br> -resistance of 3 to 4 ohms and of 250 ohms respectively.<br> -<br> -<br> -<span style="font-weight: bold;">Coil, Magnetizing.</span><br> -A coil of insulated wire for making magnets; and for experimental uses;<br> -it has a short axis and central aperture of as small size as consistent<br> -with the diameter of the bar to be magnetized, which has to pass through<br> -it readily. The wire may be quite heavy, 2 or 3 millimeters (.08--.12<br> -inch) thick, and is cemented together with carpenter's glue, or with<br> -shellac or ethereal solution of gum copal. In use it is passed over the<br> -bar a few times while a heavy current is going through it. It is used<br> -for magic circles also. (See Circle, Magic.)<br> -<br> -<br> -<img style="width: 642px; height: 215px;" alt="" - src="images/137F103.jpg"><br> -Fig. 103. MAGNETIZING COIL.<br> -<br> -<br> -<span style="font-weight: bold;">Coil, Resistance.</span><br> -A coil constructed for the purpose of offering a certain resistance to a<br> -steady current. This resistance may be for the purpose of carrying out<br> -quantitative tests, as in Wheatstone bridge work (see Wheatstone's<br> -Bridge), or simply to reduce the intensity of a current. For the first<br> -class of work the coils are wound so as to prevent the creation of a<br> -magnetic field. This is effected by first doubling the wire without<br> -breaking it, and then starting at the bend the doubled wire, which is<br> -insulated, is wound on a bobbin or otherwise until a proper resistance<br> -is shown by actual measurement. The coils are generally contained or set<br> -in closed boxes with ebonite tops. Blocks of brass are placed on the<br> -top, and one end from one coil and one end from the next connect with<br> -the same block. By inserting a plug, P, so as to connect any two blocks,<br> -which have grooves reamed out for the purpose, the coil beneath will be<br> -short circuited. German silver, platinoid or other alloy, q. v., is<br> -generally the material of the wire. A great object is to have a wire<br> -whose resistance will be unaffected by heat.<br> -<br> -<br> -138 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 682px; height: 336px;" alt="" - src="images/138F104.jpg"><br> -Fig. 104. RESISTANCE COILS AND CONNECTIONS, SHOWING PLUG.<br> -<br> -<br> -<span style="font-weight: bold;">Coil, Rhumkorff.</span><br> -The ordinary induction coil with circuit breaker, for use with original<br> -direct and constant current, is thus termed. (See Coil, Induction.)<br> -<br> -Synonym--Inductorium.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Coil, Ribbon.</span><br> -A coil made of copper ribbon wound flatwise, often into a disc-like<br> -shape, and insulated by tape or strips of other material intervening<br> -between the successive turns.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Coils, Compensating.</span><br> -Extra coils on the field magnets of dynamos or motors, which coils are<br> -in series with the armature windings for the purpose of keeping the<br> -voltage constant. In compound wound machines the regular series-wound<br> -coil is thus termed. In a separately excited dynamo a coil of the same<br> -kind in circuit with the armature may be used as a compensator.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Coils, Henry's.</span><br> -An apparatus used in repeating a classic experiment in electro-magnetic<br> -induction, due to Prof. Henry. It consists in a number of coils, the<br> -first and last ones single, the intermediate ones connected in pairs,<br> -and one of one pair placed on the top of one of the next pair. On<br> -opening or closing the circuit of an end coil the induced effect goes<br> -through the series and is felt in the circuit of the other end coil.<br> -Prof. Henry extended the series so as to include seven successive<br> -inductions, sometimes called inductions of the first, second, third and<br> -other orders. Frequently ribbon coils (see Coil, Ribbon,) are used in<br> -these experiments.<br> -<br style="font-weight: bold;"> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Coils, Sectioned.</span><br> -A device for prolonging the range of magnetic attraction. It consists of<br> -a series of magnetizing coils traversed by an iron plunger. As it passes<br> -through them, the current is turned off the one in the rear or passing<br> -to the rear and turned into the next one in advance. The principle was<br> -utilized in one of Page's electric motors about 1850, and later by<br> -others. The port-electric railroad, q. v., utilizes the same principle.<br> -<br> -<br> -139 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Collecting Ring.</span><br> -In some kinds of generators instead of the commutator a pair of<br> -collecting rings of metal, insulated from the machine and from each<br> -other, are carried on the armature shaft. A brush, q. v., presses on<br> -each, and the circuit terminals connect to these two brushes. Such rings<br> -are employed often on alternating current generators, where the current<br> -does not have to be changed or commuted. Collecting rings with their<br> -brushes are used also where a current has to be communicated to a<br> -revolving coil or circuit as in the magnetic car wheel, the cut of which<br> -is repeated here. The coil of wire surrounding the wheel and rotating<br> -with it has to receive current. This it receives through the two<br> -stationary brushes which press upon two insulated metallic rings,<br> -surrounding the shaft. The terminals of the coil connect one to each<br> -ring. Thus while the coil rotates it constantly receives current, the<br> -brushes being connected to the actuating circuit.<br> -<br> -<br> -<img style="width: 393px; height: 590px;" alt="" - src="images/139F105.jpg"><br> -Fig. 105. MAGNETIC CAR WHEEL SHOWING <br> -COLLECTING RINGS AND BRUSHES.<br> -<br> -<br> -<span style="font-weight: bold;">Collector.</span><br> -(a) A name for the brush, q. v., in mechanical electric generators, such<br> -as dynamos, a pair of which collectors or brushes press on the<br> -commutator or collecting rings, and take off the current.<br> -<br> -(b) The pointed connections leading to the prime conductor on a static<br> -machine for collecting the electricity; often called combs. The points<br> -of the combs or collectors face the statically charged rotating glass<br> -plate or cylinder of the machine.<br> -<br> -<br> -<span style="font-weight: bold;">Colombin.</span><br> -The insulating material between the carbons in a Jablochkoff candle or<br> -other candle of that type. Kaolin was originally used. Later a mixture<br> -of two parts calcium sulphate (plaster of Paris) and one part barium<br> -sulphate (barytes) was substituted.<br> -<br> -The colombin was three millimeters (.12 inch) wide, and two millimeters<br> -(.08 inch) thick. (See Candle, Jablochkoff.)<br> -<br> -<br> -<span style="font-weight: bold;">Column, Electric.</span><br> -An old name for the voltaic pile, made up of a pile of discs of copper<br> -and zinc, with flannel discs, wet with salt solution or dilute acid,<br> -between each pair of plates.<br> -<br> -<br> -140 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Comb.</span><br> -A bar from which a number of teeth project, like the teeth of a comb. It<br> -is used as a collector of electricity from the plate of a frictional or<br> -influence electric machine; it is also used in a lightning arrester to<br> -define a path of very high resistance but of low self-induction, for the<br> -lightning to follow to earth.<br> -<br> -<br> -<span style="font-weight: bold;">Communicator.</span><br> -The instrument by which telegraph signals are transmitted is sometimes<br> -thus termed.<br> -<br> -<br> -<span style="font-weight: bold;">Commutator.</span><br> -In general an apparatus for changing. It is used on electric current<br> -generators, and motors, and on induction coils, and elsewhere, for<br> -changing the direction of currents, and is of a great variety of types.<br> -<br> -Synonym--Commuter (but little used).<br> -<br> -<br> -<img style="width: 603px; height: 371px;" alt="" - src="images/140F106.jpg"><br> -Fig. 106. DYNAMO OR MOTOR COMMUTATOR.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Commutator Bars.</span><br> -The metallic segments of a dynamo or motor commutator.<br> -<br> -<br> -<span style="font-weight: bold;">Commutator, Flats in.</span><br> -A wearing away or lowering in level of one or more metallic segments of<br> -a commutator. They are probably due in many cases to sparking, set up by<br> -periodic springing in the armature mounting, or by defective commutator<br> -connections.<br> -<br> -<br> -<span style="font-weight: bold;">Commutator of Current Generators and -Motors.</span><br> -In general a cylinder, formed of alternate sections of conducting and<br> -non-conducting material, running longitudinally or parallel with the<br> -axis. Its place is on the shaft of the machine, so that it rotates<br> -therewith. Two brushes, q. v., or pieces of conducting material, press<br> -upon its surface.<br> -<br> -<br> -141 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -As a part of electric motors and generators, its function is to collect<br> -the currents produced by the cutting of lines of force so as to cause<br> -them all to concur to a desired result. The cut shows the simplest form<br> -of commutator, one with but two divisions. Its object may be to enable a<br> -current of constant direction to be taken from a rotating armature, in<br> -which the currents alternate or change direction once in each rotation.<br> -It is carried by the shaft A of the armature and rotates with it. It<br> -consists of two leaves, S S, to which the terminals of the armature are<br> -connected. Two springs, W W, the terminals of the outer circuit, press<br> -against the leaves. The springs which do this take off the current. It<br> -is so placed, with reference to the springs and armature, that just as<br> -the current changes in direction, each leaf changes from one spring to<br> -the other. Thus the springs receive constant direction currents. The<br> -changing action of this commutator appears in its changing the character<br> -of the current from alternating to constant. Were two insulated<br> -collecting rings used instead of a commutator, the current in the outer<br> -circuit would be an alternating one. On some dynamos the commutator has<br> -a very large number of leaves.<br> -<br> -Taking the Gramme ring armature, there must be as many divisions of the<br> -commutator as there are connections to the coils. In this case the<br> -function of the commutator is simply to lessen friction, for the brushes<br> -could be made to take current from the coils directly outside of the<br> -periphery of the ring.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Commutator, Split Ring.</span><br> -A two-division commutator for a motor; it consists of two segments of<br> -brass or copper plate, bent to arcs of a circle, and attached to an<br> -insulating cylinder. They are mounted on the revolving spindle, which<br> -carries the armature, and acts as a two part commutator. For an example<br> -of its application, see Armature, Revolving, Page's. (See also Fig.<br> -107.)<br> -<br> -<br> -<img style="width: 526px; height: 338px;" alt="" - src="images/141F107.jpg"><br> -Fig. 107. SECTION OF SPLIT RING COMMUTATOR, WITH BRUSHES.<br> -<br> -<br> -<span style="font-weight: bold;">Compass.</span><br> -An apparatus for utilizing the directive force of the earth upon the<br> -magnetic needle. It consists of a circular case, within which is poised<br> -a magnetized bar of steel. This points approximately to the north, and<br> -is used on ships and elsewhere to constantly show the direction of the<br> -magnetic meridian. Two general types are used. In one the needle is<br> -mounted above a fixed "card" or dial, on which degrees or points of the<br> -compass, q. v., are inscribed. In the other the card is attached to the<br> -needle and rotates with it. The latter represents especially the type<br> -known as the mariner's compass. (See Compass, Mariner's--Compass,<br> -Spirit, and other titles under compass, also Magnetic Axis--Magnetic<br> -Elements.) The needle in good compasses carries for a bearing at its<br> -centre, a little agate cup, and a sharp brass pin is the point of<br> -support.<br> -<br> -<br> -<span style="font-weight: bold;">Compass, Azimuth.</span><br> -A compass with sights on one of its diameters; used in determining the<br> -magnetic bearing of objects.<br> -<br> -<br> -142 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Compass Card.</span><br> -The card in a compass; it is circular in shape, and its centre coincides<br> -with the axis of rotation of the magnetic needle; on it are marked the<br> -points of the compass, at the ends generally of star points. (See<br> -Compass, Points of the.) It may be fixed, and the needle may be poised<br> -above it, or it may be attached to the needle and rotate with it.<br> -<br> -<br> -<span style="font-weight: bold;">Compass, Declination.</span><br> -An instrument by which the magnetic declination of any place may be<br> -determined. It is virtually a transit instrument and compass combined,<br> -the telescope surmounting the latter. In the instrument shown in the<br> -cut, L is a telescope mounted by its axis, X, in raised journals with<br> -vernier, K, and arc x, for reading its vertical angle, with level n. The<br> -azimuth circle, Q, R, is fixed. A vernier, V is carried by the box, A,<br> -E, and both turn with the telescope. A very light lozenge-shaped<br> -magnetic needle, a, b, is pivoted in the exact centre of the graduated<br> -circles, Q R, and M. The true meridian is determined by any convenient<br> -astronomical method, and the telescope is used for the purpose. The<br> -variation of the needle from the meridian thus determined gives the<br> -magnetic declination.<br> -<br> -<br> -<img style="width: 491px; height: 737px;" alt="" - src="images/142F108.jpg"><br> -FIG. 108. DECLINATION COMPASS.<br> -<br> -<br> -<span style="font-weight: bold;">Compass, Inclination.</span><br> -A magnetic needle mounted on a horizontal axis at its centre of gravity,<br> -so as to be free to assume the dip, or magnetic inclination, when placed<br> -in the magnetic meridian. It moves over the face of a vertical graduated<br> -circle, and the frame also carries a spirit level and graduated<br> -horizontal circle. In use the frame is turned until the needle is<br> -vertical. Then the axis of suspension of the needle is in the magnetic<br> -meridian. The vertical circle is then turned through 90° of the -horizon,<br> -which brings the plane of rotation of the needle into the magnetic<br> -meridian, when it assumes the inclination of the place.<br> -<br> -<br> -143 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Compass, Mariner's.</span><br> -A compass distinguished by the card being attached to and rotating with<br> -the needle. A mark, the "lubber's mark" of the sailors is made upon the<br> -case. This is placed so that the line connecting it, and the axis of<br> -rotation of the card is exactly in a plane, passing through the keel of<br> -the ship. Thus however the ship may be going, the point of the card<br> -under or in line with the "lubber's mark," shows how the ship is<br> -pointing. The case of the mariner's compass is often bowl-shaped and<br> -mounted in gimbals, a species of universal joint, so as to bc always<br> -horizontal. (See Compass, Spirit-Gimbals.)<br> -<br> -<br> -<img style="width: 699px; height: 488px;" alt="" - src="images/143F109.jpg"><br> -FIG. 109. MARINER'S COMPASS.<br> -<br> -<br> -<span style="font-weight: bold;">Compass, Points of the.</span><br> -The circle of the horizon may bc and is best referred to angular<br> -degrees. It has also been divided into thirty-two equiangular and named<br> -points. A point is 11.25°. The names of the points are as follows:<br> -North, North by East, North North-east, North-east by North, North-east,<br> -North-east by East, East North-east, East by North, East, East by South,<br> -East South-east, South-east by East, South-east, South-east by South,<br> -South South-east, South by East, South, South by West, South South-west,<br> -South-west by South, South-west, South-west by West, West South-west,<br> -West by South, West, West by North, West North-west, North-west by West,<br> -North-west, North West by North, North North-west, North by West. They<br> -are indicated by their initials as N. N. W., North North-west, N. by W.,<br> -North by West.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Compass, Spirit.</span><br> -A form of mariner's compass. The bowl or case is hermetically sealed and<br> -filled with alcohol or other nonfreezing liquid. The compass card is<br> -made with hollow compartments so as nearly to float. In this way the<br> -friction of the pivot or point of support is greatly diminished, and the<br> -compass is far more sensitive.<br> -<br> -<br> -<span style="font-weight: bold;">Compass, Surveyor's.</span><br> -A species of theodolite; a telescope with collimation lines, mounted<br> -above a compass, so as to be applicable for magnetic surveys. Its use is<br> -to be discouraged on account of the inaccuracy and changes in<br> -declination of the magnetic needle.<br> -<br> -<br> -144 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Compensating Resistances.</span><br> -In using a galvanometer shunt the total resistance of the circuit is<br> -diminished so that in some cases too much current flows through it; in<br> -such case additional resistance, termed as above, is sometimes<br> -introduced in series. The shunt in parallel with the galvanometer is<br> -thus compensated for, and the experimental or trial circuit does not<br> -take too much current.<br> -<br> -<br> -<span style="font-weight: bold;">Complementary Distribution.</span><br> -Every distribution of electricity has somewhere a corresponding<br> -distribution, exactly equal to it of opposite electricity; the latter is<br> -the complimentary distribution to the first, and the first distribution<br> -is also complimentary to it.<br> -<br> -<br> -<span style="font-weight: bold;">Component.</span><br> -A force may always be represented diagrammatically by a straight line,<br> -terminating in an arrow-head to indicate the direction, and of length to<br> -represent the intensity of the force. The line may always be assumed to<br> -represent the diagonal of a parallelogram, two of whose sides are<br> -represented by lines starting from the base of the arrow, and of length<br> -fixed by the condition that the original force shall be the diagonal of<br> -the parallelogram of which they are two contiguous sides; such lines are<br> -called components, and actually represent forces into which the original<br> -force may always be resolved. The components can have any direction.<br> -Thus the vertical component of a horizontal force is zero; its<br> -horizontal component is equal to itself. Its 450 component is equal to<br> -the square root of one-half of its square.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Condenser.</span><br> -An appliance for storing up electrostatic charges: it is also called a<br> -static accumulator. The telegraphic condenser consists of a box packed<br> -full of sheets of tinfoil. Between every two sheets is a sheet of<br> -paraffined paper, or of mica. The alternate sheets of tinfoil are<br> -connected together, and each set has its own binding post. (See<br> -Accumulator, Electrostatic.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Condenser, Sliding.</span><br> -An apparatus representing a Leyden jar whose coatings can be slid past<br> -each other. This diminishes or increases the facing area, and<br> -consequently in almost exactly similar ratio diminishes or increases the<br> -capacity of the condenser.<br> -<br> -<br> -<span style="font-weight: bold;">Conductance.</span><br> -The conducting power of a given mass of specified material of specified<br> -shape and connections. Conductance varies in cylindrical or prismatic<br> -conductors, inversely as the length, directly as the cross-section, and<br> -with the conductivity of the material. Conductance is an attribute of<br> -any specified conductor, and refers to its shape, length and other<br> -factors. Conductivity is an attribute of any specified material without<br> -direct reference to its shape, or other factors.<br> -<br> -<br> -<span style="font-weight: bold;">Conduction.</span><br> -The process or act of conducting a current.<br> -<br> -<br> -145 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Conductivity.</span><br> -The relative power of conducting the electric current possessed by<br> -different substances. A path for the current through the ether is opened<br> -by the presence of a body of proper quality, and this quality, probably<br> -correlated to opacity, is termed conductivity. There is no perfect<br> -conductor, all offer some resistance, q. v., and there is hardly any<br> -perfect non-conductor. It is the reverse and reciprocal of resistance.<br> -<br> -<br> -<span style="font-weight: bold;">Conductivity, Specific.</span><br> -The reciprocal of specific resistance. (See Resistance--Specific.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Conductivity, Unit of.</span><br> -The reciprocal of the ohm; it is a more logical unit, but has never been<br> -generally adopted; as a name the title mho (or ohm written backwards)<br> -has been suggested by Sir William Thomson, and provisionally adopted.<br> -<br> -<br> -<span style="font-weight: bold;">Conductivity, Variable.</span><br> -The conductivity for electric currents of conductors varies with their<br> -temperature, with varying magnetization, tension, torsion and<br> -compression.<br> -<br> -<br> -<span style="font-weight: bold;">Conductor.</span><br> -In electricity, anything that permits the passage of an electric<br> -current. Any disturbance in the ether takes the form of waves because<br> -the ether has restitutive force or elasticity. In a conductor, on the<br> -other hand, this force is wanting; it opens a path through the ether and<br> -a disturbance advances through it from end to end with a wave front, but<br> -with no succession of waves. This advance is the beginning of what is<br> -termed a current. It is, by some theorists, attributed to impulses given<br> -at all points along the conductor through the surrounding ether, so that<br> -a current is not merely due to an end thrust. If ether waves preclude a<br> -current on account of their restitutive force, ether waves cannot be<br> -maintained in a conductor, hence conductors should be opaque to light,<br> -for the latter is due to ether waves. This is one of the more practical<br> -every day facts brought out in Clerk Maxwell's electromagnetic theory of<br> -light. The term conductor is a relative one, as except a vacuum there is<br> -probably no substance that has not some conducting power. For relative<br> -conducting power, tables of conductivity, q. v., should be consulted.<br> -The metals beginning with silver are the best conductors, glass is one<br> -of the worst.<br> -<br> -[Transcriber's note: See "ether" for contemporary comments on this now<br> -discarded concept.]<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Conductor, Anti-Induction.</span><br> -A current conductor arranged to avoid induction from other lines. Many<br> -kinds have been invented and made the subject of patents. A fair<br> -approximation may be attained by using a through metallic circuit and<br> -twisting the wires composing it around each other. Sometimes concentric<br> -conductors, one a wire and the other a tube, are used, insulated, one<br> -acting as return circuit for the other.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Conductor, Conical.</span><br> -A prime conductor of approximately conical shape, but rounded on all<br> -points and angles. Its potential is highest at the point.<br> -<br> -<br> -146 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Conductor, Imbricated.</span><br> -A conductor used in dynamo armatures for avoiding eddy currents, made by<br> -twisting together two or more strips of copper.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Conductor, Prime.</span><br> -A body often cylindrical or spherical in shape, in any case with no<br> -points or angles, but rounded everywhere, whose surface, if the<br> -conductor itself is not metallic, is made conducting by tinfoil or gold<br> -leaf pasted over it. It is supported on an insulating stand and is used<br> -to collect or receive and retain static charges of electricity.<br> -<br> -<br> -<span style="font-weight: bold;">Conductors, Equivalent.</span><br> -Conductors of identical resistance. The quotient of the length divided<br> -by the product of the conductivity and cross-section must be the same in<br> -each, if each is of uniform diameter.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Conjugate. adj.</span><br> -Conjugate coils or conductors are coils placed in such relation that the<br> -lines of force established by one do not pass through the coils of the<br> -other. Hence variations of current in one produce no induced currents in<br> -the other.<br> -<br> -<br> -<span style="font-weight: bold;">Connect. v.</span><br> -To bring two ends of a conductor together, or to bring one end of a<br> -conductor in connection with another, or in any way to bring about an<br> -electrical connection.<br> -<br> -<br> -<span style="font-weight: bold;">Connector.</span><br> -A sleeve with screws or other equivalent device for securing the ends of<br> -wires in electrical contact. A binding-post, q. v., is an example.<br> -Sometimes wire spring-catches are used, the general idea being a device<br> -that enables wires to be connected or released at will without breaking<br> -off or marring their ends. The latter troubles result from twisting<br> -wires together.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Consequent Poles.</span><br> -A bar magnet is often purposely or accidentally magnetized so as to have<br> -both ends of the same polarity, and the center of opposite polarity. The<br> -center is said to comprise two consequent poles. (See Magnet,<br> -Anomalous.)<br> -<br> -<br> -<span style="font-weight: bold;">Conservation of Electricity.</span><br> -As every charge of electricity has its equal and opposite charge<br> -somewhere, near or far, more or less distributed, the sum of negative is<br> -equal always to the sum of positive electrical charges. For this<br> -doctrine the above title was proposed by Lippman.<br> -<br> -<br> -<span style="font-weight: bold;">Contact Breaker.</span><br> -Any contrivance for closing a circuit, and generally for opening and<br> -closing in quick succession. An old and primitive form consisted of a<br> -very coarsely cut file. This was connected to one terminal, and the<br> -other terminal was drawn over its face, making and breaking contact as<br> -it jumped from tooth to tooth. (See Circuit Breaker--do. Automatic,<br> -etc.--do. Wheel-do. Pendulum.)<br> -<br> -<br> -147 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Contact, Electric.</span><br> -A contact between two conductors, such that a current can flow through<br> -it. It may be brought about by simple touch or impact between the ends<br> -or terminals of a circuit, sometimes called a dotting contact, or by a<br> -sliding or rubbing of one terminal on another, or by a wheel rolling on<br> -a surface, the wheel and surface representing the two terminals.<br> -<br> -There are various descriptions of contact, whose names are<br> -self-explanatory. The term is applied to telegraph line faults also, and<br> -under this, includes different descriptions of contact with neighboring<br> -lines, or with the earth.<br> -<br> -<br> -<span style="font-weight: bold;">Contact Electricity.</span><br> -When two dissimilar substances are touched they assume different<br> -electric potentials. If conductors, their entire surfaces are affected;<br> -if dielectrics, only the surfaces which touch each other. (See Contact<br> -Theory.)<br> -<br> -<br> -<span style="font-weight: bold;">Contact Faults.</span><br> -A class of faults often called contacts, due to contact of the conductor<br> -of a circuit with another conductor. A full or metallic contact is where<br> -practically perfect contact is established; a partial contact and<br> -intermittent contact are self-explanatory.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Contact Point.</span><br> -A point, pin or stud, often of platinum, arranged to come in contact<br> -with a contact spring, q. v., or another contact point or surface, under<br> -any determined conditions.<br> -<br> -<br> -<span style="font-weight: bold;">Contact Potential Difference.</span><br> -The potential difference established by the contact of two dissimilar<br> -substances according to the contact theory, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Contact Series.</span><br> -An arrangement or tabulation of substances in pairs, each intermediate<br> -substance appearing in two pairs, as the last member of the first, and<br> -first member of the succeeding pair, with the statement of the potential<br> -difference due to their contact, the positively electrified substance<br> -coming first. The following table of some contact potentials is due to<br> -Ayrton and Perry:<br> -<small><span style="font-family: monospace;">CONTACT SERIES.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Difference of Potential in Volts.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Zinc--Lead -.210</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Lead--Tin -.069</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Tin--Iron -.313</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Iron--Copper -.146</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Copper--Platinum .238</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Platinum-Carbon .113</span></small> -<br> -<br> -The sum of these differences is 1.089, which is the contact potential<br> -between zinc and carbon.<br> -<br> -Volta's Law refers to this and states that--<br> - The difference of potential produced by the contact of any two<br> - substances is equal to the sum of the differences of potentials<br> - between the intervening substances in the contact series.<br> -<br> -It is to be remarked that the law should no longer be restricted to or<br> -stated only for metals.<br> -<br> -<br> -148 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Contact-spring.</span><br> -A spring connected to one lead of an electric circuit, arranged to press<br> -against another spring, or contact point, q. v., under any conditions<br> -determined by the construction of the apparatus. (See Bell,<br> -Electric--Coil, Induction.)<br> -<br> -<br> -<span style="font-weight: bold;">Contact Theory.</span><br> -A theory devised to explain electrification, the charging of bodies by<br> -friction, or rubbing, and the production of current by the voltaic<br> -battery. It holds that two bodies, by mere contact become oppositely<br> -electrified. If such contact is increased in extent by rubbing together,<br> -the intensity of their electrification is increased. This<br> -electrification is accounted for by the assumption of different kinetic<br> -energy, or energy of molecular motion, possessed by the two bodies;<br> -there being a loss and gain of energy, on the two sides respectively,<br> -the opposite electrifications are the result. Then when separated, the<br> -two bodies come apart oppositely electrified.<br> -<br> -The above accounts for the frictional production of electricity. In the<br> -voltaic battery, a separation of the atoms of hydrogen and oxygen, and<br> -their consolidation into molecules occurs, and to such separation and<br> -the opposite electrification of the electrodes by the oxygen and<br> -hydrogen, the current is attributed, because the hydrogen goes to one<br> -electrode, and the oxygen to the other, each giving up or sharing its<br> -own charge with the electrodes to which it goes. If zinc is touched to<br> -copper, the zinc is positively and the copper negatively electrified. In<br> -the separation of hydrogen and oxygen, the hydrogen is positively and<br> -the oxygen negatively electrified. In the battery, the current is due to<br> -the higher contact difference of oxygen and hydrogen compared to that<br> -between zinc and copper. It will be seen that the two contact actions in<br> -a battery work against each other, and that the current is due to a<br> -differential contact action. The zinc in a battery is electrified<br> -negatively because the negative electrification of the oxygen is greater<br> -in amount than its own positive electrification due to contact with the<br> -copper.<br> -<br> -<br> -<span style="font-weight: bold;">Contractures.</span><br> -A muscular spasm or tetanus due to the passage of a current of<br> -electricity; a term in electro-therapeutics.<br> -<br> -<br> -<span style="font-weight: bold;">Controlling Field.</span><br> -The magnetic or electro-magnetic field, which is used in galvanometers<br> -to control the magnetic needle, tending to restore it to a definite<br> -position whenever it is turned therefrom. It may be the earth's field or<br> -one artificially produced.<br> -<br> -<br> -<span style="font-weight: bold;">Controlling Force.</span><br> -In galvanometers and similar instruments, the force used to bring the<br> -needle or indicator back to zero. (See Controlling<br> -Field--Electro-Magnetic Control--Gravity Control--Magnetic<br> -Control--Spring Control.)<br> -<br> -<br> -149 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Convection, Electric.</span><br> -The production of blasts or currents of air (convection streams) from<br> -points connected to statically charged conductors. The term is sometimes<br> -applied to electric convection of heat. (See Convection of Heat,<br> -Electric.)<br> -<br> -<br> -<span style="font-weight: bold;">Convection, Electrolytic.</span><br> -The resistance of acidulated water as a true conductor is known to be<br> -very, almost immeasurably, high. As an electrolytic, its resistance is<br> -very much lower. Hence the current produced between immersed electrodes<br> -is theoretically almost null, unless the difference of potential between<br> -them is high enough to decompose the liquid. Yet a feeble current too<br> -great for a true conduction current is sometimes observed when two<br> -electrodes with potential difference too low to cause decomposition are<br> -immersed in it. Such a current is termed an electrolytic convection<br> -current. It is supposed to be due to various causes. Some attribute it<br> -to the presence of free oxygen from the air, dissolved in the water with<br> -which the hydrogen combines. Others attribute it to the diffusion of the<br> -gases of decomposition in the solution; others assume a partial<br> -polarization of the molecules without decomposition. Other theories are<br> -given, all of which are unsatisfactory. The term is due to Helmholtz.<br> -<br> -<br> -<span style="font-weight: bold;">Convection of Heat, Electric.</span><br> -The effect of a current upon the distribution of heat in an unevenly<br> -heated conductor. In some, such as copper, the current tends to equalize<br> -the varying temperatures; the convection is then said to be positive, as<br> -comparable to that of water flowing through an unequally heated tube. In<br> -others, such as platinum or iron, it is negative, making the heated<br> -parts hotter, and the cooler parts relatively cooler.<br> -<br> -The effect of the electric current in affecting the distribution of heat<br> -in unequally heated metal (Thomson's effect. q. v.), is sometimes so<br> -termed. If a current passes through unequally heated iron it tends to<br> -increase the difference of temperature, and the convection is negative;<br> -in copper it tends to equalize the temperature, and the convection is<br> -positive.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Converter.</span><br> -An induction coil used with the alternating current for changing<br> -potential difference and inversely therewith the available current. They<br> -generally lower the potential, and increase the current, and are placed<br> -between the primary high potential system that connects the houses with<br> -the central station, and the secondary low potential system within the<br> -houses. A converter consists of a core of thin iron sheets, wound with a<br> -fine primary coil of many convolutions, and a coarse secondary coil of<br> -few convolutions. The ratio of convolutions gives the ratio of maximum<br> -potential differences of their terminals between the primary and<br> -secondary coils. The coil may be jacketed with iron to increase the<br> -permeance. (See Alternating Current System.)<br> -<br> -<br> -<img style="width: 664px; height: 710px;" alt="" - src="images/150F110.jpg"><br> -Fig. 110. FERRANTI'S CONVERTER OR TRANSFORMER.<br> -<br> -<br> -<img style="width: 672px; height: 340px;" alt="" - src="images/150F111.jpg"><br> -Fig. 111. SWINBURNE'S HEDGEHOG TRANSFORMER.<br> -<br> -<br> -150 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Co-ordinates, System of.</span><br> -A system for indicating the position of points in space by reference to<br> -fixed lines, intersecting at a determined and arbitrary point 0, termed<br> -the origin of co-ordinates. In plane rectangular co-ordinates two lines<br> -are drawn through the origin, one horizontal, termed the axis of<br> -abscissas, or axis of X. All distances measured parallel to it, if<br> -unknown, are indicated by x, and are termed abscissas. The other axis is<br> -vertical, and is termed the axis of ordinates, or axis of Y. All<br> -distances measured parallel to it, if unknown, are indicated by y and<br> -are termed ordinates. Thus by naming its abscissa and ordinate a point<br> -has its position with reference to the axes determined, and by<br> -indicating the relation between a point, line or curve, and a system of<br> -abscissas and ordinates, the properties of a line or curve can be<br> -expressed algebraically. Co-ordinates may also be inclined to each other<br> -at any other angles, forming oblique co-ordinates; relations may be<br> -expressed partly in angles referred to the origin as a centre, giving<br> -polar co-ordinates. For solid geometry or calculations in three<br> -dimensions, a third axis, or axis of Z, is used, distances parallel to<br> -which if unknown are indicated by z.<br> -<br> -<br> -<img style="width: 532px; height: 401px;" alt="" - src="images/151F112.jpg"><br> -Fig. 112. AXES OF CO-ORDINATES.<br> -<br> -<br> -151 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Cooling Box.</span><br> -In a hydroelectric machine, q. v., a conduit or chest through which the<br> -steam passes on its way to the nozzles. Its object is to partially<br> -condense the steam so as to charge it with water vesicles whose friction<br> -against the sides of the nozzles produces the electrification .<br> -<br> -<br> -152 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Copper.</span><br> -A metal; one of the elements. Symbol, Cu; atomic weight, 63.5;<br> -equivalent, 63.5 and 31.75; valency, 1 and 2; specific gravity, 8.96.<br> -It is a conductor of electricity, whose conductivity is liable to<br> -vary greatly on account of impurities.<br> -<br> - - - -<span style="font-family: monospace;"><small>Annealed. Hard -drawn.</small></span><small><br style="font-family: monospace;"> -<span style="font-family: monospace;">Relative resistance (Silver = -1), -1.063 1.086</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Specific -resistance, -1.598 1.634 microhms.</span><br - style="font-family: monospace;"> -<br style="font-family: monospace;"> -<span style="font-family: monospace;">Resistance of a wire at 0° C. -(32° F.),</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Annealed. Hard Drawn.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">(a) 1 foot long, weighing 1 -grain, .2041 -ohms .2083 ohms.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">(b) 1 foot long, 1/1000 inch -thick, 9.612 -" 9.831 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">(c) 1 meter long, weighing 1 -gram, .1424 -" .1453 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">(d) 1 meter long, 1 millimeter -thick, .02034 -" .02081 "</span><br - style="font-family: monospace;"> -<br style="font-family: monospace;"> -<span style="font-family: monospace;"> -microhm. microhm.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Resistance of 1 inch cube at -0°C. (32° F.) -.6292 .6433</span><br - style="font-family: monospace;"> -<br style="font-family: monospace;"> -<span style="font-family: monospace;">Percentage of resistance change,</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">per 1° C. (1.8° F.) at -about 20° C. (68° F.) = 0.388 -per cent.</span><br style="font-family: monospace;"> -<br style="font-family: monospace;"> -<span style="font-family: monospace;">Electro-chemical Equivalent -(Hydrogen = .0105) -Cuprous .6667</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Cupric .3334</span></small> -<br> -<br> -In electricity it has been very extensively used as the negative plate<br> -of voltaic batteries. It has its most extensive application as<br> -conductors for all classes of electrical leads.<br> -<br> -<br> -<span style="font-weight: bold;">Copper Bath.</span><br> -A solution of copper used for depositing the metal in the electroplating<br> -process. For some metals, such as zinc or iron, which decompose copper<br> -sulphate solution, special baths have to be used.<br> -<br> -The regular bath for copper plating is the following:<br> -<br> -To water acidulated with 8 to 10 percent. of sulphuric acid as much<br> -copper sulphate is added as it will take up at the ordinary temperature.<br> -The saturated bath should have a density of 1.21. It is used cold and is<br> -kept in condition by the use of copper anodes, or fresh crystals may be<br> -added from time to time.<br> -<br> -For deposition on zinc, iron, tin and other metals more electropositive<br> -than copper, the following baths may be used, expressed in parts by<br> -weight:<br> -<br style="font-family: monospace;"> -<small><span style="font-family: monospace;"> -Tin</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Iron and Steel. Cast Iron</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -Cold Hot. and -Zinc. Zinc.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Sodium -Bisulphate, 500 -200 -300 100</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Potassium -Cyanide, 500 -700 -500 700</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Sodium -Carbonate, 1000 -500 ---- ---</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Copper -Acetate, -475 -500 -350 450</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Aqua -Ammoniae, -350 -300 -200 150</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Water, -2500 2500 -2500 2500</span></small> -<br> -<br> -These are due to Roseleur.<br> -<br> -<br> -153 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Copper Stripping Bath.</span><br> -There is generally no object in stripping copper from objects. It can be<br> -done with any of the regular copper baths using the objects to be<br> -stripped as anode. The danger of dissolving the base itself and thereby<br> -injuring the article and spoiling the bath is obvious.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Cord Adjuster.</span><br> -A device for shortening or lengthening the flexible cord, or flexible<br> -wire supplying the current, and by which an incandescent lamp is<br> -suspended. It often is merely a little block of wood perforated with two<br> -holes through which the wires pass, and in which they are retained in<br> -any desired position by friction and their own stiffness.<br> -<br> -<br> -<img style="width: 604px; height: 334px;" alt="" - src="images/153F113.jpg"><br> -Fig. 113. FLEXIBLE CORD ADJUSTER.<br> -<br> -<br> -<span style="font-weight: bold;">Cord, Flexible.</span><br> -A pair of flexible wire conductors, insulated lightly, twisted together<br> -and forming apparently a cord. They are used for minor services, such as<br> -single lamps and the like, and are designated according to the service<br> -they perform, such as battery cords, dental cords (for supplying dental<br> -apparatus) and other titles.<br> -<br> -<br> -<span style="font-weight: bold;">Core.</span><br> -(a) The conductor or conductors of an electric cable. (See Cable Core.)<br> -<br> -(b) The iron mass, generally central in an electro-magnet or armature,<br> -around which the wire is coiled. It acts by its high permeance to<br> -concentrate or multiply the lines of force, thus maintaining a more<br> -intense field. (See Armature--Magnet, Electro--Magnet, Field--Core,<br> -Laminated). In converters or transformers (See Converter) it often<br> -surrounds the wire coils.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Core-discs.</span><br> -Discs of thin wire, for building up armature cores. (See Laminated<br> -Core.) The usual form of core is a cylinder. A number of thin discs of<br> -iron are strung upon the central shaft and pressed firmly together by<br> -end nuts or keys. This arrangement, it will be seen, gives a cylinder as<br> -basis for winding the wire on.<br> -<br> -<br> -<span style="font-weight: bold;">Core-discs, Pierced.</span><br> -Core-discs for an armature of dynamo or motor, which are pierced around<br> -the periphery. Tubes of insulating material pass through the peripheral<br> -holes, and through these the conductors or windings are carried. The<br> -conductors are thus embedded in a mass of iron and are protected from<br> -eddy currents, and they act to reduce the reluctance of the air gaps.<br> -From a mechanical point of view they are very good. For voltages over<br> -100 they are not advised.<br> -<br> -Synonym--Perforated Core-discs.<br> -<br> -<br> -154 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Core-discs, Segmental.</span><br> -Core-discs made in segments, which are bolted together to form a<br> -complete disc or section of the core. The plan is adopted principally on<br> -large cores. The discs thus made up are placed together to form the core<br> -exactly as in the case of ordinary one piece discs.<br> -<br> -<br> -<img style="width: 622px; height: 549px;" alt="" - src="images/154F114.jpg"><br> -Fig. 114. PIERCED OR PERFORATED CORE-DISC.<br> -<br> -<br> -<span style="font-weight: bold;">Core-discs, Toothed.</span><br> -Core-discs of an armature of a dynamo or motor, which discs are cut into<br> -notches on the periphery. These are put together to form the armature<br> -core, with the notches corresponding so as to form a series of grooves<br> -in which the wire winding is laid. This construction reduces the actual<br> -air-gaps, and keeps the wires evenly spaced. Distance-pieces of<br> -box-wood, m, m, are sometimes used to lead the wires at the ends of the<br> -armature.<br> -<br> -<br> -<img style="width: 540px; height: 534px;" alt="" - src="images/154F115.jpg"><br> -Fig. 115. TOOTHED CORE-DISC.<br> -<br> -<br> -<span style="font-weight: bold;">Core, Laminated.</span><br> -A core of an armature, induction coil or converter or other similar<br> -construction, which is made up of plates insulated more or less<br> -perfectly from each other. The object of lamination is to prevent the<br> -formation of Foucault currents. (See Currents, Foucault.) As insulation,<br> -thin shellacked paper may be used, or sometimes the superficial<br> -oxidation of the plates alone is relied on. The plates, in general, are<br> -laid perpendicular to the principal convolutions of the wire, or<br> -parallel to the lines of force. The object is to break up currents, and<br> -such currents are induced by the variation in intensity of the field of<br> -force, and their direction is perpendicular to the lines of force, or<br> -parallel to the inducing conductors.<br> -<br> -A core built up of core discs is sometimes termed a tangentially<br> -laminated core. Made up of ribbon or wire wound coil fashion, it is<br> -termed a radially laminated core.<br> -<br> -<br> -155 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Core Ratio.</span><br> -In a telegraph cable the ratio existing between the diameter of the<br> -conducting core and the insulator. To get a ratio approximately accurate<br> -in practical calculations, the diameter of the core is taken at 5 per<br> -cent. less than its actual diameter. The calculations are those<br> -referring to the electric constants of the cable, such as its static<br> -capacity and insulation resistance.<br> -<br> -<br> -<span style="font-weight: bold;">Core, Ribbon.</span><br> -For discoidal ring-shaped cores of armatures, iron ribbon is often used<br> -to secure lamination and prevent Foucault currents.<br> -<br> -Synonym--Tangentially Laminated Core.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Core, Ring.</span><br> -A core for a dynamo or motor armature, which core forms a complete ring.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Core, Stranded.</span><br> -In an electric light cable, a conducting core made up of a group of<br> -wires laid or twisted together.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Core, Tubular.</span><br> -Tubes used as cores for electro-magnets. For very small magnetizing<br> -power, tubular cores are nearly as efficient as solid ones in straight<br> -magnets, because the principal reluctance is due to the air-path. On<br> -increasing the magnetization the tubular core becomes less efficient<br> -than the solid core, as the reluctance of the air-path becomes<br> -proportionately of less importance in the circuit.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Corpusants.</span><br> -The sailors' name for St. Elmo's Fire, q. v.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Coulomb.</span><br> -The practical unit of quantity of electricity. It is the quantity passed<br> -by a current of one ampere intensity in one second. It is equal to 1/10<br> -the C. G. S. electro-magnetic unit of quantity, and to 3,000,000,000 C.<br> -G. S. electrostatic units of quantity. It corresponds to the<br> -decomposition of .0935 milligrams of water, or to the deposition of<br> -1.11815 milligrams of silver.<br> -<br> -[Transcriber's note: A coulomb is approximately 6.241E18 electrons. Two<br> -point charges of one coulomb each, one meter apart, exerts a force of<br> -900,000 metric tons.]<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Coulomb's Laws of Electrostatic -Attraction and Repulsion.</span><br> -1. The repulsions or attractions between two electrified bodies are in<br> -the inverse ratio of the squares of their distance.<br> -<br> -2. The distance remaining the same, the force of attraction or repulsion<br> -between two electrified bodies is directly as the product of the<br> -quantities of electricity with which they are charged.<br> -<br> -<br> -156 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Counter, Electric.</span><br> -A device for registering electrically, or by electro-magnetic machinery,<br> -the revolutions of shafts, or any other data or factors.<br> -<br> -<br> -<span style="font-weight: bold;">Counter-electro-motive Force.</span><br> -A potential difference in a circuit opposed to the main potential<br> -difference, and hence, resisting the operation of the latter, and<br> -diminishing the current which would be produced without it. It appears<br> -in electric motors, which, to a certain extent, operate as dynamos and<br> -reduce the effective electro-motive force that operates them. It<br> -appears in the primary coils of induction coils, and when the secondary<br> -circuit is open, is almost equal to the main electro-motive force, so<br> -that hardly any current can go through them under such conditions. It<br> -appears in galvanic batteries, when hydrogen accumulates on the copper<br> -plate, and in other chemical reactions. A secondary battery is charged<br> -by a current in the reverse direction to that which it would normally<br> -produce. Its own potential difference then appears as a<br> -counter-electro-motive force.<br> -<br> -Synonym--Back Electro-motive Force.<br> -<br> -<br> -<span style="font-weight: bold;">Counter-electro-motive Force of -Polarization.</span><br> -To decompose a solution by electrolysis, enough electro-motive force is<br> -required to overcome the energy of composition of the molecule<br> -decomposed. A part of this takes the form of a counter-electromotive<br> -force, one which, for a greater or less time would maintain a current in<br> -the opposite direction if the original source of current were removed.<br> -Thus in the decomposition of water, the electrodes become covered, one<br> -with bubbles of oxygen, the others with bubbles of hydrogen; this<br> -creates a counter E. M. F. of polarization. In a secondary battery, the<br> -working current may be defined as due to this cause.<br> -<br> -Synonym--Back Electro-motive Force of Polarization.<br> -<br> -<br> -<span style="font-weight: bold;">Couple.</span><br> -Two forces applied to different points of a straight line, when opposed<br> -in direction or unequal in amount, tend to cause rotation about a point<br> -intermediate between their points of application and lying on the<br> -straight line. Such a pair constitute a couple.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Couple, Voltaic or Galvanic.</span><br> -The combination of two electrodes, and a liquid or liquids, the<br> -electrodes being immersed therein, and being acted on differentially by<br> -the liquid or liquids. The combination constitutes a source of<br> -electro-motive force and consequently of current. It is the galvanic or<br> -voltaic cell or battery. (See Battery, Voltaic--Contact<br> -Theory--Electro-motive Force--Electro-motive Series.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Coupling.</span><br> -The joining of cells of a galvanic battery, of dynamos or of other<br> -devices, so as to produce different effects as desired.<br> -<br> -<br> -157 STANDARD ELECTRICAL DICTIONARY<br> -<br> -<br> -<span style="font-weight: bold;">Couple, Astatic.</span><br> -An astatic couple is a term sometimes applied to astatic needles, q.v.<br> -<br> -<br> -<span style="font-weight: bold;">C. P.</span><br> -(a) An abbreviation of or symbol for candle power, q. v.<br> -<br> -(b) An abbreviation of chemically pure. It is used to indicate a high<br> -degree of purity of chemicals. Thus, in a standard Daniell battery, the<br> -use of C. P. chemicals may be prescribed or advised.<br> -<br> -<br> -<span style="font-weight: bold;">Crater.</span><br> -The depression that forms in the positive carbon of a voltaic arc. (See<br> -Arc, Voltaic.)<br> -<br> -<br> -<span style="font-weight: bold;">Creeping.</span><br> -A phenomenon of capillarity, often annoying in battery jars. The<br> -solution, by capillarity, rises a little distance up the sides,<br> -evaporates, and as it dries more creeps up through it, and to a point a<br> -little above it. This action is repeated until a layer of the salts may<br> -form over the top of the vessel. To avoid it, paraffine is often applied<br> -to the edges of the cup, or a layer of oil, often linseed oil, is poured<br> -on the battery solution,<br> -<br> -<br> -<span style="font-weight: bold;">Crith.</span><br> -The weight of a litre of hydrogen at 0º C. (32º F.), and 760 -mm. (30<br> -inches) barometric pressure. It is .0896 grams. The molecular weight of<br> -any gas divided by 2 and multiplied by the value of the crith, gives the<br> -weight of a litre of the gas in question. Thus a litre of electrolytic<br> -gas, a mixture of two molecules of hydrogen for one of oxygen, with a<br> -mean molecular weight of 12, weighs (12/2) * .0896 or .5376 gram.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Critical Speed.</span><br> -(a) The speed of rotation at which a series dynamo begins to excite its<br> -own field.<br> -<br> -(b) In a compound wound dynamo, the speed at which the same potential is<br> -generated with the full load being taken from the machine, as would be<br> -generated on open circuit, in which case the shunt coil is the only<br> -exciter. The speed at which the dynamo is self-regulating.<br> -<br> -(c) In a dynamo the rate of speed when a small change in the speed of<br> -rotation produces a comparatively great change in the electro-motive<br> -force. It corresponds to the same current (the critical current) in any<br> -given series dynamo.<br> -<br> -<br> -<span style="font-weight: bold;">Cross.</span><br> -(a) A contact between two electric conductors; qualified to express<br> -conditions as a weather cross, due to rain, a swinging cross when a wire<br> -swings against another, etc.<br> -<br> -(b) vb. To make such contact.<br> -<br> -<br> -<span style="font-weight: bold;">Cross-Connecting Board.</span><br> -A special switch board used in telephone exchanges and central telegraph<br> -offices. Its function is, by plugs and wires, to connect the line wires<br> -with any desired section of the main switchboard. The terminals of the<br> -lines as they enter the building are connected directly to the<br> -cross-connecting board.<br> -<br> -<br> -158 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Cross Connection.</span><br> -A method of disposing of the effects of induction from neighboring<br> -circuits by alternately crossing the two wires of a metallic telephone<br> -circuit, so that for equal intervals they lie to right and left, or one<br> -above, and one below.<br> -<br> -[Transcriber's note: Also used to cancel the effect of variations in the<br> -ambient magnetic field, such as solar activity.]<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Crossing Wires.</span><br> -The cutting out of a defective section in a telegraph line, by carrying<br> -two wires from each side of the defective section across to a<br> -neighboring conductor, pressing it for the time into service and cutting<br> -the other wire if necessary.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Cross-magnetizing Effect.</span><br> -A phase of armature interference. The current in an armature of a dynamo<br> -or motor is such as to develop lines of force approximately at right<br> -angles to those of the field. The net cross-magnetizing effect is such<br> -component of these lines, as is at right angles to the lines produced by<br> -the field alone.<br> -<br> -<br> -<span style="font-weight: bold;">Cross-over Block.</span><br> -A piece of porcelain or other material shaped to receive two wires which<br> -are to cross each other, and hold them so that they cannot come in<br> -contact. It is used in wiring buildings, and similar purposes. (See<br> -Cleat, Crossing.)<br> -<br> -<span style="font-weight: bold;">Cross Talk.</span><br> -On telephone circuits by induction or by contact with other wires sound<br> -effects of talking are sometimes received from other circuits; such<br> -effects are termed cross talk.<br> -<br> -<br> -<span style="font-weight: bold;">Crucible, Electric.</span><br> -A crucible for melting difficultly fusible substances, or for reducing<br> -ores, etc., by the electric arc produced within it. Sometimes the<br> -heating is due more to current incandescence than to the action of an<br> -arc.<br> -<br> -<br> -<img style="width: 652px; height: 250px;" alt="" - src="images/158F116.jpg"><br> -Fig. 116. ELECTRIC FURNACE OR CRUCIBLE.<br> -<br> -<br> -<span style="font-weight: bold;">Crystallization, Electric.</span><br> -Many substances under proper conditions take a crystalline form. The<br> -great condition is the passage from the fluid into the solid state. When<br> -such is brought about by electricity in any way, the term electric<br> -crystallization may be applied to the phenomenon. A solution of silver<br> -nitrate for instance, decomposed by a current, may give crystals of<br> -metallic silver.<br> -<br> -<br> -159 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Cup, Porous.</span><br> -A cup used in two-fluid voltaic batteries to keep the solutions separate<br> -to some extent. It forms a diaphragm through which diffusion inevitably<br> -takes place, but which is considerably retarded, while electrolysis and<br> -electrolytic convection take place freely through its walls. As<br> -material, unglazed pottery is very generally used.<br> -<br> -In some batteries the cup is merely a receptacle for the solid<br> -depolarizer. Thus, in the Leclanché battery, the cup contains the<br> -manganese dioxide and graphite in which the carbon electrode is<br> -embedded, but does not separate two solutions, as the battery only uses<br> -one. Nevertheless, the composition of the solution outside and inside<br> -may vary, but such variation is incidental only, and not an essential of<br> -the operation.<br> -<br> -<br> -<span style="font-weight: bold;">Current.</span><br> -The adjustment, or effects of a continuous attempt at readjustment of<br> -potential difference by a conductor, q. v., connecting two points of<br> -different potential. A charged particle or body placed in a field of<br> -force tends to move toward the oppositely charged end or portion of the<br> -field. If a series of conducting particles or a conducting body are held<br> -so as to be unable to move, then the charge of the field tends, as it<br> -were, to move through it, and a current results. It is really a<br> -redistribution of the field and as long as such redistribution continues<br> -a current exists. A current is assumed to flow from a positive to a<br> -negative terminal; as in the case of a battery, the current in the outer<br> -circuit is assumed to flow from the carbon to the zinc plate, and in the<br> -solution to continue from zinc to carbon. As a memoria technica the zinc<br> -may be thought of as generating the current delivering it through the<br> -solution to the carbon, whence it flows through the wire connecting<br> -them. (See Ohm's Law--Maxwell's Theory of Light--Conductor-Intensity.)<br> -<br> -[Transcriber's note: Supposing electric current to be the motion of <br> -positive charge causes no practical difficulty, but the current is <br> -actually the (slight) motion of negative electrons.]<br> -<br> -<br> -<span style="font-weight: bold;">Current, After.</span><br> -A current produced by the animal tissue after it has been subjected to a<br> -current in the opposite direction for some time. The tissue acts like a<br> -secondary battery. The term is used in electro-therapeutics.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Alternating.</span><br> -Usually defined and spoken of as a current flowing alternately in<br> -opposite directions. It may be considered as a succession of currents,<br> -each of short duration and of direction opposite to that of its<br> -predecessor. It is graphically represented by such a curve as shown in<br> -the cut. The horizontal line may denote a zero current, that is no<br> -current at all, or may be taken to indicate zero electro-motive force.<br> -The curve represents the current, or the corresponding electro-motive<br> -forces. The further from the horizontal line the greater is either, and<br> -if above the line the direction is opposite to that corresponding to the<br> -positions below the line. Thus the current is alternately in opposite<br> -directions, has periods of maximum intensity, first in one and then in<br> -the opposite sense, and between these, passing from one direction to the<br> -other, is of zero intensity. It is obvious that the current may rise<br> -quickly in intensity and fall slowly, or the reverse, or may rise and<br> -fall irregularly. All such phases may be shown by the curve, and a curve<br> -drawn to correctly represent these variations is called the<br> -characteristic curve of such current. It is immaterial whether the<br> -ordinates of the curve be taken as representing current strength or<br> -electromotive force. If interpreted as representing electro-motive<br> -force, the usual interpretation and best, the ordinates above the line<br> -are taken as positive and those below as negative.<br> -<br> -Synonyms--Reversed Current--Periodic Currents.<br> -<br> -<br> -<img style="width: 684px; height: 284px;" alt="" - src="images/160F117.JPG"><br> -Fig. 117. CHARACTERISTIC CURVE OF ALTERNATING CURRENT.<br> -<br> -<br> -160 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Atomic.</span><br> -A unit of current strength used in Germany; the strength of a current<br> -which will liberate in 24 hours (86,400 seconds) one gram of hydrogen<br> -gas, in a water voltameter. The atomic current is equal to 1.111<br> -amperes. In telegraphic work the milliatom is used as a unit, comparable<br> -to the milliampere. The latter is now displacing it.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Charge.</span><br> -If the external coatings of a charged and uncharged jar are placed in<br> -connection, and if the inner coatings are now connected, after<br> -separating them they are both found to be charged in the same manner. In<br> -this process a current has been produced between the outside coatings<br> -and one between the inner ones, to which Dove has given the name Charge<br> -Current, and which has all the properties of the ordinary discharge<br> -current. (Ganot.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Current, Circular.</span><br> -A current passing through a circular conductor; a current whose path is<br> -in the shape of a circle.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Current, Commuted.</span><br> -A current changed, as regards direction or directions, by a commutator,<br> -q. v., or its equivalent.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Constant.</span><br> -An unvarying current. A constant current system is one maintaining such<br> -a current. In electric series, incandescent lighting, a constant current<br> -is employed, and the system is termed as above. In arc lighting systems,<br> -the constant current series arrangement is almost universal.<br> -<br> -<br> -161 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Continuous.</span><br> -A current of one direction only; the reverse of an alternating current.<br> -(See Current, Alternating.)<br> -<br> -<br> -<span style="font-weight: bold;">Current, Critical.</span><br> -The current produced by a dynamo at its critical speed; at that speed<br> -when a slight difference in speed produces a great difference in<br> -electro-motive force. On the characteristic curve it corresponds to the<br> -point where the curve bends sharply, and where the electro-motive force<br> -is about two-thirds its maximum.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Daniell/U.S. , -Daniell/Siemens' Unit.</span><br> -A unit of current strength used in Germany. It is the strength of a<br> -current produced by one Daniell cell in a circuit of the resistance of<br> -one Siemens' unit. The current deposits 1.38 grams of copper per hour.<br> -It is equal to 1.16 amperes.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Demarcation.</span><br> -In electro-therapeutics, a current which can be taken from an injured<br> -muscle, the injured portion acting electro-negatively toward the<br> -uninjured portion.<br> -<br> -<br> -<span style="font-weight: bold;">Current Density.</span><br> -The current intensity per unit of cross-sectional area of the conductor.<br> -The expression is more generally used for electrolytic conduction, where<br> -the current-density is referred to the mean facing areas of the<br> -electrodes, or else to the facing area of the cathode only.<br> -<br> -The quality of the deposited metal is intimately related to the current<br> -density. (See Burning.)<br> -<small><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Proper Current Density for Electroplating</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -Amperes -Per Square Foot of Cathode.--(Urquhart.)</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Copper, Acid -Bath. -5.0 to 10.0</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">" -Cyanide -Bath, -3.0 " 5.0</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Silver, Double -Cyanide, -2.0 " 5.0</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Gold, Chloride dissolved in -Potassium Cyanide, 1.0 -" 2.0</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Nickel, Double -Sulphate, -6.6 " 8.0</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Brass, -Cyanide, -2.0 " 3.0</span></small><br> -<br> -<br> -<span style="font-weight: bold;">Current, Diacritical.</span><br> -A current, which, passing through a helix surrounding an iron core,<br> -brings it to one-half its magnetic saturation, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Diaphragm.</span><br> -If a liquid is forced through a diaphragm, a potential difference<br> -between the liquid on opposite sides of the diaphragm is maintained.<br> -Electrodes or terminals of platinum may be immersed in the liquid, and a<br> -continuous current, termed a diaphragm current, may be taken as long as<br> -the liquid is forced through the diaphragm. The potential difference is<br> -proportional to the pressure, and also depends on the nature of the<br> -diaphragm and on the liquid.<br> -<br> -<br> -162 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Direct.</span><br> -A current of unvarying direction, as distinguished from an alternating<br> -current. It may be pulsatory or intermittent in character, but must be<br> -of constant direction.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Direct Induced.</span><br> -On breaking a circuit, if it is susceptible of exercising<br> -self-induction, q. v., an extra current, in the direction of the<br> -original is induced, which is called "direct" because in the same<br> -direction as the original. The same is produced by a current in one<br> -circuit upon a parallel one altogether separated from it. (See<br> -Induction, Electro-Magnetic-Current, Extra.)<br> -<br> -Synonym--Break Induced Current.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Direction of.</span><br> -The assumed direction of a current is from positively charged electrode<br> -to negatively charged one; in a galvanic battery from the carbon or<br> -copper plate through the outer circuit to the zinc plate and back<br> -through the electrolyte to the carbon or copper plate. (See Current.)<br> -<br> -[Transcriber's note: Current is caused by the motion of negative<br> -electrons, from the negative pole to the positive. The electron was<br> -discovered five years after this publication.]<br> -<br> -<br> -<span style="font-weight: bold;">Current, Displacement.</span><br> -The movement or current of electricity taking place in a dielectric<br> -during displacement. It is theoretical only and can only be assumed to<br> -be of infinitely short duration. (See Displacement, Electric.)<br> -<br> -<br> -<span style="font-weight: bold;">Currents, Eddy Displacement.</span><br> -The analogues of Foucault currents, hypothetically produced in the mass<br> -of a dielectric by the separation of the electricity or by its<br> -electrification. (See Displacement.)<br> -<br> -<br> -<span style="font-weight: bold;">Current, Extra.</span><br> -When a circuit is suddenly opened or closed a current of very brief<br> -duration, in the first case in the same direction, in the other case in<br> -the opposite direction, is produced, which exceeds the ordinary current<br> -in intensity. A high potential difference is produced for an instant<br> -only. These are called extra currents. As they are produced by<br> -electro-magnetic induction, anything which strengthens the field of<br> -force increases the potential difference to which they are due. Thus the<br> -wire may be wound in a coil around an iron core, in which case the extra<br> -currents may be very strong. (See Induction, Self-Coil, Spark.)<br> -<br> -<br> -<span style="font-weight: bold;">Current, Faradic.</span><br> -A term in medical electricity for the induced or secondary alternating<br> -current, produced by comparatively high electro-motive force, such as<br> -given by an induction coil or magneto-generator, as distinguished from<br> -the regular battery current.<br> -<br> -<br> -163 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Current, Foucault.</span><br> -A current produced in solid conductors, and which is converted into heat<br> -(Ganot). These currents are produced by moving the conductors through a<br> -field, or by altering the strength of a field in which they are<br> -contained. They are the source of much loss of energy and other<br> -derangement in dynamos and motors, and to avoid them the armature cores<br> -are laminated, the plane of the laminations being parallel to the lines<br> -of force. (See Core, Laminated.)<br> -<br> -The presence of Foucault currents, if of long duration, is shown by the<br> -heating of the metal in which they are produced. In dynamo armatures<br> -they are produced sometimes in the metal of the windings, especially if<br> -the latter are of large diameter.<br> -<br> -Synonyms--Eddy Currents--Local Currents--Parasitical Currents.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Franklinic.</span><br> -In electro-therapeutics the current produced by a frictional electric<br> -machine.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Induced.</span><br> -The current produced in a conductor by varying the conditions of a field<br> -of force in which it is placed; a current produced by induction.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Current Induction.</span><br> -Induction by one current on another or by a portion of a current on<br> -another portion of itself. (See Induction.)<br> -<br> -<br> -<span style="font-weight: bold;">Current Intensity.</span><br> -Current strength, dependent on or defined by the quantity of electricity<br> -passed by such current in a given time. The practical unit of current<br> -intensity is the ampere, equal to one coulomb of quantity per second of<br> -time.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Inverse Induced.</span><br> -The current induced in a conductor, when in a parallel conductor or in<br> -one having a parallel component a current is started, or is increased in<br> -strength. It is opposite in direction to the inducing current and hence<br> -is termed inverse. (See Induction, Electro-magnetic.) The parallel<br> -conductors may be in one circuit or in two separate circuits.<br> -<br> -Synonyms--Make-induced Current--Reverse-induced Current.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Jacobi's Unit of.</span><br> -A current which will liberate one cubic centimeter of mixed gases<br> -(hydrogen and oxygen) in a water voltameter per minute, the gases being<br> -measured at 0º C. (32º F.) and 760 mm. (29.92 inches) -barometric<br> -pressure. It is equal to .0961 ampere.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Joint.</span><br> -The current given by several sources acting together. Properly, it<br> -should be restricted to sources connected in series, thus if two battery<br> -cells are connected in series the current they maintain is their joint<br> -current.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Linear.</span><br> -A current passing through a straight conductor; a current whose path<br> -follows a straight line.<br> -<br> -<br> -164 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Make and Break.</span><br> -A succession of currents of short duration, separated by absolute<br> -cessation of current. Such current is produced by a telegraph key, or by<br> -a microphone badly adjusted, so that the circuit is broken at intervals.<br> -The U. S. Courts have virtually decided that the telephone operates by<br> -the undulatory currents, and not by a make and break current. Many<br> -attempts have been made to produce a telephone operating by a<br> -demonstrable make and break current, on account of the above<br> -distinction, in hopes of producing a telephone outside of the scope of<br> -the Bell telephone patent.<br> -<br> -[Transcriber's note: Contemporary long distance telephone service is<br> -digital, as this item describes.]<br> -<br> -<br> -<span style="font-weight: bold;">Current-meter.</span><br> -An apparatus for indicating the strength of current. (See Ammeter.)<br> -<br> -<br> -<span style="font-weight: bold;">Current, Negative.</span><br> -In the single needle telegraph system the current which deflects the<br> -needle to the left.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Current, Nerve and Muscle.</span><br> -A current of electricity yielded by nerves or muscles. Under proper<br> -conditions feeble currents can be taken from nerves, as the same can be<br> -taken from muscles.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Current, Opposed.</span><br> -The current given by two or more sources connected in opposition to each<br> -other. Thus a two volt and a one volt battery may be connected in<br> -opposition, giving a net voltage of only one volt, and a current due to<br> -such net voltage.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Partial.</span><br> -A divided or branch current. A current which goes through a single<br> -conductor to a point where one or more other conductors join it in<br> -parallel, and then divides itself between the several conductors, which<br> -must join further on, produces partial currents. It produces as many<br> -partial currents as the conductors among which it divides. The point of<br> -division is termed the point of derivation.<br> -<br> -Synonym--Derived Current.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Current, Polarizing.</span><br> -In electro-therapeutics, a constant current.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Current, Positive.</span><br> -In the single needle telegraph system the current which deflects the<br> -needle to the right.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Current, Pulsatory.</span><br> -A current of constant direction, but whose strength is constantly<br> -varying, so that it is a series of pulsations of current instead of a<br> -steady flow.<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Current, Rectified.</span><br> -A typical alternating current is represented by a sine curve, whose<br> -undulations extend above and below the zero line. If by a simple two<br> -member commutator the currents are caused to go in one direction, in<br> -place of the sine curve a series of short convex curves following one<br> -another and all the same side of the zero line results. The currents all<br> -in the same direction, become what is known as a pulsating current.<br> -<br> -Synonym--Redressed Current.<br> -<br> -<br> -165 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Current, Rectilinear.</span><br> -A current flowing through a rectilinear conductor. The action of<br> -currents depending on their distance from the points where they act,<br> -their contour is a controlling factor. This contour is determined by the<br> -conductors through which they flow.<br> -<br> -<br> -<span style="font-weight: bold;">Current Reverser.</span><br> -A switch or other contrivance for reversing the direction of a<br> -current in a conductor.<br> -<br> -<br> -<span style="font-weight: bold;">Currents, Ampérian.</span><br> -The currents of electricity assumed by Ampere's theory to circulate<br> -around a magnet. As they represent the maintenance of a current or of<br> -currents without the expenditure of energy they are often assumed to be<br> -of molecular dimensions. As they all go in the same sense of rotation<br> -and are parallel to each other the result is the same as if a single set<br> -of currents circulated around the body of the magnet. More will be found<br> -on this subject under Magnetism. The Ampérian currents are purely<br> -hypothetical and are predicated on the existence of a field of force<br> -about a permanent magnet. (See Magnetism, Ampére's Theory of.)<br> -<br> -If the observer faces the north pole of a magnet the Ampérian -currents<br> -are assumed to go in the direction opposite to that of a watch, and the<br> -reverse for the south pole.<br> -<br> -<br> -<img style="width: 684px; height: 296px;" alt="" - src="images/165F118_119.jpg"><br> -Figs. 118-119 DIRECTION OF AMPÉRIAN CURRENTS.<br> -<br> -<br> -<span style="font-weight: bold;">Currents, Angular.</span><br> -Currents passing through conductors which form an angle with each other.<br> -<br> -<br> -<span style="font-weight: bold;">Currents, Angular, Laws of.</span><br> -1. Two rectilinear currents, the directions of which form an angle with<br> -each other, attract one another when both approach to or recede from the<br> -apex of the angle.<br> -<br> -2. They repel one another, if one approaches and the other recedes from<br> -the apex of the angle.<br> -<br> -<br> -166 STANDARD ELECTRICAL DICTIONARY<br> -<br> -<br> -<span style="font-weight: bold;">Currents, Earth.</span><br> -In long telegraph lines having terminal grounds or connected to earth<br> -only at their ends, potential differences are sometimes observed that<br> -are sufficient to interfere with their working and which, of course, can<br> -produce currents. These are termed earth-currents. It will be noted that<br> -they exist in the wire, not in the earth. They may be of 40 milliamperes<br> -strength, quite enough to work a telegraph line without any battery.<br> -Lines running N. E. and S. W. are most affected; those running N.W. and<br> -S. E. very much less so. These currents only exist in lines grounded at<br> -both ends, and appear in underground wires. Hence they are not<br> -attributable to atmospheric electricity. According to Wilde they are the<br> -primary cause of magnetic storms, q. v., but not of the periodical<br> -changes in the magnetic elements. (See Magnetic Elements.)<br> -<br> -Synonym--Natural Currents.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Secondary.</span><br> -(a) A current induced in one conductor by a variation in the current in<br> -a neighboring one; the current produced in the secondary circuit of an<br> -induction coil or alternating current converter.<br> -<br> -(b) The current given by a secondary battery. This terminology is not to<br> -be recommended.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Current, Secretion.</span><br> -In electro-therapeutics, a current due to stimulation of the secretory<br> -nerves.<br> -<br> -<br> -<span style="font-weight: bold;">Current Sheet.</span><br> -(a) If two terminals of an active circuit are connected to two points of<br> -a thin metallic plate the current spreads over or occupies practically a<br> -considerable area of such plate, and this portion of the current is a<br> -current sheet.<br> -<br> -The general contour of the current sheet can be laid out in lines of<br> -flux. Such lines resemble lines of force. Like the latter, they are<br> -purely an assumption, as the current is not in any sense composed -of<br> -lines.<br> -<br> -(b) A condition of current theoretically brought about by the -Ampérian<br> -currents in a magnet. Each molecule having its own current, the<br> -contiguous portions of the molecules counteract each other and give a<br> -resultant zero current. All that remains is the outer sheet of electric<br> -current that surrounds the whole.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Sinuous.</span><br> -A current passing through a sinuous conductor.<br> -<br> -<br> -<span style="font-weight: bold;">Currents, Multiphase.</span><br> -A term applied to groups of currents of alternating type which<br> -constantly differ from each other by a constant proportion of periods of<br> -alternation. They are produced on a single dynamo, the winding being so<br> -contrived that two, three or more currents differing a constant amount<br> -in phase are collected from corresponding contact rings. There are<br> -virtually as many windings on the armature as there are currents to be<br> -produced. Separate conductors for the currents must be used throughout.<br> -<br> -Synonyms--Polyphase Currents--Rotatory Currents.<br> -<br> -<br> -167 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Currents of Motion.</span><br> -In electro-therapeutics, the currents produced in living muscle or<br> -nerves after sudden contraction or relaxation.<br> -<br> -<br> -<span style="font-weight: bold;">Currents of Rest.</span><br> -In electro-therapeutics, the currents traversing muscular or nervous<br> -tissue when at rest. Their existence is disputed.<br> -<br> -<br> -<span style="font-weight: bold;">Currents, Orders of.</span><br> -An intermittent current passing through a conductor will induce<br> -secondary alternating currents in a closed circuit near it. This<br> -secondary current will induce a tertiary current in a third closed<br> -circuit near it, and so on. The induced currents are termed as of the<br> -first, second, third and other orders. The experiment is carried out by<br> -Henry's coils. (See Coils, Henry's.)<br> -<br> -<br> -<span style="font-weight: bold;">Currents, Thermo-electric.</span><br> -These currents, as produced from existing thermo-electric batteries,<br> -are generated by low potential, and are of great constancy. The opposite<br> -junctions of the plates can be kept at constant temperatures, as by<br> -melting ice and condensing steam, so that an identical current can be<br> -reproduced at will from a thermopile.<br> -<br> -Thermo-electric currents were used by Ohm in establishing his law. (See<br> -Ohm's Law.)<br> -<br> -<br> -<span style="font-weight: bold;">Current, Swelling.</span><br> -In electro-therapeutics, a current gradually increasing in strength.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Current, Undulatory.</span><br> -A current varying in strength without any abrupt transition from action<br> -to inaction, as in the make and break current. The current may be<br> -continually changing in direction (see Current, Alternating), and hence,<br> -of necessity, may pass through stages of zero intensity, but such<br> -transition must be by a graduation, not by an abrupt transition. Such<br> -current may be represented by a curve, such as the curve of sines. It is<br> -evident that the current may pass through the zero point as it crosses<br> -the line or changes direction without being a make and break current.<br> -When such a current does alternate in direction it is sometimes called a<br> -"shuttle current." The ordinary commercial telephone current and the<br> -alternating current is of this type. (See Current, Make and Break.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Current, Unit.</span><br> -Unit current is one which in a wire of unit length, bent so as to form<br> -an arc of a circle of unit length of radius, would act upon a unit pole<br> -(see Magnetic Pole, Unit,) at the center of the circle with unit force.<br> -Unit length is the centimeter; unit force is the dyne.<br> -<br> -[Transcriber's note: The SI definition of an ampere: A current in two<br> -straight parallel conductors of infinite length and negligible<br> -cross-section, 1 metre apart in vacuum, would produce a force equal to<br> -2E-7 newton per metre of length.]<br> -<br> -<br> -168 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Current, Wattless.</span><br> -Whenever there is a great difference in phase in an alternating current<br> -dynamo between volts and current, the true watts are much less than the<br> -product of the virtual volts and amperes, because the the watts are<br> -obtained by multiplying the product of the virtual volts and amperes by<br> -the cosine of the angle of lag (or lead). Any alternating current may be<br> -resolved into two components in quadrature with each other, one in phase<br> -with the volts, the other in quadrature therewith, the former is termed<br> -by S. P. Thompson the Working Current, the latter the Wattless Current.<br> -The greater the angle of lag the greater will be the wattless current.<br> -<br> -<br> -<span style="font-weight: bold;">Curve, Arrival.</span><br> -A curve representing the rate of rise of intensity of current at the end<br> -of a long conductor when the circuit has been closed at the other end.<br> -In the Atlantic cable, for instance, it would require about 108 seconds<br> -for the current at the distant end to attain 9/10 of its full value. The<br> -curve is drawn with its abscissa representing time and its ordinates<br> -current strength.<br> -<br> -<br> -<span style="font-weight: bold;">Curve, Characteristic.</span><br> -A curve indicating, graphically, the relations between any two factors,<br> -which are interdependent, or which vary simultaneously. Thus in a<br> -dynamo, the voltage increases with the speed of rotation, and a<br> -characteristic curve may be based on the relations between the speed of<br> -rotation and voltage developed. The current produced by a dynamo varies<br> -with the electro-motive force, and a curve can express the relations<br> -between the electro-motive force and the current produced.<br> -<br> -A characteristic curve is usually laid out by rectangular co-ordinates<br> -(see Co-ordinates). Two lines are drawn at right angles to each other,<br> -one vertical, and the other horizontal. One set of data are marked off<br> -on the horizontal line, say one ampere, two amperes, and so on, in the<br> -case of a dynamo's characteristic curve.<br> -<br> -For each amperage of current there is a corresponding voltage in the<br> -circuit. Therefore on each ampere mark a vertical is erected, and on<br> -that the voltage corresponding to such amperage is laid off. This gives<br> -a series of points, and these points may be connected by a curve. Such<br> -curve will be a characteristic curve.<br> -<br> -The more usual way of laying out a curve is to work directly upon the<br> -two axes. On one is laid off the series of values of one set of data; on<br> -the other the corresponding series of values of the other dependent<br> -data. Vertical lines or ordinates, q. v., are erected on the horizontal<br> -line or axis of abscissas at the points laid off; horizontal lines or<br> -abscissas, q. v., are drawn from the points laid off on the vertical<br> -line or axis of ordinates. The characteristic curve is determined by the<br> -intersections of each corresponding pair of abscissa and ordinate.<br> -<br> -<br> -169 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Variations exist in characteristic curve methods. Thus to get the<br> -characteristic of a commutator, radial lines may be drawn from a circle<br> -representing its perimeter. Such lines may be of length proportional to<br> -the voltage developed on the commutator at the points whence the lines<br> -start. A cut giving an example of such a curve is given in Fig. 125.<br> -(See Curve of Distribution of Potential in Armature.)<br> -<br> -There is nothing absolute in the use of ordinates or abscissas. They may<br> -be interchanged. Ordinarily voltages are laid off as ordinates, but the<br> -practise may be reversed. The same liberty holds good for all<br> -characteristic curves. Custom, however, should be followed.<br> -<br> -Synonym--Characteristic.<br> -<br> -<br> -<img style="width: 593px; height: 381px;" alt="" - src="images/169F120.jpg"><br> -Fig. 120. CHARACTERISTIC CURVE OF A DYNAMO <br> -WITH HORSE POWER CURVES.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Curve, Characteristic, of Converter.</span><br> -The characteristic curve of the secondary circuit of an alternating<br> -current converter. It gives by the usual methods (see Curve,<br> -Characteristic,) the relations between the electro-motive force and the<br> -current in the secondary circuit at a fixed resistance. If connected in<br> -parallel a constant electro-motive force is maintained, and the curve is<br> -virtually a straight line. If connected in series an elliptical curve is<br> -produced.<br> -<br> -<br> -170 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Curve, Charging.</span><br> -In secondary battery manipulation, a curve indicating the increase of<br> -voltage as the charging is prolonged. The rise in voltage with the<br> -duration of the charging current is not uniform. In one case, shown in<br> -the cut, there was a brief rapid rise of about 0.1 volt; then a long<br> -slow rise for 0.15 volt; then a more rapid rise for nearly 0.40 volt,<br> -and then the curve became a horizontal line indicating a cessation of<br> -increase of voltage. The charging rate should be constant.<br> -<br> -The horizontal line is laid off in hours, the vertical in volts, so that<br> -the time is represented by abscissas and the voltage by ordinates of the<br> -curve.<br> -<br> -<br> -<img style="width: 643px; height: 388px;" alt="" - src="images/170F121.jpg"><br> -Fig. 121. CHARGING CURVE OF A SECONDARY BATTERY.<br> -<br> -<br> -<span style="font-weight: bold;">Curve, Discharging.</span><br> -A characteristic curve of a storage battery, indicating the fall in<br> -voltage with hours of discharge. The volts may be laid off on the axis<br> -of ordinates, and the hours of discharging on the axis of abscissas. To<br> -give it meaning the rate of discharge must be constant.<br> -<br> -<br> -<span style="font-weight: bold;">Curve, Electro-motive Force.</span><br> -A characteristic curve of a dynamo. It expresses the relation between<br> -its entire electromotive force, as calculated by Ohm's Law, and the<br> -current intensities corresponding thereto. To obtain the data the dynamo<br> -is driven with different resistances in the external circuit and the<br> -current is measured for each resistance. This gives the amperes. The<br> -total resistance of the circuit, including that of the dynamo, is known.<br> -By Ohm's Law the electro-motive force in volts is obtained for each case<br> -by multiplying the total resistance of the circuit in ohms by the<br> -amperes of current forced through such resistance. Taking the voltages<br> -thus calculated for ordinates and the corresponding amperages for<br> -abscissas the curve is plotted. An example is shown in the cut.<br> -<br> -<br> -171 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Curve, External Characteristic.</span><br> -A characteristic curve of a dynamo, corresponding to the electro-motive<br> -force curve, except that the ordinates represent the voltages of the<br> -external circuit, the voltages as taken directly from the terminals of<br> -the machine, instead of the total electro-motive force of the circuit.<br> -The dynamo is run at constant speed. The resistance of the external<br> -circuit is varied. The voltages at the terminals of the machine and the<br> -amperages of current corresponding thereto are determined. Using the<br> -voltages thus determined as ordinates and the corresponding amperages as<br> -abscissas the external characteristic curve is plotted.<br> -<br> -This curve can be mechanically produced. A pencil may be moved against a<br> -constant force by two electro-magnets pulling at right angles to each<br> -other. One must be excited by the main current of the machine, the other<br> -by a shunt current from the terminals of the machine. The point of the<br> -pencil will describe the curve.<br> -<br> -<br> -<img style="width: 644px; height: 649px;" alt="" - src="images/171F122.jpg"><br> -Fig. 122. CHARACTERISTIC CURVE OF A DYNAMO.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Curve, Horse Power.</span><br> -Curves indicating electric horse power. They are laid out with<br> -co-ordinates, volts being laid off on the axis of ordinates, and amperes<br> -on the axis of abscissas generally. The curves are drawn through points<br> -where the product of amperes by volts equals 746. On the same diagram 1,<br> -2, 3 .... and any other horse powers can be plotted if within the<br> -limits. See Fig. 120.<br> -<br> -<br> -<span style="font-weight: bold;">Curve, Isochasmen.</span><br> -A line drawn on the map of the earth's surface indicating the locus of<br> -equal frequency of auroras.<br> -<br> -<br> -172 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Curve, Life.</span><br> -A characteristic curve showing the relations between the durability and<br> -conditions affecting the same in any appliance. It is used most for<br> -incandescent lamps. The hours of burning before failure give ordinates,<br> -and the rates of burning, expressed indirectly in volts or in<br> -candle-power, give abscissas. For each voltage or for each candle-power<br> -an average duration is deducible from experience, so that two dependent<br> -sets of data are obtained for the construction of the curve.<br> -<br> -<br> -<span style="font-weight: bold;">Curve, Load.</span><br> -A characteristic curve of a dynamo, expressing the relation between its<br> -voltage and the amount of excitation under a definite condition of<br> -ampere load, at a constant speed. The ordinates represent voltage, the<br> -abscissas ampere turns in the field, and the curves may be constructed<br> -for a flow of 0, 50, 100, or .. , or any other number of amperes.<br> -<br> -<br> -<img style="width: 643px; height: 433px;" alt="" - src="images/172F123.jpg"><br> -Fig. 123. LOAD CURVES.<br> -<br> -<br> -<span style="font-weight: bold;">Curve, Magnetization.</span><br> -A characteristic curve of an electromagnet, indicating the relation of<br> -magnetization to exciting current. Laying off on the axis of ordinates<br> -the quantities of magnetism evoked, and the corresponding strengths of<br> -the exciting current on the axis of abscissas, the curve can be plotted.<br> -It first rises rapidly, indicating a rapid increase of magnetization,<br> -but grows nearly horizontal as the iron becomes more saturated. The<br> -effect due to the coils alone, or the effect produced in the absence of<br> -iron is a straight line, because air does not change in permeability.<br> -<br> -<br> -<span style="font-weight: bold;">Curve of Distribution of Potential in -Armature.</span><br> -A characteristic curve indicating the distribution of potential<br> -difference between adjoining sections of the commutator of an armature<br> -in different positions all around it. The potential differences are<br> -taken by a volt-meter or potential galvanometer, connection with the<br> -armature being made by two small metal brushes, held at a distance apart<br> -equal to the distance from centre to centre of two adjoining commutator<br> -bars. The curve is laid out as if by polar co-ordinates extending around<br> -the cross-section of the commutator, with the distances from the<br> -commutator surface to the curve proportional to the potential<br> -differences as determined by shifting the pair of brushes all around the<br> -commutator.<br> -<br> -The above is S. P. Thompson's method. Another method of W. M. Mordey<br> -involves the use of a pilot brush. (See Brush, Pilot.) Otherwise the<br> -method is in general terms identical with the above.<br> -<br> -<br> -173 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 587px; height: 514px;" alt="" - src="images/173F124.jpg"><br> -Fig. 124. MAGNETIZATION CURVE.<br> -<br> -<br> -<img style="width: 726px; height: 272px;" alt="" - src="images/173F125_126.jpg"><br> -Fig. 125. ARMATURE: CURVE.<br> -<br> -Fig. 126. DEVELOPMENT OF ARMATURE CURVE.<br> -<br> -<br> -<span style="font-weight: bold;">Curve of Dynamo.</span><br> -The characteristic curve of a dynamo. (See Curve, Characteristic.)<br> -<br> -<br> -<span style="font-weight: bold;">Curve of Sines.</span><br> -An undulating curve representing wave motion. It is produced by<br> -compounding a simple harmonic motion, or a two and fro motion like that<br> -of an infinitely long pendulum with a rectilinear motion. Along a<br> -horizontal line points may be laid off to represent equal periods of<br> -time. Then on each point a perpendicular must be erected. The length of<br> -each must be equal to the length of path traversed by the point up to<br> -the expiration of each one of the given intervals of time. The abscissas<br> -are proportional to the times and the ordinates to the sines of angles<br> -proportional to the times. Thus if a circle be drawn upon the line and<br> -divided into thirty-two parts of equal angular value, the sines of these<br> -angles may be taken as the ordinates and the absolute distance or length<br> -of arc of the angle will give the abscissas.<br> -<br> -Synonyms--Sine Curve--Sinusoidal Curve--Harmonic Curve.<br> -<br> -<br> -<img style="width: 636px; height: 263px;" alt="" - src="images/174F127.jpg"><br> -Fig. 127. CURVE OF SINES.<br> -<br> -<br> -174 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Curve of Saturation of the Magnetic -Circuit.</span><br> -A characteristic curve whose ordinates may represent the number of<br> -magnetic lines of force induced in a magnetic circuit, and whose<br> -abscissas may represent the ampere turns of excitation or other<br> -representative of the inducing force.<br> -<br> -<span style="font-weight: bold;">Curve of Torque.</span><br> -A characteristic curve showing the relations between torque, q. v., and<br> -current in a dynamo or motor.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Curve, Permeability Temperature.</span><br> -A characteristic curve expressing the changes in permeability of a<br> -paramagnetic substance as the temperature changes. The degrees of<br> -temperature may be abscissas, and the permeabilities corresponding<br> -thereto ordinates of the curve.<br> -<br> -<br> -<span style="font-weight: bold;">Cut In. v.</span><br> -To connect any electric appliance, mechanism or conductor, into a<br> -circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Cut Out. v.</span><br> -The reverse of to cut in; to remove from a circuit any conducting<br> -device, and sometimes so arranged as to leave the circuit completed in<br> -some other way.<br> -<br> -<br> -<span style="font-weight: bold;">Cut Out.</span><br> -An appliance for removing any apparatus from an electric circuit, so<br> -that no more current shall pass through such apparatus, and sometimes<br> -providing means for closing the circuit so as to leave it complete after<br> -the removal of the apparatus.<br> -<br> -<br> -175 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Cut Out, Automatic.</span><br> -(a) A mechanism for automatically shunting an arc or other lamp when it<br> -ceases to work properly. It is generally worked by an electro-magnet of<br> -high resistance placed in parallel with the arc. If the arc grows too<br> -long the magnet attracts its armature, thereby completing a shunt of<br> -approximately the resistance of the arc, and which replaces it until the<br> -carbons approach again to within a proper distance. Sometimes a strip or<br> -wire of fusible metal is arranged in shunt with the arc. When the arc<br> -lengthens the current through the wire increases, melts it and a spring<br> -is released which acts to complete or close a shunt circuit of<br> -approximately arc-resistance.<br> -<br> -(b) See Safety Device--Safety Fuse.<br> -<br> -(c) See below.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Cut-out, Magnetic.</span><br> -A magnetic cut-out is essentially a coil of wire with attracted core or<br> -armature. When the coil is not excited the core, by pressing down a<br> -strip of metal or by some analogous arrangement, completes the circuit.<br> -When the current exceeds a certain strength the core rises as it is<br> -attracted and the circuit is opened.<br> -<br> -<br> -<span style="font-weight: bold;">Cut-out, Safety.</span><br> -A block of porcelain or other base carrying a safety fuse, which melts<br> -and breaks the circuit before the wire connected to it is dangerously<br> -heated.<br> -<br> -Synonyms--Fuse Block--Safety Catch--Safety Fuse.<br> -<br> -<br> -<span style="font-weight: bold;">Cut Out, Wedge.</span><br> -A cut out operated by a wedge. The line terminals consist of a spring<br> -bearing against a plate, the circuit being completed through their point<br> -of contact. A plug or wedge composed of two metallic faces insulated<br> -from each other is adapted to wedge the contact open. Terminals of a<br> -loop circuit are connected to the faces of the wedge. Thus on sliding it<br> -into place, the loop circuit is brought into series in the main circuit.<br> -<br> -Synonym--Plug Cut Out--Spring Jack.<br> -<br> -<br> -<span style="font-weight: bold;">Cutting of Lines of Force.</span><br> -A field of force is pictured as made up of lines of force; a conductor<br> -swept through the field is pictured as cutting these lines. By so doing<br> -it produces potential difference or electro-motive force in itself with<br> -a current, if the conductor is part of a closed circuit.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Cycle of Alternation.</span><br> -A full period of alternation of an alternating current. It begins<br> -properly at the zero line, goes to a maximum value in one sense and<br> -returns to zero, goes to maximum in the other sense and returns to zero.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Cystoscopy.</span><br> -Examination of the human bladder by the introduction of a special<br> -incandescent electric lamp. The method is due to Hitze.<br> -</big></big><big><big><br> -</big></big><big><big><br> -176 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Damper.</span><br> -(a) A copper frame on which the wire in a galvanometer is sometimes<br> -coiled, which acts to damp the oscillations of the needle.<br> -<br> -(b) A tube of brass or copper placed between the primary and secondary<br> -coils of an induction coil. It cuts off induction and diminishes the<br> -current and potential of the secondary circuit. On pulling it out, the<br> -latter increases. It is used on medical coils to adjust their strength<br> -of action.<br> -<br> -<br> -<span style="font-weight: bold;">Damping.</span><br> -Preventing the indicator of an instrument from oscillating in virtue of<br> -its own inertia or elasticity. In a galvanometer it is defined as<br> -resistance to quick vibrations of the needle, in consequence of which it<br> -is rapidly brought to rest when deflected (Ayrton). In dead-beat<br> -galvanometers (see Galvanometer, Dead-Beat,) damping is desirable in<br> -order to bring the needle to rest quickly; in ballistic galvanometers<br> -(see Galvanometer, Ballistic,) damping is avoided in order to maintain<br> -the principle of the instrument. Damping may be mechanical, the<br> -frictional resistance of air to an air-vane, or of a liquid to an<br> -immersed diaphragm or loosely fitting piston, being employed. A<br> -dash-pot, q. v., is an example of the latter. It may be<br> -electro-magnetic. A mass of metal near a swinging magnetic needle tends<br> -by induced currents to arrest the oscillations thereof, and is used for<br> -this purpose in dead-beat galvanometers. This is termed, sometimes,<br> -magnetic friction. The essence of damping is to develop resistance to<br> -movement in some ratio proportional to velocity, so that no resistance<br> -is offered to the indicator slowly taking its true position. (See<br> -Galvanometer, Dead-Beat.)<br> -<br> -<br> -<span style="font-weight: bold;">Dash-Pot.</span><br> -A cylinder and piston, the latter loosely fitting or perforated, or some<br> -equivalent means being provided to permit movement. The cylinder may<br> -contain a liquid such as glycerine, or air only. Thus the piston is<br> -perfectly free to move, but any oscillations are damped (see Damping).<br> -In some arc lamps the carbon holder is connected to a dash-pot to check<br> -too sudden movements of the carbon. The attachment may be either to the<br> -piston or to the cylinder. In the Brush lamp the top of the carbon<br> -holder forms a cylinder containing glycerine, and in it a loosely<br> -fitting piston works. This acts as a dash-pot.<br> -<br> -<br> -<span style="font-weight: bold;">Dead Beat. adj.</span><br> -Reaching its reading quickly; applied to instruments having a moving<br> -indicator, which normally would oscillate back and forth a number of<br> -times before reaching its reading were it not prevented by damping. (See<br> -Galvanometer, Aperiodic--Damping.)<br> -<br> -<br> -<span style="font-weight: bold;">Dead Earth.</span><br> -A fault in a telegraph line which consists in the wire being thoroughly<br> -grounded or connected to the earth.<br> -<br> -<br> -177 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Dead Point of an Alternator.</span><br> -A two-phase alternator of the ordinary type connected as a motor to<br> -another alternator cannot start itself, as it has dead points where the<br> -relations and polarity of field and armature are such that there is no<br> -torque or turning power.<br> -<br> -<br> -<span style="font-weight: bold;">Dead-Turns.</span><br> -In the winding of an armature, a given percentage of the turns, it may<br> -be 80 per cent., more or less, is assumed to be active; the other 20 per<br> -cent. or thereabouts, is called dead-turns. This portion represents the<br> -wire on such portions of the armature as comes virtually outside of the<br> -magnetic field. They are termed dead, as not concurring to the<br> -production of electro-motive force.<br> -<br> -<br> -<span style="font-weight: bold;">Dead Wire.</span><br> -(a) The percentage or portion of wire on a dynamo or motor armature that<br> -does not concur in the production of electromotive force. The<br> -dead-turns, q. v., of a drum armature or the inside wire in a Gramme<br> -ring armature are dead wire.<br> -<br> -(b) A disused and abandoned electric conductor, such as a telegraph<br> -wire.<br> -<br> -(c) A wire in use, but through which, at the time of speaking, no<br> -current is passing.<br> -<br> -<br> -<span style="font-weight: bold;">Death, Electrical.</span><br> -Death resulting from electricity discharged through the animal system.<br> -The exact conditions requisite for fatal results have not been<br> -determined. High electro-motive force is absolutely essential; a<br> -changing current, pulsatory or alternating, is most fatal, possibly<br> -because of the high electro-motive force of a portion of each period.<br> -Amperage probably has something to do with it, although the total<br> -quantity in coulombs may be very small. As applied to the execution of<br> -criminals, the victim is seated in a chair and strapped thereto. One<br> -electrode with wet padded surface is placed against his head or some<br> -adjacent part. Another electrode is placed against some of the lower<br> -parts, and a current from an alternating dynamo passed for 15 seconds or<br> -more. The potential difference of the electrodes is given at 1,500 to<br> -2,000 volts, but of course the maximum may be two or three times the<br> -measured amount, owing to the character of the current.<br> -<br> -<br> -<span style="font-weight: bold;">Decalescence.</span><br> -The converse of recalescence, q. v. When a mass of steel is being heated<br> -as it reaches the temperature of recalescence it suddenly absorbs a<br> -large amount of heat, apparently growing cooler.<br> -<br> -<br> -<span style="font-weight: bold;">Deci.</span><br> -Prefix originally used in the metric system to signify one-tenth of, now<br> -extended to general scientific units. Thus decimeter means one-tenth of<br> -a meter; decigram, one-tenth of a gram.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Declination, Angle of.</span><br> -The angle intercepted between the true meridian and the axis of a<br> -magnetic needle at any place. The angle is measured to east or west,<br> -starting from the true meridian as zero.<br> -<br> -<br> -178 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Declination of the Magnetic Needle.</span><br> -The deviation of the magnetic needle from the plane of the earth's<br> -meridian. It is also called the variation of the compass. (See Magnetic<br> -Elements.)<br> -<br> -<br> -<span style="font-weight: bold;">Decomposition.</span><br> -The reduction of a compound substance into its constituents, as in<br> -chemical analysis. The constituents may themselves be compounds or<br> -proximate constituents, or may be elemental or ultimate constituents.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Decomposition, Electrolytic.</span><br> -The decomposition or separation of a compound liquid into its<br> -constituents by electrolysis. The liquid must be an electrolyte, q. v.,<br> -and the decomposition proceeds subject to the laws of electrolysis, q.<br> -v. See also Electrolytic Analysis.<br> -<br> -<br> -<span style="font-weight: bold;">Decrement.</span><br> -When a suspension needle which has been disturbed is oscillating the<br> -swings gradually decrease in amplitude if there is any damping, as there<br> -always is. The decrement is the ratio of the amplitude of one<br> -oscillation to the succeeding one. This ratio is the same for any<br> -successive swings.<br> -<br> -<br> -<span style="font-weight: bold;">De-energize.</span><br> -To cut off its supply of electric energy from an electric motor, or any<br> -device absorbing and worked by electric energy.<br> -<br> -<br> -<span style="font-weight: bold;">Deflagration.</span><br> -The explosive or violent volatilizing and dissipating of a substance by<br> -heat, violent oxidation and similar means. It may be applied among other<br> -things to the destroying of a conductor by an intense current, or the<br> -volatilization of any material by the electric arc.<br> -<br> -<br> -<span style="font-weight: bold;">Deflecting Field.</span><br> -The field produced in a galvanometer by the current which is being<br> -tested, and which field deflects the needle, such deflection being the<br> -measure of the current strength.<br> -<br> -<br> -<span style="font-weight: bold;">Deflection.</span><br> -In magnetism the movement out of the plane of the magnetic meridian of a<br> -magnetic needle, due to disturbance by or attraction towards a mass of<br> -iron or another magnet.<br> -<br> -<br> -<span style="font-weight: bold;">Deflection Method.</span><br> -The method of electrical measurements in which the deflection of the<br> -index of the measuring instrument is used as the measure of the current<br> -or other element under examination. It is the opposite of and is to be<br> -distinguished from the zero or null method, q. v. In the latter<br> -conditions are established which make the index point to zero and from<br> -the conditions necessary for this the measurement is deduced. The<br> -Wheatstone Bridge, q. v., illustrates a zero method, the sine or the<br> -tangent compass, illustrates a deflection method. The use of deflection<br> -methods involves calibration, q. v., and the commercial measuring<br> -instruments, such as ammeters and volt meters, which are frequently<br> -calibrated galvanometers, are also examples of deflection instruments.<br> -<br> -<br> -179 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Degeneration, Reaction of.</span><br> -The diminished sensibility to electro-therapeutic treatment exhibited by<br> -the human system with continuance of the treatment in question. The<br> -general lines of variation are stated in works on the subject.<br> -<br> -<br> -<span style="font-weight: bold;">Deka.</span><br> -Prefix originally used in the metric system to signify multiplying by<br> -ten, as dekameter, ten meters, dekagram, ten grams; now extended to many<br> -scientific terms.<br> -<br> -<br> -<span style="font-weight: bold;">De la Rive's Floating Battery.</span><br> -A small galvanic couple, immersed in a little floating cell and<br> -connected through a coil of wire immediately above them. When the<br> -exciting battery solution is placed in the cell the whole, as it floats<br> -in a larger vessel, turns until the coil lies at right angles to the<br> -magnetic needle. Sometimes the two plates are thrust through a cork and<br> -floated thus in a vessel of dilute sulphuric acid.<br> -<br> -A magnet acts to attract or repel the coil in obedience to -Ampére's<br> -Theory, (See Magnetism, Ampere's Theory of.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Delaurier's Solution.</span><br> -A solution for batteries of the Bunsen and Grenet type. It is of the<br> -following composition:<br> - <span style="font-family: monospace;">Water, -2,000 parts;</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> potassium -bichromate, 184 parts;</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> sulphuric -acid, 428 parts.</span><br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Demagnetization.</span><br> -Removal of magnetism from a paramagnetic substance. It is principally<br> -used for watches which have become magnetized by exposure to the<br> -magnetic field surrounding dynamos or motors.<br> -<br> -The general principles of most methods are to rotate the object, as a<br> -watch, in a strong field, and while it is rotating to gradually remove<br> -it from the field, or to gradually reduce the intensity of the field<br> -itself to zero. A conical coil of wire within which the field is<br> -produced in which the watch is placed is sometimes used, the idea being<br> -that the field within such a coil is strongest at its base. Such a coil<br> -supplied by an alternating current is found effectual (J. J. Wright).<br> -<br> -If a magnetized watch is made to turn rapidly at the end of a twisted<br> -string and is gradually brought near to and withdrawn from the poles of<br> -a powerful dynamo it may be considerably improved.<br> -<br> -A hollow coil of wire connected with a pole changer and dip-battery has<br> -been used. The battery creates a strong field within the coil. The watch<br> -is placed there and the pole changer is worked so as to reverse the<br> -polarity of the field very frequently. By the same action of the pole<br> -changer the plates of the battery are gradually withdrawn from the<br> -solution so as to gradually reduce the magnetic field to zero while<br> -constantly reversing its polarity. (G. M. Hopkins.)<br> -<br> -Steel may be demagnetized by jarring when held out of the magnetic<br> -meridian, or by heating to redness.<br> -<br> -<br> -180 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Density, Electric Superficial.</span><br> -The relative quantity of electricity residing as an electric charge upon<br> -a unit area of surface. It may be positive or negative.<br> -<br> -Synonyms--Density of Charge--Surface Density.<br> -<br> -<br> -<span style="font-weight: bold;">Dental Mallet, Electric.</span><br> -A dentist's instrument for hammering the fillings as inserted into<br> -teeth. It is a little hammer held in a suitable handle, and which is<br> -made to strike a rapid succession of blows by electro-magnetic motor<br> -mechanism.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Depolarization.</span><br> -(a) The removal of permanent magnetism. (See Demagnetization.)<br> -<br> -(b) The prevention of the polarization of a galvanic cell. It is<br> -effected in the Grove battery by the reduction of nitric acid; in the<br> -Bunsen, by the reduction of chromic acid; in the Smee battery,<br> -mechanically, by the platinum coated or rather platinized negative<br> -plate. Other examples will be found under the description of various<br> -cells and batteries. A fluid which depolarizes is termed a depolarizer<br> -or depolarizing fluid or solution. (See Electropoion Fluid.)<br> -<br> -<br> -<span style="font-weight: bold;">Deposit, Electrolytic.</span><br> -The metal or other substance precipitated by the action of a battery or<br> -other current generator.<br> -<br> -<br> -<span style="font-weight: bold;">Derivation, Point of.</span><br> -A point where a circuit branches or divides into two or more leads. The<br> -separate branches then receive derived or partial currents.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Desk Push.</span><br> -A press or push button, with small flush rim, for setting into the<br> -woodwork of a desk.<br> -<br> -<br> -<span style="font-weight: bold;">Detector.</span><br> -A portable galvanometer, often of simple construction, used for rough or<br> -approximate work.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Detector, Lineman's.</span><br> -A portable galvanometer with a high and a low resistance actuating coil,<br> -constructed for the use of linemen and telegraph constructors when in<br> -the field, and actually putting up, repairing or testing lines.<br> -<br> -<br> -<span style="font-weight: bold;">Deviation, Quadrantal.</span><br> -Deviation of the compass in iron or steel ships due to the magnetization<br> -of horizontal beams by the earth's induction. The effect of this<br> -deviation disappears when the ship is in the plane of the electric<br> -meridian, or at right angles thereto; its name is taken from the fact<br> -that a swing of the ship through a quadrant brings the needle from zero<br> -deviation to a maximum and back to zero.<br> -<br> -<br> -181 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Deviation, Semicircular.</span><br> -Deviation of the compass in iron or steel ships due to vertical<br> -induction. (See Induction, Vertical.) The effect of this induction<br> -disappears when the ship is in the electric meridian. Its name is<br> -derived from the fact that a swing of the ship through half the circle<br> -brings the needle from zero deviation to a maximum and back to zero.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Dextrotorsal. adj.</span><br> -Wound in the direction or sense of a right-handed screw; the reverse of<br> -sinistrotorsal, q. v.<br> -<br> -<br> -<img style="width: 660px; height: 112px;" alt="" - src="images/181F128.jpg"><br> -Fig. 128. DEXTROTORSAL HELIX.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Diacritical. adj.</span><br> -(a) The number of ampere turns, q. v., required to bring an iron core to<br> -one half its magnetic saturation, q. v., is termed the diacritical<br> -number.<br> -<br> -(b) The diacritical point of magnetic saturation is proposed by Sylvanus<br> -P. Thompson as a term for the coefficient of magnetic saturation which<br> -gives a magnet core one-half its maximum magnetization.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Diagnosis, Electro.</span><br> -A medical diagnosis of a patient's condition based on the action of<br> -different parts of the body under electric excitement.<br> -<br> -<br> -<span style="font-weight: bold;">Diamagnetic. adj.</span><br> -Possessing a negative coefficient of magnetic susceptibility; having<br> -permeability inferior to that of air. Such substances placed between the<br> -poles of a magnet are repelled; if in the form of bars, they tend to<br> -turn so as to have their long axis at right angles to the line joining<br> -the poles. The reason is that the lines of force always seek the easiest<br> -path, and these bodies having higher reluctance than air, impede the<br> -lines of force, and hence are as far as possible pushed out of the way.<br> -The above is the simplest explanation of a not well understood set of<br> -phenomena. According to Tyndall, "the diamagnetic force is a polar<br> -force, the polarity of diamagnetic bodies being opposed to that of<br> -paramagnetic ones under the same conditions of excitement." Bismuth is<br> -the most strongly diamagnetic body known; phosphorus, antimony, zinc,<br> -and many others are diamagnetic. (See Paramagnetic.)<br> -<br> -<br> -182 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Diagometer.</span><br> -An apparatus for use in chemical analysis for testing the purity of<br> -substances by the time required for a charged surface to be discharged<br> -through them to earth. It is the invention of Rousseau.<br> -<br> -An electrometer is charged with a dry pile. One of its terminals is<br> -connected with one surface of the solution or substance to be tested,<br> -and the other with the other surface. The time of discharge gives the<br> -index of the purity of the substance.<br> -<br> -<br> -<span style="font-weight: bold;">Diamagnetic Polarity.</span><br> -Treating diamagnetism as due to a polar force, the polarity of a<br> -diamagnetic body is the reverse of the polarity of iron or other<br> -paramagnetic bodies. A bar-shaped diamagnetic body in a field of force<br> -tends to place itself at right angles to the lines of force.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Diamagnetism.</span><br> -(a) The science or study of diamagnetic substances and phenomena.<br> -<br> -(b) The magnetic property of a diamagnetic substance.<br> -<br> -<br> -<span style="font-weight: bold;">Diameter of Commutation.</span><br> -The points on the commutator of a closed circuit ring--or<br> -drum--armature, which the brushes touch, and whence they take the<br> -current, mark the extremities of the diameter of commutation. Were it<br> -not for the lag this would be the diameter at right angles to the line<br> -connecting the centers of the opposite faces of the field. It is always<br> -a little to one side of this position, being displaced in the direction<br> -of rotation. In open circuit armatures the brushes are placed on the<br> -diameter at right angles to this one, and sometimes the term diameter of<br> -commutation is applied to it. All that has been said is on the<br> -supposition that the armature divisions correspond not only in<br> -connection but in position with those of the armature coils. Of course,<br> -the commutator could be twisted so as to bring the diameter of<br> -commutation into any position desired.<br> -<br> -<br> -<span style="font-weight: bold;">Diapason, Electric.</span><br> -A tuning-fork or diapason kept in vibration by electricity. In general<br> -principle the ends of the fork act as armatures for an electro-magnet,<br> -and in their motion by a mercury cup or other form of contact they make<br> -and break the circuit as they vibrate. Thus the magnet alternately<br> -attracts and releases the leg, in exact harmony with its natural period<br> -of vibration.<br> -<br> -<br> -<span style="font-weight: bold;">Diaphragm.</span><br> -(a) In telephones and microphones a disc of iron thrown into motion by<br> -sound waves or by electric impulses, according to whether it acts as the<br> -diaphragm of a transmitter or receiver. It is generally a plate of<br> -japanned iron such as used in making ferrotype photographs. (See<br> -Telephone and Microphone.)<br> -<br> -(b) A porous diaphragm is often used in electric decomposition cells and<br> -in batteries. The porous cup represents the latter use.<br> -<br> -[Transcriber's note: Japanned--covered with heavy black lacquer, like<br> -enamel paint.]<br> -<br> -<br> -183 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Dielectric.</span><br> -A non-conductor; a substance, the different parts of which may, after an<br> -electric disturbance, remain, without any process of readjustment, and<br> -for an indefinite period of time, at potentials differing to any extent<br> -(Daniell). There is no perfect dielectric. The term dielectric is<br> -generally only used when an insulator acts to permit induction to take<br> -place through it, like the glass of a Leyden jar.<br> -<br> -<br> -<span style="font-weight: bold;">Dielectric Constant.</span><br> -The number or coefficient expressing the relative dielectric capacity of<br> -a medium or substance. (See Capacity, Specific Inductive.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Dielectric, Energy of.</span><br> -In a condenser, the conducting coatings are merely to conduct the<br> -current all over the surface they cover; the keeping the electricities<br> -separated is the work of the dielectric, and represents potential energy<br> -which appears in the discharge. The amount of energy is proportional to<br> -the charge, and to the potential difference. As any electrified body<br> -implies an opposite electrification somewhere, and a separating<br> -dielectric, the existence of a condenser is always implied.<br> -<br> -[Transcriber's note: The energy stored in a capacitor (condenser) is<br> -(Q*Q)/2C = (Q*V)/2 = (C*V*V)/2<br> -The energy is proportional to the voltage SQUARED or the charge -SQUARED.]<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Dielectric Polarization.</span><br> -A term due to Faraday. It expresses what he conceived to be the<br> -condition of a dielectric when its opposite faces are oppositely<br> -electrified. The molecules are supposed to be arranged by the<br> -electrification in a series of polar chains, possibly being originally<br> -in themselves seats of opposite polarities, or having such imparted to<br> -them by the electricities. The action is analogous to that of a magnet<br> -pole on a mass of soft iron, or on a pile of iron filings.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Dielectric Strain.</span><br> -The strain a solid dielectric is subjected to, when its opposite<br> -surfaces are electrified. A Leyden jar dilates under the strain, and<br> -when discharged gives a dull sound. The original condition is not<br> -immediately recovered. Jarring, shaking, etc., assist the recovery from<br> -strain. The cause of the strain is termed Electric Stress. (See Stress,<br> -Electric.) This is identical with the phenomenon of residual charge.<br> -(See Charge, Residual.) Each loss of charge is accompanied with a<br> -proportional return of the dielectric towards its normal condition.<br> -<br> -<br> -<span style="font-weight: bold;">Dielectric Resistance.</span><br> -The mechanical resistance a body offers to perforation or destruction by<br> -the electric discharge.<br> -<br> -<br> -<span style="font-weight: bold;">Dielectric Strength.</span><br> -The resistance to the disruptive discharge and depending on its<br> -mechanical resistance largely or entirely. It is expressible in volts<br> -per centimeter thickness. Dry air requires 40,000 volts per centimeter<br> -for a discharge.<br> -<br> -<br> -184 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Differential Winding Working.</span><br> -A method of working an electro-magnet intermittently, so as to avoid<br> -sparking. The magnet is wound with two coils. One is connected straight<br> -into the circuit, the other is connected in parallel therewith with a<br> -switch inserted. The coils are so connected that when the switch is<br> -closed the two are in opposition, the current going through them in<br> -opposite senses. Thus one overcomes the effect of the other and the<br> -magnet core shows no magnetism, provided the two coils are of equal<br> -resistance and equal number of convolutions or turns.<br> -<br> -<br> -<img style="width: 642px; height: 211px;" alt="" - src="images/184F129.jpg"><br> -Fig. 129. DIFFERENTIAL WINDING WORKING <br> -OF ELECTRO-MAGNETIC APPARATUS.<br> -<br> -<br> -<span style="font-weight: bold;">Diffusion.</span><br> -A term properly applied to the varying current density found in<br> -conductors of unequal cross sectional area. In electro-therapeutics it<br> -is applied to the distribution of current as it passes through the human<br> -body. Its density per cross-sectional area varies with the area and<br> -with the other factors.<br> -<br> -<br> -<span style="font-weight: bold;">Diffusion Creep.</span><br> -When electrodes of an active circuit are immersed in a solution of an<br> -electrolyte, a current passes electrolytically if there is a sufficient<br> -potential difference. The current passes through all parts of the<br> -solution, spreading out of the direct prism connecting or defined by the<br> -electrodes. To this portion of the current the above term is applied. If<br> -the electrodes are small enough in proportion to the distance between<br> -them the current transmission or creep outside of the line becomes the<br> -principal conveyor of the current so that the resistance remains the<br> -same for all distances.<br> -<br> -<br> -<span style="font-weight: bold;">Dimensions and Theory of Dimensions.</span><br> -The expression of the unitary value of a physical quantity in one or<br> -more of the units of length (L), time (T) and mass (M) is termed the<br> -dimensions of such quantity. Thus the dimension or dimensions of a<br> -distance is simply L; of an angle, expressible by dividing the arc by<br> -the radius is L/L; of a velocity, expressible by distance divided by<br> -time--L/T; of acceleration, which is velocity acquired in a unit of<br> -time, and is therefore expressible by velocity divided by time--L/T/T or<br> -L/T2; of momentum, which is the product of mass into velocity--M*L/T; of<br> -kinetic energy taken as the product of mass into the square of<br> -velocity--M*(L2/T2); of potential energy taken as the product of mass<br> -into acceleration into space-M*(L/T2)*L reducing to M*(L2/T2). The<br> -theory is based on three fundamental units and embraces all electric<br> -quantities. The simple units generally taken are the gram, centimeter<br> -and second and the dimensions of the fundamental compound units are<br> -expressed in terms of these three, forming the centimeter-gram-second or<br> -C. G. S. system of units. Unless otherwise expressed or implied the<br> -letters L, M and T, may be taken to indicate centimeter, gram and second<br> -respectively. It is obvious that very complicated expressions of<br> -dimensions may be built up, and that a mathematical expression of<br> -unnamed quantities may be arrived at. Dimensions in their application by<br> -these symbols are subject to the laws of algebra. They were invented by<br> -Fourier and were brought into prominence by J. Clerk Maxwell. Another<br> -excellent definition reads as follows: "By the dimensions of a physical<br> -quantity we mean the quantities and powers of quantities, involved in<br> -the measurement of it." (W. T. A. Emtage.)<br> -<br> -<br> -185 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Dimmer.</span><br> -An adjustable choking coil used for regulating the intensity of electric<br> -incandescent lights. Some operate by the introduction and withdrawal of<br> -an iron core as described for the choking coil (see Coil, Choking),<br> -others by a damper of copper, often a copper ring surrounding the coil<br> -and which by moving on or off the coil changes the potential of the<br> -secondary circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Dip of Magnetic Needle.</span><br> -The inclination of the magnetic needle. (See Elements, Magnetic.)<br> -<br> -<br> -<span style="font-weight: bold;">Dipping.</span><br> -(a) Acid or other cleaning processes applied by dipping metals in<br> -cleaning or pickling solutions before plating in the electroplater's<br> -bath.<br> -<br> -(b) Plating by dipping applies to electroplating without a battery by<br> -simple immersion. Copper is deposited on iron from a solution of copper<br> -sulphate in this way.<br> -<br> -Synonym--Simple Immersion.<br> -<br> -<br> -<span style="font-weight: bold;">Dipping Needle.</span><br> -A magnet mounted in horizontal bearings at its centre of gravity. Placed<br> -in the magnetic meridian it takes the direction of the magnetic lines of<br> -force of the earth at that point. It is acted on by the vertical<br> -component of the earth's magnetism, as it has no freedom of horizontal<br> -movement. (See Magnetic Elements, and Compass, Inclination.)<br> -<br> -<span style="font-weight: bold;">Directing Magnet.</span><br> -In a reflecting galvanometer the magnet used for controlling the<br> -magnetic needle by establishing a field. It is mounted on the spindle of<br> -the instrument above the coil and needle.<br> -<br> -Synonym--Controlling Magnet.<br> -<br> -<br> -186 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Direction.</span><br> -(a) The direction of an electric current is assumed to be from a<br> -positively charged electrode or terminal to a negatively charged one in<br> -the outer circuit. (See Current.)<br> -<br> -(b) The direction of magnetic and electro-magnetic lines of force is<br> -assumed to be from north to south pole of a magnet in the outer circuit.<br> -It is sometimes called the positive direction. Their general course is<br> -shown in the cuts diagrammatically. The circles indicate a compass used<br> -in tracing their course. The magnetic needle tends to place itself in<br> -the direction of or tangential to the lines of force passing nearest it.<br> -<br> -(c) The direction of electrostatic lines of force is assumed to be out<br> -of a positively charged and to a negatively charged surface.<br> -<br> -<br> -<img style="width: 469px; height: 705px;" alt="" - src="images/186F130_131.jpg"><br> -Fig. 130. DIRECTION OF LINES OF FORCE OF A PERMANENT MAGNET.<br> -<br> -Fig. 131, DIRECTION OF LINES OF FORCE OF AN ELECTRO-MAGNET.<br> -<br> -<br> -187 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Directive Power.</span><br> -In magnetism the power of maintaining itself in the plane of the<br> -magnetic meridian, possessed by the magnetic needle.<br> -<br> -<br> -<span style="font-weight: bold;">Discharge, Brush.</span><br> -The static discharge of electricity into or through the air may be of<br> -the brush or spark form. The brush indicates the escape of electricity<br> -in continuous flow; the spark indicates discontinuity. The conditions<br> -necessary to the production of one or the other refer to the nature of<br> -the conductor, and of other conductors in its vicinity and to the<br> -electro-motive force or potential difference; small alterations may<br> -transform one into the other. The brush resembles a luminous core whose<br> -apex touches the conductor. It is accompanied by a slight hissing noise.<br> -Its luminosity is very feeble. The negative conductor gives a smaller<br> -brush than that of the positive conductor and discharges it more<br> -readily. When electricity issues from a conductor, remote from an<br> -oppositely excited one, it gives an absolutely silent discharge, showing<br> -at the point of escape a pale blue luminosity called electric glow, or<br> -if it escapes from points it shows a star-like centre of light. It can<br> -be seen in the dark by placing a point on the excited conductor of a<br> -static-electric machine.<br> -<br> -Synonyms--Silent Discharge--Glow Discharge.<br> -<br> -<br> -<span style="font-weight: bold;">Discharge, Conductive.</span><br> -A discharge of a static charge by conduction through a conductor.<br> -<br> -<br> -<span style="font-weight: bold;">Discharge, Convective.</span><br> -The discharge of static electricity from an excited conductor through<br> -air or rarefied gas; it is also called the quiet or silent discharge.<br> -The luminous effect in air or gas at atmospheric pressures takes the<br> -form of a little brush from a small positive electrode; the negative<br> -shows a star. The phenomena of Gassiot's cascade, the philosopher's egg<br> -and Geissler tubes, all of which may be referred to, are instances of<br> -convective discharge.<br> -<br> -<br> -<span style="font-weight: bold;">Discharge, Dead Beat.</span><br> -A discharge that is not oscillatory in character.<br> -<br> -<br> -<span style="font-weight: bold;">Discharge, Disruptive.</span><br> -A discharge of a static charge through a dielectric. It involves<br> -mechanical perforation of the dielectric, and hence the mere mechanical<br> -strength of the latter has much to do with preventing it. A disruptive<br> -discharge is often oscillatory in character; this is always the case<br> -with the discharge of a Leyden jar.<br> -<br> -<br> -188 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Discharge, Duration of.</span><br> -The problem of determining this factor has been attacked by various<br> -observers. Wheatstone with his revolving mirror found it to be 1/24000<br> -second. Fedderson, by interposing resistance, prolonged it to 14/10000<br> -and again to 138/10000 second. Lucas & Cazin made it from 26 to 47<br> -millionths of a second. All these experiments were performed with Leyden<br> -jars.<br> -<br> -<br> -<span style="font-weight: bold;">Discharge, Impulsive.</span><br> -A disruptive discharge produced between conductors by suddenly produced<br> -potential differences. The self-induction of the conductor plays an<br> -especially important part in discharges thus produced.<br> -<br> -<br> -<span style="font-weight: bold;">Discharge, Lateral.</span><br> -(a) A lightning discharge, which sometimes takes place between a<br> -lightning rod and the building on which it is.<br> -<br> -(b) In the discharge of a Leyden jar or condenser the discharge which<br> -takes the alternative path, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Discharge, Oscillatory</span>.<br> -The sudden or disruptive discharge of a static condenser, such as a<br> -Leyden jar, or of many other charged conductors, is oscillatory in<br> -character. The direction of the currents rapidly changes, so that the<br> -discharge is really an alternating current of excessively short total<br> -duration. The discharge sends electro-magnetic waves through the ether,<br> -which are exactly analogous to those of light but of too long period to<br> -affect the eye.<br> -<br> -Synonym--Surging Discharge.<br> -<br> -[Transcriber's note: Marconi's transmission across the English channel<br> -occurs in 1897, five years after the publication of this book.]<br> -<br> -<br> -<img style="width: 627px; height: 541px;" alt="" - src="images/188F132.jpg"><br> -Fig. 132. DISCHARGER.<br> -<br> -<br> -<span style="font-weight: bold;">Discharger.</span><br> -An apparatus for discharging Leyden jars. It consists of a conductor<br> -terminating in balls, and either jointed like a tongs or bent with a<br> -spring-action, so that the balls can be set at distances adapted to<br> -different sized jars. It has an insulating handle or a pair of such. In<br> -use one ball is brought near to the coating and the other to the spindle<br> -ball of the jar. When nearly or quite in contact the jar discharges.<br> -<br> -Synonyms--Discharging Rod--Discharging Tongs.<br> -<br> -<br> -189 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Discharger, Universal.</span><br> -An apparatus for exposing substances to the static discharge spark. It<br> -consists of a base with three insulating posts. The central post carries<br> -an ivory table to support the object. The two side posts carry<br> -conducting rods, terminating in metal balls, and mounted with universal<br> -joints. A violent shock can be given to any object placed on the table.<br> -<br> -Synonym--Henley's Universal Discharger.<br> -<br> -<br> -<span style="font-weight: bold;">Discharge, Silent.</span><br> -This term is sometimes applied to the glow or brush discharge and<br> -sometimes to the condition of electric effluvium. (See Discharge,<br> -Brush--Effluvium, Electric.)<br> -<br> -<br> -<span style="font-weight: bold;">Discharge, Spark.</span><br> -The discontinuous discharge of high tension electricity through a<br> -dielectric or into the air produces electric sparks. These are quite<br> -strongly luminous, of branching sinuous shape, and in long sparks the<br> -luminosity varies in different parts of the same spark. A sharp noise<br> -accompanies each spark. High density of charge is requisite for the<br> -formation of long sparks.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Disconnection.</span><br> -The separation of two parts of, or opening a circuit, as by turning a<br> -switch, unscrewing a binding screw, or the like. The term is sometimes<br> -used to indicate a class of faults in telegraph circuits. Disconnections<br> -may be total, partial or intermittent, and due to many causes, such as<br> -open or partially replaced switches, oxidized or dirty contact points,<br> -or loose joints.<br> -<br> -<br> -<span style="font-weight: bold;">Displacement, Electric.</span><br> -A conception of the action of charging a dielectric. The charge is all<br> -on the surface. This fact being granted, the theory of displacement<br> -holds that charging a body is the displacing of electricity, forcing it<br> -from the interior on to the surface, or vice versa, producing a positive<br> -or negative charge by displacement of electricity. While displacement is<br> -taking place in a dielectric there is assumed to be a movement or<br> -current of electricity called a displacement current.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Disruptive Tension.</span><br> -When the surface of a body is electrified, it tends to expand, all<br> -portions of the surface repelling each other. The film of air<br> -surrounding such a body is electrified too, and is subjected to a<br> -disruptive tension, varying in intensity with the square of the density.<br> -<br> -<br> -<span style="font-weight: bold;">Dissimulated Electricity.</span><br> -The electricity of a bound charge. (See Charge, Bound.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Dissociation.</span><br> -The separation of a chemical compound into its elements by a<br> -sufficiently high degree of heat. All compounds are susceptible of<br> -dissociation, so that it follows that combustion is impossible at high<br> -temperatures.<br> -<br> -<br> -190 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Distance, Critical, of Alternative -Path.</span><br> -The length of air gap in an alternative path whose resistance joined to<br> -the impedance of the rest of the conductors of the path just balances<br> -the impedance of the other path.<br> -<br> -<br> -<span style="font-weight: bold;">Distance, Sparking.</span><br> -The distance between electrodes, which a spark from a given Leyden jar<br> -or other source will pass across.<br> -<br> -Synonym--Explosive Distance.<br> -<br> -<br> -<span style="font-weight: bold;">Distillation.</span><br> -The evaporation of a liquid by heat, and sometimes in a vacuum, followed<br> -by condensation of the vapors, which distil or drop from the end of the<br> -condenser. It is claimed that the process is accelerated by the liquid<br> -being electrified.<br> -<br> -<br> -<span style="font-weight: bold;">Distributing Box.</span><br> -In an electric conduit system, a small iron box provided for giving<br> -access to the cable for the purpose of making house and minor<br> -connections.<br> -<br> -Synonym--Hand Hole.<br> -<br> -<br> -<span style="font-weight: bold;">Distributing Switches.</span><br> -Switch systems for enabling different dynamos to supply different lines<br> -of a system as required. Spring jacks, q. v., are used for the lines,<br> -and plug switches for the dynamo leads. Thus, dynamos can be thrown in<br> -or out as desired, without putting out the lights.<br> -<br> -<br> -<span style="font-weight: bold;">Distribution of Electric Energy, -Systems of.</span><br> -The systems of electric current distribution from central stations or<br> -from private generating plants, mechanical or battery, the latter<br> -primary or secondary. They include in general the alternating current<br> -system and direct current systems. Again, these may be subdivided into<br> -series and multiple arc, multiple-series and series-multiple<br> -distribution, and the three, four, or five wire system may be applied to<br> -multiple arc or multiple series systems. (See Alternating<br> -Current--Current System--Multiple Arc--Multiple Series--Series<br> -Multiple--Three Wire System.)<br> -<br> -<br> -<span style="font-weight: bold;">Door Opener, Electric.</span><br> -An apparatus for opening a door by pushing back the latch. A spring then<br> -draws the door open, and it is closed against the force of the spring by<br> -the person entering. Electro-magnetic mechanism actuates the latch, and<br> -is operated by a switch or press-button. Thus a person on the upper<br> -floor can open the hall door without descending.<br> -<br> -<br> -<span style="font-weight: bold;">Dosage, Galvanic.</span><br> -In electro-therapeutics the amount of electric current or discharge, and<br> -duration of treatment given to patients.<br> -<br> -<br> -<span style="font-weight: bold;">Double Carbon Arc Lamp.</span><br> -An arc lamp designed to burn all night, usually constructed with two<br> -parallel sets of carbons, one set replacing the other automatically, the<br> -current being switched from the burnt out pair to the other by the<br> -action of the mechanism of the lamp.<br> -<br> -<br> -191 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Double Fluid Theory.</span><br> -A theory of electricity. Electricity is conveniently treated as a fluid<br> -or fluids. According to the double fluid hypothesis negative electricity<br> -is due to a preponderance of negative fluid and vice versa. Like fluid<br> -repels like, and unlike attracts unlike; either fluid is attracted by<br> -matter; the presence in a body of one or the other induces<br> -electrification; united in equal proportions they neutralize each other,<br> -and friction, chemical decomposition and other causes effect their<br> -separation. The hypothesis, while convenient, is overshadowed by the<br> -certainty that electricity is not really a fluid at all. (See Single<br> -Fluid Theory--Fluid, Electric.)<br> -<br> -Synonym--Symmer's Theory.<br> -<br> -[Transcriber's note: Current is the motion of negative electrons in a<br> -conductor or plasma. Unequal distribution of electrons is static<br> -electricity. The relatively immobile nuclei of atoms are positive when<br> -one or more of its electrons is absent and accounts for part of the<br> -current in electrolysis and plasmas.]<br> -<br> -<br> -<span style="font-weight: bold;">Double Fluid Voltaic Cell.</span><br> -A cell in which two fluids are used, one generally as depolarizer<br> -surrounding the negative plate, the other as excitant surrounding the<br> -positive plate. A porous diaphragm or difference in specific gravities<br> -is used to keep the solutions separate and yet permit the essential<br> -electrolytic diffusion. Grove's Cell, Bunsen's Cell, and Daniell's Cell,<br> -all of which may be referred to, are of this type, as are many others.<br> -<br> -<br> -<span style="font-weight: bold;">Double Wedge.</span><br> -A plug for use with a spring-jack. It has connection strips at its end<br> -and another pair a little distance back therefrom, so that it can make<br> -two loop connections at once.<br> -<br> -Synonym--Double Plug.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Doubler.</span><br> -A continuously acting electrophorous, q.v.; an early predecessor of the<br> -modern electric machines. It is now no longer used.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">D. P.</span><br> -Abbreviation for Potential Difference.<br> -<br> -<br> -<span style="font-weight: bold;">Drag.</span><br> -The pull exercised by a magnetic field upon a conductor moving through<br> -it or upon the motion of an armature in it.<br> -<br> -<br> -<span style="font-weight: bold;">Dreh-strom. (German)</span><br> -Rotatory currents; a system of currents alternating in periodic<br> -succession of phases and producing a rotatory field. (See Field,<br> -Rotatory--Multiphase Currents.)<br> -<br> -<br> -<span style="font-weight: bold;">Drill Electric.</span><br> -A drill for metals or rock worked by an electro-magnetic motor. For<br> -metals a rotary motion, for rocks a reciprocating or percussion action<br> -is imparted. It is used by shipbuilders for drilling holes in plates<br> -which are in place in ships, as its flexible conductors enable it to be<br> -placed anywhere. For rock-drilling a solenoid type of construction is<br> -adopted, producing rapid percussion.<br> -<br> -<br> -192 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Drip Loop.</span><br> -A looping downward of wires entering a building, so that rain water, as<br> -it runs along the wire, will drip from the lowest part of the loop<br> -instead of following the wire into or against the side of the building.<br> -<br> -<br> -<span style="font-weight: bold;">Driving Horns.</span><br> -Projections on the periphery of an armature of a dynamo for holding the<br> -winding in place and preventing its displacement. Various arrangements<br> -have been adopted. They are sometimes wedges or pins and are sometimes<br> -driven into spaces left in the drum core. The toothed disc armature<br> -cores make up an armature in which the ridges formed by the teeth form<br> -practically driving horns.<br> -<br> -<br> -<span style="font-weight: bold;">Dronier's Salt.</span><br> -A substance for solution for use in bichromate batteries. It is a<br> -mixture of one-third potassium bichromate and two-thirds potassium<br> -bisulphate. It is dissolved in water to make the exciting fluid.<br> -<br> -<br> -<span style="font-weight: bold;">Drop, Automatic.</span><br> -A switch or circuit breaker, operating to close a circuit by dropping<br> -under the influence of gravity. It is held up by a latch, the circuit<br> -remaining open, until the latch is released by a current passing through<br> -an electro-magnet. This attracting an armature lets the drop fall. As it<br> -falls it closes a local or second circuit, and thus may keep a bell<br> -ringing until it is replaced by hand. It is used in burglar alarms, its<br> -function being to keep a bell ringing even though the windows or door by<br> -which entrance was made is reclosed.<br> -<br> -<br> -193 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 597px; height: 714px;" alt="" - src="images/192F133.jpg"><br> -Fig. 133. THE MAGIC DRUM.<br> -<br> -<br> -<span style="font-weight: bold;">Drum, Electric.</span><br> -A drum with a mechanism within for striking the head with a hammer or<br> -some equivalent method so as to be used as a piece of magical apparatus.<br> -In the one shown in the cut a sort of telephone action is used to<br> -produce the sound, the electro-magnet D and armature being quite<br> -screened from observation through the hole. (See Fig. 133) A ring, C,<br> -shown in Fig. 133, with two terminals, the latter shown by the unshaded<br> -portions a a, and a suspending hook E, also with two terminals, and two<br> -suspending conductors A, B, carry the current to the magnet. A sudden<br> -opening or closing of the circuit produces a sound.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Dub's Laws.</span><br> -1. The magnetism excited at any transverse section of a magnet is<br> -proportional to the square root of the distance between the given<br> -section and the end.<br> -<br> -2. The free magnetism at any given transverse section of a magnet is<br> -proportional to the difference between the square root of half the<br> -length of the magnet and the square root of the distance between the<br> -given section and the nearest end.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Duct.</span><br> -The tube or compartment in an electric subway for the reception of a<br> -cable. (See Conduit, Electric Subway.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Dyad.</span><br> -A chemical term; an element which in combination replaces two monovalent<br> -elements; one which has two bonds or is bivalent.<br> -<br> -<br> -<span style="font-weight: bold;">Dyeing, Electric.</span><br> -The producing mordanting or other dyeing effects on goods in dyeing by<br> -the passage of an electric current.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamic Electricity.</span><br> -Electricity of relatively low potential and large quantity; current<br> -electricity as distinguished from static electricity; electricity in<br> -motion.<br> -<br> -<br> -194 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo, Alternating Current.</span><br> -A dynamo-electric machine for producing an alternating current; an<br> -alternator. They are classified by S. P. Thompson into three classes--I.<br> -Those with stationary field-magnet and rotating armature. II. Those with<br> -rotating field magnet and stationary armature. III. Those with both<br> -field magnet part and armature part stationary, the amount of magnetic<br> -induction from the latter through the former being caused to vary or<br> -alternate in direction by the revolution of appropriate pieces of iron,<br> -called inductors. Another division rests on whether they give one simple<br> -alternating current, a two phase current, or whether they give multi<br> -phase currents. (See Current, Alternating--Currents, Multiphase.)<br> -<br> -A great many kinds of alternators have been constructed. Only an outline<br> -of the general theory can be given here. They are generally multipolar,<br> -with north and south poles alternating around the field. The armature<br> -coils, equal in number in simple current machines, to the poles, are<br> -wound in opposite senses, so that the current shall be in one direction,<br> -though in opposite senses, in all of them at anyone time. As the<br> -armature rotates the coils are all approaching their poles at one time<br> -and a current in one sense is induced in every second coil, and one in<br> -the other sense in the other coils. They are all in continuous circuit<br> -with two open terminals, each connected to its own insulated connecting<br> -ring on the shaft. As the coils pass the poles and begin to recede from<br> -them the direction changes, and the current goes in the other direction<br> -until the next poles are reached and passed. Thus there are as many<br> -changes of direction of current per rotation as there are coils in the<br> -armature or poles in the field.<br> -<br> -<br> -<img style="width: 579px; height: 542px;" alt="" - src="images/194F134.jpg"><br> -Fig. 134. ALTERNATING CURRENT DYNAMO WITH<br> -SEPARATE EXCITER MOUNTED ON MAIN SHAFT.<br> -<br> -<br> -195 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The field-magnets whose windings may be in series are often excited by a<br> -separate direct current generation. Some are self-exciting, one or more<br> -of the armature coils being separated from the rest, and connected to a<br> -special commutator, which rectifies its current.<br> -<br> -By properly spacing the coils with respect to the poles of the field,<br> -and connecting each set of coils by itself to separate connecting rings,<br> -several currents can be taken from the same machine, which currents<br> -shall have a constant difference in phase. It would seem at first sight<br> -that the same result could be attained by using as many separate<br> -alternators as there were currents to be produced. But it would be<br> -almost impossible to preserve the exact relation of currents and current<br> -phase where each was produced by its own machine. The currents would<br> -overrun each other or would lag behind. In a single machine with<br> -separate sets of coils the relation is fixed and invariable.<br> -<br> -<img style="width: 753px; height: 427px;" alt="" - src="images/195F135.jpg"><br> -<br> -Fig. I35. DIAGRAM OF ARRANGEMENT OF ARMATURE COILS AND<br> -COLLECTING RINGS IN AN ALTERNATING CURRENT DYNAMO.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo, Alternating Current, -Regulation of.</span><br> -Transformers, converters, or induction coils are used to regulate<br> -alternating current dynamos, somewhat as compound winding is applied in<br> -the case of direct-current dynamos. The arrangement consists in<br> -connecting the primary of an induction coil or transformer into the<br> -external circuit with its secondary connected to the field circuit. Thus<br> -the transformer conveys current to the field picked up from the main<br> -circuit, and represents to some extent the shunt of a direct-current<br> -machine.<br> -<br> -<span style="font-weight: bold;">Dynamo, Commercial Efficiency of.</span><br> -The coefficient, q. v., obtained by dividing the mechanically useful or<br> -available work of a dynamo by the mechanical energy absorbed by it. This<br> -only includes the energy available in the outer circuit, for doing<br> -useful work.<br> -<br> -<br> -196 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 426px; height: 590px;" alt="" - src="images/196F136.jpg"><br> -Fig. 136. COMPOUND WOUND DYNAMO.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo. Compound.</span><br> -A compound wound dynamo; one which has two coils on its field magnet;<br> -one winding is in series with the external circuit and armature; the<br> -other winding is in parallel with the armature winding, or else with the<br> -armature winding and field winding, both in series. (See Winding, Long<br> -Shunt--Winding, Short Shunt.)<br> -<br> -Such a dynamo is, to a certain extent, self-regulating, the two coils<br> -counteracting each other, and bringing about a more regular action for<br> -varying currents than that of the ordinary shunt or series dynamo.<br> -<br> -The extent of the regulation of such a machine depends on the<br> -proportions given its different parts. However good the self-regulating<br> -may be in a compound wound machine, it can only be perfect at one<br> -particular speed.<br> -<br> -To illustrate the principle on which the approximate regulation is<br> -obtained the characteristic curve diagram may be consulted.<br> -<br> -<br> -<img style="width: 629px; height: 387px;" alt="" - src="images/196F137.jpg"><br> -Fig. 137. CURVES OF SERIES AND SHUNT WINDINGS SUPERIMPOSED.<br> -<br> -<br> -One curve is the curve of a series winding, the other that of a shunt<br> -winding, and shows the variation of voltage in each with resistance in<br> -the external or working circuit. The variation is opposite in each case.<br> -It is evident that the two windings could be so proportioned on a<br> -compound machine that the resultant of the two curves would be a<br> -straight line. This regulation would then be perfect and automatic, but<br> -only for the one speed.<br> -<br> -<br> -197 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo, Direct Current.</span><br> -A dynamo giving a current of unvarying direction, as distinguished from<br> -an alternator or alternating current dynamo.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo, Disc.</span><br> -A dynamo with a disc armature, such as Pacinotti's disc, q. v. (See also<br> -Disc, Armature.) The field magnets are disposed so that the disc rotates<br> -close to their poles, and the poles face or are opposite to the side or<br> -sides of the disc. The active leads of wire are those situated on the<br> -face or faces of the disc.<br> -<br> -<br> -<img style="width: 633px; height: 616px;" alt="" - src="images/197F138.jpg"><br> -Fig. 138. POLECHKO'S DISC DYNAMO.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Dynamo-electric Machine.</span><br> -A machine driven by power, generally steam power, and converting the<br> -mechanical energy expended on driving it into electrical energy of the<br> -current form. The parts of the ordinary dynamo may be summarized as<br> -follows: First, A circuit as complete as possible of iron. Such circuit<br> -is composed partly of the cores of an electro-magnet or of several<br> -electro-magnets, and partly of the cylindrical or ring-shaped core of an<br> -armature which fits as closely as practicable between the magnet ends or<br> -poles which are shaped so as to partly embrace it. Second, of coils of<br> -insulated wire wound upon the field-magnet cores. When these coils are<br> -excited the field-magnets develop polarity and the circuit just spoken<br> -of becomes a magnetic circuit, interrupted only by the air gaps between<br> -the poles and armatures. Thirdly, of coils of insulated wire upon the<br> -armature core. These coils when rotated in the magnetic field cut<br> -magnetic lines of force and develop electro-motive force.<br> -<br> -<br> -198 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Fourthly, of collecting mechanism, the commutator in direct current<br> -dynamos, attached to the armature shaft and rotating with it. This<br> -consists of insulated rings, or segments of rings to which the wire<br> -coils of the armature are connected, and on which two springs of copper<br> -or plates of carbon or some other conductor presses. The electro-motive<br> -force developed by the cutting of lines of force, by the wires of the<br> -armature, shows itself as potential difference between the two springs.<br> -If the ends of a conductor are attached, one to each of these brushes,<br> -the potential difference will establish a current through the wire. By<br> -using properly divided and connected segments on the commutator the<br> -potential difference and consequent direction of the current may be kept<br> -always in the same sense or direction. It is now clear that the external<br> -wire may be connected with the windings of the field-magnet. In such<br> -case the excitement of the field-magnets is derived from the armature<br> -and the machine is self-excited and entirely self-contained.<br> -<br> -The above is a general description of a dynamo. Sometimes the coils of<br> -the field-magnets are not connected with the armature, but derive their<br> -current from an outside source. Such are termed separately excited<br> -dynamos.<br> -<br> -Some general features of dynamo generators may be seen in the<br> -definitions under this head and elsewhere. The general conception is to<br> -cut lines of force with a conductor and thus generate electromotive<br> -force, or in some way to change the number of lines of force within a<br> -loop or circuit with the same effect.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo, Electroplating.</span><br> -A dynamo designed for low potential and high current intensity. They are<br> -wound for low resistance, frequently several wires being used in<br> -parallel, or ribbon, bar or rectangular conductors being employed. They<br> -are of the direct current type. They should be shunt wound or they are<br> -liable to reverse. They are sometimes provided with resistance in the<br> -shunt, which is changed as desired to alter the electro-motive force.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Dynamo, Equalizing.</span><br> -A combination for three and five-wire systems. A number of armatures or<br> -of windings on the same shaft are connected across the leads. If the<br> -potential drops at any pair of mains, the armature will begin to be<br> -driven by the other mains, acting to an extent as an element of a motor,<br> -and will raise the potential in the first pair.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo, Far Leading.</span><br> -A motor dynamo, used to compensate the drop of potential in long mains.<br> -Into the mains at a distant point a series motor is connected, driving a<br> -dynamo placed in shunt across the mains. The dynamo thus driven raises<br> -the potential difference between the two mains.<br> -<br> -<br> -199 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamograph.</span><br> -A printing telegraph in which the message is printed at both<br> -transmitting and receiving ends.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo, Inductor.</span><br> -A generator in which the armature or current-generating windings are all<br> -comprised upon the poles of the field magnets. Masses of iron, which<br> -should be laminated and are the inductors, are carried past the field<br> -magnet poles concentrating in their passage the lines of force, thus<br> -inducing currents in the coils. In one construction shown in the cut the<br> -field magnets a, a .. are U shaped and are arranged in a circle, their<br> -poles pointing inwards. A single exciting coil c, c ... is wound around<br> -the circle in the bend of the V-shaped segments. The poles carry the<br> -armature coils e, e ... The laminated inductors i, i ... are mounted on<br> -a shaft S, by spiders h, to be rotated inside the circle of magnets,<br> -thus generating an alternating current.<br> -<br> -Synonym--Inductor Generator.<br> -<br> -<br> -<img style="width: 622px; height: 538px;" alt="" - src="images/199F139.jpg"><br> -Fig. 139. INDUCTOR DYNAMO.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo, Interior Pole.</span><br> -A dynamo with a ring armature, with field magnet pole pieces which<br> -extend within the ring.<br> -<br> -<br> -200 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo, Iron Clad.</span><br> -A dynamo in which the iron of the field magnet is of such shape as to<br> -enclose the field magnet coils as well as the armature.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamometer.</span><br> -A device or apparatus for measuring force applied, or rate of<br> -expenditure of energy by, or work done in a given time by a machine. A<br> -common spring balance can be used as a force dynamometer, viz: to<br> -determine how hard a man is pulling and the like. The steam engine<br> -indicator represents an energy-dynamometer of the graphic type, the<br> -instrument marking an area whence, with the aid of the fixed factors of<br> -the engine, the work done may be determined. Prony's Brake, q. v., is a<br> -type of the friction dynamometer, also of the energy type. In the latter<br> -type during the experiment the whole power must be turned on or be<br> -expended on the dynamometer.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo, Motor.</span><br> -A motor dynamo is a machine for (a) converting a continuous current at<br> -any voltage to a continuous current of different strength at a different<br> -voltage or for (b) transforming a continuous current into an alternating<br> -one, and vice versa.<br> -<br> -For the first type see Transformer, Continuous Current; for the second<br> -type see Transformer, Alternating Current.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo, Multipolar.</span><br> -A dynamo having a number of field magnet poles, not merely a single<br> -north and a single south pole. The field magnet is sometimes of a<br> -generally circular shape with the poles arranged radially within it, the<br> -armature revolving between the ends.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Dynamo, Non-polar.</span><br> -A name given by Prof. George Forbes to a dynamo invented by him. In it a<br> -cylinder of iron rotates within a perfectly self-contained iron-clad<br> -field magnet. The current is taken off by brushes bearing near the<br> -periphery, at two extremities of a diameter. A machine with a disc 18<br> -inches in diameter was said to give 3,117 amperes, with 5.8 volts E. M.<br> -F. running at 1,500 revolutions per second. The E. M. F. of such<br> -machines varies with the square of the diameter of the disc or cylinder.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo, Open Coil.</span><br> -A dynamo the windings of whose armatures may be grouped in coils, which<br> -are not connected in series, but which have independent terminals. These<br> -terminals are separate divisions of the commutator and so spaced that<br> -the collecting brushes touch each pair belonging to the same coil<br> -simultaneously. As the brushes come in contact with the sections forming<br> -the terminals they take current from the coil in question. This coil is<br> -next succeeded by another one, and so on according to the number of<br> -coils employed.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo, Ring.</span><br> -A dynamo the base of whose field magnets is a ring in general shape, or<br> -perhaps an octagon, and with poles projecting inwardly therefrom.<br> -<br> -<br> -201 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo, Coupling of.</span><br> -Dynamos can be coupled exactly like batteries and with about the same<br> -general results. An instance of series coupling would be given by the<br> -dynamos in the three wire system when no current is passing through the<br> -neutral wire, and when the lamps on each side of it are lighted in equal<br> -number.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Dynamo, Self-exciting.</span><br> -A dynamo which excites its own field. The majority of dynamos are of<br> -this construction. Others, especially alternating current machines, are<br> -separately excited, the field magnets being supplied with current from a<br> -separate dynamo or current generator.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Dynamo, Separate Circuit.</span><br> -A dynamo in which the field magnet coils are entirely disconnected from<br> -the main circuit, and in which current for the field is supplied by<br> -special coils carried for the purpose by the same armature, or by a<br> -special one, in either case a special commutator being provided to<br> -collect the current.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Dynamo, Separately Excited.</span><br> -A dynamo whose field magnets are excited by a separate current<br> -generator, such as a dynamo or even a battery. Alternating current<br> -dynamos are often of this construction. Direct current dynamos are not<br> -generally so. The term is the opposite of self-exciting.<br> -<br> -<br> -<img style="width: 570px; height: 725px;" alt="" - src="images/201F140.jpg"><br> -Fig. 140. SERIES DYNAMO.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo, Series.</span><br> -A dynamo whose armature, field winding, and external circuit are all in<br> -series.<br> -<br> -In such a dynamo short circuiting or lowering the resistance of the<br> -external circuit strengthens the field, increases the electro-motive<br> -force and current strength and may injure the winding by heating the<br> -wire, and melting the insulation.<br> -<br> -<br> -202 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo, Shunt.</span><br> -A dynamo whose field is wound in shunt with the external circuit. Two<br> -leads are taken from the brushes; one goes around the field magnets to<br> -excite them; the other is the external circuit.<br> -<br> -In such a dynamo the lowering of resistance on the outer circuit takes<br> -current from the field and lowers the electro-motive force of the<br> -machine. Short circuiting has no heating effect.<br> -<br> -<br> -<img style="width: 604px; height: 698px;" alt="" - src="images/202F141.jpg"><br> -Fig. 141. SHUNT DYNAMO.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo, Single Coil.</span><br> -A dynamo whose field magnet is excited by a single coil. Several such<br> -have been constructed, with different shapes of field magnet cores, in<br> -order to obtain a proper distribution of poles.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Dynamo, Tuning Fork.</span><br> -A dynamo in which the inductive or armature coils were carried at the<br> -ends of the prongs of a gigantic tuning fork, and were there maintained<br> -in vibration opposite the field magnets. It was invented by T. A.<br> -Edison, but never was used.<br> -<br> -<br> -<span style="font-weight: bold;">Dynamo, Uni-polar.</span><br> -A dynamo in which the rotation of a conductor effects a continuous<br> -increase in the number of lines cut, by the device of arranging one part<br> -of the conductor to slide on or around the magnet. (S. P. Thomson.)<br> -Faraday's disc is the earliest machine of this type.<br> -<br> -<br> -203 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Dyne.</span><br> -The C. G. S. or fundamental unit of force. It is the force which can<br> -impart an acceleration of one centimeter per second to a mass of one<br> -gram in one second. It is equal to about 1/981 the weight of a gram,<br> -this weight varying with the latitude.</big></big><big><big><br> -<br> -<br> -<span style="font-weight: bold;">Earth.</span><br> -(a) The earth is arbitrarily taken as of zero electrostatic potential.<br> -Surfaces in such condition that their potential is unchanged when<br> -connected to the earth are said to be of zero potential. All other<br> -surfaces are discharged when connected to the earth, whose potential,<br> -for the purposes of man at least, never changes.<br> -<br> -(b) As a magnetic field of force the intensity of the earth's field is<br> -about one-half a line of force per square centimeter.<br> -<br> -(c) The accidental grounding of a telegraph line is termed an earth, as<br> -a dead, total, partial, or intermittent earth, describing the extent and<br> -character of the trouble.<br> -<br> -[Transcriber's note: Fallen power lines can produce voltage gradients on<br> -the earth's surface that make walking in the area dangerous, as in<br> -hundreds of volts per foot. Lightning may be associated with substantial<br> -changes in the static ground potential.]<br> -<br> -<br> -<span style="font-weight: bold;">Earth, Dead.</span><br> -A fault, when a telegraph or other conductor is fully connected to earth<br> -or grounded at some intermediate point.<br> -<br> -Synonyms--Solid Earth--Total Earth.<br> -<br> -<br> -<span style="font-weight: bold;">Earth, Partial.</span><br> -A fault, when a telegraph or other conductor is imperfectly connected to<br> -earth or grounded at some intermediate point.<br> -<br> -<br> -<span style="font-weight: bold;">Earth Plate.</span><br> -A plate buried in the earth to receive the ends of telegraph lines or<br> -other circuits to give a ground, q. v. A copper plate is often used. A<br> -connection to a water or gas main gives an excellent ground, far better<br> -than any plate. When the plate oxidizes it is apt to introduce<br> -resistance.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Earth Return.</span><br> -The grounding of a wire of a circuit at both ends gives the circuit an<br> -earth return.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Earth, Swinging.</span><br> -A fault, when a telegraph or other conductor makes intermittent<br> -connection with the earth. It is generally attributable to wind action<br> -swinging the wire, whence the name.<br> -<br> -<br> -<span style="font-weight: bold;">Ebonite.</span><br> -Hard vulcanized India rubber, black in color. Specific resistance in<br> -ohms per cubic centimeter at 46º C. (115º F.): 34E15 -(Ayrton); specific<br> -inductive capacity, (air = 1): 2.56 (Wüllner); 2.76 (Schiller); -3.15<br> -(Boltzmann). It is used in electrical apparatus for supporting members<br> -such as pillars, and is an excellent material for frictional generation<br> -of potential. Its black color gives it its name, and is sometimes made a<br> -point of distinction from Vulcanite, q. v.<br> -<br> -<br> -204 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Economic Coefficient.</span><br> -The coefficient of electric efficiency. (See Efficiency, Electric.)<br> -<br> -<br> -<span style="font-weight: bold;">Edison Effect.</span><br> -A continuous discharge resulting in a true current which takes place<br> -between a terminal of an incandescent lamp filament and a plate placed<br> -near it. The lamp must be run at a definitely high voltage to obtain it.<br> -<br> -<br> -<span style="font-weight: bold;">Ediswan.</span><br> -An abbreviation for Edison-Swan; the trade name of the incandescent lamp<br> -used in Great Britain, and of other incandescent system apparatus.<br> -<br> -<br> -<img style="width: 422px; height: 511px;" alt="" - src="images/204F142.jpg"><br> -Fig. 142. GYMNOTUS ELECTRICUS.<br> -<br> -<br> -<span style="font-weight: bold;">Eel, Electric (Gymnotus Electricus).</span><br> -An eel capable of effecting the discharge of very high potential<br> -electricity, giving painful or dangerous shocks. Its habitat is the<br> -fresh water, in South America. Faraday investigated it and estimated its<br> -shock as equal to that from fifteen Leyden jars, each of 1.66 square<br> -feet of coating. (See Animal Electricity and Ray, Electric.)<br> -<br> -<br> -<span style="font-weight: bold;">Effect, Counter-inductive.</span><br> -A counter-electro-motive force due to induction, and opposing a current.<br> -<br> -<br> -<span style="font-weight: bold;">Efficiency.</span><br> -The relation of work done to energy absorbed. A theoretically perfect<br> -machine would have the maximum efficiency in which the two qualities<br> -named would be equal to each other. Expressed by a coefficient, q. v.,<br> -the efficiency in such case would be equal to 1. If a machine produced<br> -but half the work represented by the energy it absorbed, the rest<br> -disappearing in wasteful expenditure, in heating the bearings, in<br> -overcoming the resistance of the air and in other ways, its efficiency<br> -would be expressed by the coefficient 1/2 or .5, or if one hundred was<br> -the basis, by fifty per centum. There are a number of kinds of<br> -efficiencies of an electric generator which are given below.<br> -<br> -<br> -<span style="font-weight: bold;">Efficiency, Commercial.</span><br> -Practical efficiency of a machine, obtained by dividing the available<br> -output of work or energy of a machine by the energy absorbed by the same<br> -machine. Thus in a dynamo part of the energy is usefully expended in<br> -exciting the field magnet, but this energy is not available for use in<br> -the outer circuit, is not a part of the output, and is not part of the<br> -dividend.<br> -<br> -If M represents the energy absorbed, and W the useful or available<br> -energy, the coefficient of commercial efficiency is equal to W/M. M is<br> -made up of available, unavailable and wasted (by Foucault currents,<br> -etc.,) energy. Calling available energy W, unavailable but utilized<br> -energy w, and wasted energy m, the expression for the coefficient of<br> -commercial efficiency becomes<br> -<br> - W / ( W + w + m )<br> - when M = W + w + m<br> -<br> -Synonym--Net efficiency.<br> -<br> -<br> -205 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Efficiency, Electrical.</span><br> -In a dynamo or generator the relation of total electric energy produced,<br> -both wasted and useful or available to the useful or available<br> -electrical energy. If we call W the useful electric and w the wasted<br> -electric energy, the coefficient of electrical efficiency is equal to<br> -<br> - W / ( W + w )<br> -<br> -Synonyms--Intrinsic Efficiency--Economic Coefficient--Coefficient of<br> -Electrical Efficiency.<br> -<br> -<br> -<span style="font-weight: bold;">Efficiency of Conversion.</span><br> -In a dynamo or generator the relation of energy absorbed to total<br> -electric energy produced. Part of the electric energy is expended in<br> -producing the field and in other ways. Thus a generator with high<br> -efficiency of conversion may be a very poor one, owing to the<br> -unavailable electric energy which it produces. The coefficient of<br> -Efficiency of Conversion is obtained by dividing the total electric<br> -energy produced by the energy absorbed in working the dynamo. If M<br> -represents the energy absorbed, or work done in driving the dynamo or<br> -generator, W the useful electric, and w the wasted electrical energy,<br> -then the coefficient of efficiency of conversion is equal to<br> -<br> -(W + w ) / M<br> -<br> -In the quantity M are included besides available (W) and unavailable (w)<br> -electric energy, the totally wasted energy due to Foucault currents,<br> -etc., calling the latter m, the above formula may be given<br> -<br> -( W+ w ) / (W + w + m )<br> -<br> -This coefficient may refer to the action of a converter, q. v., in the<br> -alternating system. Synonym--Gross Efficiency.<br> -<br> -<br> -<span style="font-weight: bold;">Efficiency of Secondary Battery, -Quantity.</span><br> -The coefficient obtained by dividing the ampere-hours obtainable from a<br> -secondary battery by the ampere hours required to charge it.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Efficiency of Secondary Battery, Real.</span><br> -The coefficient obtained by dividing the energy obtainable from a<br> -secondary battery by the energy absorbed in charging it. The energy is<br> -conveniently taken in watt-hours and includes the consideration of the<br> -spurious voltage. (See Battery, Secondary.)<br> -<br> -<br> -206 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Efflorescence.</span><br> -The appearance of a dry salt upon the walls of a vessel containing a<br> -solution above the normal water-line from evaporation of a liquid. It<br> -appears in battery jars and in battery carbons, in the latter<br> -interfering with the electrical connections, and oxidizing or rusting<br> -them. (See Creeping.)<br> -<br> -<br> -<span style="font-weight: bold;">Effluvium, Electric.</span><br> -When a gas is made to occupy the position of dielectric between two<br> -oppositely electrified surfaces a peculiar strain or condition of the<br> -dielectric is produced, which promotes chemical change. The condition is<br> -termed electrical effluvium or the silent discharge. By an apparatus<br> -specially constructed to utilize the condition large amounts of ozone<br> -are produced.<br> -<br> -Synonym--Silent Discharge.<br> -<br> -<br> -<span style="font-weight: bold;">Elastic Curve.</span><br> -A crude expression for a curve without projections or sudden<br> -sinuosities; such a curve as can be obtained by bending an elastic strip<br> -of wood.<br> -<br> -<br> -<span style="font-weight: bold;">Electrepeter.</span><br> -An obsolete name for a key, switch or pole changer of any kind.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Elasticity, Electric.</span><br> -The phenomenon of the dielectric is described under this term. When a<br> -potential difference is established between two parts of the dielectric,<br> -a flow of electricity displacement current starts through the<br> -dielectric, which current is due to the electric stress, but is<br> -instantly arrested by what has been termed the electric elasticity of<br> -the dielectric. This is expressed by<br> - ( electric stress ) / ( electric strain )<br> -and in any substance is inversely proportional to the specific inductive<br> -capacity.<br> -<br> -<br> -<span style="font-weight: bold;">Electricity.</span><br> -It is impossible in the existing state of human knowledge to give a<br> -satisfactory definition of electricity. The views of various authorities<br> -are given here to afford a basis for arriving at the general consensus<br> -of electricians.<br> -<br> -We have as yet no conception of electricity apart from the electrified<br> -body; we have no experience of its independent existence. (J. E. H.<br> -Gordon.)<br> -<br> -What is Electricity? We do not know, and for practical purposes it is<br> -not necessary that we should know. (Sydney F. Walker.)<br> -<br> -Electricity … is one of those hidden and mysterious powers of nature<br> -which has thus become known to us through the medium of effects.<br> -(Weale's Dictionary of Terms.)<br> -<br> -This word Electricity is used to express more particularly the cause,<br> -which even today remains unknown, of the phenomena that we are about to<br> -explain. (Amédée Guillemin.)<br> -<br> -207 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -Electricity is a powerful physical agent which manifests itself mainly<br> -by attractions and repulsions, but also by luminous and heating effects,<br> -by violent commotions, by chemical decompositions, and many other<br> -phenomena. Unlike gravity, it is not inherent in bodies, but it is<br> -evoked in them by a variety of causes … (Ganot's Physics.)<br> -<br> -Electricity and magnetism are not forms of energy; neither are they<br> -forms of matter. They may, perhaps, be provisionally defined as<br> -properties or conditions of matter; but whether this matter be the<br> -ordinary matter, or whether it be, on the other hand, that<br> -all-pervading ether by which ordinary matter is surrounded, is a question<br> -which has been under discussion, and which now may be fairly held to be<br> -settled in favor of the latter view. (Daniell's Physics.)<br> -<br> -The name used in connection with an extensive and important class of<br> -phenomena, and usually denoting the unknown cause of the phenomena or<br> -the science that treats of them. (Imperial Dictionary.)<br> -<br> -Electricity. . . is the imponderable physical agent, cause, force or the<br> -molecular movement, by which, under certain conditions, certain<br> -phenomena, chiefly those of attraction and repulsion, . . . are<br> -produced. (John Angell.)<br> -<br> -It has been suggested that if anything can rightly be called<br> -"electricity," this must be the ether itself; and that all electrical<br> -and magnetic phenomena are simply due to changes, strains and motions in<br> -the ether. Perhaps negative electrification. . .means an excess of<br> -ether, and positive electrification a defect of ether, as compared with<br> -the normal density. (W. Larden.)<br> -<br> -Electricity is the name given to the supposed agent producing the<br> -described condition (i. e. electrification) of bodies. (Fleeming<br> -Jenkin.)<br> -<br> -There are certain bodies which, when warm and dry, acquire by friction,<br> -the property of attracting feathers, filaments of silk or indeed any<br> -light body towards them. This property is called Electricity, and bodies<br> -which possess it are said to be electrified. (Linnaeus Cumming.)<br> -<br> -What electricity is it is impossible to say, but for the present it is<br> -convenient to look upon it as a kind of invisible something which<br> -pervades all bodies. (W. Perren Maycock.)<br> -<br> -What is electricity? No one knows. It seems to be one manifestation of<br> -the energy which fills the universe and which appears in a variety of<br> -other forms, such as heat, light, magnetism, chemical affinity,<br> -mechanical motion, etc. (Park Benjamin.)<br> -<br> -<br> -208 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The theory of electricity adopted throughout these lessons is, that<br> -electricity, whatever its true nature, is one, not two; that this<br> -Electricity, whatever it may prove to be, is not matter, and is not<br> -energy; that it resembles both matter and energy in one respect,<br> -however, in that it can neither be created nor destroyed. (Sylvanus P.<br> -Thomson.)<br> -<br> -In Physics a name denoting the cause of an important class of phenomena<br> -of attraction and repulsion, chemical decomposition, etc., or,<br> -collectively, these phenomena themselves. (Century Dictionary.)<br> -<br> -A power in nature, often styled the electric fluid, exhibiting itself,<br> -when in disturbed equilibrium or in activity, by a circuit movement, the<br> -fact of direction in which involves polarity, or opposition of<br> -properties in opposite directions; also, by attraction for many<br> -substances, by a law involving attraction between substances of unlike<br> -polarity, and repulsion between those of like; by exhibiting accumulated<br> -polar tension when the circuit is broken; and by producing heat, light,<br> -concussion, and often chemical changes when the circuit passes between<br> -the poles, or through any imperfectly conducting substance or space. It<br> -is evolved in any disturbance of molecular equilibrium, whether from a<br> -chemical, physical, or mechanical cause. (Webster's Dictionary.)<br> -<br> -In point of fact electricity is not a fluid at all, and only in a few of<br> -its attributes is it at all comparable to a fluid. Let us rather<br> -consider electricity to be a condition into which material substances<br> -are thrown. . .(Slingo & Brooker.)<br> -<br> -[Transcriber's note: 2008 Dictionary: Phenomena arising from the<br> -behavior of electrons and protons caused by the attraction of particles<br> -with opposite charges and the repulsion of particles with the same<br> -charge.]<br> -<br> -<br> -<span style="font-weight: bold;">Electricity, Cal.</span><br> -The electricity produced in the secondary of a transformer by changes of<br> -temperature in the core. This is in addition to the regularly induced<br> -current.<br> -<br> -Synonym--Acheson Effect.<br> -<br> -<br> -<span style="font-weight: bold;">Electrics.</span><br> -Substances developing electrification by rubbing or friction; as<br> -Gilbert, the originator of the term, applied it, it would indicate<br> -dielectrics. He did not know that, if insulated, any substance was one<br> -of his "electrics." A piece of copper held by a glass handle becomes<br> -electrified by friction.<br> -<br> -<br> -<span style="font-weight: bold;">Electrification.</span><br> -The receiving or imparting an electric charge to a surface; a term<br> -usually applied to electrostatic phenomena.<br> -<br> -<br> -<span style="font-weight: bold;">Electrization.</span><br> -A term in electro-therapeutics; the subjection of the human system to<br> -electric treatment for curative, tonic or diagnostic purposes.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-biology.</span><br> -The science of electricity in its relation to the living organism,<br> -whether as electricity is developed by the organism, or as it affects<br> -the same when applied from an external source.<br> -<br> -<br> -209 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-capillarity.</span><br> -The relations between surface tension, the potential difference and the<br> -electrostatic capacity of fluids in contact. Although nominally in<br> -contact such surfaces are separated by about one-twenty-millionth of a<br> -centimeter (1/50000000 inch) ; thus a globule of mercury and water in<br> -which it is immersed constitute an electrostatic accumulator of definite<br> -electrostatic capacity. Again the mercury and water being in electric<br> -connection differ in potential by contact (see Contact Theory). A<br> -definite surface tension is also established. Any change in one of these<br> -factors changes the other also. A current passed through the contact<br> -surfaces will change the surface tension and hence the shape of the<br> -mercury globule. Shaking the globule will change its shape and capacity<br> -and produce a current. Heating will do the same. (See Electrometer,<br> -Capillary; and Telephone, Capillary.) Mercury and water are named as<br> -liquids in which the phenomena are most conveniently observed. They are<br> -observable in other parallel cases.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-chemical Equivalent.</span><br> -The quantity of an element or compound liberated from or brought into<br> -combination, electrolytically, by one coulomb of electricity. The<br> -electro-chemical equivalent of hydrogen is found by experiment to be<br> -.0000105 gram. That of any other substance is found by multiplying this<br> -weight by its chemical equivalent referred to hydrogen, which is its<br> -atomic or molecular weight divided by its valency. Thus the atomic<br> -weight of oxygen is 16, its valency is 2, its equivalent is 16/2 = 8;<br> -its electro-chemical equivalent is equal to .0000105 X 8 = .000840 gram.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-chemical Series.</span><br> -An arrangement of the elements in the order of their relative electrical<br> -affinities so that each element is electro-negative to all the elements<br> -following it, and electro-positive to the elements preceding it. The<br> -usual series begins with oxygen as the most electro-negative and ends<br> -with potassium as the most electro-positive element. There is, of<br> -course, no reason why other series of compound radicals, such as<br> -sulphion (SO4), etc., should not also be constructed. For each liquid<br> -acting on substances a separate series of the substances acted on may be<br> -constructed. Thus for dilute sulphuric acid the series beginning with<br> -the negatively charged or most attacked one is zinc, amalgamated or<br> -pure, cadmium, iron, tin, lead, aluminum, nickel, antimony, bismuth,<br> -copper, silver, platinum. In other liquids the series is altogether<br> -different.<br> -<br> -<br> -<span style="font-weight: bold;">Electro--chemistry.</span><br> -The branch of electricity or of chemistry treating of the relations<br> -between electric and chemical force in different compounds and<br> -reactions. (See Electrolysis--Electrochemical series--Electro-chemical<br> -Equivalent .)<br> -<br> -<br> -210 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-culture.</span><br> -The application of electricity to the cultivation of plants. In one<br> -system wires are stretched or carried across the bed under the surface,<br> -and some are connected to one pole and others to the other pole of a<br> -galvanic battery of two or more elements. In some experiments improved<br> -results have thus been obtained.<br> -<br> -Another branch refers to the action of the electric arc light on<br> -vegetation. This has an effect on vegetation varying in results.<br> -<br> -<br> -<span style="font-weight: bold;">Electrode.</span><br> -(a) The terminal of an open electric circuit.<br> -<br> -(b) The terminals of the metallic or solid conductors of an electric<br> -circuit, immersed in an electrolytic solution.<br> -<br> -(c) The terminals between which a voltaic arc is formed, always in<br> -practice made of carbon, are termed electrodes.<br> -<br> -(d) In electro-therapeutics many different electrodes are used whose<br> -names are generally descriptive of their shape, character, or uses to<br> -which they are to be applied. Such are aural electrodes for the ears,<br> -and many others.<br> -<br> -(e) The plates of a voltaic battery.<br> -<br> -<br> -<span style="font-weight: bold;">Electrode, Indifferent.</span><br> -A term in electro-therapeutics. An electrode to which no therapeutic<br> -action is attributed but which merely provides a second contact with the<br> -body to complete the circuit through the same. The other electrode is<br> -termed the therapeutic electrode.<br> -<br> -<br> -<span style="font-weight: bold;">Electrodes, Erb's Standards of.</span><br> -Proposed standard sizes for medical electrodes as follows:<br> - <small><span style="font-family: monospace;"> -Name. -Diameter.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Fine Electrode, 1/2 -centimeter .2 inch</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -Small -" -2 -" -.8 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -Medium -" -7.5 -" -3.0 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -Large -" -6X2 -" 2.4 X .8 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Very large -" -16x8 -" 6.4 x 3.2 "</span></small><br> -<br> -<br> -<span style="font-weight: bold;">Electrodes, Non-polarizable.</span><br> -In electro-therapeutics electrodes whose contact surface is virtually<br> -porous clay saturated with zinc chloride solution. The series terminate<br> -in amalgamated zinc ends, enclosed each in a glass tube, and closed with<br> -clay. Contact of metal with the tissues is thus avoided.<br> -<br> -<br> -<span style="font-weight: bold;">Electrode, Therapeutic.</span><br> -A term in electro-therapeutics. An electrode applied to the body for the<br> -purpose of inducing therapeutic action, or for giving the basis for an<br> -electric diagnosis of the case. The other electrode is applied to<br> -complete the circuit only; it is termed the indifferent electrode.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Electro-diagnosis.</span><br> -The study of the condition of a patient by the reactions which occur at<br> -the terminals or kathode and anode of an electric circuit applied to the<br> -person. The reactions are divided into kathodic and anodic reactions.<br> -<br> -<br> -211 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-dynamic. adj.</span><br> -The opposite of electrostatic; a qualification of phenomena due to<br> -current electricity.<br> -<br> -Synonym--Electro-kinetic.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-dynamic Attraction and -Repulsion.</span><br> -The mutual attraction and repulsion exercised by currents of electricity<br> -upon each other. The theory of the cause is based upon stress of the<br> -luminiferous ether and upon the reaction of lines of force upon each<br> -other. For a resumé of the theory see Induction, -Electro-magnetic.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-dynamics.</span><br> -The laws of electricity in a state of motion; the inter-reaction of<br> -electric currents. It is distinguished from electro-magnetic induction<br> -as the latter refers to the production of currents by induction. The<br> -general laws of electro-dynamics are stated under Induction,<br> -Electro-magnetic, q. v.<br> -<br> -Synonym--Electro-kinetics.<br> -<br> -<br> -<img style="width: 537px; height: 530px;" alt="" - src="images/211F143.jpg"><br> -Fig. 143. DIAGRAM OF CONNECTIONS OF <br> -SIEMENS' ELECTRO-DYNAMOMETER.<br> -<br> -<br> -212 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-dynamometer, Siemens'.</span><br> -An apparatus for measuring currents by the reaction between two coils,<br> -one fixed and one movable, through which the current to be measured<br> -passes. It is one of the oldest commercial ammeters or current<br> -measurers. It comprises a fixed coil of a number of convolutions and a<br> -movable coil often of only one convolution surrounding the other. The<br> -movable coil is suspended by a filament or thread from a spiral spring.<br> -The spring is the controlling factor. Connection is established through<br> -mercury cups so as to bring the two coils in series. In use the spring<br> -and filament are adjusted by turning a milled head to which they are<br> -connected until the coils are at right angles. Then the current is<br> -turned on and deflects the movable coil. The milled head is turned until<br> -the deflection is overcome. The angle through which the head is turned<br> -is proportional to the square of the current. The movable coil must in<br> -its position at right angles to the fixed one lie at right angles to the<br> -magnetic meridian.<br> -<br> -Thus in the diagram, Fig. 143 A B C D is the fixed coil; E F G H is the<br> -movable coil; S is the spiral spring attached at K to the movable coil.<br> -The arrows show the course of the current as it goes through the coils.<br> -<br> -<br> -<span style="font-weight: bold;">Electrolier.</span><br> -A fixture for supporting electric lamps; the analogue in electric<br> -lighting of the gasolier or gas chandelier. Often both are combined, the<br> -same fixture being piped and carrying gas burners, as well as being<br> -wired and carrying electric lamps.<br> -<br> -<br> -<span style="font-weight: bold;">Electrolysis.</span><br> -The separation of a chemical compound into its constituent parts or<br> -elements by the action of the electric current. The compound may be<br> -decomposed into its elements, as water into hydrogen and oxygen, or into<br> -constituent radicals, as sodium sulphate into sodium and sulphion, which<br> -by secondary reactions at once give sodium hydrate and sulphuric acid.<br> -The decomposition proceeds subject to the laws of electrolysis. (See<br> -Electrolysis, Laws of.) For decomposition to be produced there is for<br> -each compound a minimum electro-motive force or potential difference<br> -required. The current passes through the electrolyte or substance<br> -undergoing decomposition entirely by Electrolytic Conduction, q. v. in<br> -accordance with Grothüss' Hypothesis, q. v. The electrolyte -therefore<br> -must be susceptible of diffusion and must be a fluid.<br> -<br> -The general theory holds that under the influence of a potential<br> -difference between electrodes immersed in an electrolyte, the molecules<br> -touching the electrodes are polarized, in the opposite sense for each<br> -electrode. If the potential difference is sufficient the molecules will<br> -give up one of their binary constituents to the electrode, and the other<br> -constituent will decompose the adjoining molecule, and that one being<br> -separated into the same two constituents will decompose its neighbor,<br> -and so on through the mass until the other electrode is reached. This<br> -one separates definitely the second binary constituent from the<br> -molecules touching it.<br> -<br> -<br> -213 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Thus there is an exact balance preserved. Just as many molecules are<br> -decomposed at one electrode as at the other, and the exact chain of<br> -decomposition runs through the mass. Each compound electrolyzed develops<br> -a binary or two-fold composition, and gives up one constituent to one<br> -electrode and the other to the other.<br> -<br> -<br> -<img style="width: 653px; height: 504px;" alt="" - src="images/213F144.jpg"><br> -Fig. 144. ACTION OF MOLECULES IN A SOLUTION<br> -BEFORE AND DURING ELECTROLYSIS.<br> -<br> -<br> -The cut shows the assumed polarization of an electrolyte. The upper row<br> -shows the molecules in irregular order before any potential difference<br> -has been produced, in other words, before the circuit is closed. The<br> -next row shows the first effects of closing the circuit, and also<br> -indicates the polarization of the mass, when the potential difference is<br> -insufficient for decomposition. The third row indicates the<br> -decomposition of a chain of molecules, one constituent separating at<br> -each pole.<br> -<br> -<br> -214 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Electrolysis, Laws of.</span><br> -The following are the principal laws, originally discovered by<br> -Faraday, and sometimes called Faraday's Laws of Electrolysis:<br> -<br> -1. Electrolysis cannot take place unless the electrolyte is a conductor.<br> -Conductor here means an electrolytic conductor, one that conducts by its<br> -own molecules traveling, and being decomposed. (See Grothüss'<br> -Hypothesis.)<br> -<br> -II. The energy of the electrolytic action of the current is the same<br> -wherever exercised in different parts of the circuit.<br> -<br> -III. The same quantity of electricity--that is the same current for the<br> -same period----- decomposes chemically equivalent quantities of the<br> -bodies it decomposes, or the weights of elements separated in<br> -electrolytes by the same quantity of electricity (in coulombs or some<br> -equivalent unit) are to each other as their chemical equivalent.<br> -<br> -IV. The quantity of a body decomposed in a given time is proportional to<br> -the strength of the current.<br> -<br> -To these may be added the following:<br> -<br> -V. A definite and fixed electro-motive force is required for the<br> -decomposition of each compound, greater for some and less for others.<br> -Without sufficient electro-motive force expended on the molecule no<br> -decomposition will take place. (See Current, Convective.)<br> -<br> -<br> -<span style="font-weight: bold;">Electrolyte.</span><br> -A body susceptible of decomposition by the electric current, and capable<br> -of electrolytic conduction. It must be a fluid body and therefore<br> -capable of diffusion, and composite in composition. An elemental body<br> -cannot be an electrolyte.<br> -<br> -<br> -<span style="font-weight: bold;">Electrolytic Analysis.</span><br> -Chemical analysis by electrolysis. The quantitative separation of a<br> -number of metals can be very effectively executed. Thus, suppose that a<br> -solution of copper sulphate was to be analyzed. A measured portion of<br> -the solution would be introduced into a weighed platinum vessel. The<br> -vessel would be connected to the zinc plate terminal of a battery. From<br> -the other terminal of the battery a wire would be brought and would<br> -terminate in a plate of platinum. This would be immersed in the solution<br> -in the vessel. As the current would pass the copper sulphate would be<br> -decomposed and eventually all the copper would be deposited in a firm<br> -coating on the platinum. The next operations would be to wash the metal<br> -with distilled water, and eventually with alcohol, to dry and to weigh<br> -the dish with the adherent copper. On subtracting the weight of the dish<br> -alone from the weight of the dish and copper, the weight of the metallic<br> -copper in the solution would be obtained.<br> -<br> -In similar ways many other determinations are effected. The processes of<br> -analysis include solution of the ores or other substances to be analyzed<br> -and their conversion into proper form for electrolysis. Copper as just<br> -described can be precipitated from the solution of its sulphate. For<br> -iron and many other metals solutions of their double alkaline oxalates<br> -are especially available forms for analysis.<br> -<br> -The entire subject has been worked out in considerable detail by<br> -Classen, to whose works reference should be made for details of<br> -processes.<br> -<br> -<br> -<span style="font-weight: bold;">Electrolytic Convection.</span><br> -It is sometimes observed that a single cell of Daniell battery, for<br> -instance, or other source of electric current establishing too low a<br> -potential difference for the decomposition of water seems to produce a<br> -feeble but continuous decomposition. This is very unsatisfactorily<br> -accounted for by the hydrogen as liberated combining with dissolved<br> -oxygen. (Ganot.) The whole matter is obscure. (See Current, Convection.)<br> -<br> -<br> -215 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Electrolytic Conduction.</span><br> -Conduction by the travel of atoms or radicals from molecule to molecule<br> -of a substance with eventual setting free at the electrodes of the atoms<br> -or radicals as elementary molecules or constituent radicals. A substance<br> -to be capable of acting as an electrolytic conductor must be capable of<br> -diffusion, and must also have electrolytic conductivity. Such a body is<br> -called an electrolyte. (See Grothüss' Hypothesis--Electrolysis--<br> -Electrolysis, Laws of--Electro-chemical Equivalent.)<br> -<br> -<br> -<span style="font-weight: bold;">Electro-magnet.</span><br> -A mass, in practice always of iron, around which an electric circuit is<br> -carried, insulated from the iron. When a current is passed through the<br> -circuit the iron presents the characteristics of a magnet. (See<br> -Magnetism, Ampére's Theory of--Solenoid--Lines of Force.) In -general<br> -terms the action of a circular current is to establish lines of force<br> -that run through the axis of the circuit approximately parallel thereto,<br> -and curving out of and over the circuit, return into themselves outside<br> -of the circuit. If a mass of iron is inserted in the axis or elsewhere<br> -near such current, it multiplies within itself the lines of force, q. v.<br> -(See also Magnetic Permeability--Permeance--Magnetic Induction,<br> -Coefficient of Magnetic Susceptibility--Magnetization, Coefficient of<br> -Induced.) These lines of force make it a magnet. On their direction,<br> -which again depends on the direction of the magnetizing current, depends<br> -the polarity of the iron. The strength of an electro-magnet, below<br> -saturation of the core (see Magnetic Saturation), is proportional nearly<br> -to the ampere-turns, q. v. More turns for the same current or more<br> -current for the same turns increase its strength.<br> -<br> -In the cut is shown the general relation of current, coils, core and<br> -line of force. Assume that the magnet is looked at endwise, the observer<br> -facing one of the poles; then if the current goes around the core in the<br> -direction opposite to that of the hands of a clock, such pole will be<br> -the north pole. If the current is in the direction of the hands of a<br> -clock the pole facing the observer will be the south pole. The whole<br> -relation is exactly that of the theoretical Ampérian currents, -already<br> -explained. The direction and course of the lines of force created are<br> -shown in the cut.<br> -<br> -The shapes of electro-magnets vary greatly. The cuts show several forms<br> -of electro- magnets. A more usual form is the horseshoe or double limb<br> -magnet, consisting generally of two straight cores, wound with wire and<br> -connected and held parallel to each other by a bar across one end, which<br> -bar is called the yoke.<br> -<br> -In winding such a magnet the wire coils must conform, as regards<br> -direction of the current in them to the rule for polarity already cited.<br> -If both poles are north or both are south poles, then the magnet cannot<br> -be termed a horseshoe magnet, but is merely an anomalous magnet. In the<br> -field magnets of dynamos the most varied types of electro-magnets have<br> -been used. Consequent poles are often produced in them by the direction<br> -of the windings and connections.<br> -<br> -To obtain the most powerful magnet the iron core should be as short and<br> -thick as possible in order to diminish the reluctance of the magnetic<br> -circuit. To obtain a greater range of action a long thin shape is<br> -better, although it involves waste of energy in its excitation.<br> -<br> -<br> -216 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 743px; height: 384px;" alt="" - src="images/216F145.jpg"><br> -Fig. 145 DIAGRAM OF AN ELECTRO-MAGNET SHOWING RELATION OF<br> -CURRENT AND WINDING TO ITS POLARITY AND LINES OF FORCE.<br> -<br> -<br> -<img style="width: 373px; height: 710px;" alt="" - src="images/216F146.jpg"><br> -Fig. 146. ANNULAR ELECTRO-MAGNET<br> -<br> -<br> -<span style="font-weight: bold;">Electro-magnet, Annular.</span><br> -An electro-magnet consisting of a cylinder with a circular groove cut in<br> -its face, in which groove a coil of insulated wire is placed. On the<br> -passage of a current the iron becomes polarized and attracts an armature<br> -towards or against its grooved face. The cut shows the construction of<br> -an experimental one. It is in practice applied to brakes and clutches.<br> -In the cut of the electro-magnetic brake (see Brake, Electro-magnetic),<br> -C is the annular magnet receiving its current through the brushes, and<br> -pressed when braking action is required against the face of the moving<br> -wheel. The same arrangement, it can be seen, may apply to a clutch.<br> -<br> -<br> -217 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 551px; height: 358px;" alt="" - src="images/217F147.jpg"><br> -Fig. 147. BAR ELECTRO-MAGNET.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Electro-magnet, Bar.</span><br> -A straight bar of iron surrounded with a magnetizing coil of wire. Bar<br> -electromagnets are not much used, the horseshoe type being by far the<br> -more usual.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-magnet, Club-foot.</span><br> -An electro-magnet, one of whose legs only is wound with wire, the other<br> -being bare.<br> -<br> -<br> -<img style="width: 707px; height: 364px;" alt="" - src="images/217F148.jpg"><br> -Fig. 148. CLUB-FOOT ELECTRO-MAGNETS WITH HINGED ARMATURES.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-magnet, Hinged.</span><br> -An electro-magnet whose limbs are hinged at the yoke. On excitation by a<br> -current the poles tend to approach each other.<br> -<br> -<br> -<img style="width: 521px; height: 330px;" alt="" - src="images/217F149.jpg"><br> -Fig. 149. ELECTRO-MAGNET, HINGED<br> -<br> -<br> -<span style="font-weight: bold;">Electro-magnetic Attraction and -Repulsion.</span><br> -The attraction and repulsion due to electromagnetic lines of force,<br> -which lines always tend to take as short a course as possible and also<br> -seek the medium of the highest permeance. This causes them to<br> -concentrate in iron and steel or other paramagnetic substance and to<br> -draw them towards a magnet by shortening the lines of force connecting<br> -the two. It is exactly the same attraction as that of the permanent<br> -magnet for its armature, Ampére's theory bringing the latter -under the<br> -same title. In the case of two magnets like poles repel and unlike<br> -attract. In the case of simple currents, those in the same direction<br> -attract and those in opposite directions repel each other. This refers<br> -to constant current reactions. Thus the attraction of unlike poles of<br> -two magnets is, by the Ampérian theory, the attraction of two -sets of<br> -currents of similar direction, as is evident from the diagram. The<br> -repulsion of like poles is the repulsion of unlike currents and the same<br> -applies to solenoids, q. v. (See Magnetism and do. Ampére's -Theory<br> -of--Induction, Electro-dynamic--Electro-magnetic Induction.)<br> -<br> -<br> -218 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-magnetic Control.</span><br> -Control of a magnet, iron armature, or magnetic needle in a<br> -galvanometer, ammeter, voltmeter or similar instrument by an<br> -electro-magnetic field, the restitutive force being derived from an<br> -electro-magnet. The restitutive force is the force tending to bring the<br> -index to zero.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-magnetic Field of Force.</span><br> -A field of electro-magnetic lines of force, q. v., established through<br> -the agency of an electric current. A wire carrying a current is<br> -surrounded by circular concentric lines of force which have the axis of<br> -the wire as the locus of their centres. Electro-magnets produce lines of<br> -force identical with those produced by permanent magnets. (See Field of<br> -Force--Magnetic Field of Force--Controlling Field--Deflecting Field.)<br> -<br> -<br> -<span style="font-weight: bold;">Electro-magnetic Induction.</span><br> -When two currents of unlike direction are brought towards each other,<br> -against their natural repulsive tendency work is done, and the<br> -consequent energy takes the form of a temporary increase in both<br> -currents. When withdrawn, in compliance with the natural tendency of<br> -repulsion, the currents are diminished in intensity, because energy is<br> -not expended on the withdrawal, but the withdrawal is at the expense of<br> -the energy of the system. The variations thus temporarily produced in<br> -the currents are examples of electro-magnetic induction. The currents<br> -have only the duration in each case of the motion of the circuits. One<br> -circuit is considered as carrying the inducer current and is termed the<br> -primary circuit and its current the primary current, the others are<br> -termed the secondary circuit and current respectively. We may assume a<br> -secondary circuit in which there is no current. It is probable that<br> -there is always an infinitely small current at least, in every closed<br> -circuit. Then an approach of the circuits will induce in the secondary<br> -an instantaneous current in the reverse direction. On separating the two<br> -circuits a temporary current in the same direction is produced in the<br> -secondary.<br> -<br> -<br> -219 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -A current is surrounded by lines of force. The approach of two circuits,<br> -one active, involves a change in the lines of force about the secondary<br> -circuit. Lines of force and current are so intimately connected that a<br> -change in one compels a change in the other. Therefore the induced<br> -current in the secondary may be attributed to the change in the field of<br> -force in which it lies, a field maintained by the primary circuit and<br> -current. Any change in a field of force induces a current or change of<br> -current in any closed circuit in such field, lasting as long as the<br> -change is taking place. The new current will be of such direction as to<br> -oppose the change. (See Lenz's Law.)<br> -<br> -The action as referred to lines of force may be figured as the cutting<br> -of such lines by the secondary circuit, and such cutting may be brought<br> -about by moving the secondary in the field. (See Lines of Force--Field<br> -of Force.) The cutting of 1E8 lines of force per second by a closed<br> -circuit induces an electro-motive force of one volt. (See Induction,<br> -Mutual, Coefficient of.)<br> -<br> -<br> -<span style="font-weight: bold;">Electro-magnet, Iron Clad.</span><br> -A magnet whose coil and core are encased in a iron jacket, generally<br> -connected to one end of the core. This gives at one end two poles, one<br> -tubular, the other solid, and concentric with each other. It is<br> -sometimes called a tubular magnet.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Electro-magnet, One Coil.</span><br> -An electro-magnet excited by one coil. In some dynamos the field magnets<br> -are of this construction, a single coil, situated about midway between<br> -the poles, producing the excitation.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-magnetic Leakage.</span><br> -The leakage of lines of force in an electro-magnet; the same as magnetic<br> -leakage. (See Magnetic Leakage.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Electro-magnetic Lines of Force.</span><br> -The lines of force produced in an electro-magnetic field. They are<br> -identical with Magnetic Lines of Force, q. v. (See also Field of<br> -Force-Line of Force.)<br> -<br> -<br> -<span style="font-weight: bold;">Electro-magnetic Stress.</span><br> -The stress in an electro-magnetic field of force, showing itself in the<br> -polarization of light passing through a transparent medium in such a<br> -field. (See Magnetic Rotary Polarization.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Electro-magnetic Theory of Light.</span><br> -This theory is due to J. Clark Maxwell, and the recent Hertz experiments<br> -have gone far to prove it. It holds that the phenomena of light are due<br> -to ether waves, identical in general factors with those produced by<br> -electro-magnetic induction of alternating currents acting on the ether.<br> -In a non-conductor any disturbance sets an ether wave in motion owing to<br> -its restitutive force; electricity does not travel through such a<br> -medium, but can create ether waves in it. Therefore a non-conductor of<br> -electricity is permeable to waves of ether or should transmit light, or<br> -should be transparent. A conductor on the other hand transmits<br> -electrical disturbances because it has no restitutive force and cannot<br> -support an ether wave. Hence a conductor should not transmit light, or<br> -should be opaque. With few exceptions dielectrics or non-conductors are<br> -transparent, and conductors are opaque.<br> -<br> -<br> -220 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Again, the relation between the electrostatic and electro-magnet units<br> -of quantity is expressed by 1 : 30,000,000,000; the latter figure in<br> -centimeters gives approximately the velocity of light. The<br> -electro-magnetic unit depending on electricity in motion should have<br> -this precise relation if an electro-magnetic disturbance was propagated<br> -with the velocity of light. If an electrically charged body were whirled<br> -around a magnetic needle with the velocity of light, it should act in<br> -the same way as a current circulating around it. This effect to some<br> -extent has been shown experimentally by Rowland.<br> -<br> -A consequence of these conclusions is (Maxwell) that the specific<br> -inductive capacity of a non-conductor or dielectric should be equal to<br> -the square of its index of refraction for waves of infinite length. This<br> -is true for some substances--sulphur, turpentine, petroleum and benzole.<br> -In others the specific inductive capacity is too high, e. g., vegetable<br> -and animal oils, glass, Iceland spar, fluor spar, and quartz.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Electro-magnetic Unit of Energy.</span><br> -A rate of transference of energy equal to ten meg-ergs per second.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-magnetism.</span><br> -The branch of electrical science treating of the magnetic relations of a<br> -field of force produced by a current, of the reactions of<br> -electro-magnetic lines of force, of the electromagnetic field of force,<br> -of the susceptibility, permeability, and reluctance of diamagnetic and<br> -paramagnetic substances, and of electro-magnets in general.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-magnet, Long Range.</span><br> -An electro-magnet so constructed with extended pole pieces or otherwise,<br> -as to attract its armature with reasonably constant force over a<br> -considerable distance. The coil and plunger, q. v., mechanisms<br> -illustrate one method of getting an extended range of action. When a<br> -true electro-magnet is used, one with an iron core, only a very limited<br> -range is attainable at the best. (See Electro-magnet, Stopped Coil--do.<br> -Plunger.)<br> -<br> -<br> -<span style="font-weight: bold;">Electro-magnet, Plunger.</span><br> -An electro-magnet with hollow coils, into which the armature enters as a<br> -plunger. To make it a true electro-magnet it must have either a yoke,<br> -incomplete core, or some polarized mass of iron.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Electro-magnet, Polarized.</span><br> -An electro-magnet consisting of a polarized or permanently magnetized<br> -core wound with magnetizing coils, or with such coils on soft iron cores<br> -mounted on its ends. The coils may be wound and connected so as to<br> -cooperate with or work against the permanent magnet on which it is<br> -mounted. In Hughes' magnet shown in the cut it is mounted in opposition,<br> -so that an exceedingly feeble current will act to displace the armature,<br> -a, which is pulled away from the magnet by a spring, s.<br> -<br> -<br> -221 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 473px; height: 576px;" alt="" - src="images/221F150.jpg"><br> -Fig. 150 HUGHES' POLARIZED ELECTRO-MAGNET<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Electro-magnets, Interlocking.</span><br> -Electro-magnets so arranged that their armatures interlock. Thus two<br> -magnets, A A and B B, may be placed with their armatures, M and N, at<br> -right angles and both normally pulled away from the poles. When the<br> -armature M is attracted a catch on its end is retained by a hole in the<br> -end of the other armature N, and when the latter armature N is attracted<br> -by its magnet the armature M is released. In the mechanism shown in the<br> -cut the movements of the wheel R are controlled. Normally it is held<br> -motionless by the catch upon the bottom of the armature M, coming<br> -against the tooth projecting from its periphery. A momentary current<br> -through the coils of the magnet A A releases it, by attracting M, which<br> -is caught and retained by N, and leaves it free to rotate. A momentary<br> -current through the coils of the magnet B B again releases M, which<br> -drops down and engages the tooth upon R and arrests its motion.<br> -<br> -<br> -<img style="width: 613px; height: 519px;" alt="" - src="images/221F151.jpg"><br> -Fig. 151. INTERLOCKING ELECTRO-MAGNETS.<br> -<br> -<br> -222 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-magnet, Stopped Coil.</span><br> -An electro-magnet consisting of a tubular coil, in which a short fixed<br> -core is contained, stopping up the aperture to a certain distance, while<br> -the armature is a plunger entering the aperture. This gives a longer<br> -range of action than usual.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-magnet, Surgical.</span><br> -An electro-magnet, generally of straight or bar form, fitted with<br> -different shaped pole pieces, used for the extraction of fragments of<br> -iron or steel from the eyes. Some very curious cases of successful<br> -operations on the eyes of workmen, into whose eyes fragments of steel or<br> -iron had penetrated, are on record.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-medical Baths.</span><br> -A bath for the person provided with connections and electrodes for<br> -causing a current of electricity of any desired type to pass through the<br> -body of the bather. Like all electro-therapeutical treatment, it should<br> -be administered under the direction of a physician only.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-metallurgy.</span><br> -(a) In the reduction of ores the electric current has been proposed but<br> -never extensively used, except in the reduction of aluminum and its<br> -alloys. (See Reduction of Ores, Electric.)<br> -<br> -(b) Electro-plating and deposition of metal from solutions is another<br> -branch. (See Electroplating and Electrotyping.)<br> -<br> -(c) The concentration of iron ores by magnetic attraction may come under<br> -this head. (See Magnetic Concentration of Ores.)<br> -<br> -<br> -<span style="font-weight: bold;">Electrometer.</span><br> -An instrument for use in the measurement of potential difference, by the<br> -attraction or repulsion of statically charged bodies. They are<br> -distinguished from galvanometers as the latter are really current<br> -measurers, even if wound for use as voltmeters, depending for their<br> -action upon the action of the current circulating in their coils.<br> -<br> -<br> -<span style="font-weight: bold;">Electrometer, Absolute.</span><br> -An electrometer designed to give directly the value of a charge in<br> -absolute units. In one form a plate, a b, of conducting surface is<br> -supported or poised horizontally below a second larger plate C, also of<br> -conducting surface. The poised plate is surrounded by a detached guard<br> -ring--an annular or perforated plate, r g r' g'--exactly level and even<br> -with it as regards the upper surface. The inner plate is carried by a<br> -delicate balance. In use it is connected to one of the conductors and<br> -the lower plate to earth or to the other. The attraction between them is<br> -determined by weighing. By calculation the results can be made absolute,<br> -as they depend on actual size of the plates and their distance, outside<br> -of the potential difference of which of course nothing can be said. If S<br> -is the area of the disc, d the distance of the plates, V-V1 the<br> -difference of their potential, which is to be measured, and F the force<br> -required to balance their attraction, we have:<br> -<br> -F = ( ( V - V1 )^2 * S ) / ( 8 * PI * d^2 )<br> -<br> -<br> -223 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -If V = 0 this reduces to<br> -<br> - F = ( V^2 * S ) / ( 8 * PI * d^2 ) (2)<br> - or<br> - V = d * SquareRoot( (8 * PI * F ) / S ) (3)<br> -<br> -As F is expressed as a weight, and S and a as measures of area and<br> -length, this gives a means of directly obtaining potential values in<br> -absolute measure. (See Idiostatic Method--Heterostatic Method.)<br> -<br> -Synonyms--Attracted Disc Electrometer--Weight Electrometer.<br> -<br> -<br> -<img style="width: 664px; height: 252px;" alt="" - src="images/223F152.jpg"><br> -Fig. 152. SECTION OF BASE OF PORTABLE ELECTROMETER.<br> -<br> -<br> -In some forms the movable disc is above the other, and supported at the<br> -end of a balance beam. In others a spring support, arranged so as to<br> -enable the attraction to be determined in weight units, is adopted. The<br> -cuts, Figs. 152 and 154, show one of the latter type, the portable<br> -electrometer. The disc portion is contained within a cylindrical vessel.<br> -<br> -<br> -<img style="width: 660px; height: 279px;" alt="" - src="images/223F153.jpg"><br> -Fig. 153. DIAGRAM ILLUSTRATING <br> -THEORY OF ABSOLUTE ELECTROMETER.<br> -<br> -<br> -Referring to Fig. 152 g is the stationary disc, charged through -the<br> -wire connection r; f is the movable disc, carried by a balance beam<br> -poised at i on a horizontal and transverse stretched platinum wire,<br> -acting as a torsional spring. The position of the end k of the balance<br> -beam shows when the disc f is in the plane of the guard ring h h. The<br> -end k is forked horizontally and a horizontal sighting wire or hair is<br> -fastened across the opening of the fork. When the hair is midway between<br> -two dots on a vertical scale the lever is in the sighted position, as it<br> -is called, and the disc is in the plane of the guard ring.<br> -<br> -<br> -224 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 425px; height: 604px;" alt="" - src="images/224F154.jpg"><br> -Fig. 154. PORTABLE ELECTROMETER.<br> -<br> -<br> -The general construction is seen in Fig. 154. There the fixed disc D is<br> -carried by insulating stem g1. The charging electrode is supported by an<br> -insulating stem g2, and without contact with the box passes out of its<br> -cover through a guard tube E, with cover, sometimes called umbrella, V.<br> -The umbrella is to protect the apparatus from air currents. At m is the<br> -sighting lens. H is a lead box packed with pumice stone, moistened with<br> -oil of vitriol or concentrated sulphuric acid, to preserve the<br> -atmosphere dry. Before use the acid is boiled with some ammonium<br> -sulphate to expel any corrosive nitrogen oxides, which might corrode the<br> -brass.<br> -<br> -In use the upper disc is charged by its insulated electrode within the<br> -tube E; the movable disc is charged if desired directly through the case<br> -of the instrument. The upper disc is screwed up or down by the<br> -micrometer head M, until the sighted position is reached. The readings<br> -of the micrometer on the top of the case give the data for calculation.<br> -<br> -<br> -225 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 642px; height: 668px;" alt="" - src="images/225F155.jpg"><br> -Fig. 155. LIPPMAN'S CAPILLARY ELECTROMETER.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Electrometer, Capillary.</span><br> -An electrometer for measuring potential difference by capillary action,<br> -which latter is affected by electrostatic excitement. A tube A contains<br> -mercury; its end drawn out to a fine aperture dips into a vessel B which<br> -contains dilute sulphuric acid with mercury under it, as shown. Wires<br> -running from the binding-posts a and b connect one with the mercury in<br> -A, the other with that in B. The upper end of the tube A connects with a<br> -thick rubber mercury reservoir T, and manometer H. The surface tension<br> -of the mercury-acid film at the lower end of the tube A keeps all in<br> -equilibrium. If now a potential difference is established between a and<br> -b, as by connecting a battery thereto, the surface tension is increased<br> -and the mercury rises in the tube B. By screwing down the compressing<br> -clamp E, the mercury is brought back to its original position. The<br> -microscope M is used to determine this position with accuracy. The<br> -change in reading of the manometer gives the relation of change of<br> -surface tension and therefore of potential. Each electrometer needs<br> -special graduation or calibration, but is exceedingly sensitive and<br> -accurate. It cannot be used for greater potential differences than .6<br> -volt, but can measure .0006 volt. Its electrostatic capacity is so small<br> -that it can indicate rapid changes. Another form indicates potential<br> -difference by the movement of a drop of sulphuric acid in a horizontal<br> -glass tube, otherwise filled with mercury, and whose ends lead into two<br> -mercury cups or reservoirs. The pair of electrodes to be tested are<br> -connected to the mercury vessels. The drop moves towards the negative<br> -pole, and its movement for small potential differences (less than one<br> -volt) is proportional to the electro-motive force or potential<br> -difference.<br> -<br> -<br> -226 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Electrometer Gauge.</span><br> -An absolute electrometer (see Electrometer, Absolute) forming an<br> -attachment to a Thomson quadrant electrometer. It is used to test the<br> -potential of the flat needle connected with the inner surface of the<br> -Leyden jar condenser of the apparatus. This it does by measuring the<br> -attraction between itself and an attracting disc, the latter connected<br> -by a conductor with the interior of the jar.<br> -<br> -<br> -<span style="font-weight: bold;">Electrometer, Lane's.</span><br> -A Leyden jar with mounted discharger, so that when charged to a certain<br> -point it discharges itself. It is connected with one coating of any jar<br> -whose charge is to be measured, which jar is then charged by the other<br> -coating. As the jar under trial becomes charged to a certain point the<br> -electrometer jar discharges itself, and the number of discharges is the<br> -measure of the charge of the other jar. It is really a unit jar, q. v.<br> -<br> -<br> -<img style="width: 433px; height: 612px;" alt="" - src="images/226F156.jpg"><br> -Fig. 156. THOMSON'S QUADRANT ELECTROMETER.<br> -<br> -<br> -<img style="width: 508px; height: 522px;" alt="" - src="images/226F157.jpg"><br> -Fig. 157. HENLEY'S QUADRANT ELECTROSCOPE.<br> -<br> -<br> -227 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Electrometer, Quadrant.</span><br> -(a) Sir William Thomson's electrometer, a simple form of which is shown<br> -in the cut, consists of four quadrants of metal placed horizontally;<br> -above these a broad flat aluminum needle hangs by a very fine wire,<br> -acting as torsional suspension. The quadrants are insulated from each<br> -other, but the opposite ones connect with each other by wires. The<br> -apparatus is adjusted so that, when the quadrants are in an unexcited<br> -condition the needle is at rest over one of the diametrical divisions<br> -between quadrants. The needle by its suspension wire is in communication<br> -with the interior of a Leyden jar which is charged. The whole is covered<br> -with a glass shade, and the air within is kept dry by a dish of<br> -concentrated sulphuric acid so that the jar retains its charge for a<br> -long time and keeps the needle at approximately a constant potential. If<br> -now two pairs of quadrants are excited with opposite electricities, as<br> -when connected with the opposite poles of an insulated galvanic cell,<br> -the needle is repelled by one pair and attracted by the other, and<br> -therefore rotates through an arc of greater or less extent. A small<br> -concave mirror is attached above the needle and its image is reflected<br> -on a graduated screen. This makes the smallest movement visible.<br> -Sometimes the quadrants are double, forming almost a complete box,<br> -within which the needle moves.<br> -<br> -(b) Henley's quadrant electrometer is for use on the prime conductor of<br> -an electric machine, for roughly indicating the relative potential<br> -thereof. It consists of a wooden standard attached perpendicularly to<br> -the conductor. Near one end is attached a semi-circular or quadrant arc<br> -of a circle graduated into degrees or angular divisions. An index,<br> -consisting of a straw with a pith-bell attached to its end hangs from<br> -the center of curvature of the arc. When the prime conductor is charged<br> -the index moves up over the scale and its extent of motion indicates the<br> -potential relatively.<br> -<br> -When the "quadrant electrometer" is spoken of it may always be assumed<br> -that Sir William Thomson's instrument is alluded to. Henley's instrument<br> -is properly termed a quadrant electroscope. (See Electroscope.)<br> -<br> -<br> -<span style="font-weight: bold;">Electro-motive Force.</span><br> -The cause which produces currents of electricity. In general it can be<br> -expressed in difference of potentials, although the term electro-motive<br> -force should be restricted to potential difference causing a current. It<br> -is often a sustained charging of the generator terminals whence the<br> -current is taken. Its dimensions are<br> -<br> -(work done/the quantity of electricity involved),<br> -<br> -or ( M * (L^2) /(T^2 ) ) / ((M^.5) * (L^.5)) = ( (M^.5) * (L^1.5) ) -/(T^2)<br> -<br> -The practical unit of electro-motive force is the volt, q. v. It is<br> -often expressed in abbreviated form, as E. M. D. P., or simply as D. P.,<br> -i. e., potential difference.<br> -<br> -Electro-motive force and potential difference are in many cases<br> -virtually identical, and distinctions drawn between them vary with<br> -different authors. If we consider a closed electric circuit carrying a<br> -current, a definite electro-motive force determined by Ohm's law from<br> -the resistance and current obtains in it. But if we attempt to define<br> -potential difference as proper to the circuit we may quite fail.<br> -Potential difference in a circuit is the difference in potential between<br> -defined points of such circuit. But no points in a closed circuit can be<br> -found which differ in potential by an amount equal to the entire<br> -electro-motive force of the circuit. Potential difference is properly<br> -the measure of electro-motive force expended on the portion of a circuit<br> -between any given points. Electro-motive force of an entire circuit, as<br> -it is measured, as it were, between two consecutive points but around<br> -the long portion of the circuit, is not conceivable as merely potential<br> -difference. Taking the circle divided in to degrees as an analogy, the<br> -electro-motive force of the entire circuit might be expressed as -360º,<br> -which are the degrees intervening between two consecutive points,<br> -measured the long way around the circle. But the potential difference<br> -between the same two points would be only 1º, for it would be -measured<br> -by the nearest path.<br> -<br> -[Transcriber's notes: If 360º is the "long" way, 0º is the -"short". A<br> -formal restatement of the above definition of EMF: "If a charge Q passes<br> -through a device and gains energy U, the net EMF for that device is the<br> -energy gained per unit charge, or U/Q. The unit of EMF is a volt, or<br> -newton-meter per coulomb."]<br> -<br> -<br> -228 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-motive Force, Counter.</span><br> -A current going through a circuit often has not only true or ohmic<br> -resistance to overcome, but meets an opposing E. M. F. This is termed<br> -counter-electro-motive force. It is often treated in calculations as<br> -resistance, and is termed spurious resistance. It may be a part of the<br> -impedance of a circuit.<br> -<br> -In a primary battery hydrogen accumulating on the negative plate<br> -develops counter E. M. F. In the voltaic arc the differential heating of<br> -the two carbons does the same. The storage battery is changed by a<br> -current passing in the opposite direction to its own natural current;<br> -the polarity of such a battery is counter E. M. F.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-motive Force, Unit.</span><br> -Unit electro-motive force is that which is created in a conductor moving<br> -through a magnetic field at such a rate as to cut one unit line of force<br> -per second. It is that which must be maintained in a circuit of unit<br> -resistance to maintain a current of unit quantity therein. It is that<br> -which must be maintained between the ends of a conductor in order that<br> -unit current may do unit work in a second.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-motive Intensity.</span><br> -The force acting upon a unit charge of electricity. The mean force is<br> -equal to the difference of potential between two points within the field<br> -situated one centimeter apart, such distance being measured along the<br> -lines of force. The term is due to J. Clerk Maxwell.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-motive Series.</span><br> -Arrangement of the metals and carbon in series with the most<br> -electro-positive at one end, and electronegative at the other end. The<br> -following are examples for different exciting liquids:<br> -<br> -<small><span style="font-family: monospace;">Dilute -Sulphuric Dilute Hydrochloric -Caustic Potassium</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Acid -Acid. -Potash. Sulphide.</span><br style="font-family: monospace;"> -<br style="font-family: monospace;"> -<span style="font-family: monospace;">Zinc -Zinc -Zinc Zinc</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Cadmium -Cadmium -Tin Copper</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Tin -Tin -Cadmium Cadmium</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Lead -Lead -Antimony Tin</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Iron -Iron -Lead Silver</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Nickel -Copper -Bismuth Antimony</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Bismuth -Bismuth -Iron Lead</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Antimony -Nickel -Copper Bismuth</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Copper -Silver -Nickel Nickel</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Silver -Antimony -Silver Iron</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Gold</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Platinum</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Carbon</span></small> -<br> -<br> -In each series the upper metal is the positive, dissolved or attacked<br> -element.<br> -<br> -<br> -229 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-motograph.</span><br> -An invention of Thomas A. Edison. A cylinder of chalk, moistened with<br> -solution of caustic soda, is mounted so as to be rotated by a handle. A<br> -diaphragm has an arm connected to its center. This arm is pressed<br> -against the surface of the cylinder by a spring. When the cylinder is<br> -rotated, a constant tension is exerted on the diaphragm. If a current is<br> -passed through the junction of arm and cylinder the electrolytic action<br> -alters the friction so as to change the stress upon the diaphragm.<br> -<br> -If the current producing this effect is of the type produced by the<br> -human voice through a microphone the successive variations in strain<br> -upon the diaphragm will cause it to emit articulate sounds. These are<br> -produced directly by the movement of the cylinder, the electrolytic<br> -action being rather the regulating portion of the operation. Hence very<br> -loud sounds can be produced by it. This has given it the name of the<br> -loud- speaking telephone.<br> -<br> -The same principle may be applied in other ways. But the practical<br> -application of the motograph is in the telephone described.<br> -<br> -<br> -<img style="width: 432px; height: 680px;" alt="" - src="images/229F158.jpg"><br> -Fig. 158. ELECTRO-MOTOGRAPH TELEPHONE<br> -<br> -<br> -<span style="font-weight: bold;">Electro-motor.</span><br> -This term is sometimes applied to a current generator, such as a voltaic<br> -battery.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-muscular Excitation.</span><br> -A term in medical electricity indicating the excitation of muscle as the<br> -effect of electric currents of any kind.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-negative. adj.</span><br> -Appertaining to negative electrification; thus of the elements oxygen is<br> -the most electro-negative, because if separated by electrolytic action<br> -from any combination, it will be charged with negative electricity.<br> -<br> -<br> -230 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-optics.</span><br> -The branch of natural science treating of the relations between light<br> -and electricity. Both are supposed to be phenomena of or due to the<br> -luminiferous ether. To it may be referred the following:<br> -<br> -(a) Electro-magnetic Stress and Magnetic Rotary Polarization;<br> -<br> -(b) Dielectric Strain; all of which may be referred to in this book;<br> -<br> -(c) Change in the resistance of a conductor by changes in light to which<br> -it is exposed (see Selenium);<br> -<br> -(d) The relation of the index of refraction of a dielectric to the<br> -dielectric constant (see Electro-magnetic Theory of Light);<br> -<br> -(e) The identity (approximate) of the velocity of light in centimeters<br> -and the relative values of the electrostatic and electro-magnet units<br> -of intensity, the latter being 30,000,000,000 times greater than the<br> -former, while the velocity of light is 30,000,000,000 centimeters per<br> -second.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Electrophoric Action.</span><br> -The action of an electrophorous; utilized in influence machines. (See<br> -Electrophorous.)<br> -<br> -<br> -<img style="width: 631px; height: 500px;" alt="" - src="images/230F159.jpg"><br> -Fig. 159. ELECTROPHOROUS.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Electrophorous.</span><br> -An apparatus for the production of electric charges of high potential by<br> -electrostatic induction, q. v. It consists of a disc of insulating<br> -material B, such as resin or gutta percha, which is held in a shallow<br> -metal-lined box or form. The disc may be half an inch thick and a foot<br> -or more in diameter, or may be much smaller and thinner. A metal disc A,<br> -smaller in diameter is provided with an insulating handle which may be<br> -of glass, or simply silk suspension strings. To use it the disc B is<br> -excited by friction with a cat-skin or other suitable substance. The<br> -metallic disc is then placed on the cake of resin exactly in its centre,<br> -so that the latter disc or cake projects on all sides. Owing to<br> -roughness there is little real electric contact between the metal and<br> -dielectric. On touching the metal disc a quantity of negative<br> -electricity escapes to the earth. On raising it from the cake it comes<br> -off excited positively, and gives a spark and is discharged. It can be<br> -replaced, touched, removed and another spark can be taken from it, and<br> -so on as long as the cake stays charged.<br> -<br> -The successive discharges represent electrical energy expended. This is<br> -derived from the muscular energy expended by the operator in separating<br> -the two discs when oppositely excited. As generally used it is therefore<br> -an apparatus for converting muscular or mechanical energy into electric<br> -energy.<br> -<br> -<br> -231 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-physiology.</span><br> -The science of the electric phenomena of the animal system. It may also<br> -be extended to include plants. The great discovery of Galvani with the<br> -frog's body fell into this branch of science. The electric fishes,<br> -gymnotus, etc., present intense phenomena in the same.<br> -<br> -<br> -<span style="font-weight: bold;">Electroplating.</span><br> -The deposition by electrolysis of a coating of metal upon a conducting<br> -surface. The simplest system makes the object to be plated the negative<br> -electrode or plate in a galvanic couple. Thus a spoon or other object<br> -may be connected by a wire to a plate of zinc. A porous cup is placed<br> -inside a battery jar. The spoon is placed in the porous cup and the zinc<br> -outside it. A solution of copper sulphate is placed in the porous cup,<br> -and water with a little sodium or zinc sulphate dissolved in it,<br> -outside. A current starts through the couple, and copper is deposited on<br> -the spoon.<br> -<br> -A less primitive way is to use a separate battery as the source of<br> -current; to connect to the positive plate by a wire the object to be<br> -plated, and a plate of copper, silver, nickel or other metal to the<br> -other pole of the battery. On immersing both object and plate (anode) in<br> -a bath of proper solution the object will become plated.<br> -<br> -In general the anode is of the same material as the metal to be<br> -deposited, and dissolving keeps up the strength of the bath. There are a<br> -great many points of technicality involved which cannot be given here.<br> -The surface of the immersed object must be conductive. If not a fine<br> -wire network stretched over it will gradually fill up in the bath and<br> -give a matrix. More generally the surface is made conductive by being<br> -brushed over with plumbago. This may be followed by a dusting of iron<br> -dust, followed by immersion in solution ot copper sulphate. This has the<br> -effect of depositing metallic copper over the surface as a starter for<br> -the final coat.<br> -<br> -Attention must be paid to the perfect cleanliness of the objects, to the<br> -condition of the bath, purity of anodes and current density.<br> -<br> -Voltaic batteries are largely used for the current as well as special<br> -low resistance dynamos. Thermo-electric batteries are also used to some<br> -extent but not generally.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-pneumatic Signals.</span><br> -Signals, such as railroad signals or semaphores, moved by compressed<br> -air, which is controlled by valves operated by electricity. The House<br> -telegraph, which was worked by air controlled by electricity, might come<br> -under this term, but it is always understood as applied to railroad<br> -signals, or their equivalent.<br> -<br> -<br> -232 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Electropoion Fluid.</span><br> -An acid depolarizing solution for use in zinc-carbon couples, such as<br> -the Grenet battery. The following are formulae for its preparation:<br> -<br> -(a) Dissolve one pound of potassium bichromate in ten pounds of water,<br> -to which two and one-half pounds of concentrated sulphuric acid have<br> -been gradually added. The better way is to use powdered potassium<br> -bichromate, add it to the water first, and then gradually add the<br> -sulphuric acid with constant stirring.<br> -<br> -(b) To three pints of water add five fluid ounces of concentrated<br> -sulphuric acid; add six ounces pulverized potassium bichromate.<br> -<br> -(c) Mix one gallon concentrated sulphuric acid and three gallons of<br> -water. In a separate vessel dissolve six pounds potassium bichromate in<br> -two gallons of boiling water. Mix the two.<br> -<br> -The last is the best formula. Always use electropoion fluid cold. (See<br> -Trouvé's Solution--Poggendorff's Solution--Kakogey's Solution--<br> -Tissandrier's Solution--Chutaux's Solution.)<br> -<br> -<br> -<span style="font-weight: bold;">Electro-positive. adj.</span><br> -Appertaining to positive electrification; thus potassium is the most<br> -electro-positive of the elements. (See Electro-negative.)<br> -<br> -<br> -<span style="font-weight: bold;">Electro-puncture.</span><br> -The introduction into the system of a platinum point or needle,<br> -insulated with vulcanite, except near its point, and connected as the<br> -anode of a galvanic battery. The kathode is a metal one, covered with a<br> -wet sponge and applied on the surface near the place of puncture. It is<br> -used for treatment of aneurisms or diseased growths, and also for<br> -removal of hair by electrolysis. (See Hair, Removal of by Electrolysis.)<br> -<br> -Synonym--Galvano-puncture.<br> -<br> -<br> -<span style="font-weight: bold;">Electro-receptive. adj.</span><br> -A term applied to any device or apparatus designed to receive and absorb<br> -electric energy. A motor is an example of an electro-receptive<br> -mechanism.<br> -<br> -<br> -<span style="font-weight: bold;">Electroscope.</span><br> -An apparatus for indicating the presence of an electric charge, and also<br> -for determining the sign, or whether the charge is positive or negative.<br> -The simplest form consists of a thread doubled at its centre and hung<br> -therefrom. On being charged, or on being connected to a charged body the<br> -threads diverge. A pair of pith balls may be suspended in a similar way,<br> -or a couple of strips of gold leaf within a flask (the gold leaf<br> -electroscope). To use an electroscope to determine the sign of the<br> -charge it is first slightly charged. The body to be tested is then<br> -applied to the point of suspension, or other charging point. If at once<br> -further repelled the charge of the body is of the same sign as the<br> -slight charge first imparted to the electroscope leaves; the leaves as<br> -they become more excited will at once diverge more. If of different sign<br> -they will at first approach as their charge is neutralized and will<br> -afterwards diverge.<br> -<br> -The gold-leaf electroscope is generally enclosed in a glass bell jar or<br> -flask. Sometimes a pair of posts rise, one on each side, to supply<br> -points of induction from the earth to intensify the action. (See<br> -Electrometer, Quadrant--Electroscope, Gold leaf, and others.)<br> -<br> -<br> -233 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Electroscope, Bennett's.</span><br> -A gold-leaf electroscope, the suspended leaves of which are contained in<br> -a glass shade or vessel of dry air. On the inside of the glass shade are<br> -two strips of gold leaf, which rise from the lower edge a short<br> -distance, being pasted to the glass, and connected to the ground. These<br> -act by induction to increase the sensitiveness of the instruments.<br> -<br> -<br> -<span style="font-weight: bold;">Electroscope, Bohenberger's.</span><br> -A condensing electroscope (see Electroscope, Condensing) with a single<br> -strip of gold leaf suspended within the glass bell. This is at an equal<br> -distance from the opposite poles of two dry piles (see Zamboni's Dry<br> -Pile) standing on end, one on each side of it. As soon as the leaf is<br> -excited it moves toward one and away from the other pile, and the sign<br> -of its electrification is shown by the direction of its motion.<br> -<br> -<br> -<span style="font-weight: bold;">Electroscope, Condensing.</span><br> -A gold leaf electroscope, the glass bell of which is surmounted by an<br> -electrophorous or static condenser, to the lower plate of which the<br> -leaves of gold are suspended or connected.<br> -<br> -In use the object to be tested is touched to the lower plate, and the<br> -upper plate at the same time is touched by the finger. The plates are<br> -now separated. This reduces the capacity of the lower plate greatly and<br> -its charge acquires sufficient potential to affect the leaves, although<br> -the simple touching may not have affected them at all.<br> -<br> -<br> -<span style="font-weight: bold;">Electroscope, Gold Leaf.</span><br> -An electroscope consisting of two leaves of gold leaf hung in contact<br> -with each other from the end of a conductor. When excited they diverge.<br> -The leaves are enclosed in a glass vessel.<br> -<br> -<br> -<img style="width: 350px; height: 718px;" alt="" - src="images/233F160.jpg"><br> -Fig. 160. GOLD LEAF ELECTROSCOPE.<br> -<br> -<br> -234 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Electroscope, Pith Ball.</span><br> -Two pith balls suspended at opposite ends of a silk thread doubled in<br> -the middle. When charged with like electricity they repel each other.<br> -The extent of their repulsion indicates the potential of their charge.<br> -<br> -<br> -<span style="font-weight: bold;">Electrostatic Attraction and Repulsion.</span><br> -The attraction and repulsion of electrostatically charged bodies for<br> -each other, shown when charged with electricity. If charged with<br> -electricity of the same sign they repel each other. If with opposite<br> -they attract each other. The classic attraction and subsequent repulsion<br> -of bits of straw and chaff by the excited piece of amber is a case of<br> -electrostatic attraction and repulsion. (See Electricity,<br> -Static--Electrostatics--Coulomb's Laws of Electrostatic Attraction and<br> -Repulsion.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Electrostatic Induction, Coefficient -of.</span><br> -The coefficient expressing the ratio of the charge or change of charge<br> -developed in one body to the potential of the inducing body.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Electrostatic Lines of Force.</span><br> -Lines of force assumed to exist in an electrostatic field of force, and<br> -to constitute the same. In general they correspond in action and<br> -attributes with elcctro-magnetic lines of force. They involve in almost<br> -all cases either a continuous circuit, or a termination at both ends in<br> -oppositely charged surfaces.<br> -<br> -<br> -<img style="width: 624px; height: 124px;" alt="" - src="images/234F161.jpg"><br> -Fig. 161. ELECTROSTATIC LINES OF FORCE <br> -BETWEEN NEAR SURFACES.<br> -<br> -<br> -<img style="width: 650px; height: 399px;" alt="" - src="images/234F162.jpg"><br> -Fig. 162. ELECTROSTATIC LINKS OF FORCE <br> -BETWEEN DISTANT SURFACES.<br> -<br> -<br> -235 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The cut, Fig. 161, shows the general course taken by lines of force<br> -between two excited surfaces when near together. Here most of them are<br> -straight lines reaching straight across from surface to surface, while a<br> -few of them arch across from near the edges, tending to spread. If the<br> -bodies are drawn apart the spreading tendency increases and the<br> -condition of things shown in the next cut, Fig. 162, obtains. There is<br> -an axial line whose prolongations may be supposed to extend<br> -indefinitely, as occupying a position of unstable equilibrium. Here the<br> -existence of a straight and unterminated line of force may be assumed.<br> -<br> -A direction is predicated to lines of force corresponding with the<br> -direction of an electric current. They are assumed to start from a<br> -positively charged and to go towards a negatively charged surface. A<br> -positively charged body placed in an electrostatic field of force will<br> -be repelled from the region of positive into or towards the region of<br> -negative potential following the direction of the lines of force, not<br> -moving transversely to them, and having no transverse component in its<br> -motion.<br> -<br> -[Transcriber's note: More precisely, "A positively charged body placed<br> -in an electrostatic field of force will be repelled from the region of<br> -positive into or towards the region of negative potential ACCELERATING<br> -in the direction of the lines of force, not ACCELERATING transversely to<br> -them, and having no transverse component in its ACCELERATION."<br> -Previously acquired momentum can produce a transverse component of<br> -VELOCITY.]<br> -<br> -<br> -<span style="font-weight: bold;">Electrostatics.</span><br> -The division of electric science treating of the phenomena of electric<br> -charge, or of electricity in repose, as contrasted with electro-dynamics<br> -or electricity in motion or in current form. Charges of like sign repel,<br> -and of unlike sign attract each other. The general inductive action is<br> -explained by the use of the electrostatic field of force and<br> -electrostatic lines of force, q. v. The force of attraction and<br> -repulsion of small bodies or virtual points, which are near enough to<br> -each other, vary as the square of the distance nearly, and with the<br> -product of the quantities of the charges of the two bodies.<br> -<br> -<br> -<span style="font-weight: bold;">Electrostatic Refraction.</span><br> -Dr. Kerr found that certain dielectrics exposed to electric strain by<br> -being placed between two oppositely excited poles of a Holtz machine or<br> -other source of very high tension possess double refracting powers, in<br> -other words can rotate a beam of polarized light, or can develop two<br> -complimentary beams from common light. Bisulphide of carbon shows the<br> -phenomenon well, acting as glass would if the glass were stretched in<br> -the direction of the electrostatic lines of force. To try it with glass,<br> -holes are drilled in a plate and wires from an influence machine are<br> -inserted therein. The discharge being maintained through the glass it<br> -polarizes light.<br> -<br> -Synonym--Kerr Effect.<br> -<br> -<br> -<span style="font-weight: bold;">Electrostatic Series.</span><br> -A table of substances arranged in the order in which they are<br> -electrostatically charged by contact, generally by rubbing against each<br> -other. The following series is due to Faraday. The first members become<br> -positively excited when rubbed with any of the following members, and<br> -vice versa. The first elements correspond to the carbon plate in a<br> -galvanic battery, the succeeding elements to the zinc plate.<br> -<br> -Cat, and Bear-skin--Flannel--Ivory--Feathers--Rock Crystal--Flint<br> -Glass--Cotton--Linen--Canvas--White Silk--the Hand--Wood--Shellac--the<br> -Metals (Iron-Copper-Brass-Tin-Silver-Platinum)--Sulphur. There are some<br> -irregularities. A feather lightly drawn over canvas is negatively<br> -electrified; if drawn through folds pressed against it it is positively<br> -excited. Many other exceptions exist, so that the table is of little<br> -value.<br> -<br> -<br> -236 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Electrostatic Stress.</span><br> -The stress produced upon a transparent medium in an electrostatic field<br> -of force by which it acquires double refracting or polarizing properties<br> -as regards the action of such medium upon light. (See Electrostatic<br> -Refraction.)<br> -<br> -<br> -<span style="font-weight: bold;">Electro-therapeutics or Therapy.</span><br> -The science treating of the effects of electricity upon the animal<br> -system in the treatment and diagnosis of disease.<br> -<br> -<br> -<span style="font-weight: bold;">Electrotonus.</span><br> -An altered condition of functional activity occurring in a nerve<br> -subjected to the passage of an electric current. If the activity is<br> -decreased, which occurs near the anode, the state is one of<br> -anelectrotonus, if the activity is increased which occurs near the<br> -kathode the condition is one of kathelectrotonus.<br> -<br> -<br> -<span style="font-weight: bold;">Electrotype.</span><br> -The reproduction of a form of type or of an engraving or of the like by<br> -electroplating, for printing purposes. The form of type is pressed upon<br> -a surface of wax contained in a shallow box. The wax is mixed with<br> -plumbago, and if necessary some more is dusted and brushed over its<br> -surface and some iron dust is sprinkled over it also. A matrix or<br> -impression of the type is thus obtained, on which copper is deposited by<br> -electroplating, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Element, Chemical.</span><br> -The original forms of matter that cannot be separated into constituents<br> -by any known process. They are about seventy in number. Some of the<br> -rarer ones are being added to or cancelled with the progress of chemical<br> -discovery. For their electric relations see Electro-chemical<br> -Equivalents--Electro-chemical Series.<br> -<br> -The elements in entering into combination satisfy chemical affinity and<br> -liberate energy, which may take the form of electric energy as in the<br> -galvanic battery, or of heat energy, as in the combustion of carbon or<br> -magnesium. Therefore an uncombined element is the seat of potential<br> -energy. (See Energy, Potential.) In combining the elements always<br> -combine in definite proportions. A series of numbers, one being proper<br> -to each element which denote the smallest common multipliers of these<br> -proportions, are called equivalents. Taking the theory of valency into<br> -consideration the product of the equivalents by the valencies gives the<br> -atomic weights.<br> -<br> -<br> -237 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Element, Mathematical.</span><br> -A very small part of anything, corresponding in a general way to a<br> -differential, as the element of a current.<br> -<br> -<br> -<span style="font-weight: bold;">Element of a Battery Cell.</span><br> -The plates in a galvanic couple are termed elements, as the carbon and<br> -zinc plates in a Bunsen cell. The plate unattacked by the solution, as<br> -the carbon plate in the above battery, is termed the negative plate or<br> -element; the one attacked, as the zinc plate, is termed the positive<br> -plate or element.<br> -<br> -Synonym--Voltaic Element.<br> -<br> -<br> -<span style="font-weight: bold;">Elements, Electrical Classification of.</span><br> -This may refer to Electro-chemical Series, Electrostatic Series, or<br> -Thermo-electric Series, all of which may be referred to.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Element, Thermo-electric.</span><br> -One of the metals or other conductors making a thermo-electric couple,<br> -the heating of whose junction produces electro-motive force and a<br> -current, if on closed circuit. The elements of a couple are respectively<br> -positive and negative, and most conductors can be arranged in a series<br> -according to their relative polarity. (See Thermo-electric Series.)<br> -<br> -<br> -<span style="font-weight: bold;">Elongation.</span><br> -The throw of the magnetic needle. (See Throw.)<br> -<br> -Synonym--Throw.<br> -<br> -<br> -<span style="font-weight: bold;">Embosser, Telegraph.</span><br> -A telegraphic receiver giving raised characters on a piece of paper. It<br> -generally refers to an apparatus of the old Morse receiver type, one<br> -using a dry point stylus, which pressing the paper into a groove in the<br> -roller above the paper, gave raised characters in dots and lines.<br> -<br> -<br> -<img style="width: 690px; height: 495px;" alt="" - src="images/237F163.jpg"><br> -Fig. 163. MORSE RECEIVER.<br> -<br> -<br> -238 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">E. M. D. P.</span><br> -Abbreviation for "electro-motive difference of potential" or for<br> -electro-motive force producing a current as distinguished from mere<br> -inert potential difference.<br> -<br> -<span style="font-weight: bold;">E. M. F.</span><br> -Abbreviation for "electro-motive force."<br> -<br> -<br> -<img style="width: 638px; height: 433px;" alt="" - src="images/238F164.jpg"><br> -Fig. 164. END-ON METHOD.<br> -<br> -<br> -<span style="font-weight: bold;">End-on Method.</span><br> -A method of determining the magnetic moment of a magnet. The magnet<br> -under examination, N S, is placed at right angles to the magnetic<br> -meridian, M O R, and pointing directly at or "end on" to the centre of a<br> -compass needle, n s. From the deflection a of the latter the moment is<br> -calculated.<br> -<br> -<br> -<span style="font-weight: bold;">Endosmose, Electric.</span><br> -The inflowing current of electric osmose. (See Osmose, Electric.)<br> -<br> -<br> -<span style="font-weight: bold;">End Play.</span><br> -The power to move horizontally in its bearings sometimes given to<br> -armature shafts. This secures a more even wearing of the commutator<br> -faces. End play is not permissible in disc armatures, as the attraction<br> -of the field upon the face of the armature core would displace it<br> -endwise. For such armatures thrust-bearings preventing end play have to<br> -be provided.<br> -<br> -<br> -<span style="font-weight: bold;">Energy.</span><br> -The capacity for doing work. It is measured by work units which involve<br> -the exercise of force along a path of some length. A foot-pound,<br> -centimeter-gram, and centimeter-dyne are units of energy and work.<br> -<br> -The absolute unit of energy is the erg, a force of one dyne exercised<br> -over one centimeter of space. (See Dyne.)<br> -<br> -The dimensions of energy are<br> - force (M * L / T^2) * space (L) = M * (L^2 / T^2).<br> -Energy may be chemical (atomic or molecular), mechanical,<br> -electrical, thermal, physical, potential, kinetic, or actual, and other<br> -divisions could be formulated.<br> -<br> -<br> -239 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Energy, Atomic.</span><br> -The potential energy due to atomic relations set free by atomic change;<br> -a form of chemical energy, because chemistry refers to molecular as well<br> -as to atomic changes. When atomic energy loses the potential form it<br> -immediately manifests itself in some other form, such as heat or<br> -electric energy. It may be considered as always being potential energy.<br> -(See Energy, Chemical.)<br> -<br> -[Transcriber's note: This item refers to chemical energy, that is<br> -manifest in work done by electric forces during re-arrangement of<br> -electrons. Atomic energy now refers to re-arrangement of nucleons<br> -(protons and neutrons) and the resulting conversion of mass into<br> -energy.]<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Energy, Chemical.</span><br> -A form of potential energy (see Energy, Potential) possessed by elements<br> -in virtue of their power of combining with liberation of energy, as in<br> -the combination of carbon with oxygen in a furnace; or by compounds in<br> -virtue of their power of entering into other combinations more<br> -satisfying to the affinities of their respective elements or to their<br> -own molecular affinity. Thus in a galvanic couple water is decomposed<br> -with absorption of energy, but its oxygen combines with zinc with<br> -evolution of greater amount of energy, so that in a voltaic couple the<br> -net result is the setting free of chemical energy, which is at once<br> -converted into electrical energy in current form, if the battery is on a<br> -closed circuit.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Energy, Conservation of.</span><br> -A doctrine accepted as true that the sum of energy in the universe is<br> -fixed and invariable. This precludes the possibility of perpetual<br> -motion. Energy may be unavailable to man, and in the universe the<br> -available energy is continually decreasing, but the total energy is the<br> -same and never changes.<br> -<br> -[Transcriber's note: If mass is counted a energy (E=m*(c^2)) then energy<br> -is strictly conserved.]<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Energy, Degradation of.</span><br> -The reduction of energy to forms in which it cannot be utilized by man.<br> -It involves the reduction of potential energy to kinetic energy, and the<br> -reduction of kinetic energy of different degrees to energy of the same<br> -degree. Thus when the whole universe shall have attained the same<br> -temperature its energy will have become degraded or non-available. At<br> -present in the sun we have a source of kinetic energy of high degree, in<br> -coal a source of potential energy. The burning of all the coal will be<br> -an example of the reduction of potential to kinetic energy, and the<br> -cooling of the sun will illustrate the lowering in degree of kinetic<br> -energy. (See Energy, Conservation of--Energy, Potential--Energy,<br> -Kinetic.)<br> -<br> -<br> -<span style="font-weight: bold;">Energy, Electric.</span> <br> -The capacity for doing work possessed by electricity<br> -under proper conditions. Electric energy may be either kinetic or<br> -potential. As ordinary mechanical energy is a product of force and<br> -space, so electric energy is a product of potential difference and<br> -quantity. Thus a given number of coulombs of electricity in falling a<br> -given number of volts develop electric energy. The dimensions are found<br> -therefore by multiplying electric current intensity quantity<br> - ((M^.5) * (L^.5)),<br> -by electric potential<br> - ((M^.5)*(L^1.5) / (T^2)),<br> -giving (M * (L^2)/(T^2)),<br> -the dimensions of energy in general as it should be.<br> -<br> -The absolute unit of electric energy in electro-magnetic measure is<br> -(1E-7) volt coulombs.<br> -<br> -<br> -240 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The practical unit is the volt-coulomb. As the volt is equal to 1E8<br> -absolute units of potential and the coulomb to 0.1 absolute units of<br> -quantity, the volt-coulomb is equal to 1E7 absolute units of energy.<br> -<br> -The volt-coulomb is very seldom used, and the unit of Electric Activity<br> -or Power (see Power, Electric), the volt-ampere, is universally used.<br> -This unit is sometimes called the Watt, q. v., and it indicates the rate<br> -of expenditure or of production of electric energy.<br> -<br> -The storing up in a static accumulator or condenser of a given charge of<br> -electricity, available for use with a given change of potential<br> -represents potential electric energy.<br> -<br> -The passing of a given quantity through a conductor with a given fall of<br> -potential represents kinetic electric energy.<br> -<br> -In a secondary battery there is no storage of energy, but the charging<br> -current simply accumulates potential chemical energy in the battery,<br> -which chemical energy is converted into electric energy in the discharge<br> -or delivery of the battery.<br> -<br> -It is customary to discuss Ohm's law in this connection; it is properly<br> -treated under Electric Power, to which the reader is referred. (See<br> -Power, Electric.)<br> -<br> -[Transcriber's note: A volt-ampere or watt is a unit of power. A<br> -volt-coulomb-second or watt-second is a unit of energy. Power -multiplied by<br> -time yields energy.]<br> -<br> -<br> -<span style="font-weight: bold;">Energy, Electric Transmission of.</span><br> -If an electric current passes through a conductor all its energy is<br> -expended in the full circuit. Part of the circuit may be an electrical<br> -generator that supplies energy as fast as expended. Part of the circuit<br> -may be a motor which absorbs part of the energy, the rest being expended<br> -in forcing a current through the connecting wires and through the<br> -generator. The electric energy in the generator and connecting wires is<br> -uselessly expended by conversion into heat. That in the motor in great<br> -part is utilized by conversion into mechanical energy which can do<br> -useful work. This represents the transmission of energy. Every electric<br> -current system represents this operation, but the term is usually<br> -restricted to the transmission of comparatively large quantities of<br> -energy.<br> -<br> -A typical installation might be represented thus. At a waterfall a<br> -turbine water wheel is established which drives a dynamo. From the<br> -dynamo wires are carried to a distant factory, where a motor or several<br> -motors are established, which receive current from the dynamo and drive<br> -the machinery. The same current, if there is enough energy, may be used<br> -for running lamps or electroplating. As electric energy (see Energy,<br> -Electric,) is measured by the product of potential difference by<br> -quantity, a very small wire will suffice for the transmission of a small<br> -current at a high potential, giving a comparatively large quantity of<br> -energy. It is calculated that the energy of Niagara Falls could be<br> -transmitted through a circuit of iron telegraph wire a distance of over<br> -1,000 miles, but a potential difference of 135,000,000 volts would be<br> -required, something quite impossible to obtain or manage.<br> -<br> -[Transcriber's note: Contemporary long distance power transmission lines<br> -use 115,000 to 1,200,000 volts. At higher voltages corona discharges<br> -(arcing) create unacceptable losses.]<br> -<br> -<br> -241 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Energy, Kinetic.</span><br> -Energy due to matter being actually in motion. It is sometimes called<br> -actual energy. The energy varies directly with the mass and with the<br> -square of the velocity. It is represented in formula by .5 *M * (v^2).<br> -<br> -Synonyms--Actual Energy--Energy of Motion--Dynamic Energy.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Energy, Mechanical.</span><br> -The energy due to mechanical change or motion, virtually the same as<br> -molar energy. (See Energy, Molar.)<br> -<br> -<br> -<span style="font-weight: bold;">Energy, Molar.</span><br> -The energy of masses of matter due to movements of or positions of<br> -matter in masses; such as the kinetic energy of a pound or of a ton in<br> -motion, or the potential energy of a pound at an elevation of one<br> -hundred feet.<br> -<br> -<br> -<span style="font-weight: bold;">Energy, Molecular.</span><br> -The potential energy due to the relations of molecules and set free by<br> -their change in the way of combination. It is potential for the same<br> -reason that applies to atomic and chemical energy, of which latter it is<br> -often a form, although it is often physical energy. The potential energy<br> -stored up in vaporization is physical and molecular energy; the<br> -potential energy stored up in uncombined potassium oxide and water, or<br> -calcium oxide (quicklime) and water is molecular, and when either two<br> -substances are brought together kinetic, thermal or heat energy is set<br> -free, as in slaking lime for mortar.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Energy of an Electrified Body.</span><br> -An electrified body implies the other two elements of a condenser. It is<br> -the seat of energy set free when discharged. (See Dielectric, Energy<br> -of.) The two oppositely charged bodies tend to approach. This tendency,<br> -together with the distances separating them, represents a potential<br> -energy.<br> -<br> -<br> -<span style="font-weight: bold;">Energy of Stress.</span><br> -Potential energy due to stress, as the stretching of a spring. This is<br> -hardly a form of potential energy. A stressed spring is merely in a<br> -position to do work at the expense of its own thermal or kinetic energy<br> -because it is cooled in doing work. If it possessed true potential<br> -energy of stress it would not be so cooled.<br> -<br> -<br> -<span style="font-weight: bold;">Energy of Position.</span><br> -Potential energy due to position, as the potential energy of a pound<br> -weight raised ten feet (ten foot lbs.). (See Energy, Potential.)<br> -<br> -<br> -<span style="font-weight: bold;">Energy, Physical.</span><br> -The potential energy stored up in physical position or set free in<br> -physical change. Thus a vapor or gas absorbs energy in its vaporization,<br> -which is potential energy, and appears as heat energy when the vapor<br> -liquefies.<br> -<br> -<br> -242 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Energy, Potential, or Static Energy.</span><br> -The capacity for doing work in a system due to advantage of position or<br> -other cause, such as the stress of a spring. A pound weight supported<br> -ten feet above a plane has ten foot lbs. of potential energy of position<br> -referred to that plane. A given weight of an elementary substance<br> -represents potential chemical energy, which will be liberated as actual<br> -energy in its combination with some other element for which it has an<br> -affinity. Thus a ton of coal represents a quantity of potential chemical<br> -energy which appears in the kinetic form of thermal energy when the coal<br> -is burning in a furnace. A charged Leyden jar represents a source of<br> -potential electric energy, which becomes kinetic heat energy as the same<br> -is discharged.<br> -<br> -<br> -<span style="font-weight: bold;">Energy, Thermal.</span><br> -A form of kinetic molecular energy due to the molecular motion of bodies<br> -caused by heat.<br> -<br> -<br> -<span style="font-weight: bold;">Entropy.</span><br> -Non-available energy. As energy may in some way or other be generally<br> -reduced to heat, it will be found that the equalizing of temperature,<br> -actual and potential, in a system, while it leaves the total energy<br> -unchanged, makes it all unavailable, because all work represents a fall<br> -in degree of energy or a fall in temperature. But in a system such as<br> -described no such fall could occur, therefore no work could be done. The<br> -universe is obviously tending in that direction. On the earth the<br> -exhaustion of coal is in the direction of degradation of its high<br> -potential energy, so that the entropy of the universe tends to zero.<br> -(See Energy, Degradation of.)<br> -<br> -[Transcriber's note: Entropy (disorder) INCREASES, while AVAILABLE<br> -ENERGY tends to zero.]<br> -<br> -<br> -<span style="font-weight: bold;">Entropy, Electric.</span><br> -Clerk Maxwell thought it possible to recognize in the Peltier effect, q.<br> -v., a change in entropy, a gain or loss according to whether the<br> -thermo-electric junction was heated or cooled. This is termed Electric<br> -Entropy. (See Energy, Degradation of.)<br> -<br> -<br> -243 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 683px; height: 503px;" alt="" - src="images/242F165.jpg"><br> -Fig. 165. EPINUS' CONDENSER,<br> -<br> -<br> -<span style="font-weight: bold;">Epinus' Condenser.</span><br> -Two circular brass plates, A and B, are mounted on insulating supports,<br> -and arranged to be moved towards or away from each other as desired.<br> -Between them is a plate of glass, C, or other dielectric. Pith balls may<br> -be suspended back of each brass plate as shown. The apparatus is charged<br> -by connecting one plate to an electric machine and the other to the<br> -earth. The capacity of the plate connected to the machine is increased<br> -by bringing near to it the grounded plate, by virtue of the principle of<br> -bound charges. This apparatus is used to illustrate the principles of<br> -the electric condenser. It was invented after the Leyden jar was<br> -invented.<br> -<br> -<br> -<img style="width: 693px; height: 445px;" alt="" - src="images/243F166.jpg"><br> -Fig. 166. EPINUS' CONDENSER.<br> -<br> -<br> -<span style="font-weight: bold;">E. P. S.</span><br> -Initials of Electrical Power Storage; applied to a type of secondary<br> -battery made by a company bearing that title.<br> -<br> -<br> -<img style="width: 686px; height: 678px;" alt="" - src="images/243F167.jpg"><br> -Fig. 167. CAM EQUALIZER.<br> -<br> -<br> -244 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<span style="font-weight: bold;">Equalizer.</span><br> -In electro-magnetic mechanism an arrangement for converting the pull of<br> -the electro-magnet varying in intensity greatly over its range of<br> -action, into a pull of sensibly equal strength throughout. The use of a<br> -rocking lever acting as a cam, with leverage varying as the armature<br> -approaches or recedes from the magnet core is one method of effecting<br> -the result. Such is shown in the cut. E is an electro-magnet, with<br> -armature a. A and B are the equalizer cams. The pull on the short end of<br> -the cam B is sensibly equal for its whole length.<br> -<br> -Many other methods have been devised, involving different shapes of pole<br> -pieces, armatures or mechanical devices other than the one just shown.<br> -<br> -<br> -<span style="font-weight: bold;">Equipotential. adj.</span><br> -Equal in potential; generally applied to surfaces. Thus every magnetic<br> -field is assumed to be made up of lines of force and intersecting those<br> -lines, surfaces, plane, or more or less curved in contour, can be<br> -determined, over all parts of each one of which the magnetic intensity<br> -will be identical. Each surface is the locus of equal intensity. The<br> -same type of surface can be constructed for any field of force, such as<br> -an electrostatic field, and is termed an equipotential surface.<br> -<br> -<br> -<span style="font-weight: bold;">Equipotential Surface, Electrostatic.</span><br> -A surface in an electrostatic field of force, which is the locus of all<br> -points of a given potential in such field; a surface cutting all the<br> -lines of force at a point of identical potential. Lines of force are cut<br> -perpendicularly by an equipotential surface, or are normal thereto.<br> -<br> -<br> -<span style="font-weight: bold;">Equipotential Surface, Magnetic and -Electro-magnetic.</span><br> -A surface bearing the same relation to a magnetic or electro-magnetic<br> -field of force that an electrostatic equipotential surface (see<br> -Equipotential Surface, Electrostatic,) does to an electrostatic field of<br> -force.<br> -<br> -<br> -<span style="font-weight: bold;">Equivalent, Chemical.</span><br> -The quotient obtained by dividing the atomic weight of an element by its<br> -valency.<br> -<br> -<br> -<span style="font-weight: bold;">Equivalents, Electro-chemical.</span><br> -The weight of any substance set free by one coulomb of electricity. The<br> -following give some equivalents expressed in milligrams:<br> -<br> -<small><span style="font-family: monospace;">Hydrogen -.0105 Mercury (mercurous) 2.10</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Gold -.6877 Iron -(ferric) .1964</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Silver -1.134 Iron -(ferrous) .294</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Copper -(cupric) .3307 -Nickel -.3098</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Mercury (mercuric) -1.05 -Zinc -.3413</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Lead -1.0868 -Chlorine -.3728</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Oxygen -.89</span></small><br> -<br> -<br> -245 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Equivalent, Electro-mechanical.</span><br> -The work or energy equivalent to unit quantities of electric energy, q.<br> -v.; or equivalent to a unit current in a conductor whose ends differ one<br> -unit of potential. The unit of electric energy taken is the watt-second<br> -or volt-coulomb. One volt-coulomb is equal to<br> - -<small><span style="font-family: monospace;">Ergs -1E7 [10000000]</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Foot -Pound -.737337</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Gram-degree -C. .24068</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Horse Power -Second .0013406</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Pound-degree -F. .000955</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> One horse power is equal -to 745.943 volt coulombs per second.</span></small><br> -<br> -<br> -<span style="font-weight: bold;">Equivalent, Electro-thermal.</span><br> -The heat produced by a unit current passing through a conductor with<br> -unit difference of potential at its ends; the heat equivalent of a<br> -volt-coulomb or watt-second. It is equal to<br> - Gram-degree C. .24068<br> - Pound-degree F. .000955<br> -<br> -<br> -<span style="font-weight: bold;">Equivalent, Thermo-chemical.</span><br> -The calories evolved by the combination of one gram of any substance<br> -with its equivalent of another substance being determined, the product<br> -obtained by multiplying this number by the equivalent (atomic or<br> -molecular weight / valency) of the first element or substance is the<br> -thermo-chemical equivalent. If expressed in kilogram calories, the<br> -product of the thermo-chemical equivalent by 0.43 gives the voltage<br> -required to effect such decomposition.<br> -<br> -The following are thermo-chemical equivalents of a few combinations:<br> -<span style="font-family: monospace;"> -Water -34.5</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Zinc -oxide 43.2</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Iron -protoxide 34.5</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Iron -Sesquioxide 31.9 X 3</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Copper -oxide 19.2</span><br> -<br> -<br> -<span style="font-weight: bold;">Equivolt.</span><br> -"The mechanical energy of one volt electro-motive force exerted under<br> -unit conditions through one equivalent of chemical action in grains."<br> -(J. T. Sprague.) This unit is not in general use as the unit of electric<br> -energy, the volt-coulomb and (for rate of electric energy) the<br> -volt-ampere being always used.<br> -<br> -<br> -<span style="font-weight: bold;">Erg.</span><br> -The absolute or fundamental C. G. S. unit of work or energy. The work<br> -done or energy expended in moving a body through one centimeter against<br> -a resistance of one dyne.<br> -<br> -<br> -<span style="font-weight: bold;">Erg-ten.</span><br> -Ten millions of ergs, or ten meg-ergs.<br> -<br> -<br> -<span style="font-weight: bold;">Escape.</span><br> -A term applied to leakage of current.<br> -<br> -<br> -<span style="font-weight: bold;">Etching, Electric.</span><br> -A process of producing an etched plate. The plate is coated with wax,<br> -and the design traced through as in common etching. It is then placed in<br> -a bath and is connected to the positive terminal from a generator, whose<br> -negative is immersed in the same bath, so that the metal is dissolved by<br> -electrolytic action. By attaching to the other terminal and using a<br> -plating bath, a rough relief plate may be secured, by deposition in the<br> -lines of metal by electroplating.<br> -<br> -Synonym--Electric Engraving.<br> -<br> -<br> -246 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Ether.</span><br> -The ether is a hypothetical thing that was invented to explain the<br> -phenomena of light. Light is theoretically due to transverse vibrations<br> -of the ether. Since the days of Young the conception of the ether has<br> -extended, and now light, "radiant heat," and electricity are all treated<br> -as phenomena of the ether. Electrical attraction and repulsion are<br> -explained by considering them due to local stresses in the ether;<br> -magnetic phenomena as due to local whirlpools therein. The ether was<br> -originally called the luminiferous ether, but the adjective should now<br> -be dropped. Its density is put at 936E-21 that of water, or equal to<br> -that of the atmosphere at 210 miles above the earth's surface. Its<br> -rigidity is about 1E-9 that of steel (see Ten, Powers of); as a whole it<br> -is comparable to an all-pervading jelly, with almost perfect elasticity.<br> -The most complete vacuum is filled with ether.<br> -<br> -All this is a hypothesis, for the ether has never been proved to exist.<br> -Whether gravitation will ever be explained by It remains to be seen.<br> -<br> -[Transcriber's note: The Michelson-Morley experiment in 1887 (five years<br> -before this book) cast serious doubt on the ether. In 1905 Einstein<br> -explained electromagnetic phenomenon with photons. In 1963 Edward M.<br> -Purcell used special relativity to derive the existence of magnetism and<br> -radiation.]<br> -<br> -<br> -<span style="font-weight: bold;">Eudiometer.</span><br> -A graduated glass tube for measuring the volumes of gases. In its<br> -simplest form it is simply a cylindrical tube, with a scale etched or<br> -engraved upon it, closed at one end and open at the other. The gas to be<br> -measured is collected in it over a liquid, generally water, dilute<br> -sulphuric acid in the gas voltameter, or mercury. Many different shapes<br> -have been given them by Hoffmann, Ure, Bunsen and others.<br> -<br> -<br> -<span style="font-weight: bold;">Evaporation, Electric.</span><br> -The superficial sublimation or evaporation of a substance under the<br> -influence of negative electricity. It is one of the effects investigated<br> -by Crookes in his experiments with high vacua. He found that when a<br> -metal, even so infusible as platinum, was exposed to negative<br> -electrification in one of his high vacuum tubes, that it was volatilized<br> -perceptibly. A cadmium electrode heated and electrified negatively was<br> -found to give a strong coating of metal on the walls of the tube. Even<br> -in the open air the evaporation of water was found to be accelerated by<br> -negative electrification.<br> -<br> -<br> -<span style="font-weight: bold;">Exchange, Telephone.</span><br> -The office to which telephone wires lead in a general telephone system.<br> -In the office by a multiple switch board, or other means, the different<br> -telephones are interconnected by the office attendants, so that any<br> -customers who desire it may be put into communication with each other.<br> -The exchange is often termed the Central Office, although it may be only<br> -a branch office.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Excitability, Faradic.</span><br> -The action produced in nerve or muscle of the animal system by an<br> -alternating or intermitting high potential discharge from an induction<br> -coil.<br> -<br> -<br> -247 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Excitability, Galvanic.</span><br> -The same as Faradic excitability, except that it refers to the effects<br> -of the current from a galvanic battery.<br> -<br> -<br> -<span style="font-weight: bold;">Excitability of Animal System, -Electric.</span><br> -The susceptibility of a nerve or muscle to electric current shown by the<br> -effect produced by its application.<br> -<br> -<br> -<span style="font-weight: bold;">Exciter.</span><br> -A generator used for exciting the field magnet of a dynamo. In<br> -alternating current dynamos, e. g., of the Westinghouse type, a special<br> -dynamo is used simply to excite the field magnet. In central station<br> -distribution the same is often done for direct current dynamos.<br> -<br> -<br> -<span style="font-weight: bold;">Exosmose, Electric.</span><br> -The outflowing current of electric osmose. (See Osmose, Electric.)<br> -<br> -<br> -<span style="font-weight: bold;">Expansion, Coefficient of.</span><br> -The number expressing the proportional increase in size, either length,<br> -area or volume, of a substance under the influence generally of heat.<br> -There are three sets of coefficients, (1) of linear expansion, (2) of<br> -superficial expansion, (3) of cubic expansion or expansion of volume.<br> -The first and third are the only ones much used. They vary for different<br> -substances, and for the same substance at different temperatures. They<br> -are usually expressed as decimals indicating the mixed number referred<br> -to the length or volume of the body at the freezing point as unity.<br> -<br> -<br> -<span style="font-weight: bold;">Expansion, Electric.</span><br> -(a) The increase in volume of a condenser, when charged<br> -electrostatically. A Leyden jar expands when charged, and contracts when<br> -discharged.<br> -<br> -(b) The increase in length of a bar of iron when magnetized.<br> -<br> -This is more properly called magnetic expansion or magnetic elongation.<br> -<br> -<br> -<span style="font-weight: bold;">Exploder.</span><br> -(a) A small magneto-generator for producing a current for heating the<br> -wire in an electric fuse of the Abel type (see Fuse, Electric), and<br> -thereby determining an explosion.<br> -<br> -(b) The term may also be applied to a small frictional or influence<br> -machine for producing a spark for exploding a spark fuse.<br> -<br style="font-weight: bold;"> -<br> -<span style="font-weight: bold;">Explorer.</span><br> -A coil, similar to a magnetizing coil (see Coil, Magnetizing), used for<br> -investigating the electro-magnetic circuit and for similar purposes. If<br> -placed around an electro-magnet and connected with a galvanometer, it<br> -will produce a deflection, owing to a momentary induced current, upon<br> -any change in the magnet, such as removing or replacing the armature. It<br> -is useful in determining the leakage of lines of force and for general<br> -investigations of that nature. It is often called an exploring coil.<br> -Hughes' Induction Balance (see Induction Balance, Hughes') is sometimes<br> -called a Magnetic Explorer. The exploring coil may be put in circuit<br> -with a galvanometer for quantitative measurements or with a telephone<br> -for qualitative ones.<br> -<br> -<br> -248 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Extension Bell Call.</span><br> -A system of relay connection, q. v., by which a bell is made to continue<br> -ringing after the current has ceased coming over the main line. It is<br> -designed to prolong the alarm given by a magneto call bell, q. v., which<br> -latter only rings as long as the magneto handle is turned. A vibrating<br> -electric bell (see Bell, Electric,) is connected in circuit with a local<br> -battery and a switch normally open, but so constructed as to close the<br> -circuit when a current is passed and continue to do so indefinitely. The<br> -distant circuit is connected to this switch. When the magneto is worked<br> -it acts upon the switch, closes the local battery circuit and leaves it<br> -closed, while the bell goes on ringing until the battery is exhausted or<br> -the switch is opened by hand.<br> -<br> -<br> -<span style="font-weight: bold;">Eye, Electro-magnetic.</span><br> -An apparatus used in exploring a field of electro-magnetic radiations.<br> -It is a piece of copper wire 2 millimeters (.08 inch) in diameter, bent<br> -into an almost complete circle 70 millimeters (.28 inch) in diameter,<br> -with terminals separated by an air gap. This is moved about in the<br> -region under examination, and by the production of a spark indicates the<br> -locality of the loops or venters in systems of stationary waves.<br> -</big></big><br> -<big><big><br> -</big></big><big><big><br> -248 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">F.</span><br> -Abbreviation for Fahrenheit, as 10º F., meaning 10º -Fahrenheit. (See<br> -Fahrenheit Scale.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Fahrenheit Scale.</span><br> -A thermometer scale in use in the United States and England. On this<br> -scale the temperature of melting ice is 32°; that of condensing -steam is<br> -212°; the degrees are all of equal length. Its use is indicated by -the<br> -letter F., as 180° F. To convert its readings into centigrade, -subtract<br> -32 and multiply by 5/9. (b) To convert centigrade into F. multiply by<br> -9/5 and add 32. Thus 180° F. = ((180-32) * 5/9)° C. = 82.2° -C. Again<br> -180° C. = (180 * 9/5) + 32 = 324° F.<br> -<br> -[Transcribers note: 180° C. = (180 * 9/5) + 32 = 356° F. ]<br> -<br> -The additions and subtractions must be algebraic in all cases. Thus when<br> -the degrees are minus or below zero the rules for conversion might be<br> -put thus: To convert degrees F. below zero into centigrade to the number<br> -of degrees F. add 32, multiply by 5/9 and place a minus sign (-) before<br> -it. (b) To convert degrees centigrade below zero into Fahrenheit,<br> -multiply the number of degrees by 9/5, subtract from 32 if smaller; if<br> -greater than 32 subtract 32 therefrom, and prefix a minus sign, thus:<br> --10° C. = 32 - (10 * 9/5) = 14°. Again, -30°C. = (30 * 9/5) -- 32 = 22 =<br> --22° F.<br> -<br> -<br> -249 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Farad.</span><br> -The practical unit of electric capacity; the capacity of a conductor<br> -which can retain one coulomb of electricity at a potential of one volt.<br> -<br> -The quantity of electricity charged upon a conducting surface raises its<br> -potential; therefore a conductor of one farad capacity can hold two<br> -coulombs at two volts potential, and three coulombs at three volts, and<br> -so on. The electric capacity of a conductor, therefore, is relative<br> -compared to others as regards its charge, for the latter may be as great<br> -as compatible with absence of sparking and disruptive discharge. In<br> -other words, a one farad or two farad conductor may hold a great many<br> -coulombs. Charging a conductor with electricity is comparable to pumping<br> -air into a receiver. Such a vessel may hold one cubic foot of air at<br> -atmospheric pressure and two at two atmospheres, and yet be of one cubic<br> -foot capacity however much air is pumped into it.<br> -<br> -The farad is equal to one fundamental electrostatic unit of capacity<br> -multiplied by 9E11 and to one electro-magnetic unit multiplied by 1E-9.<br> -<br> -The farad although one of the practical units is far too large, so the<br> -micro-farad is used in its place. The capacity of a sphere the size of<br> -the earth is only .000636 of a farad.<br> -<br> -[Transcriber's note: Contemporary calculations give about .000720<br> -farad.]<br> -<br> -<br> -<span style="font-weight: bold;">Faraday, Effect.</span><br> -The effect of rotation of its plane produced upon a polarized beam of<br> -light by passage through a magnetic field. (See Magnetic Rotary<br> -Polarization.)<br> -<br> -<br> -<span style="font-weight: bold;">Faraday's Cube.</span><br> -To determine the surface action of a charge, Faraday constructed a room,<br> -twelve feet cube, insulated, and lined with tinfoil. This room he<br> -charged to a high potential, but within it he could detect no excitement<br> -whatever. The reason was because the electricity induced in the bodies<br> -within the room was exactly equal to the charge of the room-surface, and<br> -was bound exactly by it. The room is termed Faraday's cube.<br> -<br> -<br> -<span style="font-weight: bold;">Faraday's Dark Space.</span><br> -A non-luminous space between the negative and positive glows, produced<br> -in an incompletely exhausted tube through which a static discharge, as<br> -from an induction coil, is produced. It is perceptible in a rarefaction<br> -of 6 millimeters (.24 inch) and upwards. If the exhaustion is very high<br> -a dark space appears between the negative electrode and its discharge.<br> -This is known as Crookes' dark space.<br> -<br> -<br> -<span style="font-weight: bold;">Faraday's Disc.</span><br> -A disc of any metal, mounted so as to be susceptible of rotation in a<br> -magnetic field of force, with its axis parallel to the general direction<br> -of the lines of force. A spring bears against its periphery and another<br> -spring against its axle. When rotated, if the springs are connected by a<br> -conductor, a current is established through the circuit including the<br> -disc and conductor. The radius of the disc between the spring contacts<br> -represents a conductor cutting lines of force and generating a potential<br> -difference, producing a current. If a current is sent through the<br> -motionless wheel from centre to periphery it rotates, illustrating the<br> -doctrine of reversibility. As a motor it is called Barlow's or<br> -Sturgeon's Wheel. If the disc without connections is rapidly rotated it<br> -produces Foucault currents, q. v., within its mass, which resist its<br> -rotation and heat the disc.<br> -<br> -<br> -250 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 419px; height: 657px;" alt="" - src="images/250F168.jpg"><br> -Fig. 168. "FARADAY'S NET."<br> -<br> -<br> -<span style="font-weight: bold;">Faraday's Net.</span><br> -An apparatus for showing that the electric charge resides on the<br> -surface. It consists of a net, conical in shape and rather deep, to<br> -whose apex two threads, one on each side, are attached. Its mouth is<br> -fastened to a vertical ring and the whole is mounted on an insulating<br> -support.<br> -<br> -It is pulled out to its full extent and is electrified. No charge can be<br> -detected inside it. By pulling one of the threads it is turned with the<br> -other side out. Now all the charge is found on the outside just as<br> -before, except that it is of course on the former inside surface of the<br> -bag. The interior shows no charge.<br> -<br> -<br> -<span style="font-weight: bold;">Faraday's Transformer.</span><br> -The first transformer. It was made by Michael Faraday. It was a ring of<br> -soft iron 7/8 inch thick, and 6 inches in external diameter. It was<br> -wound with bare wire, calico being used to prevent contact of the wire<br> -with the ring and of the layers of wire with each other, while twine was<br> -wound between the convolutions to prevent the wires from touching.<br> -Seventy-two feet of copper wire, 1/20 inch diameter, were wound in three<br> -superimposed coils, covering about one-half of the ring. On the other<br> -half sixty feet of copper wire were wound in two superimposed coils.<br> -Faraday connected his coils in different ways and used a galvanometer to<br> -measure the current produced by making and breaking one of the circuits<br> -used as a primary.<br> -<br> -The coil is of historic interest.<br> -<br> -<br> -<span style="font-weight: bold;">Faraday's Voltameter.</span><br> -A voltameter, in which the coulombs of current are measured by the<br> -volume of the gas evolved from acidulated water. (See Voltameter, Gas.)<br> -<br> -<br> -<span style="font-weight: bold;">Faradic. adj.</span><br> -Referring to induced currents, produced from induction coils. As Faraday<br> -was the original investigator of the phenomena of electro-magnetic<br> -induction, the secondary or induced electro-magnetic currents and their<br> -phenomena and apparatus are often qualified by the adjective Faradic,<br> -especially in electro-therapeutics. A series of alternating<br> -electrostatic discharges, as from an influence machine (Holtz), are<br> -sometimes called Franklinic currents. They are virtually Faradic, except<br> -as regards their production.<br> -<br> -<br> -251 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Faradic Brush.</span><br> -A brush for application of electricity to the person. It is connected as<br> -one of the electrodes of an induction coil or magneto generator. For<br> -bristles wire of nickel plated copper is generally employed.<br> -<br> -<br> -<span style="font-weight: bold;">Faradization.</span><br> -In medical electricity the analogue of galvanization; the effects due to<br> -secondary or induced currents; galvanization referring to currents from<br> -a galvanic battery; also the process of application of such currents.<br> -<br> -<br> -<span style="font-weight: bold;">Faults.</span><br> -Sources of loss of current or of increased resistance or other troubles<br> -in electric circuits.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Feeder.</span><br> -A lead in an electric central station distribution system, which lead<br> -runs from the station to some point in the district to supply current.<br> -It is not used for any side connections, but runs direct to the point<br> -where current is required, thus "feeding" the district directly. In the<br> -two wire system a feeder may be positive or negative; in the three wire<br> -system there is also a neutral feeder. Often the term feeder includes<br> -the group of two or of three parallel lines.<br> -<br> -<br> -<span style="font-weight: bold;">Feeder Equalizer.</span><br> -An adjustable resistance connected in circuit with a feeder at the<br> -central station. The object of the feeder being to maintain a definite<br> -potential difference at its termination, the resistance has to be varied<br> -according to the current it is called on to carry.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Feeder, Main or Standard.</span><br> -The main feeder of a district. The standard regulation of pressure<br> -(potential difference between leads) in the district is often determined<br> -by the pressure at the end of the feeder.<br> -<br> -<br> -<span style="font-weight: bold;">Feeder, Negative.</span><br> -The lead or wire in a set of feeders, which is connected to the negative<br> -terminal of the generator.<br> -<br> -<br> -<span style="font-weight: bold;">Feeder, Neutral.</span><br> -In the three wire system the neutral wire in a set of feeders. It is<br> -often made of less diameter than the positive and negative leads.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Feeder, Positive.</span><br> -The lead or wire in a set of feeders, which wire is connected to the<br> -positive terminal of the generator.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Ferranti Effect.</span><br> -An effect as yet not definitely explained, observed in the mains of the<br> -Deptford, Eng., alternating current plant. It is observed that the<br> -potential difference between the members of a pair of mains rises or<br> -increases with the distance the place of trial is from the station.<br> -<br> -[Transcriber's note: This effect is due to the voltage drop across the<br> -line inductance (due to charging current) being in phase with the<br> -sending end voltages. Both capacitance and inductance are responsible<br> -for producing this phenomenon. The effect is more pronounced in<br> -underground cables and with very light loads.]<br> -<br> -<br> -252 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Ferro-magnetic. adj.</span><br> -Paramagnetic; possessing the magnetic polarity of iron.<br> -<br> -<br> -<span style="font-weight: bold;">Fibre and Spring Suspension.</span><br> -A suspension of the galvanometer needle used in marine galvanometers.<br> -The needle is supported at its centre of gravity by a vertically<br> -stretched fibre attached at both its ends, but with a spring<br> -intercalated between the needle and one section of the fibre.<br> -<br> -<br> -<span style="font-weight: bold;">Fibre Suspension.</span><br> -Suspension, as of a galvanometer needle, by a vertical or hanging fibre<br> -of silk or cocoon fibre, or a quartz fibre. (See Quartz.)<br> -<br> -This suspension, while the most delicate and reliable known, is very<br> -subject to disturbance and exacts accurate levelling of the instrument.<br> -<br> -Fibre suspension is always characterized by a restitutive force. Pivot<br> -suspension, q. v., on the other hand, has no such force.<br> -<br> -<br> -<span style="font-weight: bold;">Field, Air.</span><br> -A field the lines of force of which pass through air; the position of a<br> -field comprised within a volume of air.<br> -<br> -<br> -<span style="font-weight: bold;">Field, Alternating.</span><br> -Polarity or direction being attributed to lines of force, if such<br> -polarity is rapidly reversed, an alternating field results. Such field<br> -may be of any kind, electro-magnetic or electrostatic. In one instance<br> -the latter is of interest. It is supposed to be produced by high<br> -frequency discharges of the secondary of an induction coil, existing in<br> -the vicinity of the discharging terminals.<br> -<br> -<br> -<span style="font-weight: bold;">Field Density.</span><br> -Field density or density of field is expressed in lines of force per<br> -unit area of cross-section perpendicular to the lines of force.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Field, Distortion of.</span><br> -The lines of force reaching from pole to pole of an excited field magnet<br> -of a dynamo are normally symmetrical with respect to some axis and often<br> -with respect to several. They go across from pole to pole, sometimes<br> -bent out of their course by the armature core, but still symmetrical.<br> -The presence of a mass of iron in the space between the pole pieces<br> -concentrates the lines of force, but does not destroy the symmetry of<br> -the field.<br> -<br> -When the armature of the dynamo is rotated the field becomes distorted,<br> -and the lines of force are bent out of their natural shape. The new<br> -directions of the lines of force are a resultant of the lines of force<br> -of the armature proper and of the field magnet. For when the dynamo is<br> -started the armature itself becomes a magnet, and plays its part in<br> -forming the field. Owing to the lead of the brushes the polarity of the<br> -armature is not symmetrical with that of the field magnets. Hence the<br> -compound field shows distortion. In the cut is shown diagrammatically<br> -the distortion of field in a dynamo with a ring armature. The arrow<br> -denotes the direction of rotation, and n n * * * and s s * * * indicate<br> -points of north and south polarity respectively.<br> -<br> -<br> -253 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The distorted lines must be regarded as resultants of the two induced<br> -polarities of the armature, one polarity due to the induction of the<br> -field, the other to the induction from its own windings. The positions<br> -of the brushes have much to do with determining the amount and degree of<br> -distortion. In the case of the ring armature it will be seen that some<br> -of the lines of force within the armature persist in their polarity and<br> -direction, almost as induced by the armature windings alone, and leak<br> -across without contributing their quota to the field. Two such lines are<br> -shown in dotted lines.<br> -<br> -In motors there is a similar but a reversed distortion.<br> -<br> -<br> -<img style="width: 721px; height: 345px;" alt="" - src="images/253F169.jpg"><br> -Fig. 169. DISTORTION OF FIELD IN A <br> -RING ARMATURE OF AN ACTIVE DYNAMO.<br> -<br> -<br> -<img style="width: 718px; height: 545px;" alt="" - src="images/253F170.jpg"><br> -Fig. 170. DISTORTION OF FIELD IN A <br> -RING ARMATURE OF AN ACTIVE MOTOR.<br> -<br> -<br> -254 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Field, Drag of.</span><br> -When a conductor is moved through a field so that a current is generated<br> -in it, the field due to that current blends with the other field and<br> -with its lines of force, distorting the field, thereby producing a drag<br> -upon its own motion, because lines of force always tend to straighten<br> -themselves, and the straightening would represent cessation of motion in<br> -the conductor. This tendency to straightening therefore resists the<br> -motion of the conductor and acts a drag upon it.<br> -<br> -<br> -<span style="font-weight: bold;">Field of Force.</span><br> -The space in the neighborhood of an attracting or repelling mass or<br> -system. Of electric fields of force there are two kinds, the<br> -Electrostatic and the Magnetic Fields of Force, both of which may be<br> -referred to. A field of force may be laid out as a collection of<br> -elements termed Lines of Force, and this nomenclature is universally<br> -adopted in electricity. The system of lines may be so constructed that<br> -(a) the work done in passing from one equipotential surface to the next<br> -is always the same; or (b) the lines of force are so laid out and<br> -distributed that at a place in which unit force is exercised there is a<br> -single line of force passing through the corresponding equipotential<br> -surface in each unit of area of that surface. The latter is the<br> -universal method in describing electric fields. It secures the following<br> -advantages:--First: The potential at any point in the field of space<br> -surrounding the attracting or repelling mass or masses is found by<br> -determining on which imaginary equipotential surface that point lies.<br> -Second: If unit length of a line of force cross n equipotential<br> -surfaces, the mean force along that line along the course of that part<br> -of it is equal to n units; for the difference of potential of the two<br> -ends of that part of the line of force = n; it is also equal to F s (F<br> -= force), because it represents numerically a certain amount of work;<br> -but s = I, whence n = F. Third: The force at any part of the field<br> -corresponds to the extent to which the lines of force are crowded<br> -together; and thence it may be determined by the number of lines of<br> -force which pass through a unit of area of the corresponding<br> -equipotential surface, that area being so chosen as to comprise the<br> -point in question. (Daniell.)<br> -<br> -<br> -<span style="font-weight: bold;">Field of Force, Electrostatic.</span><br> -The field established by the attracting, repelling and stressing<br> -influence of an electrostatically charged body. It is often termed an<br> -Electrostatic Field. (See Field of Force.)<br> -<br> -<br> -255 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Field of Force of a Current.</span><br> -A current establishes a field of force around itself, whose lines of<br> -force form circles with their centres on the axis of the current. The<br> -cut, Fig. 172, shows the relation of lines of force to current.<br> -<br> -<br> -<img style="width: 564px; height: 476px;" alt="" - src="images/255F171.jpg"><br> -Fig. 171. EXPERIMENT SHOWING LINES OF FORCE <br> -SURROUNDING AN ACTIVE CONDUCTOR.<br> -<br> -<br> -<img style="width: 300px; height: 539px;" alt="" - src="images/255F172.jpg"><br> -Fig. 172. DIAGRAM OF FIELD OF FORCE <br> -SURROUNDING AN ACTIVE CONDUCTOR.<br> -<br> -<br> -<img style="width: 702px; height: 236px;" alt="" - src="images/255F173.jpg"><br> -Fig. 173. LINK OF FORCE INDUCED BY A <br> -CURRENT SHOWING THE MAGNETIC -WHIRLS.<br> -<br> -<br> -The existence of the field is easily shown by passing a conductor<br> -vertically through a horizontal card. On causing a current to go through<br> -the wire the field is formed, and iron filings dropped upon the card,<br> -tend, when the latter is gently tapped, to take the form of circles. The<br> -experiment gives a version of the well-known magnetic figures, q. v. See<br> -Fig. 171.<br> -<br> -The cut shows by the arrows the relation of directions of current to the<br> -direction of the lines of force, both being assumptions, and merely<br> -indicating certain fixed relations, corresponding exactly to the<br> -relations expressed by the directions of electro-magnetic or magnetic<br> -lines of force<br> -<br> -<br> -256 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Field, Pulsatory.</span><br> -A field produced by pulsatory currents. By induction such field can<br> -produce an alternating current.<br> -<br> -<br> -<span style="font-weight: bold;">Field, Rotating.</span><br> -In a dynamo the field magnets are sometimes rotated instead of the<br> -armature, the latter being stationary. In Mordey's alternator the<br> -armature, nearly cylindrical, surrounds the field, and the latter<br> -rotates within it, the arrangement being nearly the exact reverse of the<br> -ordinary one. This produces a rotating field.<br> -<br> -<br> -<span style="font-weight: bold;">Field, Rotatory.</span><br> -A magnetic field whose virtual poles keep rotating around its centre of<br> -figure. If two alternating currents differing one quarter period in<br> -phase are carried around four magnetizing coils placed and connected in<br> -sets of two on the same diameter and at right angles to each other, the<br> -polarity of the system will be a resultant of the combination of their<br> -polarity, and the resultant poles will travel round and round in a<br> -circle. In such a field, owing to eddy currents, masses of metal,<br> -journaled like an armature, will rotate, with the speed of rotation of<br> -the field.<br> -<br> -<br> -<span style="font-weight: bold;">Field, Stray.</span><br> -The portion of a field of force outside of the regular circuit;<br> -especially applied to the magnetic field of force of dynamos expressing<br> -the portion which contributes nothing to the current generation.<br> -<br> -Synonym--Waste Field.<br> -<br> -<br> -<span style="font-weight: bold;">Field, Uniform.</span><br> -A field of force of uniform density. (See Field Density.)<br> -<br> -<br> -<span style="font-weight: bold;">Figure of Merit.</span><br> -In the case of a galvanometer, a coefficient expressing its delicacy. It<br> -is the reciprocal of the current required to deflect the needle through<br> -one degree. By using the reciprocal the smaller the current required the<br> -larger is the figure of merit. The same term may be applied to other<br> -instruments.<br> -<br> -It is often defined as the resistance of a circuit through which one<br> -Daniell's element will produce a deflection of one degree on the scale<br> -of the instrument. The circuit includes a Daniell's cell of resistance<br> -r, a rheostat R, galvanometer G and shunt S. Assume that with the shunt<br> -in parallel a deflection of a divisions is obtained. The resistance of<br> -the shunted galvanometer is (GS/G+S ; the multiplying power m of the<br> -shunt is S+G/S; the formula or figure of merit is m d (r+R +G S/G+S).<br> -<br> -The figure of merit is larger as the instrument is more sensitive.<br> -Synonym--Formula of Merit.<br> -<br> -<br> -257 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Filament.</span><br> -A thin long piece of a solid substance. In general it is so thin as to<br> -act almost like a thread, to be capable of standing considerable<br> -flexure. The distinction between filament and rod has been of much<br> -importance in some patent cases concerning incandescent lamps. As used<br> -by electricians the term generally applies to the carbon filament of<br> -incandescent lamps. This as now made has not necessarily any fibres, but<br> -is entitled to the name of filament, partly by convention, partly by its<br> -relative thinness and want of stiffness. (See Incandescent<br> -Lamps--Magnetic Filament.)<br> -<br> -<br> -<span style="font-weight: bold;">Fire Alarm, Electric, Automatic.</span><br> -A system of telegraph circuits, at intervals supplied with thermostats<br> -or other apparatus affected by a change of temperature, which on being<br> -heated closes the circuit and causes a bell to ring. (See Thermostat.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Fire Alarm Telegraph System.</span><br> -A system of telegraphic lines for communicating the approximate location<br> -of a fire to a central station and thence to the separate fire-engine<br> -houses in a city or district. It includes alarm boxes, distributed at<br> -frequent intervals, locked, with the place where the key is kept<br> -designated, or in some systems left unlocked. On opening the door of the<br> -box and pulling the handle or otherwise operating the alarm, a<br> -designated signal is sent to the central station. From this it is<br> -telegraphed by apparatus worked by the central station operator to the<br> -engine houses. The engines respond according to the discipline of the<br> -service.<br> -<br> -<br> -<span style="font-weight: bold;">Fire Cleansing.</span><br> -Freeing the surface of an article to be plated from grease by heating.<br> -<br> -<br> -<span style="font-weight: bold;">Fire Extinguisher, Electric, Automatic.</span><br> -A modification of the electric fire alarm (see Fire Alarm, Electric,<br> -Automatic), in which the thermostats completing the circuits turn on<br> -water which, escaping through the building, is supposed to reach and<br> -extinguish a fire.<br> -<br> -<br> -<span style="font-weight: bold;">Flashing in a Dynamo or -Magneto-electric Generator.</span><br> -Bad adjustment of the brushes at the commutator, or other fault of<br> -construction causes the production of voltaic arcs at the commutator of<br> -a generator, to which the term flashing is applied.<br> -<br> -<br> -<span style="font-weight: bold;">Flashing of Incandescent Lamp Carbons.</span><br> -A process of treatment for the filaments of incandescent lamps. The<br> -chamber before sealing up is filled with a hydro-carbon vapor or gas,<br> -such as the vapor of a very light naphtha (rhigolene). A current is then<br> -passed through the filament heating it to redness. The more attenuated<br> -parts or those of highest resistance are heated the highest, and<br> -decompose most rapidly the hydro-carbon vapor, graphitic carbon being<br> -deposited upon these parts, while hydrogen is set free. This goes on<br> -until the filament is of uniform resistance throughout. It gives also a<br> -way of making the resistance of the filament equal to any desired number<br> -of ohms, provided it is originally of high enough resistance. The<br> -process increases the conductivity of the filament.<br> -<br> -After flashing the chambers are pumped out and sealed up.<br> -<br> -<br> -258 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Flashing Over.</span><br> -A phenomenon observed in high potential dynamos. On a sudden alteration<br> -of the resistance of the circuit a long blue spark will be drawn out<br> -around the surface of the commutator from brush to brush. The spark is<br> -somewhat of the nature of an arc, and may seriously injure commutators<br> -whose sections are only separated by mica, or other thin insulation. In<br> -the case of commutators whose sections are separated by air spaces it is<br> -not so injurious.<br> -<br> -<br> -<span style="font-weight: bold;">Flats.</span><br> -In a commutator of a dynamo, the burning or wearing away of a commutator<br> -segment to a lower level than the rest. Sometimes two adjacent bars will<br> -be thus affected, causing a flat place on the commutator. It is not<br> -always easy to account for the formation of flats. They may have their<br> -origin in periodic vibrations due to bad mounting, or to sparking at the<br> -particular point.<br> -<br> -<br> -<span style="font-weight: bold;">Floor Push.</span><br> -A press or push button constructed to be set into the floor to be<br> -operated by pressing with the foot. It is used to ring an alarm bell,<br> -sound a buzzer or for similar service.<br> -<br> -<br> -<span style="font-weight: bold;">Fluid, Depolarizing.</span><br> -A fluid used in voltaic batteries to dispose of the hydrogen, which goes<br> -to the negative plate. This it does by oxidizing it. Chromic acid,<br> -nitric acid, and chloric acids are among the constituents of liquid<br> -depolarizers. (See Electropoion Fluid.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Fluid, Electric.</span><br> -The electric current and charge have sometimes been attributed to a<br> -fluid. The theory, which never was much more than hypothetical, survives<br> -to some extent in the single and double fluid theory. (See Single Fluid<br> -Theory-Double Fluid Theory.)<br> -<br> -<br> -<span style="font-weight: bold;">Fluorescence.</span><br> -The property of converting ether waves of one length, sometimes of<br> -invisible length, into waves of another length (visible). AEsculin,<br> -quinine salts, uranium glass and other substances exhibit this<br> -phenomenon. The phenomenon is utilized in the production of Geissler<br> -tubes.<br> -<br> -<br> -<span style="font-weight: bold;">Flush Boxes.</span><br> -A heavy iron box covered with a heavy hand plate and laid flush (whence<br> -the name), or even with the surface of a roadway. Into it conductors of<br> -an underground system lead, and it is used to make connections therewith<br> -and for examining the leakage of the conductors and for similar<br> -purposes. It is a "man-hole" (q. v.) in miniature.<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Fluviograph.</span><br> -An electric registering tide gauge or water level gauge.<br> -<br> -<br> -259 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Fly or Flyer, Electric.</span><br> -A little wheel, ordinarily poised on a point, like a compass needle. It<br> -carries several tangentially directed points, all pointing in the same<br> -sense. When connected with a source of electricity of high potential it<br> -revolves by reaction. The tension of its charge is highest at the<br> -points, the air there is highly electrified and repelled, the reaction<br> -pushing the wheel around like a Barker's mill or Hero's steam engine.<br> -Sometimes the flyer is mounted with its axis horizontal and across the<br> -rails on a railroad along which it travels.<br> -<br> -Synonym--Reaction Wheel.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Foci Magnetic.</span><br> -The two points on the earth's surface where the magnetic intensity is<br> -greatest. They nearly coincide in position with the magnetic poles.<br> -<br> -<br> -<span style="font-weight: bold;">Fog, Electric.</span><br> -Fogs occurring when the atmosphere is at unusually high potential and<br> -accompanied by frequent change of such polarity.<br> -<br> -<br> -<span style="font-weight: bold;">Following Horns.</span><br> -In dynamo-electric machines the projecting ends of the pole pieces<br> -towards which the outer uncovered perimeter of the armature turns in its<br> -regular operations. The leading horns are those away from which the<br> -armature rotates. In considering rotation the exposed portion of the<br> -superficies of the armature is considered. The definition would have to<br> -be reversed if the part facing the pole pieces were considered.<br> -<br> -Synonym--Trailing Horns.<br> -<br> -<br> -<span style="font-weight: bold;">Foot-candle.</span><br> -A unit of illuminating power; the light given by one standard candle at<br> -a distance of one foot. The ordinary units of illuminating power are<br> -entirely relative; this is definite. It is due to Carl Herring.<br> -<br> -<br> -<span style="font-weight: bold;">Foot-pound.</span><br> -A practical unit of work or energy. The quantity of work required to<br> -raise a pound one foot, or one hundred pounds one-hundredth of a foot,<br> -and so on; or the potential energy represented by a weight at an<br> -elevation under these conditions.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Foot-step.</span><br> -In a dynamo with armature at the lower end of its field magnets, the<br> -plate generally of zinc, interposed between it and the iron base plate<br> -to prevent the leakage of lines of force outside of the circuit. Any<br> -diamagnetic material which is mechanically suitable may be used.<br> -<br> -<br> -<span style="font-weight: bold;">Force.</span><br> -Force may be variously defined.<br> -(a) Any cause of change of the condition of matter with respect to<br> -motion or rest.<br> -<br> -(b) A measurable action upon a body under which the state of rest of<br> -that body, or its state of uniform motion in a straight line, suffers<br> -change.<br> -<br> -(c) It may be defined by its measurement as the rate of change of<br> -momentum, or<br> -<br> -(d) as the rate at which work is done per unit of space traversed.<br> -<br> -Force is measured by the acceleration or change of motion it can impart -<br> -to a body of unit mass in a unit of time, or, calling<br> -force, F,<br> -mass, m<br> -acceleration per second a<br> -we have F = m a.<br> -<br> -The dimensions of force are <br> -mass (M) * acceleration (L/(T^2)) = (M*L)/(T^2).<br> -<br> -<br> -260 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Force de Cheval. Horse power (French). -</span><br> -It is the French or metric horse power.<br> -It is equal to:<br> - <span style="font-family: monospace;">542.496 -Foot lbs. per second.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -.9864 English Horse Power.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -75.0 Kilogram-meters per -second.</span><br> -<br> -<br> -<span style="font-weight: bold;">Force, Electro-magnetic.</span><br> -The mechanical force of attraction or repulsion acting on the<br> -electro-magnetic unit of quantity. Its intensity varies with the square<br> -of the distance. It may also be defined as electric force in the<br> -electro-magnetic system.<br> -<br> -Its dimensions are equal to <br> -mechanical force ((M*L)/(T^2)) divided by quantity ((M^.5)*(L^.5)) <br> -= ((M^.5)*(L^.5))/(T^2).<br> -<br> -<br> -<span style="font-weight: bold;">Force, Electrostatic.</span><br> -The force by which electric matter or electrified surfaces attract or<br> -repel each other. It is also termed electric force (not good) and<br> -electro-motive intensity. It is the mechanical force acting upon a unit<br> -quantity of electricity. Its intensity varies with the square of the<br> -distance.<br> -<br> -Its dimensions are therefore equal to<br> -(quantity * unity / (square of distance) Q. * 1 / (L^2)<br> - = ((M^.5) * (L^1.5) )/ T*1 / (L^2)<br> - = ((M^.5) * (L^.5)) / T<br> -These dimensions are also those of potential difference.<br> -<br> -<img style="width: 675px; height: 71px;" alt="" src="images/260T.jpg"><br> -[Transcriber's Note: The image of the preceding paragraph is included<br> -for "clarity".]<br> -<br> -The objection to the term electric force is that it may be applied also<br> -to electro-magnetic force, and hence be a source of confusion.<br> -<br> -<br> -<span style="font-weight: bold;">Forces, Parallelogram of.</span><br> -The usual method of composing forces or resolving a force. The sides of<br> -a parallelogram of forces represent component forces and the diagonal<br> -represents the resultant. See Component--Resultant--Forces, Composition<br> -of--Forces, Resolution of.<br> -<br> -<br> -<span style="font-weight: bold;">Forces, Composition of.</span><br> -When several forces act in a different direction upon a point they may<br> -be drawn or graphically represented as arrows or lines emanating from<br> -the point in the proper direction and of lengths proportional to the<br> -force they exercise. Any two can be treated as contiguous sides of a<br> -parallelogram and the parallelogram can be completed. Then its diagonal,<br> -called the resultant, will represent the combined action of the two<br> -forces, both as regards direction and intensity. This is the composition<br> -of two forces.<br> -<br> -If more than two forces act upon the given point the resultant can be<br> -composed with any of the others and a new force developed. The new<br> -resultant can be combined with another force, and the process kept up,<br> -eliminating the components one by one until a final resultant of all is<br> -obtained. This will give the exact direction and intensity of the<br> -forces, however many or varied.<br> -<br> -<br> -261 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Forces, Resolution of.</span><br> -The developing from a single force treated as a resultant, two other<br> -forces in any desired direction. The reverse of composition of forces.<br> -(See Forces, Composition of--Forces, Parallelogram<br> -of--Components--Resultant.)<br> -<br> -<br> -<span style="font-weight: bold;">Force, Tubes of.</span><br> -Aggregations of lines of force, either electrostatic or magnetic. They<br> -generally have a truncated, conical or pyramidal shape and are not<br> -hollow. Every cross-section contains the same number of lines. The name<br> -it will seem is not very expressive.<br> -<br> -<br> -<span style="font-weight: bold;">Force, Unit of.</span><br> -The fundamental or C. G. S. unit or force is the dyne, q. v.<br> -<br> -The British unit of force is the poundal (the force which will produce<br> -an acceleration of one foot per second in a mass of one pound). It is<br> -equal to about 10/322 pound. A force cannot be expressed accurately in<br> -weight units, because weight varies with the latitude.<br> -<br> -<br> -<span style="font-weight: bold;">Forming.</span><br> -The process of producing secondary battery plates from lead plates by<br> -alternately passing a charging current through the cell and then<br> -allowing it to discharge itself and repeating the operation. (See<br> -Battery, Secondary, Planté's.)<br> -<br> -<br> -<span style="font-weight: bold;">Foundation Ring.</span><br> -In a dynamo armature the ring-shaped core on which Gramme ring armatures<br> -and other ring armatures are wound.<br> -<br> -<br> -<span style="font-weight: bold;">Fourth State of Matter.</span><br> -Gas so rarefied that its molecules do not collide, or rarely do so;<br> -radiant matter, q. v.<br> -<br> -[Transcriber's note: This term now refers to plasma, an ionized gas,<br> -which contains free electrons. The ions and electrons move somewhat<br> -independently making plasma electrically conductive. It responds<br> -strongly to electromagnetic fields.]<br> -<br> -<br> -<span style="font-weight: bold;">Frame.</span><br> -In a dynamo the bed-piece is sometimes called the frame.<br> -<br> -<br> -<span style="font-weight: bold;">Franklin's Experiment.</span><br> -Franklin proved the identity of lightning and electricity by flying a<br> -kite in a thunder storm. The kite was of silk so as to endure the<br> -wetting. When the string became wet sparks could be taken from a key<br> -attached to its end. The main string was of hemp; at the lower end was a<br> -length of silk to insulate it. The key was attached near the end of and<br> -to the hemp string.<br> -<br> -<br> -<span style="font-weight: bold;">Franklin's Plate.</span><br> -A simple form of condenser. It consists of a plate of glass coated on<br> -each side with tinfoil with a margin of about an inch of clear glass.<br> -One coating may be grounded as indicated in the cut, and the plate<br> -charged like a Leyden jar. Or one side may be connected with one<br> -terminal, and the other with the other terminal of an influence machine<br> -and the pane will be thus charged.<br> -<br> -Synonym--Fulminating Pane.<br> -<br> -<br> -262 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 525px; height: 496px;" alt="" - src="images/262F174.jpg"><br> -Fig. 174. FRANKLIN'S PLATE.<br> -<br> -<br> -<span style="font-weight: bold;">Franklin's Theory.</span><br> -The single fluid theory, q. v., of electricity.<br> -<br> -<br> -<span style="font-weight: bold;">Frequency.</span><br> -The number of double reversals or complete alternations per second in an<br> -alternating current.<br> -<br> -Synonym--Periodicity.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Frictional Electricity.</span><br> -Electricity produced by friction of dissimilar substances. (See<br> -Electrostatic Series.) The contact theory holds that friction plays only<br> -a secondary rôle in this process; that it increases the -thoroughness of<br> -contact, and tends to dry the rubbing surfaces, but that the charges<br> -induced are due to contact of dissimilar substances, not to friction of<br> -one against the other.<br> -<br> -<br> -<span style="font-weight: bold;">Frictional Heating.</span><br> -The heating of a conductor by the passage of a current; the Joule<br> -effect, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Fringe.</span><br> -The outlying edge of a magnetic field.<br> -<br> -<br> -<span style="font-weight: bold;">Frog, Galvani's Experiment With.</span><br> -A classic experiment in electricity, leading to the discovery of current<br> -or dynamic electricity. If a pair of legs of a recently killed frog are<br> -prepared with the lumbar nerves exposed near the base of the spinal<br> -column, and if a metallic conductor, one half-length zinc and the other<br> -half-length copper, is held, one end between the lumbar nerves and the<br> -spine, and the other end against one of the muscles of the thigh or<br> -lower legs, the moment contact occurs and the circuit is completed<br> -through the animal substance the muscles contract and the leg is<br> -violently drawn upwards. Galvani, in 1786, first performed, by accident,<br> -this famous experiment, it is said, with a scalpel with which he was<br> -dissecting the animal. He gave his attention to the nerves and muscles.<br> -Volta, more happily, gave his attention to the metals and invented the<br> -voltaic battery, described by him in a letter to Sir Joseph Banks, dated<br> -1800.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Frog, Rheoscopic.</span><br> -If the nerve or living muscle of a frog is suddenly dropped upon another<br> -living muscle so as to come in contact with its longitudinal and<br> -transverse sections, the first muscle will contract on account of the<br> -stimulation of its nerve due to the passage of a current derived from<br> -the second muscle (Ganot). The experiment goes under the above title.<br> -<br> -<br> -263 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Frying.</span><br> -A term applied to a noise sometimes produced in a voltaic arc due to too<br> -close approach of the carbons to each other. It has been suggested that<br> -it may be due to volatilization of the carbon. (Elihu Thomson.)<br> -<br> -<br> -<span style="font-weight: bold;">Fulgurite.</span><br> -An irregular and tubular mass of vitrified quartz, believed to be formed<br> -by melting under the lightning stroke.<br> -<br> -<br> -<img style="width: 637px; height: 241px;" alt="" - src="images/263F175.jpg"><br> -Fig. 175. CRUCIBLE, ELECTRIC.<br> -<br> -<br> -<span style="font-weight: bold;">Furnace, Electric.</span><br> -A furnace in which the heat is produced by the electric current. It has<br> -hitherto been practically used only in the extraction of aluminum and<br> -silicium from their ores. The general principle involves the -formation<br> -of an arc between carbon electrodes. The substances to be treated are<br> -exposed to the heat thus produced. Sometimes the substances in the arc<br> -form imperfect conductors, and incandescence takes a part in the action.<br> -Sometimes the substances are merely dropped through the arc.<br> -<br> -[Transcriber's note: Silicium is silicon.]<br> -<br> -<br> -<span style="font-weight: bold;">Fuse Board.</span><br> -A tablet on which a number of safety fuses are mounted. Slate is<br> -excellent material for the tablet, as it is incombustible, and is easily<br> -drilled and worked.<br> -<br> -<br> -<span style="font-weight: bold;">Fuse Box.</span><br> -A box containing a safety fuse. Porcelain is an excellent material for<br> -its base. No combustible material should enter into its composition.<br> -<br> -<br> -<span style="font-weight: bold;">Fuse, Cockburn.</span><br> -A safety fuse or cut off which consists of a wire of pure tin running<br> -from terminal to terminal, to whose centre a leaden ball is secured by<br> -being cast into position. The connection with the terminals is made by<br> -rings at the ends of the wire through which the terminal screws are<br> -passed and screwed home. When the tin softens under too heavy a current<br> -the weight of the shot pulls it apart.<br> -<br> -<br> -<img style="width: 445px; height: 318px;" alt="" - src="images/263F176.jpg"><br> -Fig. 176 COCKBURN SAFETY FUSE.<br> -<br> -<br> -264 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 653px; height: 562px;" alt="" - src="images/264F177.jpg"><br> -Fig. 177. ELECTRIC FUSE.<br> -<br> -<br> -<span style="font-weight: bold;">Fuse, Electric.</span><br> -A fuse for igniting an explosive by electricity. There are two kinds. In<br> -one a thin wire unites the ends of the two conducting wires as they<br> -enter the case of the fuse. The larger wires are secured to the case, so<br> -that no strain comes on the fine wire. On passing a current of<br> -sufficient strength the small wire is heated. In use the fuse is bedded<br> -in powder, which again may be surrounded by fulminating powder, all<br> -contained in a copper or other metallic case. Such a detonator is used<br> -for exploding guncotton and other high explosives.<br> -<br> -The other kind of fuse is similar, but has no thin connecting wire. The<br> -ends of the conductors are brought nearer together without touching. In<br> -use a static discharge is produced across from end to end of the<br> -conductors, igniting a proper explosive placed there as in the other<br> -case.<br> -<br> -The first kind of fuse is generally operated by a battery or small<br> -mechanical generator--the latter by a spark coil, frictional or<br> -influence machine or by a Leyden jar.<br> -<br> -</big></big><big><big><br> -264 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Galvanic. adj.</span><br> -Voltaic; relating to current electricity or the electrolytic and<br> -electro-chemical relations of metals. (For titles in general under this<br> -head see Voltaic--or the main title.)<br> -<br> -<br> -<span style="font-weight: bold;">Galvanic Element.</span><br> -A galvanic couple with exciting fluid and adjuncts; a galvanic cell. The<br> -word element is sometimes applied to the electrodes of a cell, as the<br> -carbon element or zinc element.<br> -<br> -<br> -265 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Galvanic Polarization.</span><br> -The polarization of a voltaic couple. (See Polarization.)<br> -<br> -<br> -<span style="font-weight: bold;">Galvanism.</span><br> -The science of voltaic or current electricity.<br> -<br> -<br> -<span style="font-weight: bold;">Galvanization.</span><br> -(a) Electroplating or depositing a metal over the surface of another by<br> -electrolysis.<br> -<br> -(b) In medical electricity the effects produced on any part of the<br> -system by the current of voltaic battery. Various descriptive<br> -qualifications are prefixed, such as "general" galvanization, indicating<br> -its application as applied to the whole body, "local" for the reverse<br> -case, and so on.<br> -<br> -<br> -<span style="font-weight: bold;">Galvanization, Labile.</span><br> -Application of the galvanic current in electro-therapeutics where one<br> -sponge electrode is employed which is rubbed or moved over the body, the<br> -other being in constant contact with the body.<br> -<br> -<br> -<span style="font-weight: bold;">Galvanized Iron.</span><br> -Iron coated with zinc by cleaning and immersion in melted zinc. The iron<br> -is prevented from rusting by galvanic action. It forms the negative<br> -element in a couple of which the zinc is the positive element. From this<br> -electric protective action the name is derived.<br> -<br> -<br> -<span style="font-weight: bold;">Galvano-cautery, Chemical.</span><br> -Electro-therapeutic treatment with sharp electrodes, one of which is<br> -inserted in the tissue and a current passed by completing the circuit<br> -through the tissue so as to electrolyze or decompose the fluids of the<br> -tissue. It is applied in the removal of hair or extirpation of the<br> -follicle. The process is not one of heating, and is improperly named<br> -cautery.<br> -<br> -<br> -<span style="font-weight: bold;">Galvano-faradization.</span><br> -In medical electricity the application of the voltaic and induced or<br> -secondary current simultaneously to any part of the system.<br> -<br> -<br> -<span style="font-weight: bold;">Galvanometer.</span><br> -An instrument for measuring current strength and sometimes for measuring<br> -inferentially potential difference, depending on the action of a<br> -magnetic field established by the current, such action being exerted on<br> -a magnetic needle or its equivalent.<br> -<br> -A current passing through a conductor establishes circular lines of<br> -force. A magnetic needle placed in their field is acted on and tends to<br> -place itself parallel with the lines, in accordance with the principles<br> -of current induction. (See Induction, Electro-magnetic.) A common<br> -compass held near a conductor through which a current is passing tends<br> -to place itself at right angles to such conductor. For a maximum effect<br> -the conductor or the part nearest the needle should lie in the magnetic<br> -meridian. If at right angles thereto its action will only strengthen the<br> -directive force of the earth's induction or magnetic field, as the<br> -needle naturally points north and south. Such combination is virtually a<br> -galvanometer.<br> -<br> -<br> -266 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -A typical galvanometer comprises a flat coil of wire placed horizontally<br> -within which a magnetic needle is delicately poised, so as to be free to<br> -rotate with the least possible friction. The needle may be supported on<br> -a sharp point like a compass needle, or may be suspended by a long fine<br> -filament. It should be covered by a glass plate and box, or by a glass<br> -shade. Finally a graduated disc may be arranged to show the amount of<br> -deflection of the needle.<br> -<br> -In use the apparatus is turned about until the needle, as acted on by<br> -the earth's magnetic field, lies parallel to the direction of the coils<br> -of wire. On passing a current through the coil the needle is deflected,<br> -more or less, according to its strength.<br> -<br> -By using exceedingly fine wire, long enough to give high resistance, the<br> -instrument can be used for very high potentials, or is in condition for<br> -use in determining voltage. By using a coil of large wire and low<br> -resistance it can be employed in determining amperage. In either case<br> -the deflection is produced by the current.<br> -<br> -The needle is often placed above or below the coil so as only to receive<br> -a portion of its effect, enough for all practical purposes in the<br> -commoner class of instruments.<br> -<br> -The galvanometer was invented by Schweigger a short time after Oersted's<br> -discovery, q. v.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Galvanometer, Absolute.</span><br> -A galvanometer giving absolute readings; properly one whose law of<br> -calibration can be deduced from its construction. Thus the diameter of<br> -the coil, and the constants and position of a magnetic needle suspended<br> -in its field being known, the current intensity required to deflect the<br> -needle a given number of degrees could be calculated.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Galvanometer, Aperiodic.</span><br> -A galvanometer whose needle is damped (see Damping) as, for instance, by<br> -the proximity of a plate of metal, by an air vane or otherwise, so that<br> -it reaches its reading with hardly any oscillation. A very light needle<br> -and a strong magnetic field also conduce to vibrations of short period<br> -dying out very quickly. Such galvanometers are termed "dead-beat." No<br> -instrument is absolutely dead-beat, only relatively so.<br> -<br> -<br> -267 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 419px; height: 557px;" alt="" - src="images/266F178.jpg"><br> -Fig. 178. ASTATIC GALVANOMETER.<br> -<br> -<br> -<span style="font-weight: bold;">Galvanometer, Astatic.</span><br> -A galvanometer with a pair of magnetic needles connected astatically, or<br> -parallel with their poles in opposition. (See Astatic Needle.) Each<br> -needle has its own coil, the coils being wound in opposite directions so<br> -as to unite in producing deflections in the same sense. As there should<br> -be some directive tendency this is obtained by one of the magnets being<br> -slightly stronger than the other or by the proximity of a fixed and<br> -adjustable controlling magnet, placed nearer one needle than the other.<br> -<br> -For small deflections the currents producing them are proportional to<br> -their extent.<br> -<br> -<br> -<span style="font-weight: bold;">Galvanometer, Ballistic.</span><br> -A galvanometer whose deflected element has considerable moment of<br> -inertia; the exact opposite of an aperiodic or dead beat galvanometer.<br> -(See Galvanometer, Aperiodic.) All damping by air vanes or otherwise<br> -must be carefully done away with.<br> -<br> -<br> -<img style="width: 437px; height: 683px;" alt="" - src="images/267F179.jpg"><br> -Fig. 179. SIEMENS & HALSKE'S GALVANOMETER.<br> -<br> -<br> -Siemens & Halske's galvanometer is of the reflecting or mirror type -(see<br> -Galvanometer, Reflecting) with suspended, bell-shaped magnet, in place<br> -of the ordinary magnetic needle, or astatic combination of the lightest<br> -possible weight in the regular instrument. A copper ball drilled out to<br> -admit the magnet is used as damper in the ordinary use of the<br> -instrument. To convert it into a ballistic galvanometer the copper ball<br> -is removed. The heavy suspended magnet then by its inertia introduces<br> -the desired element into the instrument.<br> -<br> -<br> -268 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Referring to the cut, Fig. 179, M is the suspended magnet, with north<br> -and south poles n and s; S is the reflecting mirror; r is the tube<br> -containing the suspending thread; R is the damper removed for ballistic<br> -work.<br> -<br> -The ballistic galvanometer is used to measure quantities of electricity<br> -in an instantaneous discharge, which discharge should be completed<br> -before the heavy needle begins to move. The extreme elongation or throw<br> -of the needle is observed, and depends (1) on the number of coulombs (K)<br> -that pass during the discharge; (2) on the moment of inertia of the<br> -needle and attached parts; (3) on the moment of the controlling forces,<br> -i. e., the forces tending to pull the needle back to zero; (4) on the<br> -moment of the damping forces; (5) on the moment of the deflecting forces<br> -due to a given constant current. The formula is thus expressed:<br> -<br> -K = (P / PI ) * A * sin( kº / 2 ) / tan( aº )<br> -<br> -in which K = coulombs discharged; P = periodic time of vibration of<br> -needle; A = amperes producing a steady deflection equal to -aº ; kº =<br> -first angular deflection of needle. For accuracy kº and aº -should both<br> -be small and the damping so slight as to be negligible. Otherwise a<br> -correction for the latter must be applied. For approximate work for -kº<br> -and aº the deflections read on the scale may be used with the -following<br> -formula:<br> -<br> -K = (P / PI ) * ( A / 2 ) * ( kº / aº )<br> -<br> -<br> -<span style="font-weight: bold;">Galvanometer Constant.</span><br> -Assume a galvanometer with a very short needle and so placed with<br> -respect to its coils that the magnetic field produced by a current<br> -circulating in them is sensibly uniform in the neighborhood of the<br> -needle, with its lines of force at right angles thereto. The field is<br> -proportional to the current i, so that it may be denoted by G i. Then G<br> -is the galvanometer constant. If now the angle of deflection of the<br> -needle is ? against the earth's field H, M being the magnetic moment of<br> -the needle we have G i M cos ? = H M sin ? or i = (H/G)* tan ?. H/G is<br> -the reduction factor; variable as H varies for different places.<br> -<br> -For a tangent galvanometer the constant G is equal to 2*PI*(n/a), -in<br> -which n denotes the number of turns of wire, and a denotes the radius of<br> -the circle.<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Galvanometer, Differential.</span><br> -A galvanometer in which the needle is acted on by two coils wound in<br> -opposition, each of equal deflecting action and of equal resistance. If<br> -a current is divided between two branches or parallel conductors, each<br> -including one of the coils, when the needle points to zero the<br> -resistances of the two branches will bc equal. In the cut, C C'<br> -represent the coils, and A and B the two leads into which the circuit, P<br> -Q, is divided.<br> -<br> -<br> -269 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 612px; height: 274px;" alt="" - src="images/269F180.jpg"><br> -Fig. 180. THEORY OF DIFFERENTIAL GALVANOMETER.<br> -<br> -<br> -<img style="width: 513px; height: 740px;" alt="" - src="images/269F181.jpg"><br> -Fig. 181. DIFFERENTIAL GALVANOMETER.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Galvanometer, Direct Reading.</span><br> -A calibrated galvanometer, whose scale is graduated by volts or amperes,<br> -instead of degrees.<br> -<br> -<br> -<span style="font-weight: bold;">Galvanometer, Marine. (Sir William -Thomson's.)</span><br> -A galvanometer of the reflecting type, for use on shipboard. A fibre<br> -suspension is adopted for the needle. The fibre is attached to a fixed<br> -support at one end and to a spring at the other, and the needle is<br> -suspended by its centre of gravity. This secures it to a considerable<br> -extent from disturbance due to the rolling of the ship. A thick iron box<br> -encloses the needle, etc., to cut off any magnetic action from the ship.<br> -(See Galvanometer, Reflecting.)<br> -<br> -<br> -<span style="font-weight: bold;">Galvanometer, Potential.</span><br> -A galvanometer wound with fine German silver wire to secure high<br> -resistance used for determination of potential difference.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Galvanometer, Proportional.</span><br> -A galvanometer so constructed that the deflections of its index are<br> -proportional to the current passing. It is made by causing the<br> -deflecting force to increase as the needle is deflected, more and more,<br> -or by causing the restitutive force to diminish under like conditions,<br> -or by both. The condition is obtained in some cases by the shape and<br> -position of the deflecting coils.<br> -<br> -<br> -<span style="font-weight: bold;">Galvanometer, Quantity.</span><br> -A galvanometer for determining quantities of electricity, by the<br> -deflections produced by discharging the quantities through their coils.<br> -It is a ballistic galvanometer with very little or no damping.<br> -<br> -<br> -270 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 626px; height: 301px;" alt="" - src="images/270F182.jpg"><br> -Fig. 182. PRINCIPLE OF REFLECTING GALVANOMETER.<br> -<br> -<br> -<img style="width: 647px; height: 418px;" alt="" - src="images/270F183.jpg"><br> -Fig. 183. REFLECTING GALVANOMETER.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Galvanometer, Reflecting.</span><br> -A galvanometer the deflections of whose needle are read by an image<br> -projected by light reflected from a mirror attached to the needle or to<br> -a vertical wire carrying the needle. A lamp is placed in front of the<br> -instrument facing the mirror. The light of the lamp is reflected by the<br> -mirror upon a horizontal scale above the lamp. An image of a slit or of<br> -a wire may be caused thus to fall upon the scale, the mirror being<br> -slightly convex, or a lens being used to produce the projection.<br> -<br> -<br> -271 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -If the mirror swings through a horizontal arc, the reflected image will<br> -move, in virtue of a simple geometrical principle, through an arc of<br> -twice as many degrees. The scale can be placed far from the mirror, so<br> -that the ray of light will represent a weightless index of very great<br> -length, and minute deflections of the needle will be shown distinctly<br> -upon the scale.<br> -<br> -In the cut, Fig. 182, the ray of light from the lamp passes through the<br> -aperture, m m, and is made parallel by the lens, L. At s is the mirror<br> -attached to the needle and moving with it. A scale placed at t receives<br> -the reflection from the mirror. The cut, Fig. 183, shows one form of the<br> -instrument set up for use.<br> -<br> -Synonym--Mirror Galvanometer.<br> -<br> -<br> -<span style="font-weight: bold;">Galvanometer Shunt.</span><br> -To prevent too much current passing through a galvanometer (for fear of<br> -injury to its insulation) a shunt is sometimes placed in parallel with<br> -it. The total current will be distributed between galvanometer and shunt<br> -in the inverse ratio of their respective resistances. (See Multiplying<br> -Power of a Shunt.)<br> -<br> -<br> -272 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 555px; height: 728px;" alt="" - src="images/271F184.jpg"><br> -Fig. 184. SINE GALVANOMETER.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Galvanometer, Sine.</span><br> -A galvanometer whose measurements depend upon the sine of the angle of<br> -deflection produced when the coil and needle lie in the same vertical<br> -plane.<br> -<br> -The needle, which may be a long one, is surrounded by a coil, which can<br> -be rotated about a vertical axis passing through the point of suspension<br> -of the needle. Starting with the needle at rest in the plane of the<br> -coil, a current is passed through the coil deflecting the needle, the<br> -coil is swung around deflecting the needle still more, until the needle<br> -lies in the plane of the coil; the intensity of the current will then be<br> -in proportion to the sine of the angle through which the coil and needle<br> -move.<br> -<br> -In the galvanometer M is a circle carrying the coil, N is a scale over<br> -which the needles, m and n, move, the former being a magnetic needle,<br> -the latter an index at right angles and attached thereto; a and b are<br> -wires carrying the current to be measured. The circles, M and N, are<br> -carried by a base, O, around which they rotate. H is a fixed horizontal<br> -graduated circle. In use the circle, M, is placed in the magnetic<br> -meridian, the current is passed through the coil, M; the needle is<br> -deflected; M is turned until its plane coincides with the direction of<br> -the needle, m. The current strength is proportional to the sine of the<br> -angle of deflection. This angle is measured by the vernier, C, on the<br> -circle, H. The knob, A, is used to turn the circle, M.<br> -<br> -<br> -273 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 614px; height: 754px;" alt="" - src="images/272F185.jpg"><br> -Fig. 185. TANGENT GALVANOMETER.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Galvanometer, Tangent.</span><br> -A galvanometer in which the tangents of the angles of deflection are<br> -proportional to the currents producing such deflections.<br> -<br> -For this law to apply the instrument in general must fulfill the<br> -following conditions:<br> -<br> -(1) The needle must be controlled by a uniform magnetic field such as<br> -that of the earth;<br> -<br> -(2) the diameter of the coil must be large compared to the length of the<br> -needle;<br> -<br> -(3) the centre of suspension of the needle must be at the centre of the<br> -coil;<br> -<br> -(4) the magnetic axis of the needle must lie in the plane of the coil<br> -when no current is passing.<br> -<br> -If a single current strength is to be measured the best results will be<br> -attained when the deflection is 45°; in comparing two currents the -best<br> -results will be attained when the deflections as nearly as possible are<br> -at equal distances on both sides of 45°.<br> -<br> -The needle should not exceed in length one-tenth the diameter of the<br> -coil.<br> -<br> -For very small deflections any galvanometer follows the law of<br> -tangential deflection.<br> -<br> -As for very small deflections the tangents are practically equal to the<br> -arcs subtended, for such deflections the currents are proportional to<br> -the deflections they produce.<br> -<br> -The sensibility is directly proportional to the number of convolutions<br> -of wire and inversely proportional to their diameter.<br> -<br> -The tangent law is most accurately fulfilled when the depth of the coil<br> -in the radial direction is to the breadth in the axial direction as<br> -squareRoot(3):squareRoot(2), or about as 11:9.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Galvanometer, Torsion.</span><br> -A galvanometer whose needle is suspended by a long filament or by a<br> -thread and spiral spring against whose force of torsion the movements of<br> -the needle are produced. The current strength is determined by bringing<br> -the needle back to its position of rest by turning a hand-button or<br> -other arrangement. The angle through which this is turned gives the<br> -angle of torsion. From this the current strength is calculated on the<br> -general basis that it is proportional to the angle of torsion.<br> -<br> -<br> -<img style="width: 483px; height: 752px;" alt="" - src="images/273F186.jpg"><br> -Fig. 186. TORSION GALVANOMETER.<br> -<br> -<br> -274 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Galvanometer, Vertical.</span><br> -A galvanometer whose needle is mounted on a horizontal axis and is<br> -deflected in a vertical plane. One of the poles is weighted to keep it<br> -normally vertical, representing the control. It is not used for accurate<br> -work.<br> -<br> -Synonym--Upright Galvanometer.<br> -<br> -<br> -<img style="width: 513px; height: 590px;" alt="" - src="images/274F187.jpg"><br> -Fig. 187. VERTICAL GALVANOMETER.<br> -<br> -<br> -<span style="font-weight: bold;">Galvanometer, Volt- and Ampere-meter. </span><br> -A galvanometer of Sir William Thomson's invention embodying the tangent -<br> -principle, and having its sensibility adjustable by moving the magnetic -<br> -needle horizontally along a scale (the "meter") towards or away from -the <br> -coil. A curved magnet is used to adjust the control. The leads are <br> -twisted to prevent induction.<br> -<br> -The instrument is made with a high resistance coil for voltage<br> -determinations, and with a low resistance coil for amperage<br> -determinations.<br> -<br> -At one end of a long base board a vertical coil with its plane at right<br> -angles to the axis of the board is mounted. A scale (the "meter" of the<br> -name) runs down the centre of the board. A groove also runs down the<br> -centre. The magnetic needle is contained in a quadrant-shaped<br> -glass-covered box which slides up and down the groove. A number of short<br> -parallel needles mounted together, with an aluminum pointer are used.<br> -<br> -<br> -</big></big><big><big><img style="width: 647px; height: 308px;" alt="" - src="images/274F188.jpg"></big></big><br> -<big><big>Fig. 188. SIR WILLIAM THOMSON'S <br> -AMPERE-METER GALVANOMETER.<br> -<br> -<br> -275 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -In the cut P is the base board, M is a glass covered case containing the<br> -magnetic needle, and sliding along the base board, being guided by the<br> -central groove, C, is the coil. Between the coil and the needle is the<br> -arched or bent controlling magnet. The long twisted connecting wires are<br> -seen on the right hand.<br> -<br> -<br> -<span style="font-weight: bold;">Galvano-plastics.</span><br> -The deposition of metals by electrolysis, a disused term replaced<br> -by electro-deposition, electroplating, and electro-metallurgy.<br> -<br> -<br> -<span style="font-weight: bold;">Galvano-puncture.</span><br> -An operation in medical electricity. (See Electro-puncture.)<br> -<br> -<br> -<span style="font-weight: bold;">Galvanoscope.</span><br> -An instrument, generally of the galvanometer type, used for ascertaining<br> -whether a current is flowing or not. Any galvanoscope, when calibrated,<br> -if susceptible thereof, becomes a galvanometer.<br> -<br> -<br> -<span style="font-weight: bold;">Gas, Electrolytic.</span><br> -Gas produced by the decomposition, generally of water, by electrolysis.<br> -It may be hydrogen or oxygen, or a mixture of the two, according to how<br> -it is collected. (See Gases, Mixed.)<br> -<br> -<br> -<span style="font-weight: bold;">Gases, Mixed.</span><br> -The mixture of approximately one volume of oxygen and two volumes of<br> -hydrogen collected in the eudiometer of a gas voltameter or other<br> -electrolytic apparatus.<br> -<br> -<br> -<span style="font-weight: bold;">Gassing.</span><br> -The evolution of gas from the plates of a storage battery in the<br> -charging process, due to too high voltage in the circuit of the charging<br> -dynamo.<br> -<br> -<br> -<span style="font-weight: bold;">Gastroscope.</span><br> -An apparatus for illuminating by an incandescent lamp the interior of<br> -the stomach, and with prisms to refract the rays of light so that the<br> -part can be seen. The stomach is inflated with air, if desirable, to<br> -give a better view. An incandescent platinum spiral in a water jacket<br> -has been employed for the illumination.<br> -<br> -<br> -<span style="font-weight: bold;">Gassiot's Cascade.</span><br> -A goblet lined for half its interior surface with tinfoil. It is placed<br> -in the receiver of an air pump from the top of whose bell a conductor<br> -descends into it, not touching the foil. On producing a good<br> -rarefaction, and discharging high tension electricity from between the<br> -conductor just mentioned and the metal of the machine, a luminous effect<br> -is produced, as if the electricity, pale blue in color, was overflowing<br> -the goblet.<br> -<br> -<br> -<span style="font-weight: bold;">Gauss.</span><br> -A name suggested for unit intensity of magnetic field. Sylvanus P.<br> -Thomson proposed for its value the intensity of a field of 1E8 C. G. S.<br> -electro-magnetic units. J. A. Fleming proposed the strength of field<br> -which would develop one volt potential difference in a wire 1E6<br> -centimeters long, moving through such field with a velocity of one<br> -centimeter per second. This is one hundred times greater than Thomson's<br> -standard. Sir William Thomson suggested the intensity of field produced<br> -by a current of one ampere at a distance of one centimeter<br> -<br> -The gauss is not used to any extent; practical calculations are based on<br> -electro-magnetic lines of force.<br> -<br> -<br> -276 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Gauss' Principle.</span><br> -An electric circuit acts upon a magnetic pole in such a way as to make<br> -the number of lines of force that pass through the circuit a maximum.<br> -<br> -<br> -<img style="width: 643px; height: 434px;" alt="" - src="images/276F189.jpg"><br> -Fig. 189. GAUSS' TANGENT POSITION.<br> -<br> -<br> -<span style="font-weight: bold;">Gauss, Tangent Positions of.</span><br> -The "end on" and "broadside" methods of determining magnetization<br> -involve positions which have been thus termed. (See Broadside Method and<br> -End on Method.)<br> -<br> -<br> -<span style="font-weight: bold;">Gear, Magnetic Friction.</span><br> -Friction gear in which the component wheels are pressed against each<br> -other by electromagnetic action. In the cut, repeated from Adherence,<br> -Electro-magnetic, the magnetizing coil makes the wheels, which are of<br> -iron, press strongly together.<br> -<br> -<br> -<img style="width: 507px; height: 660px;" alt="" - src="images/276F190.jpg"><br> -Fig. 190. MAGNETIC FRICTION GEAR.<br> -<br> -<br> -277 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Geissler Tubes.</span><br> -Sealed tubes of glass containing highly rarefied gases, and provided<br> -with platinum electrodes extending through the glass tightly sealed as<br> -they pass through it, and often extending a short distance beyond its<br> -interior surface.<br> -<br> -On passing through them the static discharge luminous effects are<br> -produced varying with the degree of exhaustion, the contents (gas), the<br> -glass itself, or solutions surrounding it. The two latter conditions<br> -involve fluorescence phenomena often of a very beautiful description.<br> -<br> -The pressure of the gas is less than one-half of a millimeter of<br> -mercury. If a complete vacuum is produced the discharge will not pass.<br> -If too high rarefaction is produced radiant matter phenomena (see<br> -Radiant State) occur.<br> -<br> -Geissler tubes have been used for lighting purposes as in mines, or for<br> -illuminating the interior cavities of the body in surgical or medical<br> -operations.<br> -<br> -<br> -<span style="font-weight: bold;">Generating Plate.</span><br> -The positive plate in a voltaic couple, or the plate which is dissolved;<br> -generally a plate of zinc.<br> -<br> -Synonyms--Positive Plate--Positive Element.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Generator, Current.</span><br> -Any apparatus for maintaining an electric current. It may be as regards<br> -the form of energy it converts into electrical energy, mechanical, as a<br> -magneto or dynamo electric machine or generator; thermal, as a<br> -thermo-electric battery; or chemical, as a voltaic battery; all of which<br> -may be consulted.<br> -<br> -<br> -<span style="font-weight: bold;">Generator, Secondary.</span><br> -A secondary or storage battery. (See Battery, Secondary.)<br> -<br> -<br> -<span style="font-weight: bold;">German Silver.</span><br> -An alloy of copper, 2 parts, nickel, 1 part, and zinc, 1 part. Owing to<br> -its high resistance and moderate cost and small variation in resistance<br> -with change of temperature, it is much used for resistances. From Dr.<br> -Mathiessen's experiment the following constants are deduced in legal<br> -ohms:<br> - <small><span style="font-family: monospace;">Relative -Resistance (Silver = 1), -13.92</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Specific Resistance at -0° C. (32F.), 20.93 -microhms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Resistance of a wire,</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> (a) 1 foot long, weighing -1 grain, -2.622 ohms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> 1 foot long, 1/1000 inch -thick, -125.91 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> 1 meter long, weighing 1 -gram, -1.830 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> 1 meter long, 1 millimeter -thick, 0.2666 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Resistance of a 1 inch -cube at 0°C. (32° -F.), 8.240 microhms.</span></small><br> -<br> -Approximate percentage increase of resistance per 1° C. (1.8° -F.) at<br> -about 20° C. (68° F.), 0.044 per cent.<br> -<br> -<br> -<span style="font-weight: bold;">Gilding, Electro-.</span><br> -The deposition of gold by an electric current, or electrolytically in<br> -the electroplating bath.<br> -<br> -<br> -<span style="font-weight: bold;">Gilding Metal.</span><br> -A special kind of brass, with a high percentage of copper, used to make<br> -objects which are to be gilded by electrolysis.<br> -<br> -<br> -278 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Gimbals.</span><br> -A suspension used for ships' compasses and sometimes for other<br> -apparatus. It consists of a ring held by two journals, so as to bc free<br> -to swing in one plane. The compass is swung upon this ring, being placed<br> -concentrically therewith. Its journals are at right angles to those of<br> -the ring. This gives a universal joint by which the compass, weighted<br> -below its line of support, is always kept horizontal.<br> -<br> -<br> -<img style="width: 697px; height: 495px;" alt="" - src="images/278F191.jpg"><br> -Fig. 191. COMPASS SUSPENDED IN GIMBALS.<br> -<br> -<br> -<span style="font-weight: bold;">Glass.</span><br> -A fused mixture of silicates of various oxides. It is of extremely<br> -varied composition and its electric constants vary greatly. Many<br> -determinations of its specific resistance have been made. For flint<br> -glass at 100° C. (212° F.) about (2.06E14) ohms --at 60° C -(140° F.)<br> -(1.020E15) (Thomas Gray) is given, while another observer (Beetz) gives<br> -for glass at ordinary temperatures an immeasurably high resistance. It<br> -is therefore a non-conductor of very high order if dry. As a dielectric<br> -the specific inductive capacity of different samples of flint glass is<br> -given as 6.57--6.85--7.4--10.1 (Hopkinson), thus exceeding all other<br> -ordinary dielectrics. The densest glass, other things being equal, has<br> -the highest specific inductive capacity.<br> -<br> -<br> -<span style="font-weight: bold;">Gold.</span><br> -A metal, one of the elements; symbol Au. c .; atomic weight, 196.8;<br> -equivalent, 65.6; valency, 3; specific gravity 19.5.<br> -It is a conductor of electricity.<br> -<small><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Annealed. Hard drawn.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Relative Resistance (Annealed -Silver = 1), -1.369 1.393</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Specific -Resistance, -2.058 2.094</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Resistance of a wire at 0° C. -(32°F.)</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">(a) 1 foot long, weighing 1 -grain, -57.85 58.84 ohms</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">(b) 1 foot long, 1/1000 inch -thick, -12.38 12.60 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">(c) 1 meter long, weighing 1 -gram, -.4035 .4104 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">(d) 1 meter long, 1 millimeter -thick, -.02620 .02668 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Resistance of a 1 inch cube at -0° C.(32° F.) -.8102 .8247</span><br - style="font-family: monospace;"> -<br style="font-family: monospace;"> -<span style="font-family: monospace;">Approximate increase in -resistance per 0° C., (1.8° F)</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">at about 20° C. (68° F.), -0.365 per cent.</span><br style="font-family: monospace;"> -<br style="font-family: monospace;"> -<span style="font-family: monospace;">Electro-chemical equivalent -(Hydrogen = .0105), .6888</span></small> -<br> -<br> -<br> -279 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Gold Bath.</span><br> -A solution of gold used for depositing the metal in the electroplating<br> -process.<br> -<br> -A great number of formulae have been devised, of which a few<br> -representative ones are given here.<br> -<small><span style="font-family: monospace;"> -COLD -BATHS. -HOT BATHS.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Water, -10,000 10,000 10,000 10,000 5,000 -3,000</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Potassium -Cyanide, -200 --- -200 -10 -- 50</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Gold, -100 -15 -100 -10 10 10</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Potassium Ferrocyanide, --- -200 --- -- -150 --</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Potassium -Carbonate, --- -150 --- -- -50 --</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Ammonium -Chloride, --- -30 --- -- -20 --</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Aqua -Ammoniae, --- -- -500 --- -- --</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Sodium -Phosphate, --- --- -- -600 -- --</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Sodium -Bisulphite, --- --- -- -100 -- --</span></small><br> -<br> -(Roseleur.)<br> -<br> -In the baths the gold is added in the form of neutral chloride, Auric<br> -chloride (Au Cl6).<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Gold Stripping Bath</span>.<br> -A bath for removing gold from plated articles without dissolving the<br> -base in order to save the precious metal. A bath of 10 parts of<br> -potassium cyanide and 100 parts of water may be used, the articles to be<br> -stripped being immersed therein as the anode of an active circuit. If<br> -the gilding is on a silver or copper basis, or on an alloy of these<br> -metals the same solution attacks the base and dissolves it, which is<br> -objectionable. For silver articles it is enough to heat to cherry red<br> -and throw into dilute sulphuric acid. The gold scales off in metallic<br> -spangles. For copper articles, a mixture of 10 volumes concentrated<br> -sulphuric acid, 1 volume nitric acid, and 2 volumes hydrochloric acid<br> -may be used by immersion only, or with a battery. The sulphuric acid in<br> -such large excess is supposed to protect the copper. For copper articles<br> -concentrated sulphuric acid alone with the battery may be used. This<br> -does not sensibly attack the copper if it is not allowed to become<br> -diluted. Even the dampness of the air may act to dilute it.<br> -<br> -<br> -<span style="font-weight: bold;">Graduator.</span><br> -Apparatus for enabling the same line to be used for telegraph signals<br> -and telephoning.<br> -<br> -One type consists in coils with iron cores or simply electromagnets.<br> -These act to retard the current in reaching its full power and also<br> -prolong it. This gives a graduated effect to the signals, so that the<br> -telephone diaphragm is not audibly affected by the impulses.<br> -<br> -The telephoning current is so slight and so rapid in its characteristic<br> -changes that it is without effect upon the ordinary telegraph.<br> -<br> -<br> -280 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Gram. </span><br> -The unit of weight in the metric system; accepted as the unit of<br> -mass in the absolute of C. G. S. system of units. It is the<br> -one-thousandth part of mass of a standard weight preserved under proper<br> -conditions in Paris, and supposed to be the mass of a cubic decimeter of<br> -distilled water at the temperature of the maximum density of water. The<br> -standard is the kilogram; the temperature is 3.9º C. (39º -F.). The<br> -standard kilogram is found to be not exactly the weight of a cubic<br> -decimeter of water, the latter weighing 1.000013 kilogram.<br> -<br> -If therefore the defined gram on the water basis is taken as the unit it<br> -varies very slightly from the accepted gram.<br> -<br> -1 gram is equal to 15.43234874 grains. (Prof. W. H. Miller.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Gram-atom.</span><br> -The number of grams of an element equal numerically to the atomic<br> -weight, as 16 grams of oxygen, 1 gram of hydrogen, 35.5 grams of<br> -chlorine; all which might be expressed as gram-atoms of oxygen, hydrogen<br> -and chlorine respectively.<br> -<br> -The gram-atom approximately expresses the number of gram-calories<br> -required to heat one gram of the substance 1º C. (1.8º F.). -This is in<br> -virtue of Dulong and Petit's discovery that the atomic weight of an<br> -element multiplied by its specific heat gives approximately a constant<br> -for all elements.<br> -<br> -[Transcriber's note: A gram-atom is the mass, in grams, of one mole of<br> -atoms in a monatomic element. A mole consists of Avogadro's number of<br> -atoms, approximately 6.02214E23.]<br> -<br> -<br> -<span style="font-weight: bold;">Gram-molecule.</span><br> -The number of grams of a substance equal numerically to its molecular<br> -weight.<br> -<br> -<br> -<span style="font-weight: bold;">Graphite.</span><br> -Carbon; one of three allotropic modifications of this element. It occurs<br> -in nature as a mineral.<br> -<br> -It is used as a lubricant for machinery; for commutator brushes; for<br> -making surfaces to be plated conductive, and for mixing with manganese<br> -binoxide in Leclanché cells.<br> -<br> -<br> -<span style="font-weight: bold;">Gravitation.</span><br> -A natural force which causes all masses of matter to attract each other.<br> -Its cause is unknown; it is often supposed to be due to the luminiferous<br> -ether.<br> -<br> -[Transcriber's note: Einstein's explanation of gravity, General<br> -Relativity and the curvature of space-time, came 23 years later, 1915.]<br> -<br> -<br> -281 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Gravity, Acceleration of.</span><br> -The velocity imparted to a body in one second by the action of<br> -gravitation at any standard point upon the earth's surface in a vacuum.<br> -This will vary at different places, owing principally to the variation<br> -in centrifugal force due to the earth's rotation. For standard valuation<br> -it must be reduced to sea level. The following are examples of its<br> -variation:<br> -<br> -<small><span style="font-family: monospace;">Equator, -978.1028 centimeters per second</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Paris, -980.94 -"</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Greenwich -981.I7 -"</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Edinburgh, -981.54 -"</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Pole (N. or S.), 983.1084 -(theoretical) "</span></small><br> -<br> -As round numbers for approximate calculations 981 centimeters or 32.2<br> -feet may be employed.<br> -<br> -[Transcriber's note: The acceleration of gravity at the equator is also<br> -reduced by the increased distance from the center of the earth<br> -(equatorial bulge). Increased altitude reduces gravity. Reduced air<br> -density at altitude reduces buoyancy and increases apparent weight.<br> -Local variations of rock density affects gravity.]<br> -<br> -<br> -<span style="font-weight: bold;">Gravity, Control.</span><br> -Control by weight. In some ammeters and voltmeters gravity is the<br> -controlling force.<br> -<br> -<br> -<span style="font-weight: bold;">Grid.</span><br> -A lead plate perforated or ridged for use in a storage battery as the<br> -supporter of the active materials and in part as contributing thereto<br> -from its own substance.<br> -<br> -<br> -<span style="font-weight: bold;">Ground.</span><br> -The contact of a conductor of an electric circuit with the earth,<br> -permitting the escape of current if another ground exists.<br> -<br> -<br> -<span style="font-weight: bold;">Ground-wire.</span><br> -A metaphorical term applied to the earth when used as a return circuit.<br> -<br> -<br> -<img style="width: 664px; height: 487px;" alt="" - src="images/281F192.jpg"><br> -Fig. 192. GROVE'S GAS BATTERY.<br> -<br> -<br> -<span style="font-weight: bold;">Grove's Gas Battery.</span><br> -A voltaic battery depending for its action on the oxidation of hydrogen<br> -instead of the oxidation of zinc. Its action is more particularly<br> -described under Battery, Gas. In the cut B, B1 * * * are the terminals<br> -of the positive or hydrogen electrodes, marked H, and A, Al * * * are<br> -the terminals of the negative or oxygen electrodes marked O, while M, M1<br> -* * * is dilute sulphuric acid.<br> -<br> -<br> -282 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Guard Ring.</span><br> -An annular horizontal surface surrounding the balanced disc in the<br> -absolute electrometer. (See Electrometer, Absolute.)<br> -<br> -<br> -<span style="font-weight: bold;">Guard Tube.</span><br> -A metal tube surrounding a dry pile used with a quadrant electrometer,<br> -or other electrometers of that type. It prevents the capacity of the<br> -lower brass end of the pile (which brass end closes the glass tube<br> -containing the discs) from momentary change by approach of some<br> -conductor connected to the earth. There are other guard tubes also.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Gun, Electro-magnetic.</span><br> -An electro-magnet with tubular core. If, when it is excited a piece of<br> -an iron rod is pushed into the central aperture of the core and is<br> -released, the magnetic circle will try to complete itself by pushing the<br> -rod out so that it can thus be discharged, as if from a popgun.<br> -<br> -Synonym--Electric Popgun.<br> -<br> -<br> -<img style="width: 564px; height: 454px;" alt="" - src="images/282F193.jpg"><br> -Fig. 193. "ELECTRIC POPGUN."<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Gutta Percha.</span><br> -The hardened milky juice of a tree, the Isonandra gutta, growing in<br> -Malacca and other parts of the Eastern Archipelago. It is much used as<br> -an insulator or constituent of insulators.<br> -<br> -Resistance after several minutes electrification per 1 centimeter cube<br> -at 54º C. (75º F.), 4.50E14 ohms.<br> -<br> -The specific resistance varies--from 2.5E13 to 5.0E14 ohms. A usual<br> -specification is 2.0E14 ohms. The influence of temperature on its<br> -resistance is given in Clark & Bright's empirical formula, R = R0 -at, in<br> -which R is the resistance at temperature tº C--Ro the resistance -at 0º C<br> -(32º F), a is the coefficient .8944.<br> -<br> -The resistance increases with the time of passage of the current, the<br> -variation being less the higher the temperature.<br> -<br> -<br> -283 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<small><span style="font-family: monospace;">Time -of -Relative Resistance Relative Resistance</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Electrification. at -0º C (32º -F.) at 24º C (75º -F.)</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> 1 -minute -100 -5.51</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> 2 -" -127.9 -6.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> 5 -" -163.1 -6.66</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> 10 -" -190.9 -6.94</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> 20 -" -230.8 -7.38</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> 30 -" -250.6 -7.44</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> 60 -" -290.4 -7.6</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> 90 -" -318.3 -7.66</span></small><br> -<br> -In cable testing one minute is generally taken as the time of<br> -electrification.<br> -<br> -Pressure increases the resistance by the formula Rp=R (1+ .00327 P) in<br> -which Rp is the resistance at pressure p--R resistance at atmospheric<br> -pressure--p pressure in atmospheres. Thus in the ocean at a depth of<br> -4,000 meters (2.4855 miles), the resistance is more than doubled. The<br> -longer the pressure is applied, the greater is the resistance.<br> -<br> -The specific inductive capacity of gutta percha is 4.2.<br> -<br> -Good gutta percha should not break when struck with a hammer, should<br> -recover its shape slowly, and it should support much more than 300 times<br> -its own weight.<br> -<br> -<br> -<span style="font-weight: bold;">Gyrostatic Action of Armatures.</span><br> -Owing to gyrostatic action a rotating armature resists any change of<br> -direction of its axis. On ships and in railway motors which have to turn<br> -curves this action occurs. A 148 lb. armature running at 1,300<br> -revolutions per minute may press with 30 lbs. on each journal as the<br> -ship rolls through an angle of 20° in 16 seconds.<br> -</big></big><br> -<big><big><br> -</big></big><big><big><br> -283 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<small><span style="font-family: monospace;"></span></small><span - style="font-weight: bold;">H.</span><br> -(a) The symbol for the horizontal component of the earth's<br> -magnetization.<br> -<br> -(b) The symbol for the intensity of a magnetizing force or field. The<br> -symbol H, as it is generally used, may mean either the number of dynes<br> -which act upon a unit pole, or the number of lines of force per<br> -centimeter.<br> -<br> -(c) The symbol for the unit of self-induction.<br> -<br> -<br> -<span style="font-weight: bold;">Hair, Removal of, by Electrolysis.</span><br> -A method of depilation by destruction of individual hair follicles by<br> -electrolysis.<br> -<br> -A fine platinum electrode is thrust into a hair follicle. It is the<br> -negative electrode. The positive electrode is in contact with the body<br> -of the person under treatment; it is often a sponge electrode simply<br> -held in his hand. A current of two to four milliamperes from an E. M. F.<br> -of 15 to 20 volts, is passed. This destroys the follicle, the hair is<br> -removed and never grows again. A gradual increase of current is advised<br> -for the face. As only one hair is removed at once, but a small number<br> -are taken out at a sitting.<br> -<br> -<br> -284 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Haldat's Figures.</span><br> -With a pole of a strong bar magnet, used like a pencil, imaginary<br> -figures are drawn upon a hard steel plate, such as a saw-blade. The<br> -pattern is gone over several times. By dusting iron filings on a sheet<br> -of paper laid over the steel plate, while horizontal, very complicated<br> -magnetic figures are produced.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Hall's Experiment.</span><br> -A cross of thin metal, such as gold leaf, is secured upon a pane of<br> -glass. To two opposite arms a battery is connected in circuit with them.<br> -To the other two arms a galvanometer is connected in circuit. If the<br> -cross is put into a field of force whose lines are perpendicular<br> -thereto, the galvanometer will disclose a constant current. The current<br> -is pushed, as it were, into the galvanometer circuit. Other metals have<br> -been used with similar results. They must be thin or the experiment<br> -fails. If the arm receiving the battery current is horizontal, and if it<br> -flows from left to right, and if the lines of force go from downward<br> -through the cross, the current in the galvanometer circuit will flow<br> -from the observer through the other arms of the cross, if the cross is<br> -of gold, silver, platinum or tin, and the reverse if of iron. The<br> -experiment has indicated a possible way of reaching the velocity of<br> -electricity in absolute measure.<br> -<br> -<br> -<span style="font-weight: bold;">Hall Effect.</span><br> -The effect observed in Hall's experiment, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Hall Effect, Real.</span><br> -A transverse electro-motive force in a conductor through which a current<br> -is passing produced by a magnetic field.<br> -<br> -<br> -<span style="font-weight: bold;">Hall Effect, Spurious.</span><br> -A spurious electro-motive force produced in a conductor, through which a<br> -current is passing by changes in conductivity of the conductor brought<br> -about by a magnetic field.<br> -<br> -<br> -<span style="font-weight: bold;">Hanger Board.</span><br> -A board containing two terminals, a suspending hook, and a switch, so<br> -that an arc lamp can be introduced into a circuit thereby, or can be<br> -removed as desired.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Harmonic Receiver.</span><br> -A receiver containing a vibrating reed, acted on by an electro-magnet.<br> -Such a reed answers only to impulses tuned to its own pitch. If such are<br> -received from the magnet it will vibrate. Impulses not in tune with it<br> -will not affect it. (See Telegraph, Harmonic.)<br> -<br> -<br> -<span style="font-weight: bold;">Head Bath, Electric.</span><br> -A fanciful name for an electro-medical treatment of the head. The<br> -patient is insulated by an insulating stool or otherwise. His person is<br> -connected with one terminal of an influence machine. An insulated<br> -metallic circle, with points of metal projecting inward or downward, is<br> -placed about the head. The circle is connected with the other pole of<br> -the machine. On working it a silent or brush discharge with air<br> -convection streams occurs between the patient's head and the circle of<br> -points.<br> -<br> -<br> -285 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Head-light, Electric.</span><br> -An electric head-light for locomotives has been experimented with. It<br> -includes the parabolic reflection of the regular light with an arc-lamp<br> -in place of the oil lamp. An incandescent lamp may be used in the same<br> -place, but has no great advantage over oil as regards illuminating<br> -power.<br> -<br> -<br> -<span style="font-weight: bold;">Heat.</span><br> -A form of kinetic energy, due to a confused oscillatory movement of the<br> -molecules of a body. Heat is not motion, as a heated body does not<br> -change its place; it is not momentum, but it is the energy of motion. If<br> -the quantity of molecular motion is doubled the momentum of the<br> -molecules is also doubled, but the molecular mechanical energy or heat<br> -is quadrupled.<br> -<br> -As a form of energy it is measured by thermal units. The calorie is the<br> -most important, and unfortunately the same term applies to two units,<br> -the gram-degree C. and the kilogram-degree C. (See Calorie.) Calories<br> -are determined by a calorimeter, q. v.<br> -<br> -Independent of quantity of heat a body may be hotter or colder.<br> -Thermometers are used to determine its temperature.<br> -<br> -Heat is transmitted by conduction, a body conducting it slowly for some<br> -distance through its own substance. Bodies vary greatly in their<br> -conductivity for heat. It is also transmitted by convection of gases or<br> -liquids, when the heated molecules traveling through the mass impart<br> -their heat to other parts. Finally it is transmitted by ether waves with<br> -probably the speed of light. This mode of transmission and the phenomena<br> -of it were attributed to radiant heat. As a scientific term this is now<br> -dropped by many scientists. This practice very properly restricts the<br> -term "heat" to kinetic molecular motion.<br> -<br> -The mechanical equivalent of heat is the number of units of work which<br> -the energy of one unit quantity of heat represents. (See Equivalents,<br> -Mechanical and Physical.)<br> -<br> -<br> -<span style="font-weight: bold;">Heat, Atomic.</span><br> -The product of the specific heat of an element by its atomic weight. The<br> -product is approximately the same for all the elements, and varies as<br> -determined between 5.39 and 6.87. The variations are by some attributed<br> -principally to imperfection of the work in determining them. The atomic<br> -heat represents the number of gram calories required to raise the<br> -temperature of a gram atom (a number of grams equal numerically to the<br> -atomic weight) one degree centigrade.<br> -<br> -<br> -286 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Heat, Electric.</span><br> -This term has been given to the heat produced by the passage of a<br> -current of electricity through a conductor. It is really electrically<br> -produced heat, the above term being a misnomer.<br> -<br> -The rise of temperature produced in a cylindrical conductor by a current<br> -depends upon the diameter of the conductor and on the current. The<br> -length of the wire has only the indirect connection that the current<br> -will depend upon the resistance and consequently upon its length.<br> -<br> -The quantity of heat produced in a conductor by a current is in<br> -gram-degree C. units equal to the product of the current, by the<br> -electro-motive force or potential difference maintained between the ends<br> -of the wire, by .24.<br> -<br> -The cube of the diameter of a wire for a given rise of temperature<br> -produced in such conductor by a current is equal approximately to the<br> -product of the square of the current, by the specific resistance (q. v.)<br> -of the material of the conductor, by .000391, the whole divided by the<br> -desired temperature in centigrade units.<br> -<br> -<br> -<span style="font-weight: bold;">Heat, Electrical Convection of.</span><br> -A term applied to the phenomena included under the Thomson effect, q.<br> -v., the unequal or differential heating effect produced by a current of<br> -electricity in conductors whose different parts are maintained at<br> -different temperatures.<br> -<br> -<br> -<span style="font-weight: bold;">Heater, Electric.</span><br> -An apparatus for converting electrical energy into thermal energy.<br> -<br> -An incandescent lamp represents the principle, and in the Edison meter<br> -has been used as such to maintain the temperature of the solutions.<br> -Heaters for warming water and other purposes have been constructed,<br> -utilizing conductors heated by the passage of the current as a source of<br> -heat. (See also Heating Magnet.)<br> -<br> -<br> -<span style="font-weight: bold;">Heating Error.</span><br> -In voltmeters the error due to alteration of resistance of the coil by<br> -heating. If too strong a current is sent through the instrument, the<br> -coils become heated and their resistance increased. They then do not<br> -pass as much current as they should for the potential difference to<br> -which they may be exposed. Their readings then will be too low. One way<br> -of avoiding the trouble is to have a key in circuit, and to pass only an<br> -instantaneous or very brief current through the instrument and thus get<br> -the reading before the coils have time to heat.<br> -<br> -The heating error does not exist for ammeters, as they are constructed<br> -to receive the entire current, and any heating "error" within their<br> -range is allowed for in the dividing of the scale.<br> -<br> -<br> -<span style="font-weight: bold;">Heating Magnet.</span><br> -An electro-magnet designed to be heated by Foucault currents induced in<br> -its core by varying currents in the windings. It has been proposed as a<br> -source of artificial heat, a species of electric heating apparatus for<br> -warming water, or other purposes.<br> -<br> -<br> -287 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Heat, Irreversible.</span><br> -The heat produced by an electric current in a conductor of identical<br> -qualities and temperature throughout. Such heat is the same whatever the<br> -direction of the current. The heating effect is irreversible because of<br> -the absence of the Thomson effect, q. v.) or Peltier effect, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Heat, Mechanical Equivalent of.</span><br> -The mechanical energy corresponding to a given quantity of heat energy.<br> -Mechanical energy is generally represented by some unit of weight and<br> -height, such as the foot-pound; and heat energy is represented by a<br> -given weight of water heated a given amount, such as a pound-degree<br> -centigrade. Joule's equivalent is usually accepted; it states that<br> -772.55 foot pounds of mechanical energy are equivalent to 1 pound-degree<br> -F. (one pound avds. of water raised in temperature one degree<br> -Fahrenheit). Other equivalencies have also been deduced.<br> -<br> -<br> -<span style="font-weight: bold;">Heat, Molecular.</span><br> -The product of a specific heat of the compound by its molecular weight.<br> -It is approximately equal to the sum of the atomic heats of its<br> -constituent elements.<br> -<br> -The molecular heat represents the number of gram calories required to<br> -raise the temperature of a gram-molecule (a number of grams equal<br> -numerically to the molecular weight) one degree centigrade.<br> -<br> -The molecular heat is approximately equal for all substances.<br> -<br> -<br> -<span style="font-weight: bold;">Heat, Specific.</span><br> -The capacity of a body for heat; a coefficient representing the relative<br> -quantity of heat required to raise the temperature of an identical<br> -weight of a given body a defined and identical amount.<br> -<br> -The standard of comparison is water; its specific heat is taken as<br> -unity. The specific heats by weight of other substances are less than<br> -unity. The specific heat varies with the temperature. Thus the specific<br> -heat of water is more strictly 1+.00015 tº C.<br> -<br> -Specific heat is greater when a substance is in the liquid than when it<br> -is in the solid state. Thus the specific heat of ice is 0.489; less<br> -than half that of water. It differs with the allotropic modifications of<br> -bodies; the specific heat of graphite is .202; of diamond, .147.<br> -<br> -The product of the specific heat by the atomic weight of elements gives<br> -a figure approximately the same. A similar law applies in the case of<br> -molecules. (See Heat, Atomic-Heat, Molecular.)<br> -<br> -The true specific heat of a substance should be separated from the heat<br> -expended in expanding a body against molecular and atomic forces, and<br> -against the atmospheric pressure. So far this separation has not been<br> -possible to introduce in any calculations.<br> -<br> -<br> -288 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Heat, Specific, of Electricity.</span><br> -A proposed term to account for the heat absorbed or given out in<br> -unhomogeneous conductors, by the Thomson effect, or Peltier effect (see<br> -Effect, Thomson--Effect, Peltier.) If a current of electricity be<br> -assumed to exist, then under the action of these effects it may be<br> -regarded as absorbing or giving out so many coulombs of heat, and thus<br> -establishing a basis for specific heat.<br> -<br> -<br> -<span style="font-weight: bold;">Heat Units.</span><br> -The British unit of heat is the pound degree F--the quantity of heat<br> -required to raise the temperature of a pound of water from 32° to -33° F.<br> -<br> -The C. G. S. unit is the gram-degree C.; another metric unit is the<br> -kilogram-degree C. The latter is the calorie; the former is sometimes<br> -called the small calorie or the joule; the latter is sometimes called<br> -the large calorie. The term joule is also applied to a quantity of heat<br> -equivalent to the energy of a watt-second or volt-coulomb. This is equal<br> -to .24l gram degree calorie.<br> -<br> -<br> -<span style="font-weight: bold;">Hecto.</span><br> -A prefix to terms of measurement--meaning one hundred times, as<br> -hectometer, one hundred meters.<br> -<br> -<br> -<span style="font-weight: bold;">Heliograph.</span><br> -An apparatus for reflecting flashes of light to a distant observer. By<br> -using the Morse telegraph code messages may thus be transmitted long<br> -distances. When possible the sun's light is used.<br> -<br> -<br> -<span style="font-weight: bold;">Helix.</span><br> -A coil of wire; properly a coil wound so as to follow the outlines of a<br> -screw without overlaying itself.<br> -<br> -<br> -<img style="width: 712px; height: 299px;" alt="" - src="images/288F194_195.jpg"><br> -Fig. 194. LEFT-HANDED HELIX.<br> -<br> -Fig. 195. RIGHT-HANDED HELIX.<br> -<br> -<br> -<span style="font-weight: bold;">Henry.</span><br> -The practical unit of electro-magnetic or magnetic inductance. It is<br> -equal to 1E9 C. G. S., or absolute units of inductance. As the<br> -dimensions of inductance are a length the henry is equal to 1E9<br> -centimeters, or approximately to one quadrant of the earth measured on<br> -the meridian.<br> -<br> -Synonyms--Secohm--Quadrant--Quad.<br> -<br> -<br> -289 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Hermetically Sealed.</span><br> -Closed absolutely tight. Glass vessels, such as the bulbs of<br> -incandescent lamps, are hermetically sealed often by melting the glass<br> -together over any opening into their interior.<br> -<br> -<br> -<span style="font-weight: bold;">Heterostatic Method.</span><br> -A method of using the absolute or attracted disc electrometer. (See<br> -Electrometer Absolute.) The formula for its idiostatic use, q. v.,<br> -involves the determination of d, the distance between the suspended and<br> -fixed discs. As this is difficult to determine the suspended disc and<br> -guard ring may be kept at one potential and the lower fixed disc is then<br> -connected successively with the two points whose potential difference is<br> -to be determined. Their difference is determined by the difference<br> -between d and d', the two distances between the discs. This difference<br> -is the distance through which the micrometer screw is moved. The<br> -heterostatic formula is:<br> -<br> -V' - V = (d' - d)* squareRoot( 8*PI*F / S )<br> -<br> -in which V and V' are potentials of the two points; d' and d the two<br> -distances between the discs necessary for equilibrium; S the area of the<br> -disc and F the force of attraction in dynes. (See Idiostatic Method.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">High Bars of Commutator.</span><br> -Commutator bars, which in the natural wear of the commutator, project<br> -beyond the others. The surface then requires turning down, as it should<br> -be quite cylindrical.<br> -<br> -<br> -<span style="font-weight: bold;">High Frequency.</span><br> -A term used as a noun or as an adjective to indicate in an alternating<br> -current, the production of a very great number of alternations per unit<br> -of time--usually expressed as alternations per second.<br> -<br> -<br> -<span style="font-weight: bold;">Hissing.</span><br> -A term applied to a noise sometimes produced by a voltaic arc; probably<br> -due to the same cause as frying, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Hittorf's Solution.</span><br> -A solution used as a resistance. It is a solution of cadmium iodide in<br> -amylic alcohol. Ten per cent. of the salt is used. It is contained in a<br> -tube with metallic cadmium electrodes. (See Resistance, Hittorf' s.)<br> -<br> -<br> -<img style="width: 339px; height: 579px;" alt="" - src="images/289F196.jpg"><br> -Fig. 196. HITTORF'S RESISTANCE TUBE.<br> -<br> -<br> -290 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Holders.</span><br> -(a) The adjustable clamps for holding the armature brushes of dynamos<br> -and motors.<br> -<br> -(b) The clamps for holding the carbons of arc lamps.<br> -<br> -(c) The clamps for holding safety fuses, q. v.<br> -<br> -(d) Holders for Jablochkoff candles and other electric candles. (See<br> -Candle Holders.)<br> -<br> -(e) A box or block of porcelain for holding safety fuses.<br> -<br> -<br> -<span style="font-weight: bold;">Hood.</span><br> -A tin hood placed over an arc-lamp. Such hoods are often truncated cones<br> -in shape, with the small end upwards. They reflect a certain amount of<br> -light besides protecting the lamp to some extent from rain.<br> -<br> -<br> -<span style="font-weight: bold;">Horns.</span><br> -The extensions of the pole pieces of a dynamo or motor. (See Following<br> -Horns-Leading Horns.)<br> -<br> -Synonym--Pole Tips.<br> -<br> -<br> -<span style="font-weight: bold;">Horse Power.</span><br> -A unit of rate of work or activity. There are two horse powers.<br> -<br> -The British horse power is equal to 33,000 pounds raised one foot per<br> -minute, or 550 foot pounds per second, or 1.0138 metric horse power.<br> -<br> -The metric horse power (French) is equal to 75 kilogram-meters, or 542<br> -foot pounds per second, or .986356 British horse power.<br> -<br> -H. P. is the abbreviation for horse power. (See Horse Power, Electric.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Horse Power, Actual.</span><br> -The rate of activity of a machine, as actually developed in condition<br> -for use. It is less than the indicated or total horse power, because<br> -diminished by the hurtful resistances of friction, and other sources of<br> -waste. It is the horse power that can be used in practise, and which in<br> -the case of a motor can be taken from the fly-wheel.<br> -<br> -<br> -<span style="font-weight: bold;">Horse Power, Electric.</span><br> -The equivalent of a mechanical horse power in electric units, generally<br> -in volt-amperes or watts; 745.943 watts are equivalent to the activity<br> -of one British horse power; 735.75 are equivalent to one metric horse<br> -power. The number 746 is usually taken in practical calculations to give<br> -the equivalency.<br> -<br> -[Transcriber's note: Contemporary values are: Mechanical (British)<br> -horsepower = 745.6999 Watts; Metric horsepower = 735.49875 Watts]<br> -<br> -<br> -<span style="font-weight: bold;">Horse Power, Indicated.</span><br> -The horse power of an engine as indicated by its steam pressure, length<br> -of stroke, and piston area, and vacuum, without making any deduction for<br> -friction or hurtful resistances. The steam pressure is in accurate work<br> -deduced from indicator diagrams.<br> -<br> -<br> -<span style="font-weight: bold;">Horse Power, Hour.</span><br> -A horse power exerted for one hour, or the equivalent thereof. As the<br> -horse power is a unit of activity, the horse power hour is a unit of<br> -work or of energy. It is equal to 1,980,000 foot pounds.<br> -<br> -<br> -<span style="font-weight: bold;">H. P.</span><br> -Abbreviation for "horse power."<br> -<br> -<br> -291 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Hughes' Electro-magnet.</span><br> -A horseshoe electro-magnet with polarized core. It is made by mounting<br> -two bobbins of insulated wire on the ends of a permanent horseshoe<br> -magnet. It was devised for use in Hughes' printing telegraph, where very<br> -quick action is required. The contact lasts only .053 second, 185<br> -letters being transmitted per minute.<br> -<br> -<br> -<img style="width: 398px; height: 479px;" alt="" - src="images/291F197.jpg"><br> -Fig. 197 HUGHES' ELECTRO-MAGNET.<br> -<br> -<br> -<img style="width: 555px; height: 761px;" alt="" - src="images/291F198.jpg"><br> -Fig. 198. HUGHES' INDUCTION BALANCE.<br> -<br> -<br> -<span style="font-weight: bold;">Hughes' Induction Balance.</span><br> -An apparatus for determining the presence of a concealed mass of metal.<br> -The apparatus is variously connected. The cut shows a representative<br> -form; a and a' are two primary coils, each consisting of 100 meters (328<br> -feet) of No. 32 silk covered copper wire (0.009 inch diameter) wound on<br> -a boxwood spool ten inches in depth; b and b' are secondary coils. All<br> -coils are supposed to be alike. The primary coils are joined in series<br> -with a battery of three or four Daniell cells. A microphone m is<br> -included in the same circuit. The secondary coils are joined in series<br> -with a telephone and in opposition with each other. The clock is used to<br> -produce a sound affecting the microphone. If all is exactly balanced<br> -there will be no sound produced in the telephone. This balance is<br> -brought about by slightly varying the distance of one of the secondaries<br> -from the primary, until there is no sound in the telephone. If now a<br> -piece of metal is placed within either of the coils, it disturbs the<br> -balance and the telephone sounds.<br> -<br> -<br> -292 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -To measure the forces acting a sonometer or audiometer is used. This is<br> -shown in the upper part of the cut. Two fixed coils, c and e are mounted<br> -at the ends of a graduated bar. A movable coil d is connected in the<br> -telephone circuit; c and e by a switch can be connected with the battery<br> -and microphone circuit, leaving out the induction balance coils. The<br> -ends of the coils c and e, facing each other are of the same polarity.<br> -If these coils, c and e, were equal in all respects, no sound would be<br> -produced when d was midway between them. But they are so wound that the<br> -zero position for d is very near one of them, c.<br> -<br> -Assume that a balance has been obtained in the induction balance with<br> -the coil d at zero. No sound is heard whether the switch is moved to<br> -throw the current into one or the other circuit. A piece of metal placed<br> -in one of the balance coils will cause the production of a sound. The<br> -current is turned into the sonometer and d is moved until the same<br> -sound, as tested by rapid movements of the switch, is heard in both<br> -circuits. The displacement of d gives the value of the sound.<br> -<br> -A milligram of copper is enough to produce a loud sound. Two coins can<br> -be balanced against each other, and by rubbing one of them, or by<br> -breathing on one of them, the balance will be disturbed and a sound will<br> -be produced.<br> -<br> -Prof. Hughes has also dispensed with the audiometer. He has used a strip<br> -of zinc tapering from a width of 4 mm. (.16 inch) at one end to a sharp<br> -edge or point at the other. The piece to be tested being in place in one<br> -coil, the strip is moved across the face of the other until a balance is<br> -obtained.<br> -<br> -As possible uses the detection of counterfeit coins, the testing of<br> -metals for similarity of composition and the location of bullets in the<br> -body have been suggested. Care has to be taken that no masses of metal<br> -interfere. Thus in tests of the person of a wounded man, the presence of<br> -an iron truss, or of metallic bed springs may invalidate all<br> -conclusions.<br> -<br> -The same principle is carried out in an apparatus in which the parts are<br> -arranged like the members of a Wheatstone bridge. One pair of coils is<br> -used, which react on each other as primary and secondary coils. One of<br> -the coils is in series with a telephone in the member of the bridge<br> -corresponding to that containing the galvanometer of the Wheatstone<br> -bridge. The latter is more properly termed an induction bridge.<br> -<br> -Synonyms--Inductance Bridge--Inductance Balance--Induction Bridge.<br> -<br> -<br> -293 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Hydro-electric. adj.</span><br> -(a) A current produced by a voltaic couple or the couple itself is<br> -sometimes thus characterized or designated as a "hydro-electric current"<br> -or a "hydro-electric couple." It distinguishes them from<br> -thermo-electric.<br> -<br> -(b) Armstrong's steam boiler electric machine (see Hydroelectric<br> -Machine) is also termed a hydro-electric machine.<br> -<br> -<br> -<span style="font-weight: bold;">Hydro-electric Machine.</span><br> -An apparatus for generating high potential difference by the escape of<br> -steam through proper nozzles.<br> -<br> -It consists of a boiler mounted on four glass legs or otherwise<br> -insulated. An escape pipe terminates in a series of outlets so shaped as<br> -to impede the escape of the steam by forcing it out of the direct<br> -course. These jets are lined with hard wood. They are enclosed in or led<br> -through a box which is filled with cold water.<br> -<br> -<br> -<img style="width: 693px; height: 792px;" alt="" - src="images/293F199.jpg"><br> -Fig. 199. ARMSTRONG'S HYDRO-ELECTRIC MACHINE.<br> -<br> -<br> -This is to partly condense the steam so as to get it into the vesicular<br> -state, which is found essential to its action. Dry steam produces no<br> -excitation. If the boiler is fired and the steam is permitted to escape<br> -under the above conditions the vesicles presumably, or the "steam" is<br> -found to be electrified. A collecting comb held against the jet becomes<br> -charged and charges any connected surface.<br> -<br> -<br> -294 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The boiler in the above case is negatively and the escaping "steam" is<br> -positively charged. By changing the material of the linings of the jets,<br> -or by adding turpentine the sign of the electricity is reversed. If the<br> -water contains acid or salts no electricity is produced. The regular<br> -hydro-electric machine is due to Sir William Armstrong.<br> -<br> -Faraday obtained similar results with moist air currents.<br> -<br> -<br> -<span style="font-weight: bold;">Hydrogen.</span><br> -An element existing under all except the most extreme artificial<br> -conditions of pressure and cold as a gas. It is the lightest of known<br> -substances. Atomic weight, 1; molecular weight, 2; equivalent, 1;<br> -valency, 1; specific gravity, .0691-.0695. (Dumas & Boussingault.)<br> -<br> -It is a dielectric of about the same resistance as air. Its specific<br> -inductive capacity at atmospheric pressure is:<br> - .9997 (Baltzman) .9998 (Ayrton)<br> -<br> -Electro-chemical equivalent, .0105 milligram.<br> -The above is usually taken as correct. Other values are as follows:<br> -.010521 (Kohllrausch) .010415 (Mascart)<br> -<br> -The electro-chemical equivalent of any element is obtained by<br> -multiplying its equivalent by the electro-chemical equivalent of<br> -hydrogen. The value .0105 has been used throughout this book.<br> -<br> -<br> -<span style="font-weight: bold;">Hygrometer.</span><br> -An instrument for determining the moisture in the air. One form consists<br> -of a pair of thermometers, one of which has its bulb wrapped in cloth<br> -which is kept moist during the observation. The evaporation is more or<br> -less rapid according to the dryness or moisture of the air, and as the<br> -temperature varies with this evaporation the relative readings of the<br> -two thermometers give the basis for calculating the hygrometric state of<br> -the air. Another form determines the temperature at which dew is<br> -deposited on a silver surface, whence the calculations are made.<br> -<br> -<br> -<span style="font-weight: bold;">Hysteresis, Magnetic.</span><br> -A phenomenon of magnetization of iron. It may be attributed to a sort of<br> -internal or molecular friction, causing energy to be absorbed when iron<br> -is magnetized. Whenever therefore the polarity or direction of<br> -magnetization of a mass of iron is rapidly changed a considerable<br> -expenditure of energy is required. It is attributed to the work done in<br> -bringing the molecules into the position of polarity.<br> -<br> -<br> -295 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The electric energy lost by hysteresis may be reduced by vibrations or<br> -jarring imparted to the iron, thus virtually substituting mechanical for<br> -electrical work.<br> -<br> -On account of hysteresis the induced magnetization of a piece of iron or<br> -steel for fields of low intensity will depend on the manner in which the<br> -material has been already magnetized. Let the intensity of field<br> -increase, the magnetization increasing also; then lower the intensity;<br> -the substance tends to and does retain some of its magnetism. Then on<br> -again strengthening the field it will have something to build on, so<br> -that when it attains its former intensity the magnetization will exceed<br> -its former value. For a moderate value of intensity of field the<br> -magnetization can have many values within certain limits.<br> -<br> -Synonym--Hysteresis--Hysteresis, Static--Magnetic Friction.<br> -<br> -<br> -<span style="font-weight: bold;">Hysteresis, Viscous.</span><br> -The gradual increase or creeping up of magnetization when a magnetic<br> -force is applied with absolute steadiness to a piece of iron. It may<br> -last for half an hour or more and amount to several per cent. of the<br> -total magnetization. It is a true magnetic lag.<br> -</big></big><br> -<big><big><br> -295 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">I.</span><br> -A symbol sometimes used to indicate current intensity. Thus Ohm's law is<br> -often expressed I = E/R, meaning current intensity is equal to<br> -electro-motive force divided by resistance. C is the more general symbol<br> -for current intensity.<br> -<br> -<br> -<span style="font-weight: bold;">Ideoelectrics or Idioelectrics.</span><br> -Bodies which become electric by friction. This was the old definition,<br> -the term originating with Gilbert. It was based on a misconception, as<br> -insulation is all that is requisite for frictional electrification,<br> -metals being thus electrified if held by insulating handles. The term is<br> -virtually obsolete; as far as it means anything it means insulating<br> -substances such as scaling wax, sulphur, or glass.<br> -<br> -<br> -<span style="font-weight: bold;">Idle Coils.</span><br> -Coils in a dynamo, in which coils no electro-motive force is being<br> -generated. This may occur when, as a coil breaks connection with the<br> -commutator brush, it enters a region void of lines of magnetic force, or<br> -where the lines are tangential to the circle of the armature.<br> -<br> -<br> -<span style="font-weight: bold;">Idiostatic Method.</span><br> -A method of using the absolute or attracted disc electrometer. (See<br> -Electrometer, Absolute.) The suspended disc and guard ring are kept at<br> -the same potential, which is that of one of the points whose potential<br> -difference is to be determined; the lower fixed disc is connected to the<br> -other of the points whose potential difference is to be determined. Then<br> -we have the formula<br> -<br> -V = d * SquareRoot( 8 * PI * F ) / S<br> -<br> -in which d is the distance between the discs, V is the difference of<br> -potential of the two points, F the force of attraction between the discs<br> -in dynes, and S the area of the suspended disc. (See Heterostatic<br> -Method.)<br> -<br> -<br> -296 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Idle Poles.</span><br> -Poles of wire sealed into Crookes' tubes, not used for the discharge<br> -connections, but for experimental connections to test the effect of<br> -different excitation on the discharge.<br> -<br> -<br> -<span style="font-weight: bold;">Idle Wire.</span><br> -In a dynamo the wire which plays no part in generating electro-motive<br> -force. In a Gramme ring the wire on the inside of the ring is idle wire.<br> -<br> -<br> -<span style="font-weight: bold;">Igniter.</span><br> -In arc lamps with fixed parallel carbons of the Jablochkoff type (see<br> -Candle, Jablochkoff) a strip of carbon connects the ends of the carbons<br> -in the unused candle. This is necessary to start the current. Such strip<br> -is called an igniter. It burns away in a very short time when an arc<br> -forms producing the light, and lasts, if all goes well, until the candle<br> -burns down to its end. Without the igniter the current would not start<br> -and no arc would form.<br> -<br> -<br> -<span style="font-weight: bold;">I. H. P.</span><br> -Symbol for indicated horse-power.<br> -<br> -<br> -<span style="font-weight: bold;">Illuminating Power.</span><br> -The relative light given by any source compared with a standard light,<br> -and stated in terms of the same, as a burner giving an illuminating<br> -power of sixteen candles. For standards see Candle, Carcel--Methven<br> -Standard--Pentane Standard.<br> -<br> -<br> -<span style="font-weight: bold;">Illuminating Power, Spherical.</span><br> -The illuminating power of a lamp or source of light may vary in<br> -different directions, as in the case of a gas burner or incandescent<br> -lamp. The average illuminating power determined by photometric test or<br> -by calculation in all directions from the source of light is called the<br> -spherical illuminating power, or if stated in candles is called the<br> -spherical candle power.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Illumination, Unit of.</span><br> -An absolute standard of light received by a surface. Preece proposed as<br> -such the light received from a standard candle (see Candle, Standard) at<br> -a distance of 12.7 inches. The object of selecting this distance was to<br> -make it equal to the Carcel Standard (see Carcel), which is the light<br> -given by a Carcel lamp at a distance of one meter.<br> -<br> -From one-tenth to one-fiftieth this degree of illumination was found in<br> -gas-lighted streets by Preece, depending on the proximity of the gas<br> -lamps.<br> -<br> -<br> -<span style="font-weight: bold;">Image, Electric.</span><br> -An electrified point or system of points on one side of a surface which<br> -would produce on the other side of that surface the same electrical<br> -action which the actual electrification of that surface really does<br> -produce. (Maxwell.)<br> -<br> -The method of investigating the distribution of electricity by electric<br> -images is due to Sir William Thomson. The conception is purely a<br> -theoretical one, and is of mathematical value and interest.<br> -<br> -<br> -297 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Impedance.</span><br> -The ratio of any impressed electro-motive force to the current which it<br> -produces in a conductor. For steady currents it is only the resistance.<br> -For variable currents it may include besides resistance inductance and<br> -permittance. It is the sum of all factors opposing a current, both ohmic<br> -and spurious resistances. It is often determined and expressed as ohms.<br> -<br> -Synonym--Apparent Resistance--Virtual Resistance.<br> -<br> -<br> -<span style="font-weight: bold;">Impedance, Oscillatory.</span><br> -The counter-electro-motive force offered to an oscillatory discharge, as<br> -that of a Leyden jar. It varies with the frequency of the discharge<br> -current.<br> -<br> -Synonym--Impulsive Impedance.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Impressed Electro-motive Force.</span><br> -The electro-motive force expending itself in producing current induction<br> -in a neighboring circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Impulse.</span><br> -(a) An electro-magnetic impulse is the impulse produced upon the<br> -luminiferous ether by an oscillatory discharge or other varying type of<br> -current; the impulse is supposed to be identical, except as regards<br> -wave-length, with a light wave.<br> -<br> -(b) An electro-motive impulse is the electro-motive force which rises so<br> -high as to produce an impulsive or oscillatory discharge, such as that<br> -of a Leyden jar.<br> -<br> -<br> -<span style="font-weight: bold;">Incandescence, Electric.</span><br> -The heating or a conductor to red, or, more etymologically, to white<br> -heat by the passage of an electric current. The practical conditions are<br> -a high intensity of current and a low degree of conductance of the<br> -conductor relatively speaking.<br> -<br> -<br> -<span style="font-weight: bold;">Inclination Map.</span><br> -A map showing the locus of equal inclination or dips of the magnetic<br> -needle. The map shows a series of lines, each one of which follows the<br> -places at which the dip of the magnetic needle is identical. The map<br> -changes from year to year. (See Magnetic Elements.)<br> -<br> -<br> -<span style="font-weight: bold;">Independence of Currents in Parallel -Circuits.</span><br> -If a number of parallel circuits of comparatively high resistance are<br> -supplied by a single generator of comparatively low resistance, the<br> -current passed through each one will be almost the same whether a single<br> -one or all are connected. Under the conditions named the currents are<br> -practically independent of each other.<br> -<br> -[Transcriber's note: The current in each parallel branch depends on the<br> -resistance/impedance of that branch. Only if they all have the same<br> -</big></big><big><big>impedance</big></big><big><big> will the current -be the same.]<br> -<br> -<br> -<span style="font-weight: bold;">Indicating Bell.</span><br> -An electric bell arranged to drop a shutter or disclose in some other<br> -way a designating number or character when rung.<br> -<br> -<br> -298 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Indicator.</span><br> -(a) An apparatus for indicating the condition of a distant element, such<br> -as the water level in a reservoir, the temperature of a drying room or<br> -cold storage room or any other datum. They are of the most varied<br> -constructions.<br> -<br> -(b) The receiving instrument in a telegraph system is sometimes thus<br> -termed.<br> -<br> -<br> -<span style="font-weight: bold;">Indicator, Circuit.</span><br> -A galvanometer used to show when a circuit is active, and to give an<br> -approximate measurement of its strength. It is a less accurate and<br> -delicate form of instrument than the laboratory appliance.<br> -<br> -<br> -<span style="font-weight: bold;">Inductance.</span><br> -The property of a circuit in virtue of which it exercises induction and<br> -develops lines of force. It is defined variously. As clear and<br> -satisfactory a definition as any is the following, due to Sumpner and<br> -Fleming: Inductance is the ratio between the total induction through a<br> -circuit to the current producing it. "Thus taking a simple helix of five<br> -turns carrying a current of two units, and assuming that 1,000 lines of<br> -force passed through the central turn, of which owing to leakage only<br> -900 thread the next adjacent on each side, and again only 800 through<br> -the end turns, there would be 800 + 900 + 1000 + 900 + 800, or 4,400<br> -linkages of lines with the wire, and this being with 2 units of current,<br> -there would be 2,200 linkages with unit current, and consequently the<br> -self-inductance of the helix would be 2,200 centimetres." (Kennelly.)<br> -Inductance, as regards its dimensions is usually reduced to a length,<br> -hence the last word of the preceding quotation.<br> -<br> -The practical unit of inductance is termed the henry, from Prof. Joseph<br> -Henry; the secohm, or the quad or quadrant. The latter alludes to the<br> -quadrant of the earth, the value in length of the unit in question.<br> -<br> -[Transcriber's note: (L (di/dt) = V). A current changing at the rate of<br> -one ampere per second through a one henry inductance produces one volt.<br> -A sinusoidal current produces a voltage 90 degrees ahead of the current,<br> -a cosine (the derivative of sine is cosine). One volt across one henry<br> -causes the current to increase at one ampere per second.]<br> -<br> -<br> -<span style="font-weight: bold;">Induction, Coefficient of Self.</span><br> -The coefficient of self-induction of a circuit is the quantity of<br> -induction passing through it per unit current in it. If a given circuit<br> -is carrying a varying current it is producing a varying quantity of<br> -magnetic induction through itself. The quantity of induction through the<br> -circuit due to its current is generally proportional to its current. The<br> -quantity for unit current is the coefficient of self-induction.<br> -(Emtage.)<br> -<br> -<br> -<span style="font-weight: bold;">Induction, Cross.</span><br> -The induction of magnetic lines of force in a dynamo armature core by<br> -the current passing around such armature. These lines in a symmetrical<br> -two pole machine are at right angles to the lines of force which would<br> -normally extend across the space between the two magnet poles. The joint<br> -magnetizing effect of the field and of the cross induction produces a<br> -distorted field between the poles .<br> -<br> -Synonym--Cross-magnetizing Effect.<br> -<br> -<br> -299 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Induction, Electro-magnetic.</span><br> -The inter-reaction of electromagnetic lines of force with the production<br> -of currents thereby.<br> -<br> -A current passing through a conductor establishes around it a field of<br> -force representing a series of circular lines of force concentric with<br> -the axis of the conductor and perpendicular thereto. These lines of<br> -force have attributed to them, as a representative of their polarity,<br> -direction. This is of course purely conventional. If one is supposed to<br> -be looking at the end of a section of conductor, assuming a current be<br> -passing through it towards the observer, the lines of force will have a<br> -direction opposite to the motion of the hands of a watch. The idea of<br> -direction may be referred to a magnet. In it the lines of force are<br> -assumed to go from the north pole through the air or other surrounding<br> -dielectric to the south pole.<br> -<br> -Two parallel wires having currents passing through them in the same<br> -direction will attract each other. This is because the oppositely<br> -directed segments of lines of force between the conductors destroy each<br> -other, and the resultant of the two circles is an approximation to an<br> -ellipse. As lines of force tend to be as short as possible the<br> -conductors tend to approach each other to make the ellipse become of as<br> -small area as possible, in other words to become a circle.<br> -<br> -If on the other hand the currents in the conductors are in opposite<br> -directions the segments of the lines of force between them will have<br> -similar directions, will, as it were, crowd the intervening ether and<br> -the wires will be repelled.<br> -<br> -<br> -<img style="width: 638px; height: 291px;" alt="" - src="images/299F200.jpg"><br> -Fig. 200. ATTRACTION OF CONDUCTORS CARRYING SIMILAR CURRENTS.<br> -<br> -<br> -By Ampére's theory of magnetism, (see Magnetism, Ampére's -Theory of,) a<br> -magnet is assumed to be encircled by currents moving in the direction<br> -opposite to that of the hands of a watch as the observer faces the north<br> -pole. A magnet near a wire tends to place the Ampérian currents -parallel<br> -to the wire, and so that the portion of the Ampérian currents -nearest<br> -thereto will correspond in direction with the current in the wire.<br> -<br> -<br> -300 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -This is the principle of the galvanometer. A number of methods of<br> -memoria technica have been proposed to remember it by.<br> -<br> -Thus if we imagine a person swimming with the current and always facing<br> -the axis of the conductor, a magnetic needle held where the person is<br> -supposed to be will have its north pole deflected to the right hand of<br> -the person.<br> -<br> -<br> -<img style="width: 639px; height: 288px;" alt="" - src="images/300F201.jpg"><br> -Fig. 201. REPULSION OF CONDUCTORS <br> -CARRYING OPPOSITE CURRENTS.<br> -<br> -<br> -Again if we think of a corkscrew, which as it is turned screws itself<br> -along with the current, the motion of the handle shows the direction of<br> -the lines of force and the direction in which the north pole of a needle<br> -is deflected. This much is perhaps more properly electro-dynamics, but<br> -is necessary as a basis for the expression of induction.<br> -<br> -If a current is varied in intensity in one conductor it will induce a<br> -temporary current in another conductor, part of which is parallel to the<br> -inducing current and which conductor is closed so as to form a circuit.<br> -If the inducing current is decreased the induced current in the near and<br> -parallel portion of the other circuit will be of identical direction; if<br> -increased the induced current will be of opposite direction.<br> -<br> -This is easiest figured by thinking of the lines of force surrounding<br> -the inducing conductor. If the current is decreased these can be<br> -imagined as receiving a twist or turn contrary to their normal<br> -direction, as thereby establishing a turn or twist in the ether<br> -surrounding the other wire corresponding in direction with the direction<br> -of the original lines of force, or what is the same thing, opposite in<br> -direction to the original twist. But we may assume that the<br> -establishment of such a disturbance causes a current, which must be<br> -governed in direction with the requirements of the new lines of force.<br> -<br> -The same reasoning applies to the opposite case.<br> -<br> -<br> -301 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The general statement of a variable current acting on a neighboring<br> -circuit also applies to the approach or recession of an unvarying<br> -current, and to the cutting of lines of force by a conductor at right<br> -angles thereto. For it is evident that the case of a varying current is<br> -the case of a varying number of lines of force cutting or being cut by<br> -the neighboring conductor. As lines of force always imply a current,<br> -they always imply a direction of such current. The cutting of any lines<br> -of force by a closed conductor always implies a change of position with<br> -reference to all portions of such conductor and to the current and<br> -consequently an induced current or currents in one or the other<br> -direction in the moving conductor.<br> -<br> -As the inducing of a current represents energy abstracted from that of<br> -the inducing circuit, the direction of the induced current is determined<br> -by (Lenz's Law) the rule that the new current will increase already<br> -existing resistances or develop new ones to the disturbance of the<br> -inducing field.<br> -<br> -In saying that a conductor cutting lines of force at right angles to<br> -itself has a current induced in it, it must be understood that if not at<br> -right angles the right angle component of the direction of the wire acts<br> -in generating the current. The case resolves itself into the number of<br> -lines of force cut at any angle by the moving wire.<br> -<br> -The lines of force may be produced by a magnet, permanent or electro.<br> -This introduces no new element. The magnet may be referred, as regards<br> -direction of its lines of force, to its encircling currents, actual or<br> -Ampérian, and the application of the laws just cited will cover -all<br> -cases.<br> -<br> -<br> -<span style="font-weight: bold;">Induction, Coefficient of Mutual.</span><br> -The coefficient of mutual induction of two circuits is the quantity of<br> -magnetic induction passing through either of them per unit current in<br> -the other. (Emtage.) It is also defined as the work which must be done<br> -on either circuit, against the action of unit current in each, to take<br> -it away from its given position to an infinite distance from the other;<br> -and also as the work which would be done by either circuit on the other<br> -in consequence of unit current in each, as the other moves from an<br> -infinite distance to its given position with respect to the other<br> -conductor. It depends on the form, size, and relative position of the<br> -two circuits; and on the magnetic susceptibilities of neighboring<br> -substances.<br> -<br> -The ether surrounding two circuits of intensity i' and i" must possess<br> -energy, expressible (Maxwell) as 1/2 L i2 + M i i + 1/2 N i12. It can be<br> -shown that M i i1 in any given position of the two circuits is<br> -numerically equal (1) to the mutual potential energy of the two circuits<br> -(2) to the number of lines of induction, which being due to A, pass from<br> -A through B, or equally being due to B, pass from B through A, and M is<br> -styled the coefficient of mutual induction. (Daniell.)<br> -<br> -<br> -302 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Induction, Electrostatic.</span><br> -An electrostatic charge has always an opposite and bound charge. This<br> -may be so distributed as not to be distinguishable, in which case the<br> -charge is termed, incorrectly but conventionally, a free charge. But<br> -when a charge is produced an opposite and equal one always is formed,<br> -which is the bound charge. The region between the two charges and<br> -permeated by their lines of force, often curving out so as to embrace a<br> -volume of cross-sectional area larger than the mean facing area of the<br> -excited surfaces, is an electrostatic field of force. The establishing<br> -of an electrostatic field, and the production of a bound charge are<br> -electrostatic induction.<br> -<br> -An insulated conductor brought into such a field suffers a<br> -redistribution of its electricity, or undergoes electrostatic induction.<br> -The parts nearest respectively, the two loci of the original and the<br> -bound charges, are excited oppositely to such charges. The conductor<br> -presents two new bound charges, one referred to the original charge, the<br> -other to the first bound charge.<br> -<br> -<br> -<span style="font-weight: bold;">Induction, Horizontal.</span><br> -In an iron or steel ship the induction exercised upon the compass needle<br> -by the horizontal members of the structure, such as deck-beams, when<br> -they are polarized by the earth's magnetic induction. This induction<br> -disappears four times in swinging a ship through a circle; deviation due<br> -to it is termed quadrantal deviation. (See Deviation, Quadrantal.)<br> -<br> -<br> -<span style="font-weight: bold;">Induction, Lateral.</span><br> -A term formerly used to express the phenomenon of the alternative<br> -discharge of a Leyden jar or other oscillatory discharge of electricity.<br> -(See Discharge, Alternative.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Induction, Magnetic.</span><br> -The magnetization of iron or other paramagnetic substance by a magnetic<br> -field.<br> -<br> -On account of its permeability or multiplying power for lines of force,<br> -a paramagnetic body always concentrates lines of force in itself if<br> -placed in a magnetic field, and hence becomes for the time being a<br> -magnet, or is said to be polarized.<br> -<br> -As the tendency of lines of force is to follow the most permeable path,<br> -a paramagnetic bar places itself lengthwise or parallel with the<br> -prevailing direction of the lines of force so as to carry them as far on<br> -their way as possible. Every other position of the bar is one of<br> -unstable equilibrium or of no equilibrium. The end of the bar where the<br> -lines of force enter (see Lines of Force) is a south pole and is<br> -attracted towards the north pole of the magnet.<br> -<br> -The production of magnetic poles under these conditions in the bar is<br> -shown by throwing iron filings upon it. They adhere to both ends but not<br> -to the middle.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Induction, Mutual, Electro-magnetic.</span><br> -The induction due to two electric currents reacting on each other.<br> -<br> -<br> -303 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Induction, Mutual, Electrostatic.</span><br> -A charged body always induces a charge upon any other body near it; and<br> -the same charge in the second body will induce the other charge in the<br> -first body if the latter is unexcited. In other words the second body's<br> -induction from the first is the measure of the charge the second would<br> -require to induce in the first its own (the second's) induced charge.<br> -This is the law of mutual electrostatic induction.<br> -<br> -<br> -<span style="font-weight: bold;">Induction, Open Circuit.</span><br> -Inductive effects produced in open circuits. By oscillatory discharges a<br> -discharge can be produced across a break in a circuit otherwise<br> -complete. The requirements for its production involve a correspondence<br> -or relation of its dimensions to the inducing discharge. The whole is<br> -analogous to the phenomena of sound resonators and sympathetic<br> -vibrations. Synonym--Oscillatory induction.<br> -<br> -<br> -<span style="font-weight: bold;">Induction, Self-.</span><br> -(a) A phenomenon of electric currents analogous to the inertia of<br> -matter. Just as water which fills a pipe would resist a sudden change in<br> -its rate of motion, whether to start from rest, to cease or decrease its<br> -motion, so an electric current requires an appreciable time to start and<br> -stop. It is produced most strongly in a coiled conductor, especially if<br> -a core of iron is contained within it.<br> -<br> -As in the case of two parallel wires, one bearing currents which vary,<br> -momentary currents are induced in the other wire, so in a single<br> -conductor a species of inertia is found which retards and prolongs the<br> -current. If a single conductor is twisted into a helix or corresponding<br> -shape, its separate turns react one on the other in accordance with the<br> -general principles of electromagnetic induction. (See Induction,<br> -Electro-magnetic.) Thus when a current is suddenly formed the coils<br> -acting upon each other retard for an instant its passage, producing the<br> -effect of a reverse induced current or extra current opposing the<br> -principal current. Of course no extra current is perceptible, but only<br> -the diminution. When the current is passing regularly and the current is<br> -broken, the corresponding action prolongs the current or rather<br> -intensifies it for an instant, producing the true extra current. This is<br> -current self-induction.<br> -<br> -[Transcriber's note: See inductance.]<br> -<br> -Synonyms--Electric Inertia--Electro-dynamic Capacity.<br> -<br> -(b) A permanent magnet is said to tend to repel its own magnetism, and<br> -thus to weaken itself; the tendency is due to magnetic self-induction.<br> -<br> -<br> -<span style="font-weight: bold;">Induction Sheath.</span><br> -In the brush dynamo a thin sheet of copper surrounding the magnet cores<br> -with edges soldered together. The winding is outside of it. Its object<br> -is to absorb extra currents set up by variations in magnetic intensity<br> -in the cores. These currents otherwise would circulate in the cores.<br> -<br> -<br> -304 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Induction, Unit of Self-.</span><br> -The unit of self-induction is the same as that of induction in general.<br> -It is the henry, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Induction, Unipolar.</span><br> -Induction produced in a conductor which continuously cuts the lines of<br> -force issuing from one pole of a magnet. As the lines of force are<br> -always cut in the same sense a continuous and constant direction current<br> -is produced.<br> -<br> -<br> -<span style="font-weight: bold;">Induction, Vertical.</span><br> -In an iron or steel ship the induction or attraction exercised in the<br> -compass by vertical elements of the structure. Such vertical masses of<br> -iron in the northern hemisphere would have their upper ends polarized as<br> -south poles, and would affect the magnet as soon as the vessel swung out<br> -of the magnetic meridian. Thus this induction disappears twice in<br> -swinging a ship through a complete circle; deviation due to it is termed<br> -semi-circular deviation. (See Deviation, Semi-circular.)<br> -<br> -<br> -<img style="width: 620px; height: 534px;" alt="" - src="images/304F202.jpg"><br> -Fig. 202. INDUCTOR DYNAMO.<br> -<br> -<br> -<span style="font-weight: bold;">Inductophone.</span><br> -A method of train telegraphy. The train carries a circuit including a<br> -coil, and messages are picked up by it from coils along the line into<br> -which an alternating current is passed. A telephone is used as a<br> -receiver in place of a sounder or relay. The invention, never<br> -practically used, is due to Willoughby Smith.<br> -<br> -<br> -305 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Inductor.</span><br> -(a) In a current generator a mass of iron, generally laminated, which is<br> -moved past a magnet pole to increase the number of lines of force<br> -issuing therefrom. It is used in inductor dynamos. (See Dynamo<br> -Inductor.) In the cut Fig. 202, of an inductor dynamo i, i, are the<br> -laminated inductors.<br> -<br> -(b) In influence machines the paper or tinfoil armatures on which the<br> -electrification is induced.<br> -<br> -<br> -<span style="font-weight: bold;">Inertia.</span><br> -A force in virtue of which every body persists in its state of motion or<br> -rest except so far as it is acted on by some force.<br> -<br> -<br> -<span style="font-weight: bold;">Inertia, Electro-magnetic.</span><br> -This term is sometimes applied to the phenomena of self-induction, or<br> -rather to the cause of these phenomena.<br> -<br> -<br> -<span style="font-weight: bold;">Infinity Plug.</span><br> -A plug in a resistance box, which on being pulled out of its seat opens<br> -the circuit or makes it of infinite resistance. The plug seats itself<br> -between two brass plates which are not connected with each other in any<br> -way. The other plates are connected by resistance coils of varying<br> -resistance.<br> -<br> -<br> -<span style="font-weight: bold;">Influence, Electric.</span><br> -Electric induction, which may be either electrostatic, current, or<br> -electro-magnetic.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Insolation, Electric.</span><br> -Exposure to powerful arc-light produces effects resembling those of<br> -sun-stroke. The above term or the term "electric sun-stroke" has been<br> -applied to them.<br> -<br> -[Transcriber's note: Operators of arc welders are prone to skin cancer<br> -from ultra violet rays if not properly protected.]<br> -<br> -<br> -<span style="font-weight: bold;">Installation.</span><br> -The entire apparatus, buildings and appurtenances of a technical or<br> -manufacturing establishment. An electric light installation, for<br> -instance, would include the generating plant, any special buildings, the<br> -mains and lamps.<br> -<br> -<br> -<span style="font-weight: bold;">Insulating Stool.</span><br> -A support for a person, used in experiments with static generators. It<br> -has ordinarily a wooden top and glass legs. It separates one standing on<br> -it from the earth and enables his surface to receive an electrostatic<br> -charge. This tends to make his hair stand on end, and anyone on the<br> -floor who touches him will receive a shock.<br> -<br> -<br> -<span style="font-weight: bold;">Insulating Tape.</span><br> -Prepared tape used in covering the ends of wire where stripped for<br> -making joints. After the stripped ends of two pieces are twisted<br> -together, and if necessary soldered and carefully cleaned of soldering<br> -fluid, they may be insulated by being wound with insulating tape.<br> -<br> -The tape is variously prepared. It may be common cotton or other tape<br> -saturated with any insulating compound, or may be a strip of gutta<br> -percha or of some flexible cement-like composition.<br> -<br> -<br> -306 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Insulating Varnish.</span><br> -Varnish used to coat the surface of glass electrical apparatus, to<br> -prevent the deposition of hygrometric moisture, and also in the<br> -construction of magnetizing and induction coils and the like. Shellac<br> -dissolved in alcohol is much used. Gum copal dissolved in ether is<br> -another. A solution of sealing wax in alcohol is also used. If applied<br> -in quantities these may need baking to bring about the last drying. (See<br> -Shellac Varnish.)<br> -<br> -<br> -<span style="font-weight: bold;">Insulator.</span><br> -(a) Any insulating substance.<br> -<br> -(b) A telegraph or line insulator for telegraph wires. (See Insulator,<br> -Line or Telegraph.)<br> -<br> -Synonyms--Dielectric--Non-conductor.<br> -<br> -<br> -<span style="font-weight: bold;">Insulator Cap.</span><br> -A covering or hood, generally of iron, placed over an insulator to<br> -protect it from injury by fracture with stones or missiles.<br> -<br> -<br> -<span style="font-weight: bold;">Insulator, Fluid.</span><br> -(a) For very high potentials, as in induction coils or alternating<br> -circuits, fluid insulators, such as petroleum or resin oil, have been<br> -used. Their principal merit is that if a discharge does take place<br> -through them the opening at once closes, so that they are self-healing.<br> -<br> -(b) Also a form of telegraph or line insulator in which the lower rim is<br> -turned up and inwards, so as to form an annular cup which is filled with<br> -oil.<br> -<br> -<br> -<span style="font-weight: bold;">Insulator, Line or Telegraph.</span><br> -A support often in the shape of a collar or cap, for a telegraph or<br> -other wire, made of insulating material. Glass is generally used in the<br> -United States, porcelain is adopted for special cases; pottery or stone<br> -ware insulators have been used a great deal in other countries.<br> -Sometimes the insulator is an iron hook set into a glass screw, which is<br> -inserted into a hole in a telegraph bracket. Sometimes a hook is caused<br> -to depend from the interior of an inverted cup and the space between the<br> -shank of the hook and cup is filled with paraffine run in while melted.<br> -<br> -Insulators are tested by measuring their resistance while immersed in a<br> -vessel of water.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Intensity. Strength.</span><br> -The intensity of a current or its amperage or strength; the intensity or<br> -strength of a magnetic field or its magnetic density; the intensity or<br> -strength of a light are examples of its use. In the case of dynamic<br> -electricity it must be distinguished from tension. The latter<br> -corresponds to potential difference or voltage and is not an attribute<br> -of current; intensity has no reference to potential and is a<br> -characteristic of current.<br> -<br> -<br> -<span style="font-weight: bold;">Intensity of a Magnetic Field.</span><br> -The intensity of a magnetic field at any point is measured by the force<br> -with which it acts on a unit magnet pole placed at that point. Hence<br> -unit intensity of field is that intensity of field which acts on a unit<br> -pole with a force of one dyne. (S. P. Thomson.) (See Magnetic Lines of<br> -Force.)<br> -<br> -<br> -307 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Intercrossing.</span><br> -Crossing a pair of conductors of a metallic circuit from side to side to<br> -avoid induction from outside sources.<br> -<br> -<br> -<span style="font-weight: bold;">Intermittent.</span><br> -Acting at intervals, as an intermittent contact, earth, or grounding of<br> -a telegraph wire.<br> -<br> -<br> -<span style="font-weight: bold;">Interpolar Conductor.</span><br> -A conductor connecting the two poles of a battery or current generator;<br> -the external circuit in a galvanic circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Interpolation.</span><br> -A process used in getting a closer approximation to the truth from two<br> -varying observations, as of a galvanometer. The process varies for<br> -different cases, but amounts to determining an average or deducing a<br> -proportional reading from the discrepant observed ones.<br> -<br> -<br> -<span style="font-weight: bold;">Interrupter.</span><br> -A circuit breaker. It may be operated by hand or be automatic. (See<br> -Circuit Breaker--Circuit Breaker, Automatic--and others.)<br> -<br> -<br> -<span style="font-weight: bold;">Interrupter, Electro-magnetic, for a -Tuning Fork.</span><br> -An apparatus for interrupting a current which passes through an<br> -electromagnet near and facing one of the limbs of a tuning fork. The<br> -circuit is made and broken by the vibrations of another tuning fork<br> -through which the current passes. The second one is thus made to<br> -vibrate, although it may be very far off and may not be in exact unison<br> -with the first. The first tuning fork has a contact point on one of its<br> -limbs, to close the circuit; it may be one which dips into a mercury<br> -cup.<br> -<br> -<br> -<span style="font-weight: bold;">Intrapolar Region.</span><br> -A term in medical electricity, denoting the part of a nerve through<br> -which a current is passing.<br> -<br> -<br> -<span style="font-weight: bold;">Ions.</span><br> -The products of decomposition produced in any given electrolysis are<br> -termed ions, the one which appears at the anode or negative electrode is<br> -the anion. The electrode connected to the carbon or copper plate of a<br> -wet battery is an anode. Thus in the electrolysis of water oxygen is the<br> -anion and hydrogen is termed the kation. In this case both anion and<br> -kation are elements. In the decomposition of copper sulphate the anion<br> -is properly speaking sulphion (S O4), a radical, and the kation is<br> -copper, an element. Electro-negative elements or radicals are anions,<br> -such as oxygen, sulphion, etc., while electro-positive ones are kations,<br> -such as potassium. Again one substance may be an anion referred to one<br> -below it and a kation referred to one above it, in the electro-chemical<br> -series, q. v. Anion means the ion which goes to the anode or positive<br> -electrode; kation, the ion which goes to the kathode or negative<br> -electrode.<br> -<br> -[Transcriber's note: An ion is an atom or molecule that has lost or<br> -gained one or more valence electrons, giving it a positive or negative<br> -electrical charge. A negatively charged ion, with more electrons than<br> -protons in its nuclei, is an anion. A positively charged ion, with fewer<br> -electrons than protons, is a cation. The electron was discovered five<br> -years after this publication.]<br> -<br> -<br> -308 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Iron.</span><br> -A metal; one of the elements; symbol, Fe; atomic weight, 56;<br> -equivalent, 28 and 14, ; valency, 4 and 2.<br> -It is a conductor of electricity. The following data are at<br> -0° C. 32° F., with annealed metal.<br> -<br> -<small><span style="font-family: monospace;"> Specific -Resistance, 9.716 microhms.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Relative -Resistance. 6.460</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Resistance of a wire,</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> (a) 1 foot long weighing 1 -grain, -1.085 ohms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> (b) 1 foot long 1/1000 -inch thick, -58.45 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> (c) 1 meter long weighing -1 -gram, .7570 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> (d) 1 meter long, 1 -millimeter thick, -.1237 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Percentage increase in resistance -per degree C. (1.8° F.)</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> at about 20° C. -(68°F.), about 0.5 per cent.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Resistance of a 1 inch -cube, 3.825 microhms.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Electro-chemical equivalent -(Hydrogen = .0105), .147 and .294</span></small><br> -<br> -<br> -<span style="font-weight: bold;">Iron, Electrolytic.</span><br> -Iron deposited by electrolytic action. Various baths are employed for<br> -its formation. (See Steeling.) It has very low coercive power, only<br> -seven to ten times that of nickel.<br> -<br> -<br> -<span style="font-weight: bold;">Ironwork Fault of a Dynamo.</span><br> -A short circuiting of a dynamo by, or any connection of its coils with,<br> -the iron magnet cores or other iron parts.<br> -<br> -<br> -<span style="font-weight: bold;">Isochronism.</span><br> -Equality of periodic time; as of the times of successive beats of a<br> -tuning fork, or of the times of oscillations of a pendulum.<br> -<br> -<br> -<span style="font-weight: bold;">Isoclinic Lines.</span><br> -The lines denoting the locus of sets of equal dips or inclinations of<br> -the magnetic needle upon the earth's surface, the magnetic parallels, q.<br> -v. These lines are very irregular. (See Magnetic Elements.)<br> -<br> -<br> -<span style="font-weight: bold;">Isoclinic Map.</span><br> -A map showing the position of isoclinic lines.<br> -<br> -<br> -<span style="font-weight: bold;">Isodynamic Lines.</span><br> -Lines marking the locus of places of equal magnetic intensity on the<br> -earth's surface. (See Magnetic Elements, Poles of Intensity.)<br> -<br> -<br> -<span style="font-weight: bold;">Isodynamic Map.</span><br> -A map showing the position of isodynamic lines. (See Poles of<br> -Intensity.)<br> -<br> -<span style="font-weight: bold;">Isogonic Lines.</span><br> -Lines on a map marking the locus of or connecting those points where the<br> -declination or variation of the magnetic needle is the same. (See<br> -Magnetic Elements--Declination of Magnetic Needle.)<br> -<br> -Synonyms--Isogonal Lines--Halleyan Lines.<br> -<br> -<br> -309 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Isogonic Map.</span><br> -A map showing the isogonic lines. On such a map each line is<br> -characterized and marked with the degrees and direction of variation of<br> -the compass upon itself.<br> -<br> -Synonym--Declination Map.<br> -<br> -<img style="width: 372px; height: 327px;" alt="" - src="images/309_Declination_1590_1990.gif"><br> -[Transcriber's note: The file Earth_Declination_1590_1990.gif provided<br> -by the U.S. Geological Survey (http://www.usgs.gov) is an animation of<br> -the declination of the entire earth.]<br> -<br> -<br> -<span style="font-weight: bold;">Isolated Plant, Distribution or Supply.</span><br> -The system of supplying electric energy by independent generating<br> -systems, dynamo or battery, for each house, factory or other place, as<br> -contra-distinguished from Central Station Distribution or Supply.<br> -<br> -<br> -<span style="font-weight: bold;">Isotropic.<br> -<img style="width: 633px; height: 42px;" alt="" src="images/309Pic.jpg"><br> -</span>(Greek, equal in manner.)<br> -<br> -Having equal properties in all directions; the reverse of anisotropic,<br> -q. v. Thus a homogeneous mass of copper or silver has the same specific<br> -resistance in all directions and is an isotropic conductor. Glass has<br> -the same specific inductive capacity in all directions and is an<br> -isotropic medium or dielectric. The same applies to magnetism. Iron is<br> -an isotropic paramagnetic substance. (See Anisotropic.) The term applies<br> -to other branches of physics also.<br> -<br> -<br> -<span style="font-weight: bold;">I. W. G.</span><br> -Contraction for Indian Wire Gauge--the gauge adopted in British India.<br> -</big></big><big><big><br> -<span style="text-decoration: underline;"></span></big></big><big><big><br> -309 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">J.</span><br> -Symbol for the unit joule, the unit of electric energy.<br> -<br> -<br> -<span style="font-weight: bold;">Jacobi's Law.</span><br> -A law of electric motors. It states that the maximum work of a motor is<br> -performed when the counter-electromotive force is equal to one-half the<br> -electro-motive force expended on the motor.<br> -<br> -<br> -<span style="font-weight: bold;">Jewelry.</span><br> -Small incandescent lamps are sometimes mounted as articles of jewelry in<br> -scarf-pins or in the hair. They may be supplied with current from<br> -storage or from portable batteries carried on the person.<br> -<br> -<br> -<span style="font-weight: bold;">Joint, American Twist.</span><br> -A joint for connecting telegraph wires, especially aerial lines. Its<br> -construction is shown in the cut. The end of each wire is closely wound<br> -around the straight portion of the other wire for a few turns.<br> -<br> -<br> -<img style="width: 672px; height: 184px;" alt="" - src="images/309F203.jpg"><br> -Fig. 203. AMERICAN TWIST JOINT.<br> -<br> -<br> -310 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Joint, Britannia.</span><br> -A joint for uniting the ends of telegraph and electric wires. The ends<br> -of the wires are scraped clean and laid alongside each other for two<br> -inches, the extreme ends being bent up at about right angles to the<br> -wire. A thin wire is wound four or five times around one of the wires,<br> -back of the joint, the winding is then continued over the lapped<br> -portion, and a few more turns are taken around the other single wire.<br> -The whole is then soldered.<br> -<br> -<br> -<img style="width: 680px; height: 121px;" alt="" - src="images/310F204.jpg"><br> -Fig. 204. BRITANNIA JOINT.<br> -<br> -<br> -<span style="font-weight: bold;">Joint, Butt.</span><br> -A joint in belting or in wire in which the ends to be joined are cut off<br> -square across, placed in contact and secured. It ensures even running<br> -when used in belting. Any irregularity in thickness of a belt affects<br> -the speed of the driven pulley. As dynamos are generally driven by<br> -belts, and it is important to drive them at an even speed to prevent<br> -variations in the electro-motive force, butt joints should be used on<br> -belting for them, unless a very perfect lap joint is made, which does<br> -not affect either the thickness or the stiffness of the belt.<br> -<br> -When a butt joint is used in wire a sleeve may be used to receive the<br> -abutting ends, which may be secured therein by soldering. This species<br> -of joint has been used on lightning rods and may more properly be termed<br> -a sleeve joint.<br> -<br> -<br> -<span style="font-weight: bold;">Joint, Lap.</span><br> -(a) In belting a joint in which the ends are overlapped, and riveted or<br> -otherwise secured in place. If made without reducing the thickness of<br> -the ends it is a bad joint for electrical work, as it prevents even<br> -running of machinery to which it is applied. Hence dynamo belts should<br> -be joined by butt joints, or if by lap joints the ends should be shaved<br> -off so that when joined and riveted, there will be no variation in the<br> -thickness of the belt.<br> -<br> -(b) In wire lap joints are made by overlapping the ends of the wire and<br> -soldering or otherwise securing. The Britannia joint (see Joint,<br> -Britannia,) may be considered a lap-joint.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Joint, Marriage.</span><br> -A joint for stranded conductors used for Galende's cables. It is made<br> -somewhat like a sailor's long splice. Each one of the strands is wound<br> -separately into the place whence the opposite strand is unwound and the<br> -ends are cut off so as to abutt. In this way all are smoothly laid in<br> -place and soldering is next applied.<br> -<br> -<br> -<img style="width: 685px; height: 118px;" alt="" - src="images/310F205.jpg"><br> -Fig. 205. MARRIAGE JOINT.<br> -<br> -<br> -311 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Joint, Sleeve.</span><br> -A joint in electric conductors, in which the ends of the wires are<br> -inserted into and secured in a metallic sleeve or tube, whose internal<br> -diameter is just sufficient to admit them.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Joint, Splayed.</span><br> -The method of joining the ends of stranded conductors. The insulating<br> -covering is removed, the wires are opened out, and the center wire,<br> -heart or core of the cable is cut off short. The two ends are brought<br> -together, the opened out wires are interlaced or crotched like the<br> -fingers of the two hands, and the ends are wound around the body of the<br> -cable in opposite directions. The joint is trimmed and well soldered.<br> -Tinned wire with rosin flux for the soldering is to be recommended.<br> -Insulating material is finally applied by hand, with heat if necessary.<br> -<br> -<br> -<span style="font-weight: bold;">Joints in Belts.</span><br> -Belt-joints for electric plants where the belts drive dynamos should be<br> -made with special care. The least inequality affects the electro-motive<br> -force. Butt joints are, generally speaking, the best, where the ends of<br> -the belt are placed in contact and laced. Lap-joints are made by<br> -overlapping the belt, and unless the belt is carefully tapered so as to<br> -preserve uniform strength, the speed of the dynamo will vary and also<br> -the electromotive force.<br> -<br> -<br> -<span style="font-weight: bold;">Joulad.</span><br> -A name proposed to be substituted for "joule," q. v. It has not been<br> -adopted.<br> -<br> -<br> -<span style="font-weight: bold;">Joule.</span><br> -This term has been applied to several units.<br> -<br> -(a) The practical C. G. S. unit of electric energy and work--the<br> -volt-coulomb. It is equal to 1E7 ergs--0.73734 foot pound.--.00134 horse<br> -power seconds. A volt-ampere represents one joule per second.<br> -<br> -(b) It has also been used as the name of the gram-degree C. thermal<br> -unit--the small calorie.<br> -<br> -Synonym--Joulad.<br> -<br> -<br> -<span style="font-weight: bold;">Joule Effect.</span><br> -The heating effect of a current passing through a conductor. It varies<br> -with the product of the resistance by the square of the current, or with<br> -(C^2)*R.<br> -<br> -<br> -<span style="font-weight: bold;">Joule's Equivalent.</span><br> -The mechanical equivalent of heat, which if stated in foot-pounds per<br> -pound-degree F. units, is 772 (772.55). (See Equivalents.)<br> -<br> -<br> -<span style="font-weight: bold;">Junction Box.</span><br> -In underground distribution systems, an iron casing or box in which the<br> -feeders and mains are joined, and where other junctions are made.<br> -<br> -Synonym--Fishing Box.<br> -</big></big><br> -<big><big><span style="text-decoration: underline;"></span></big></big><big><big><br> -311 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">K.</span><br> -The symbol for electrostatic capacity.<br> -<br> -<br> -<span style="font-weight: bold;">Kaolin.</span><br> -A product of decomposition of feldspar, consisting approximately of<br> -silica, 45, alumina, 40, water, 15. It was used in electric candles of<br> -the Jablochkoff type as a constituent of the insulating layer or<br> -colombin. Later it was abandoned for another substance, as it was found<br> -that it melted and acted as a conductor.<br> -<br> -<br> -312 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Kapp Line of Force.</span><br> -A line of force proposed by Kapp. It is equal to 6,000 C. G. S. lines of<br> -force, and the unit of area is the square inch. Unfortunately it has<br> -been adopted by many manufacturers, but its use should be discouraged,<br> -as it is a departure from the uniform system of units.<br> -<br> -One Kapp line per square inch = 930 C. G. S. lines per square<br> -centimeter.<br> -<br> -<br> -<span style="font-weight: bold;">Kathelectrotonus.</span><br> -A term used in medical electricity or electro-therapeutics to indicate<br> -the increased functional activity induced in a nerve by the proximity of<br> -the kathode of an active circuit which is completed through the nerve.<br> -The converse of anelectrotonus.<br> -<br> -<br> -<span style="font-weight: bold;">Kathode.</span><br> -The terminal of an electric circuit whence an electrolyzing current<br> -passes from a solution. It is the terminal connected to the zinc plate<br> -of a primary battery.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Kathodic Closure Contraction.</span><br> -A term in electro-therapeutics; the contractions near where the kathode<br> -of an active circuit is applied to the body, which are observed at the<br> -instant when the circuit is closed.<br> -<br> -<br> -<span style="font-weight: bold;">Kathodic Duration Contraction.</span><br> -A term in electro-therapeutics; the contraction near where the kathode<br> -of an active circuit is applied to the body for a period of time.<br> -<br> -<br> -<span style="font-weight: bold;">K. C. C.</span><br> -Abbreviation for Kathodic Closure Contraction, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">K. D. C.</span><br> -Abbreviation for Kathodic Duration Contraction, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Keeper.</span><br> -A bar of soft iron used to connect the opposite poles of a horseshoe<br> -magnet or the opposite poles of two bar magnets placed side by side. It<br> -is designed to prevent loss of magnetism. The armature of a horseshoe<br> -magnet is generally used as its keeper. For bar magnets a keeper is used<br> -for each end, the magnets being laid side by side, with their poles in<br> -opposite direction but not touching, and a keeper laid across at each<br> -end connecting the opposite poles.<br> -<br> -<br> -<span style="font-weight: bold;">Kerr Effect.</span><br> -The effect of an electrostatic field upon polarized light traversing a<br> -dielectric contained within the field. (See Electrostatic Refraction.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Kerr's Experiment.</span><br> -Polarized light reflected from the polished face of a magnet pole has<br> -its plane of polarization rotated; when it is reflected from the north<br> -pole the rotation is from left to right.<br> -<br> -<br> -313 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Key.</span><br> -A switch adapted for making and breaking contact easily when worked by<br> -hand, as a Morse telegraph key.<br> -<br> -<br> -<span style="font-weight: bold;">Key Board.</span><br> -A board or tablet on which keys or switches are mounted.<br> -<br> -<br> -<span style="font-weight: bold;">Key-board.</span><br> -(a) A switch board, q. v.<br> -<br> -(b) A set of lettered keys similar to those of a typewriter employed in<br> -some telegraph instruments. As each key is depressed it produces the<br> -contact or break requisite for the sending of the signal corresponding<br> -to the letter marked upon the key. The signal in printing telegraphs, on<br> -which such key-boards are used, is the reprinting of the letter at the<br> -distant end of the line.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Key, Bridge.</span><br> -A key for use with a Wheatstone Bridge, q.v. It is desirable to first<br> -send a current through the four arms of the bridge in using it for<br> -testing resistances and then through the galvanometer, because it takes<br> -a definite time for the current to reach its full strength. This is<br> -especially the case if the element being measured has high static<br> -capacity, as a long ocean cable. If the galvanometer connections were<br> -completed simultaneously with the bridge connections a momentary swing<br> -would be produced even if the arms bore the proper relation to each<br> -other. This would cause delay in the testing. A bridge key avoids this<br> -by first connecting the battery circuit through the arms of the bridge,<br> -and then as it is still further depressed the galvanometer circuit is<br> -completed.<br> -<br> -<br> -314 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 668px; height: 505px;" alt="" - src="images/313F206.jpg"><br> -Fig. 206. CHARGE AND DISCHARGE KEY<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Key, Charge and Discharge.</span><br> -A key for use in observing the discharge of a condenser immediately<br> -after removing the battery. In one typical form it has two contacts, one<br> -below and one above, and being a spring in itself is pressed up against<br> -the upper one. Connections are so made that when in its upper position<br> -it brings the two coatings of the condenser in circuit with the<br> -galvanometer. When depressed it does the same for a battery. In use it<br> -is depressed and suddenly released when the galvanometer receives the<br> -full charge, before there has been time for leakage. This is one method<br> -of connection illustrating its principle.<br> -<br> -In the cut L is the spring-key proper. S2, is the upper contact screw<br> -against which the spring normally presses. In this position the<br> -galvanometer G is in circuit with the opposite coatings of the condenser<br> -C. On depressing the contact S2, is broken and S1, is made. This brings<br> -the battery B in circuit with the condenser coatings. On releasing the<br> -key it springs up and the galvanometer receives the effect of the charge<br> -of the condenser as derived from the battery.<br> -<br> -<br> -<span style="font-weight: bold;">Key, Double Contact.</span><br> -A key arranged to close two distinct circuits, holding the first closed<br> -until the second is completed. It is used for Wheatstone bridge work.<br> -<br> -<br> -<span style="font-weight: bold;">Key, Double Tapper.</span><br> -A telegraph key giving contacts alternately for currents in opposite<br> -directions, used in needle telegraphy.<br> -<br> -<br> -<span style="font-weight: bold;">Key, Increment.</span><br> -A key for use in duplex and quadruplex telegraphy. Its action is to<br> -increase the line current, not merely to suddenly turn current into it.<br> -<br> -<br> -315 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 720px; height: 499px;" alt="" - src="images/314F207.jpg"><br> -Fig. 207. KEMPE'S DISCHARGE KEY.<br> -<br> -<br> -<span style="font-weight: bold;">Key, Kempe's Discharge.</span><br> -A key giving a charging, discharging and insulating connection, for<br> -static condenser work. Referring to the cut l is a lever or spring with<br> -upper discharging contact s, and lower charging contact s'. In use it is<br> -pressed down by the insulating handle or finger piece C, until caught by<br> -the hook attached to the key I. This hook is lower down than that on the<br> -key D, and holds it in contact with the charging contact piece S'. On<br> -pressing the key I, marked or designated "Insulate," it springs up,<br> -breaks contact at S', and catching against the hook on D, which key is<br> -designated "Discharge," remains insulated from both contacts; next on<br> -pressing D it is released and springs up and closes the discharge<br> -contact S. It is a form of charge and discharge key. (See Key, Charge<br> -and Discharge.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Key, Magneto-electric.</span><br> -A telegraph key whose movements operate what is virtually a small<br> -magneto-generator, so as to produce currents of alternating direction,<br> -one impulse for each motion of the key. It is employed for telegraphing<br> -without a line battery, a polarized relay being used. In one very simple<br> -form a key is mounted on a base with a permanent magnet and connected to<br> -the armature, so that when the key is pressed downwards it draws the<br> -armature away from the poles of the magnet. If the magnet or its<br> -armature is wound with insulated wire this action of the key will cause<br> -instantaneous currents to go through a circuit connected to the magnet<br> -or armature coils.<br> -<br> -<br> -<img style="width: 750px; height: 368px;" alt="" - src="images/315F208.jpg"><br> -Fig. 208. SIEMENS' MAGNETO-ELECTRIC KEY.<br> -<br> -<br> -In Siemens & Halske's key an H armature E is pivoted between the -poles N<br> -S, of a powerful compound horseshoe magnet, G G. It is wound with fine<br> -wire and a key handle H is provided for working it. In its normal<br> -position the handle is drawn upward, and the end S S of the armature<br> -core is in contact with the south pole S of the permanent magnet, and<br> -the end D D with the north pole. This establishes the polarity of the<br> -armature. On depressing the key the contacts are broken and in their<br> -place the end D D comes in contact with the south pole and the end S S<br> -with the north pole. This suddenly reverses the polarity of the armature<br> -and sends a momentary current through the armature coil which is in<br> -circuit with the line. The cut only shows the principle of the key,<br> -whose construction is quite complicated.<br> -<br> -<br> -316 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Key, Make and Break.</span><br> -An ordinary electric key, usually making a contact when depressed, and<br> -rising by spring action when released, and in its rise breaking the<br> -contact.<br> -<br> -<br> -<img style="width: 305px; height: 258px;" alt="" - src="images/316F209.jpg"><br> -Fig. 209. PLUG KEY<br> -<br> -<br> -<span style="font-weight: bold;">Key, Plug.</span><br> -An appliance for closing a circuit. Two brass blocks are connected to<br> -the terminals, but are disconnected from each other. A brass plug<br> -slightly coned or with its end split so as to give it spring action is<br> -thrust between the blocks to complete the circuit. It is used in<br> -Resistance coils and elsewhere. (See Coil, Resistance.) Grooves are<br> -formed in the blocks to receive the plug.<br> -<br> -<br> -<span style="font-weight: bold;">Key, Reversing.</span><br> -(a) A double key, arranged so that by depressing one key a current flows<br> -in one direction, and by depressing the other a current flows in the<br> -opposite direction. It is used in connection with a galvanometer in<br> -experimental, testing or measuring operations.<br> -<br> -(b) A key effecting the same result used in quadruplex telegraphy.<br> -<br> -<br> -<span style="font-weight: bold;">Key, Sliding-Contact.</span><br> -A name given to the key used for making instantaneous contacts with the<br> -metre wire of a metre bridge, q. v. The name is not strictly correct,<br> -because it is important that there should be no sliding contact made, as<br> -it would wear out the wire and make it of uneven resistance.<br> -<br> -It is a key which slides along over the wire and which, when depressed,<br> -presses a platinum tipped knife edge upon the wire. On being released<br> -from pressure the key handle springs up and takes the knife edge off the<br> -wire. This removal is essential to avoid wearing the wire, whose<br> -resistance per unit of length must be absolutely uniform.<br> -<br> -<br> -<span style="font-weight: bold;">Key, Telegraph.</span><br> -The key used in telegraphy for sending currents as desired over the<br> -line. It consists of a pivoted lever with finger piece, which lever when<br> -depressed makes contact between a contact point on its end and a<br> -stationary contact point on the base. This closes the circuit through<br> -the line. When released it springs up and opens the line circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Kilo.</span><br> -A prefix to the names of units; it indicates one thousand times, as<br> -kilogram, one thousand grams. A few such units are given below.<br> -<br> -<br> -<span style="font-weight: bold;">Kilodyne.</span><br> -A compound unit; one thousand dynes. (See Dyne.)<br> -<br> -<br> -<span style="font-weight: bold;">Kilogram.</span><br> -A compound unit; one thousand grams; 2.2046 pounds avds.<br> -<br> -<br> -317 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Kilojoule.</span><br> -A compound unit; one thousand joules, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Kilometer.</span><br> -A compound unit; one thousand meters; 3280.899 feet; 0.621382 statute<br> -miles. (See Meter.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Kilowatt.</span><br> -A compound unit; one thousand watts, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Kine.</span><br> -An absolute or C. G. S. unit of velocity or rate of motion; one<br> -centimeter per second; proposed by the British Association.<br> -<br> -<br> -<span style="font-weight: bold;">Kirchoff's Laws.</span><br> -These relate to divided circuits.<br> -<br> -I. When a steady current branches, the quantity of electricity arriving<br> -by the single wire is equal to the quantity leaving the junction by the<br> -branches. The algebraical sum of the intensities of the currents passing<br> -towards (or passing from) the junction is equal to zero; Summation(C) =<br> -0 (Daniell.) In the last sentence currents flowing towards the point are<br> -considered of one sign and those flowing away from it of the other.<br> -<br> -II. In a metallic circuit comprising within it a source of permanent<br> -difference of potential, E, the products of the intensity of the current<br> -within each part of the circuit into the corresponding resistance are,<br> -if the elements of current be all taken in cyclical order together,<br> -equal to E; Summation(C * r) =E. In a metallic circuit in which there is<br> -no source of permanent difference of potential E = 0, and Summation(C *<br> -r) = 0.<br> -<br> -This law applies to each several mesh of a wire network as well as to a<br> -single metallic loop, and it holds good even when an extraneous current<br> -is passed through the loop. (Daniell.)<br> -<br> -In this statement of the two laws E stands for electro-motive force, C<br> -for current intensity; and r for resistance of a single member of the<br> -circuit.<br> -<br> -[Transcriber's note: These laws may be restated as: At any point in an<br> -steady-state electrical circuit, the directed sum of currents flowing<br> -towards that point is zero. The directed sum of the electrical potential<br> -differences around any closed circuit is zero.]<br> -<br> -<br> -<span style="font-weight: bold;">Knife-edge Suspension.</span><br> -The suspension of an object on a sharp edge of steel or agate. The knife<br> -edge should abut against a plane. The knife edge is generally carried by<br> -the poised object. Its edge then faces downward and on the support one<br> -or more plane or approximately plane surfaces are provided on which it<br> -rests. In the ordinary balance this suspension can be seen. It is<br> -sometimes used in the dipping needle.<br> -<br> -It is applied in cases where vertical oscillations are to be provided<br> -for.<br> -<br> -<br> -<span style="font-weight: bold;">Knot.</span><br> -The geographical mile; a term derived from the knots on the log line,<br> -used by navigators. It is equal to 6,087 feet.<br> -<br> -Synonyms--Nautical Mile--Geographical Mile.<br> -<br> -[Transcriber's note: A knot is a velocity, 1 nautical mile per hour, not<br> -a distance. The contemporary definition is: 1 international knot = 1<br> -nautical mile per hour = 1.852 kilometres per hour = 1.1507794 miles per<br> -hour = 0.51444444 meters per second = 6076.1152 feet per hour.]<br> -<br> -<br> -318 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Kohlrausch's Law.</span><br> -A law of the rate of travel of the elements and radicals in solutions<br> -under the effects of electrolysis. It states that each element under the<br> -effects of electrolysis has a rate of travel for a given liquid, which<br> -is independent of the element with which it was combined. The rates of<br> -travel are stated for different elements in centimeters per hour for a<br> -potential difference of one or more volts per centimeter of path.<br> -<br> -[Friedrich Wilhelm Georg Kohlrausch (1840-1910)]<br> -<br> -<br> -<span style="font-weight: bold;">Kookogey's Solution.</span><br> -An acid exciting and depolarizing solution for a zinc-carbon couple,<br> -such as a Bunsen battery. Its formula is: Potassium bichromate, 227<br> -parts; water, boiling, 1,134 parts; while boiling add very carefully and<br> -slowly 1,558 parts concentrated sulphuric acid. All parts are by weight.<br> -Use cold.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Krizik's Cores.</span><br> -Cores of iron for use with magnetizing coils, q. v. They are so shaped,<br> -the metal increasing in quantity per unit of length, as the centre is<br> -approached, that the pull of the excited coil upon them will as far as<br> -possible be equal in all positions. A uniform cylinder is attracted with<br> -varying force according to its position; the Krizik bars or cores are<br> -attracted approximately uniformly through a considerable range.<br> -<br> -</big></big><br> -<big><big><br> -318 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">L.</span><br> -Symbol for length and also for the unit of inductance or coefficient of<br> -induction, because the dimensions of inductance are length.<br> -<br> -<br> -<span style="font-weight: bold;">Lag, Angle of.</span><br> -(a) The angle of displacement of the magnetic axis of an armature of a<br> -dynamo, due to its magnetic lag. The axis of magnetism is displaced in<br> -the direction of rotation. (See Magnetic Lag.)<br> -<br> -(b) The angle expressing the lag of alternating current and<br> -electro-motive force phases.<br> -<br> -<br> -<span style="font-weight: bold;">Laminated. adj.</span><br> -Made up of thin plates, as a laminated armature core or converter core.<br> -<br> -<br> -<span style="font-weight: bold;">Lamination.</span><br> -The building up of an armature core or other thing out of plates. The<br> -cores of dynamo armatures or of alternating current converters are often<br> -laminated. Thus a drum armature core may consist of a quantity of thin<br> -iron discs, strung upon a rod and rigidly secured, either with or<br> -without paper insulation between the discs. If no paper is used the film<br> -of oxide on the iron is relied on for insulation. The object of<br> -lamination is to break up the electrical continuity of the core, so as<br> -to avoid Foucault currents. (See Currents, Foucault.) The laminations<br> -should be at right angles to the direction of the Foucault currents<br> -which would be produced, or in most cases should be at right angles to<br> -the active parts of the wire windings.<br> -<br> -<br> -319 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Lamination of Armature Conductors.</span><br> -These are sometimes laminated to prevent the formation of eddy currents.<br> -The lamination should be radial, and the strips composing it should be<br> -insulated from each other by superficial oxidation, oiling or<br> -enamelling, and should be united only at their ends.<br> -<br> -<br> -<img style="width: 336px; height: 633px;" alt="" - src="images/319F210.jpg"><br> -Fig. 210. PILSEN ARC LAMP.<br> -<br> -<br> -<span style="font-weight: bold;">Lamp, Arc.</span><br> -A lamp in which the light is produced by a voltaic arc. Carbon<br> -electrodes are almost universally employed. Special mechanism, operating<br> -partly by spring or gravity and partly by electricity, is employed to<br> -regulate the distance apart of the carbons, to let them touch when no<br> -current passes, and to separate them when current is first turned on.<br> -<br> -The most varied constructions have been employed, examples of which will<br> -be found in their places. Lamps may in general be divided into classes<br> -as follows, according to their regulating mechanism and other features:<br> -<br> -(a) Single light regulators or monophotes. Lamps through whose<br> -regulating mechanism the whole current passes. These are only adapted to<br> -work singly; if several are placed in series on the same circuit, the<br> -action of one regulator interferes with that of the next one.<br> -<br> -(b) Multiple light regulators or polyphotes. In these the regulating<br> -mechanism and the carbons with their arc are in parallel; the regulating<br> -device may be a single magnet or solenoid constituting a derived or<br> -shunt-circuit lamp, or it may include two magnets working differentially<br> -against or in opposition to each other constituting a differential lamp.<br> -<br> -<br> -320 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -(c) Lamps with fixed parallel carbons termed candles (q. v., of various<br> -types).<br> -<br> -(d) Lamps without regulating mechanism. These include lamps with<br> -converging carbons, whose object was to dispense with the regulating<br> -mechanism, but which in some cases have about as much regulating<br> -mechanism as any of the ordinary arc lamps.<br> -<br> -<br> -<span style="font-weight: bold;">Lamp, Contact.</span><br> -A lamp depending for its action on loose contact between two carbon<br> -electrodes. At the contact a species of incandescence with incipient<br> -arcs is produced. One of the electrodes is usually flat or nearly so,<br> -and the other one of pencil shape rests upon it.<br> -<br> -<br> -<span style="font-weight: bold;">Lamp, Differential Arc.</span><br> -An arc lamp, the regulation of the distance between whose carbons<br> -depends on the differential action of two separate electrical coils. The<br> -diagram illustrates the principle. The two carbons are seen in black;<br> -the upper one is movable, The current arrives at A. It divides, and the<br> -greater part goes through the low resistance coil M to a contact roller<br> -r, and thence by the frame to the upper carbon, and through the arc and<br> -lower carbon to B, where it leaves the lamp. A smaller portion of the<br> -current goes through the coil M1 of higher resistance and leaves the<br> -lamp also at B. A double conical iron core is seen, to which the upper<br> -carbon holder is attached. This is attracted in opposite directions by<br> -the two coils. If the arc grows too long its resistance increases and<br> -the coil M1 receiving more current draws it down and thus shortens the<br> -arc. If the arc grows too short, its resistance falls, and the coil M<br> -receives more current and draws the core upwards, thus lengthening the<br> -arc. This differential action of the two cores gives the lamp its name.<br> -R is a pulley over which a cord passes, one end attached to the core and<br> -the other to a counterpoise weight, W.<br> -<br> -<br> -<img style="width: 195px; height: 700px;" alt="" - src="images/320F211.jpg"><br> -Fig. 211. DIAGRAM OF THE PILSEN DIFFERENTIAL ARC LAMP.<br> -<br> -<br> -321 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Lamp, Holophote.</span><br> -A lamp designed for use alone upon its own circuit. These have the<br> -regulating mechanism in series with the carbon and arc, so that the<br> -whole current goes through both. (See Lamp, Arc.)<br> -<br> -Synonym--Monophote Lamp.<br> -<br> -<br> -<span style="font-weight: bold;">Lamp-hour.</span><br> -A unit of commercial supply of electric energy; the volt-coulombs<br> -required to maintain an electric lamp for one hour. A sixteen-candle<br> -power incandescent lamp is practically the lamp alluded to, and requires<br> -about half an ampere current at 110 volts, making a lamp-hour equal to<br> -about 198,000 volt-coulombs.<br> -<br> -[Transcriber's note: 0.55 KW hours.]<br> -<br> -<br> -<span style="font-weight: bold;">Lamp, Incandescent.</span><br> -An electric lamp in which the light is produced by heating to whiteness<br> -a refractory conductor by the passage of a current of electricity. It is<br> -distinguished from an arc lamp (which etymologically is also an<br> -incandescent lamp) by the absence of any break in the continuity of its<br> -refractory conductor. Many different forms and methods of construction<br> -have been tried, but now all have settled into approximately the same<br> -type.<br> -<br> -The incandescent lamp consists of a small glass bulb, called the<br> -lamp-chamber, which is exhausted of air and hermetically sealed. It<br> -contains a filament of carbon, bent into a loop of more or less simple<br> -shape. This shape prevents any tensile strain upon the loop and also<br> -approximates to the outline of a regular flame.<br> -<br> -<br> -<img style="width: 245px; height: 652px;" alt="" - src="images/321F212.jpg"><br> -Fig. 212. INCANDESCENT ELECTRIC LAMP.<br> -<br> -<br> -322 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The loop is attached at its ends to two short pieces of platinum wire,<br> -which pass through the glass of the bulb and around which the glass is<br> -fused. As platinum has almost exactly the same coefficient of<br> -heat-expansion as glass, the wires do not cause the glass to crack.<br> -<br> -The process of manufacture includes the preparation of the filament.<br> -This is made from paper, silk, bamboo fibre, tamidine, q. v., or other<br> -material. After shaping into the form of the filament the material is<br> -carbonized at a high heat, while embedded in charcoal, or otherwise<br> -protected from the air. The flashing process (see Flashing of<br> -incandescent Lamp Carbons) may also be applied. The attachment to the<br> -platinum wires is effected by a minute clamp or by electric soldering.<br> -The loop is inserted and secured within the open globe, which the glass<br> -blower nearly closes, leaving one opening for exhaustion.<br> -<br> -The air is pumped out, perhaps first by a piston pump, but always at the<br> -end by a mercurial air pump. (See Pump, Geissler--and others.) As the<br> -exhaustion becomes high a current is passed through the carbons heating<br> -them eventually to white heat so as to expel occluded gas. The occluded<br> -gases are exhausted by the pump and the lamp is sealed by melting the<br> -glass with a blowpipe or blast-lamp flame. For the exhaustion several<br> -lamps are usually fastened together by branching glass tubes, and are<br> -sealed off one by one.<br> -<br> -The incandescent lamps require about 3.5 watts to the candle power, or<br> -give about 12 sixteen-candle lamps to the horse power expended on them.<br> -<br> -Generally incandescent lamps are run in parallel or on multiple arc<br> -circuits. All that is necessary in such distribution systems is to<br> -maintain a proper potential difference between the two leads across<br> -which the lamps are connected. In the manufacture of lamps they are<br> -brought to an even resistance and the proper voltage at which they<br> -should be run is often marked upon them. This may be fifty volts and<br> -upward. One hundred and ten volts is a very usual figure. As current one<br> -ampere for a fifty-volt, or about one-half an ampere for a one hundred<br> -and ten volt lamp is employed.<br> -<br> -<br> -<span style="font-weight: bold;">Lamp, Incandescent, Three Filament.</span><br> -A three filament lamp is used for three phase currents. It has three<br> -filaments whose inner ends are connected, and each of which has one<br> -leading-in wire. The three wires are connected to the three wires of the<br> -circuit. Each filament receives a current varying in intensity, so that<br> -there is always one filament passing a current equal to the sum of the<br> -currents in the other two filaments.<br> -<br> -<br> -<span style="font-weight: bold;">Lamp, Lighthouse.</span><br> -A special type of arc light. It is adapted for use in a lighthouse<br> -dioptric lantern, and hence its arc has to be maintained in the same<br> -position, in the focus of the lenses. The lamps are so constructed as to<br> -feed both carbons instead of only one, thereby securing the above<br> -object.<br> -<br> -<br> -323 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Lamp, Pilot.</span><br> -A lamp connected to a dynamo, and used by its degree of illumination to<br> -show when the dynamo on starting becomes excited, or builds itself up.<br> -<br> -<br> -<span style="font-weight: bold;">Lamp, Polyphote.</span><br> -An arc lamp adapted to be used, a number in series, upon the same<br> -circuit. The electric regulating mechanism is placed in shunt or in<br> -parallel with the carbons and arc. (See Lamp, Arc.)<br> -<br> -<br> -<span style="font-weight: bold;">Lamps, Bank of.</span><br> -A number of lamps mounted on a board or other base, and connected to<br> -serve as voltage indicator or to show the existence of grounds, or for<br> -other purposes.<br> -<br> -<br> -<span style="font-weight: bold;">Lamp, Semi-incandescent.</span><br> -A lamp partaking of the characteristics of both arc and incandescence; a<br> -lamp in which the imperfect contact of two carbon electrodes produces a<br> -part of or all of the resistance to the current which causes<br> -incandescence.<br> -<br> -The usual type of these lamps includes a thin carbon rod which rests<br> -against a block of carbon. The species of arc formed at the junction of<br> -the two heats the carbons. Sometimes the upper carbon or at least its<br> -end is heated also by true incandescence, the current being conveyed<br> -near to its end before entering it.<br> -<br> -Semi-incandescent lamps are not used to any extent now.<br> -<br> -<br> -<span style="font-weight: bold;">Lamp Socket.</span><br> -A receptacle for an incandescent lamp; the lamp being inserted the<br> -necessary connections with the two leads are automatically made in most<br> -sockets. The lamps may be screwed or simply thrust into the socket and<br> -different ones are constructed for different types of lamps. A key for<br> -turning the current on and off is often a part of the socket.<br> -<br> -<br> -<span style="font-weight: bold;">Latent Electricity.</span><br> -The bound charge of static electricity. (See Charge, Bound.)<br> -<br> -<br> -<span style="font-weight: bold;">Law of Intermediate Metals.</span><br> -A law of thermo-electricity. The electro-motive force between any two<br> -metals is equal to the sum of electro-motive forces between each of the<br> -two metals and any intermediate metal in the thermo-electric series, or<br> -the electro-motive force between any two metals is equal to the sum of<br> -the electromotive forces between all the intermediate ones and the<br> -original two metals; it is the analogue of Volta's Law, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Law of Inverse Squares.</span><br> -When force is exercised through space from a point, its intensity varies<br> -inversely with the square of the distance. Thus the intensity of light<br> -radiated by a luminous point at twice a given distance therefrom is of<br> -one-fourth the intensity it had at the distance in question.<br> -Gravitation, electric and magnetic attraction and repulsion and other<br> -radiant forces are subject to the same law.<br> -<br> -<br> -324 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Law of Successive Temperatures.</span><br> -A law of thermo-electricity. The electro-motive force due to a given<br> -difference of temperature between the opposite junctions of the metals<br> -is equal to the sum of the electro-motive forces produced by fractional<br> -differences of temperature, whose sum is equal to the given difference<br> -and whose sum exactly fills the given range of temperature.<br> -<br> -<br> -<span style="font-weight: bold;">Law, Right-handed Screw.</span><br> -This rather crude name is given by Emtage to a law expressing the<br> -relation of direction of current in a circuit to the positive direction<br> -of the axis of a magnet acted on by such current. It is thus expressed:<br> -A right-handed screw placed along the axis of the magnet and turned in<br> -the direction of the current will move in the positive direction, i. e.,<br> -towards the north pole of the axis of the magnet.<br> -<br> -<br> -<span style="font-weight: bold;">Lead.</span><br> -A metal; one of the elements; symbol Pb. Atomic weight, 207;<br> -equivalent, 103-1/2; valency, 2.<br> -Lead may also be a tetrad, when its equivalent is 51.75.<br> -The following data are at 0º C. (32º F.) with compressed -metal:<br> -<small><span style="font-family: monospace;">Relative Resistance, -(Silver = l) 13.05</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Specific -Resistance, -19.63 microhms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Resistance of a wire,</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">(a) 1 ft. long, weighing 1 -grain, -3.200 ohms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">(b) 1 meter long, weighing 1 -gram, -2.232 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">(c) 1 meter long, 1 millimeter -thick, .2498 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Resistance of 1 inch -cube, -7.728 microhms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Electro-Chemical Equivalent -(Hydrogen = .0105) -1.086 mgs.</span></small><br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Leading Horns.</span><br> -The tips of pole pieces in a dynamo, which extend in the direction of<br> -movement of the armature.<br> -<br> -<br> -<span style="font-weight: bold;">Leading-in Wires.</span><br> -The platinum wires passing through the glass of an incandescent<br> -lamp-chamber, to effect the connection of the carbon filament with the<br> -wires of the circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Lead of Brushes, Negative.</span><br> -In a motor the brushes are set backwards from their normal position, or<br> -in a position towards the direction of armature rotation or given a<br> -negative lead instead of a positive one, such as is given to dynamo<br> -brushes.<br> -<br> -<br> -<span style="font-weight: bold;">Leak.</span><br> -A loss or escape of electricity by accidental connection either with the<br> -ground or with some conductor. There are various kinds of leak to which<br> -descriptive terms are applied.<br> -<br> -<br> -<span style="font-weight: bold;">Leakage.</span><br> -The loss of current from conductors; due to grounding at least at two<br> -places, or to very slight grounding at a great many places, or all along<br> -a line owing to poor insulation. In aerial or pole telegraph lines in<br> -wet weather there is often a very large leakage down the wet poles from<br> -the wire. (See Surface Leakage--Magnetic Leakage.)<br> -<br> -<br> -325 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Leakage Conductor.</span><br> -A conductor placed on telegraph poles to conduct directly to earth any<br> -leakage from a wire and thus prevent any but a very small portion<br> -finding its way into the other wires on the same pole. It presents a<br> -choice of evils, as it increases the electrostatic capacity of the line,<br> -and thus does harm as well as good. It consists simply of a wire<br> -grounded and secured to the pole.<br> -<br> -<br> -<span style="font-weight: bold;">Leg of Circuit.</span><br> -One lead or side of a complete metallic circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Lenz's Law.</span><br> -A law expressing the relations of direction of an inducing current or<br> -field of force to the current induced by any disturbance in the<br> -relations between such field and any closed conductor within its<br> -influence. It may be variously expressed.<br> -<br> -(a) If the relative position of two conductors, A and B, be changed, of<br> -which A is traversed by a current, a current is induced in B in such a<br> -direction that, by its electro-dynamic action on the current in A, it<br> -would have imparted to the conductors a motion of the contrary kind to<br> -that by which the inducing action was produced. (Ganot.)<br> -<br> -(b) The new (induced) current will increase the already existing<br> -resistances, or develop new resistance to that disturbance of the field<br> -which is the cause of induction. (Daniell.)<br> -<br> -(c) When a conductor is moving in a magnetic field a current is induced<br> -in the conductor in such a direction as by its mechanical action to<br> -oppose the motion. (Emtage.)<br> -<br> -(d) The induced currents are such as to develop resistance to the change<br> -brought about.<br> -<br> -<br> -<span style="font-weight: bold;">Letter Boxes, Electric.</span><br> -Letter boxes with electrical connections to a bell or indicator of some<br> -sort, which is caused to act by putting a letter into the box.<br> -<br> -<br> -<span style="font-weight: bold;">Leyden Jar.</span><br> -A form of static condenser.<br> -<br> -In its usual form it consists of a glass jar. Tinfoil is pasted around<br> -the lower portions of its exterior and interior surfaces, covering from<br> -one-quarter to three-quarters of the walls in ordinary examples. The<br> -rest of the glass is preferably shellacked or painted over with<br> -insulating varnish, q. v. The mouth is closed with a wooden or cork<br> -stopper and through its centre a brass rod passes which by a short chain<br> -or wire is in connection with the interior coating of the jar. The top<br> -of the rod carries a brass knob or ball.<br> -<br> -If such a jar is held by the tinfoil-covered surface in one hand and its<br> -knob is held against the excited prime conductor of a static machine its<br> -interior becomes charged; an equivalent quantity of the same electricity<br> -is repelled through the person of the experimenter to the earth and when<br> -removed from the conductor it will be found to hold a bound charge. If<br> -the outer coating and knob are both touched or nearly touched by a<br> -conductor a disruptive discharge through it takes place.<br> -<br> -<br> -326 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 612px; height: 530px;" alt="" - src="images/326F213.jpg"><br> -Fig. 213. LEYDEN JAR WITH DISCHARGER.<br> -<br> -<br> -If one or more persons act as discharging conductors they will receive a<br> -shock. This is done by their joining hands, a person at one end touching<br> -the outer coating and another person at the other end touching the knob.<br> -<br> -From an influence machine a charge can be taken by connecting the<br> -coating to one electrode and the knob to the other.<br> -<br> -<br> -<img style="width: 574px; height: 622px;" alt="" - src="images/326F214.jpg"><br> -Fig. 214. SULPHURIC ACID LEYDEN JAR.<br> -<br> -<br> -327 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Leyden Jar, Sir William Thomson's.</span><br> -An especially efficient form of Leyden jar. It consists of a jar with<br> -outer tinfoil coating only. For the interior coating is substituted a<br> -quantity of concentrated sulphuric acid. The central rod is of lead with<br> -a foot, which is immersed in the acid and from which the rod rises. A<br> -wooden cover partly closes the jar, as the central tube through which<br> -the rod passes is so large as not to allow the wood to touch it. Thus<br> -any leakage from inner to outer coating has to pass over the inside and<br> -outside glass surfaces. In the common form of jar the wooden cover may<br> -short circuit the uncoated portion of the inner glass surface. In the<br> -cut a simplified form of Thomson's Leyden jar is shown, adapted for<br> -scientific work.<br> -<br> -<br> -<span style="font-weight: bold;">Lichtenberg's Figures.</span><br> -If the knob of a Leyden jar or other exited electrode is rubbed over the<br> -surface of ebonite, shellac, resin or other non-conducting surface it<br> -leaves it electrified in the path of the knob. If fine powder such as<br> -flowers of sulphur or lycopodium is dusted over the surface and the<br> -excess is blown away, the powder will adhere where the surface was<br> -electrified, forming what are called Lichtenberg's Figures, Lycopodium<br> -and sulphur show both positive and negative figures, that is to say,<br> -figures produced by a positively or negatively charged conductor. Red<br> -lead adheres only to negative figures. If both positive and negative<br> -figures are made and the surface is sprinkled with both red lead and<br> -flowers of sulphur each picks out its own figure, the sulphur going<br> -principally to the positive one.<br> -<br> -The red lead takes the form of small circular heaps, the sulphur<br> -arranges itself in tufts with numerous diverging branches. This<br> -indicates the difference in the two electricities. The figures have been<br> -described as "a very sensitive electrosope for investigating the<br> -distribution of electricity on an insulating surface." (Ganot.)<br> -<br> -<br> -<span style="font-weight: bold;">Life of Incandescent Lamps.</span><br> -The period of time a lamp remains in action before the carbon filament<br> -is destroyed. The cause of a lamp failing may be the volatilization of<br> -the carbon of the filament, causing it to become thin and to break; or<br> -the chamber may leak. The life of the lamp varies; 600 hours is a fair<br> -estimate. Sometimes they last several times this period.<br> -<br> -The higher the intensity at which they are used the shorter is their<br> -life. From their prime cost and the cost of current the most economical<br> -way to run them can be approximately calculated.<br> -<br> -[Transcriber's note: Contemporary incandecent buls are rated for 1000<br> -hours; flourescent bulbs up to 24000 hours; LED lamps up to 100000 -hours.]<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Lightning.</span><br> -The electrostatic discharge to the earth or among themselves of clouds<br> -floating in the atmosphere. The discharge is accompanied by a spark or<br> -other luminous effect, which may be very bright and the effects, thermal<br> -and mechanical, are often of enormous intensity.<br> -<br> -The lightning flash is white near the earth, but in the upper regions<br> -where the air is rarefied it is of a blue tint, like the spark of the<br> -electric machine. The flashes are often over a mile in length, and<br> -sometimes are four or five miles long. They have sometimes a curious<br> -sinuous and often a branching shape, which has been determined by<br> -photography only recently. To the eye the shape seems zigzag.<br> -<br> -<br> -328 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -In the case of a mile-long flash it has been estimated that 3,516,480 De<br> -la Rue cells, q. v., would be required for the development of the<br> -potential, giving the flash over three and one-half millions of volts.<br> -But as it is uncertain how far the discharge is helped on its course by<br> -the rain drops this estimate may be too high.<br> -<br> -There are two general types of flash. The so-called zigzag flash<br> -resembles the spark of an electric machine, and is undoubtedly due to<br> -the disruptive discharge from cloud to earth. Sheet lightning has no<br> -shape, simply is a sudden glow, and from examination of the spectrum<br> -appears to be brush discharges (see Discharge, Brush) between clouds.<br> -Heat lightning is attributed to flashes below the horizon whose light<br> -only is seen by us. Globe or ball lightning takes the form of globes of<br> -fire, sometimes visible for ten seconds, descending from the clouds. On<br> -reaching the earth they sometimes rebound, and sometimes explode with a<br> -loud detonation. No adequate explanation has been found for them.<br> -<br> -The flash does not exceed one-millionth of a second in duration; its<br> -absolute light is believed to be comparable to that of the sun, but its<br> -brief duration makes its total light far less than that of the sun for<br> -any period of time.<br> -<br> -If the disruptive discharge passes through a living animal it is often<br> -fatal. As it reaches the earth it often has power enough to fuse sand,<br> -producing fulgurites, q. v. (See also Back Shock or Stroke of<br> -Lightning.)<br> -<br> -Volcanic lightning, which accompanies the eruptions of volcanoes, is<br> -attributed to friction of the volcanic dust and to vapor condensation.<br> -<br> -[Transcriber's note: The origin of lightning is still (2008) not fully<br> -understood, but is thought to relate to charge separation in the<br> -vertical motion of water droplets and ice crystals in cloud updrafts. A<br> -lightning bolt carries a current of 40,000 to 120,000 amperes, and<br> -transfers a charge of about five coulombs. Nearby air is heated to about<br> -10,000 °C (18,000 °F), almost twice the temperature of the Sun’s<br> -surface.]<br> -<br> -<br> -<span style="font-weight: bold;">Lightning Arrester.</span><br> -An apparatus for use with electric lines to carry off to earth any<br> -lightning discharge such lines may pick up. Such discharge would imperil<br> -life as well as property in telegraph offices and the like.<br> -<br> -Arresters are generally constructed on the following lines. The line<br> -wires have connected to them a plate with teeth; a second similar plate<br> -is placed near this with its teeth opposite to those of the first plate<br> -and nearly touching it. The second plate is connected by a low<br> -resistance conductor to ground. Any lightning discharge is apt to jump<br> -across the interval, of a small fraction of an inch, between the<br> -oppositely placed points and go to earth.<br> -<br> -Another type consists of two plates, placed face to face, and pressing<br> -between them a piece of paper or mica. The lightning is supposed to<br> -perforate this and go to earth. One plate is connected to the line, the<br> -other one is grounded.<br> -<br> -The lightning arrester is placed near the end of the line before it<br> -reaches any instrument. (See Alternative Paths.)<br> -<br> -<br> -329 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 721px; height: 453px;" alt="" - src="images/329F215.jpg"><br> -Fig. 215. COMB OR TOOTHED LIGHTNING ARRESTER.<br> -<br> -<br> -<img style="width: 646px; height: 310px;" alt="" - src="images/329F216.jpg"><br> -Fig. 216. FILM OR PLATE LIGHTNING ARRESTER.<br> -<br> -<br> -<span style="font-weight: bold;">Lightning Arrester, -Counter-electro-motive Force.</span><br> -An invention of Prof. Elihu Thompson. A lightning arrester in which the<br> -lightning discharge sets up a counter-electro-motive force opposed to<br> -its own. This it does by an induction coil. If a discharge to earth<br> -takes place it selects the primary of the coil as it has low<br> -self-induction. In its discharge it induces in the secondary a reverse<br> -electro-motive force which protects the line.<br> -<br> -<br> -<span style="font-weight: bold;">Lightning Arrester Plates.</span><br> -The toothed plates nearly in contact, tooth for tooth, or the flat<br> -plates of a film lightning arrester, which constitute a lightning<br> -arrester. Some advocate restricting the term to the plate connected to<br> -the line.<br> -<br> -<br> -<span style="font-weight: bold;">Lightning Arrester, Vacuum.</span><br> -A glass tube, almost completely exhausted, into which the line wire is<br> -fused, while a wire leading to an earth connection has its end fused in<br> -also.<br> -<br> -A high tension discharge, such as that of lightning, goes to earth<br> -across the partial vacuum in preference to going through the line, which<br> -by its capacity and self-induction opposes the passage through it of a<br> -lightning discharge.<br> -<br> -It is especially adapted for underground and submarine lines.<br> -<br> -<br> -330 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Lightning, Ascending.</span><br> -Lightning is sometimes observed which seems to ascend. It is thought<br> -that this may be due to positive electrification of the earth and<br> -negative electrification of the clouds.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Lightning, Globe or Globular.</span><br> -A very unusual form of lightning discharge, in which the flashes appear<br> -as globes or balls of light. They are sometimes visible for ten seconds,<br> -moving so slowly that the eye can follow them. They often rebound on<br> -striking the ground, and sometimes explode with a noise like a cannon.<br> -They have never been satisfactorily explained. Sometimes the phenomenon<br> -is probably subjective and due to persistence of vision.<br> -<br> -<br> -<span style="font-weight: bold;">Lightning Jar.</span><br> -A Leyden jar whose coatings are of metallic filings dusted on to the<br> -surface while shellacked, and before the varnish has had time to dry. In<br> -its discharge a scintillation of sparks appears all over the surface.<br> -<br> -<br> -<span style="font-weight: bold;">Line of Contact.</span><br> -The line joining the points of contact of the commutator brushes in a<br> -dynamo or motor.<br> -<br> -Synonym--Diameter of Commutation.<br> -<br> -<br> -<span style="font-weight: bold;">Lines of Force.</span><br> -Imaginary lines denoting the direction of repulsion or attraction in a<br> -field of force, q. v. They may also be so distributed as to indicate the<br> -relative intensity of all different parts of the field. They are normal<br> -to equipotential surfaces. (See Electro-magnetic Lines of<br> -Force--Electrostatic Lines of Force--Magnetic Lines of Force.)<br> -<br> -<br> -<span style="font-weight: bold;">Lines of Induction.</span><br> -Imaginary lines within a body marking the direction taken within it by<br> -magnetic induction. These are not necessarily parallel to lines of<br> -force, but may, in bodies of uniform agglomeration, or in crystalline<br> -bodies, take various directions.<br> -<br> -Synonym--Lines of Magnetic Induction.<br> -<br> -<br> -<span style="font-weight: bold;">Lines of Slope.</span><br> -Lines in a field of force which mark the directions in which the<br> -intensity of force in the field most rapidly falls away.<br> -<br> -<br> -<span style="font-weight: bold;">Links, Fuse.</span><br> -Links made of more or less easily fusible metal, for use as safety<br> -fuses.<br> -<br> -<br> -<span style="font-weight: bold;">Listening Cam.</span><br> -In a telephone exchange a cam or species of switch used to connect the<br> -operator's telephone with a subscriber's line.<br> -<br> -<br> -331 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Lithanode.</span><br> -A block of compressed lead binoxide, with platinum connecting foils for<br> -use as an electrode in a storage battery. It has considerable capacity,<br> -over 5 ampere-hours per pound of plates, but has not met with any<br> -extended adoption.<br> -<br> -<br> -<span style="font-weight: bold;">Load.</span><br> -In a dynamo the amperes of current delivered by it under any given<br> -conditions.<br> -<br> -<br> -<span style="font-weight: bold;">Local Action.</span><br> -(a) In its most usual sense the electric currents within a battery, due<br> -to impurities in the zinc, which currents may circulate in exceedingly<br> -minute circuits, and which waste zinc and chemicals and contribute<br> -nothing to the regular current of the battery. Amalgamated or chemically<br> -pure zinc develops no local action.<br> -<br> -(b) The term is sometimes applied to currents set up within the armature<br> -core or pole pieces of a dynamo. (See Currents, Foucault.)<br> -<br> -<br> -<span style="font-weight: bold;">Local Battery.</span><br> -A battery supplying a local circuit (q. v.); in telegraphy, where it is<br> -principally used, the battery is thrown in and out of action by a relay,<br> -and its current does the work of actuating the sounder and any other<br> -local or station instruments. (See Relay.)<br> -<br> -<br> -<span style="font-weight: bold;">Local Circuit.</span><br> -A short circuit on which are placed local apparatus or instruments. Such<br> -circuit is of low resistance and its current is supplied by a local<br> -battery, q. v. Its action is determined by the current from the main<br> -line throwing its battery in and out of circuit by a relay, q. v., or<br> -some equivalent.<br> -<br> -<br> -<span style="font-weight: bold;">Local Currents.</span><br> -Currents within the metal parts of a dynamo. (See Currents, Foucault.)<br> -In a galvanic battery. where there is local action, q. v., there are<br> -also local currents, though they are not often referred to.<br> -<br> -<br> -<span style="font-weight: bold;">Localization.</span><br> -Determining the position of anything, such as a break in a cable, or a<br> -grounding in a telegraph line. In ocean cables two typical cases are the<br> -localization of a break in the conductor and of a defect in the<br> -insulation admitting water. The first is done by determining the static<br> -capacity of the portion of the line which includes the unbroken portion<br> -of the conductor; the other by determining the resistance of the line on<br> -a grounded circuit.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Locus.</span><br> -A place. The word is used to designate the locality or position of, or<br> -series of positions of definite conditions and the like. Thus an<br> -isogonic line is the locus of equal declinations of the magnetic needle;<br> -it is a line passing through all places on the earth's surface where the<br> -condition of a given declination is found to exist.<br> -<br> -<br> -332 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Lodestone.</span><br> -Magnetic magnetite; magnetite is an ore of iron, Fe3 04 which is<br> -attracted by the magnet. Some samples possess polarity and attract iron.<br> -The latter are lodestones.<br> -<br> -Synonym--Hercules Stone<br> -<br> -<br> -<span style="font-weight: bold;">Logarithm.</span><br> -The exponent of the power to which it is necessary to raise a fixed<br> -number to produce a given number. The fixed number is the base of the<br> -system. There are two systems; one, called the ordinary system, has 10<br> -for its base, the other, called the Naperian system, has 2.71828 for its<br> -base. The latter are also termed hyperbolic logarithms, and are only<br> -used in special calculations.<br> -<br> -<br> -<span style="font-weight: bold;">Log, Electric.</span><br> -An apparatus for measuring the speed of a ship. A rotating helical vane<br> -of known pitch is dragged behind the vessel. As the helix rotates its<br> -movements may actuate electric machinery for registering its rotations.<br> -The number of these in a given time, multiplied by the pitch of the<br> -vane, gives the distance traversed in such time.<br> -<br> -<br> -<span style="font-weight: bold;">Loop.</span><br> -A portion of a circuit introduced in series into another circuit. The<br> -latter circuit is opened by a spring-jack, q. v. or other device, and<br> -the loop inserted. By loops any number of connections can be inserted<br> -into a circuit in series therewith, and in series or in parallel with<br> -one another.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Loop Break.</span><br> -A double bracket or similar arrangement for holding on insulators the<br> -ends of a conductor which is cut between them, and to which are<br> -connected the ends of a loop. The space between the insulators may be<br> -about a foot.<br> -<br> -<br> -<span style="font-weight: bold;">Luces.</span><br> -This may be used as the plural of lux, q. v. It is the Latin plural.<br> -<br> -<br> -<span style="font-weight: bold;">Luminous Jar.</span><br> -A Leyden jar whose coatings are of lozenge-shaped pieces of tinfoil<br> -between which are very short intervals. When discharged, sparks appear<br> -all over the surface where the lozenges nearly join.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Lux.</span><br> -A standard of illumination, q. v., as distinguished from illuminating<br> -power.<br> -<br> -It is the light given by one candle at a distance of 12.7 inches--by a<br> -carcel, q. v., at a distance of one meter---or by 10,000 candles at<br> -105.8 feet.<br> -<br> -It was proposed by W. H. Preece. All the above valuations are identical.<br> -</big></big><big><big><span style="text-decoration: underline;"><br> -</span></big></big><big><big><br> -332 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">M.</span><br> -(a) Symbol of gaseous pressure equal to one-millionth of an atmosphere.<br> -<br> -(b) The Greek m, µ, is used as the symbol of magnetic -permeability.<br> -<br> -<br> -333 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Machine, Cylinder Electric.</span><br> -A frictional electric machine whose rotating glass is in the shape of a<br> -cylinder instead of a disc as in the more recent machines.<br> -<br> -<br> -<img style="width: 589px; height: 680px;" alt="" - src="images/333F217.jpg"><br> -Fig. 217. PLATE FRICTIONAL ELECTRIC MACHINE.<br> -<br> -<br> -<span style="font-weight: bold;">Machine, Frictional Electric.</span><br> -An apparatus for development of high tension electricity by contact<br> -action, brought about by friction.<br> -<br> -It consists of a plate or cylinder of glass mounted on insulating<br> -standards and provided with a handle for turning it. One or more<br> -cushions of leather are held on an insulated support, so as to rub<br> -against the plate or cylinder as it is turned. A metal comb or combs are<br> -held on another insulating support so as to be nearly in contact with<br> -the surface of the glass plate at a point as far removed as possible<br> -from the rubbers. The combs are attached to a brass ball or round-ended<br> -cylinder, which is termed the prime conductor.<br> -<br> -In use either the prime conductor or cushions are connected by a chain<br> -or otherwise with the earth. Assume it to be the cushions. As the<br> -machine is worked by turning the plate, the glass and cushion being in<br> -contact develop opposite electricities. The glass is charged with<br> -positive electricity, and as it turns carries it off and as it reaches<br> -the prime conductor by induction and conduction robs it of its negative<br> -electricity. Meanwhile the cushions negatively excited deliver their<br> -charge to the earth. The action thus goes on, the prime conductor being<br> -charged with positive electricity.<br> -<br> -<br> -334 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -If the prime conductor is connected to the earth and the cushions are<br> -left insulated, negative electricity can be collected from the cushions.<br> -<br> -In some machines both prime conductor and cushions are kept insulated<br> -and without ground contact. Electrodes connecting with each are brought<br> -with their ends close enough to maintain a sparking discharge.<br> -<br> -<br> -<span style="font-weight: bold;">Machine Influence.</span><br> -A static electric machine working by induction to build up charges of<br> -opposite nature on two separate prime conductors. In general they are<br> -based on the principle of the electrophorous. Work is done by the<br> -operator turning the handle. This rotates a disc and draws excited parts<br> -of it away from their bound charges. This represents a resistance to<br> -mechanical motion. The work absorbed in overcoming this mechanical<br> -resistance appears as electric energy. There are various types of<br> -influence machines, the Holtz, Toeppler-Holtz and Wimshurst being the<br> -most used. The electrophorous, q. v., is a type of influence machine.<br> -<br> -<br> -<span style="font-weight: bold;">Machine, Holtz Influence.</span><br> -A static electric machine. It includes two plates, one of which is<br> -rapidly rotated in front of the other. Two armatures of paper are<br> -secured to the back of the stationary plate at opposite ends of a<br> -diameter. To start it one of these is charged with electricity. This<br> -charge by induction acts through the two thicknesses of glass upon a<br> -metal bar carrying combs, which lies in front of the further side of the<br> -movable plate. The points opposite the armature repel electrified air,<br> -which strikes the movable disc and charges it. A second rod with comb at<br> -the opposite end of the same diameter acts in the reverse way. Thus<br> -opposite sections of the disc are oppositely charged and the combs with<br> -them. By induction these portions of the disc react upon the two<br> -armatures. The opposite electricities escape from the armatures by paper<br> -tongues which are attached thereto and press against the back of the<br> -movable plate. As the plate rotates the opposite electricities on its<br> -face neutralize the electricity repelled from the combs. The charges on<br> -the back strengthen the charges of the armatures and brass combs. Thus<br> -the machine builds up, and eventually a discharge of sparks takes place<br> -from the poles of the brass combs.<br> -<br> -<br> -335 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Machine, Toeppler-Holtz.</span><br> -A modification of the Holtz machine. The priming charge of the armatures<br> -is produced by friction of metallic brushes against metallic buttons on<br> -the face of the rotating plate. (See Machine, Holtz.)<br> -<br> -<br> -<span style="font-weight: bold;">Machine, Wimshurst.</span><br> -A form of static influence machine. It consists of two plates of glass,<br> -on which radial sectors of tinfoil are pasted. Both plates are rotated<br> -in opposite directions. The sectors of the two plates react one upon the<br> -other, and electric charges of opposite sign accumulate on the opposite<br> -sides of the plates and are collected therefrom by collecting combs.<br> -<br> -<br> -<span style="font-weight: bold;">Mack.</span><br> -A name, derived from Maxwell, and suggested for the unit of inductance.<br> -It is due to Oliver Heaviside, but has never been adopted. (See Henry.)<br> -<br> -<br> -<span style="font-weight: bold;">Magne-Crystallic Action.</span><br> -The action of a supposed force of the same name, proposed by Faraday. It<br> -relates to the different action of a magnetic field upon crystalline<br> -bodies, according to the position of their axes of crystallization. A<br> -needle of tourmaline, normally paramagnetic, if poised with its axis<br> -horizontal, is diamagnetic. Bismuth illustrates the same phenomenon. The<br> -subject is obscure. Faraday thought that he saw in it the action of a<br> -specific force.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet.</span><br> -A body which tends when suspended by its centre of gravity to lay itself<br> -in a definite direction, and to place a definite line within it, its<br> -magnetic axis, q. v., in a definite direction, which, roughly speaking,<br> -lies north and south. The same bodies have the power of attracting iron<br> -(Daniell), also nickel and cobalt.<br> -<br> -Magnets are substances which possess the power of attracting iron.<br> -(Ganot.)<br> -<br> -[Transcriber's note: Edward Purcell and others have explained magnetic<br> -and electromagnetic phenomenon as relativistic effects related to<br> -electrostatic attraction. Magnetism is caused by Lorentz contraction of<br> -space along the direction of a current. Electromagnetic waves are caused<br> -by charge acceleration and the resulting disturbance of the<br> -electrostatic field. (Electricity and Magnetism: Berkeley Physics<br> -Course Volume 2, 1960)]<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Anomalous.</span><br> -A magnet possessing more than the normal number (two) of poles. If two<br> -straight magnets are placed end to end with their south poles in<br> -juxtaposition the compound bar will seem to possess three poles, one at<br> -each end and one in the middle. The apparent pole in the middle is<br> -really made up of two consequent poles, q. v. It sometimes happens that<br> -when a single long thin bar is magnetized consequent poles are produced,<br> -although such magnet is in one piece. This may be accidental, as in such<br> -case it is quite hard to avoid anomalous poles, or, as in the field<br> -magnets of some forms of dynamos, anomalous poles may be purposely<br> -produced.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Artificial.</span><br> -A magnet formed artificially by any method of magnetization (see<br> -Magnetism) applicable to permanent magnets, electro-magnets and<br> -solenoids. It expresses the distinction from the natural magnets or<br> -lodestone, q. v. It is made of steel in practice magnetized by some of<br> -the methods described under Magnetization.<br> -<br> -<br> -336 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnet, Axial.</span><br> -A straight-solenoid with axial core.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Bar.</span><br> -A bar magnet is one in the shape of a bar, i. c., straight with parallel<br> -sides and considerably longer than wide or deep.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Bell-shaped.</span><br> -A form of permanent magnet used in some galvanometers. In shape it is a<br> -thick-sided cylindrical box with two slots cut out of opposite sides, so<br> -as to make it represent a horseshoe magnet. Its shape enables it to be<br> -surrounded closely by a mass of copper, for damping its motion, to<br> -render the instrument dead-beat. Such a magnet is used in Siemens &<br> -Halske's galvanometer.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnet Coil.</span><br> -A coil to be thrust over an iron core, to make an electro-magnet. They<br> -are often wound upon paper or wooden bobbins or spools, so as to be<br> -removable from the core if desired.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Compensating.</span><br> -(a) A magnet fastened near a compass on an iron or steel ship to<br> -compensate the action of the metal of the ship upon the magnetic needle.<br> -The ship itself always has some polarity and this is neutralized by one<br> -or more compensating magnets.<br> -<br> -(b) See below.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Controlling.</span><br> -A magnet attached to a galvanometer by which the directive tendency of<br> -its magnetic needle is adjusted. In the reflecting galvanometer it often<br> -is a slightly curved magnet carried by a vertical brass spindle rising<br> -from the center of the instrument, and which magnet may be slid up and<br> -down on the spindle to regulate or adjust its action.<br> -<br> -Synonym--Compensating Magnet.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnet, Compound.</span><br> -A permanent magnet, built up of a number of magnets. Small bars can be<br> -more strongly magnetized than large. Hence a compound magnet may be made<br> -more powerful than a simple one.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet Core.</span><br> -The iron bar or other mass of iron around which insulated wire is wound<br> -for the production of an electro-magnet. The shapes vary greatly,<br> -especially for field magnets of dynamos and motors. For these they are<br> -usually made of cast iron, although wrought iron is preferable from the<br> -point of view of permeability.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnet, Damping.</span><br> -A damping magnet is one used for bringing an oscillating body to rest.<br> -The body may be a metallic disc or needle, and the action of the magnet<br> -depends on its lines of force which it establishes, so that the body has<br> -to cut them, and hence has its motion resisted.<br> -<br> -<br> -337 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnet, Deflection of.</span><br> -The change of position of a magnet from the plane of the earth's<br> -meridian in which it normally is at rest into another position at some<br> -angle thereto, by the effect of an artificial magnetic field, as the<br> -deflection of a galvanometer needle.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Electro-.</span><br> -A magnet consisting of a bar of iron, bundle of iron wires, iron tube or<br> -some equivalent, around which a coil of insulated wire is wound. Such<br> -combination becomes polarized when a current is passed through it and is<br> -an active magnet. On the cessation of the current its magnetism in part<br> -or almost completely disappears. (See Electro-magnet.)<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Equator of.</span><br> -In a magnet the locus of points of no attractive power and of no<br> -polarity. In a symmetrical, evenly polarized magnet it is the imaginary<br> -line girdling the centre. The terms Neutral Point or Neutral Line have<br> -displaced it.<br> -<br> -Synonyms--Neutral Line--Neutral Point.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Field.</span><br> -A magnet, generally an electro-magnet, used to produce the field in a<br> -dynamo or motor.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Haarlem.</span><br> -Celebrated magnets made in Haarlem, Holland. Logeman, Van Wetteren,<br> -Funckler and Van der Willigen were the makers who gave the celebrity to<br> -the magnets. They were generally horseshoe magnets, and would carry<br> -about twenty times their own weight.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnet, Horseshoe.</span><br> -A magnet of U shape--properly one with the poles brought a little closer<br> -together than the rest of the limbs. For direct lifting and attractive<br> -effects it is the most generally adopted type. Its advantage as regards<br> -lifting effect is due to small reluctance, q. v., offered by a complete<br> -iron circuit, such as the armature and magnet together produce. As the<br> -term is now used it is applied to any U shaped magnet.<br> -<br> -<br> -<img style="width: 676px; height: 482px;" alt="" - src="images/337F218.jpg"><br> -Fig. 218. JOULE'S ELECTRO-MAGNET.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Joule's Electro.</span><br> -An electro-magnet of the shape of a cylinder with a longitudinal segment<br> -cut-off. It is wound with wire as shown. The segment cut-off is a piece<br> -of the same shape as the armature. It is of high power.<br> -<br> -<br> -338 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Adherence.</span><br> -The tendency of a mass of iron to adhere to the poles of a magnet. It is<br> -best figured as due to the virtual shortening of lines of force, as the<br> -more permeable iron gives a better path for them than the air can<br> -afford, and consequently a virtually shorter one.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Attraction and Repulsion.</span><br> -The attraction of a magnet for iron, steel, nickel and cobalt and of<br> -unlike poles of magnets for each other. It is identical with<br> -electro-magnetic attraction, q.v. (Also see Electro-magnetism.)<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Attraction and Repulsion, -Coulomb's Law of.</span><br> -Magnetic attraction and repulsion are inversely as the square of the<br> -distance. (Ganot.)<br> -<br> -While theoretically true in the case of isolated poles, in practise it<br> -does not generally apply on account of the large diameter and relative<br> -shortness of magnets.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Axis.</span><br> -The line connecting the poles of a magnet. It does not generally<br> -coincide exactly with any symmetrical axis of figure. In such cases an<br> -error is introduced into the indications of the needle which must be<br> -determined and allowed for in compasses. To determine it with a magnetic<br> -needle the suspension cup is made removable, so that the needle can be<br> -reversed. Readings are taken with one side of the needle and then with<br> -the other side of the needle up, and the average corresponds with the<br> -position of the magnetic axis in both positions of the needle.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Azimuth.</span><br> -The angle, measured on a horizontal circle, between the magnetic<br> -meridian and a great circle of the earth passing through the observer<br> -and any observed body. It is the astronomical azimuth of a body referred<br> -to the magnetic meridian and therefore subject to the variation of the<br> -compass. The angle is the magnetic azimuth of the observed body.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Battery.</span><br> -A name for a compound permanent magnet; one made up by bolting or<br> -clamping together, or to single soft iron pole pieces, a number of<br> -single permanent magnets. There are a number of forms of compound<br> -magnets. In making them care has to be taken to have them of even<br> -strength. It is also well to have them slightly separated. The object of<br> -both these precautions is to prevent a stronger element or magnet from<br> -depolarizing its neighbor.<br> -<br> -Synonym--Compound Magnet.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Bridge.</span><br> -An apparatus for testing the relative permeability of iron. It consists<br> -of a rectangular system of iron cores. Three of the sides are wound with<br> -wire as shown. The other side is built up of double bars, and from the<br> -centre two curved arms rise, as shown in the cut. The arms do not touch.<br> -Between them a short magnet is suspended by a filament, which also<br> -carries a mirror and an index.<br> -<br> -<br> -339 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 669px; height: 265px;" alt="" - src="images/339F219.jpg"><br> -Fig. 219. MAGNETIC BRIDGE.<br> -<br> -<br> -A lamp and scale are provided as in the reflecting galvanometer. When<br> -adjusted the magnetic needle hangs as shown in the cut, Fig. 219,<br> -without any tendency to turn towards either curved pole piece. If all<br> -iron parts are symmetrical and of similar metal, a current through the<br> -coils will make no difference. It will work in magnetic opposition upon<br> -the two arms, or, in other words, will maintain both arms at identical<br> -potential.<br> -<br> -<br> -<img style="width: 644px; height: 288px;" alt="" - src="images/339F220.jpg"><br> -Fig. 220. POLE PIECES, MAGNETIC NEEDLE <br> -AND MIRROR OF MAGNETIC BRIDGE.<br> -<br> -<br> -If there is the least difference in permeability, length or thickness<br> -between any of the iron bars the magnetic potential of the two curved<br> -arms will differ, and the magnetic needle will turn one way or the<br> -other. In practical use different samples of iron are substituted for<br> -the unwound members of the fourth side of the parallelogram, and the<br> -needle by its motions indicates the permeability.<br> -<br> -In the cut, Fig. 220, D D are the ends of the curved pole pieces; A the<br> -wire carrying the mirror B and magnetic needle N, and E is the index<br> -which shows the larger deflections.<br> -<br> -<br> -340 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Circuit.</span><br> -A magnetic field of force is characterized by the presence of lines of<br> -force, which, while approximately parallel, curve around and tend to<br> -form closed curves. The polarity of a field of force is referred to an<br> -imaginary direction of the lines of force from the north pole through<br> -space to the south pole, and in the part of the field corresponding to<br> -the body of the magnet, from the south to the north pole. The cut<br> -indicates these features. Hence the magnetic field of force is termed<br> -the magnetic circuit, and to it are attributed a species of resistance<br> -termed reluctance, q. v., and the producing cause of the field or lines<br> -of force is termed sometimes magneto-motive force, q. v.) corresponding<br> -to the electro-motive force. The modern treatment of the magnetic<br> -circuit is similar to the application of Ohm's law and the laws of<br> -resistance and conductivity to the electric circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Circuit, Double.</span><br> -A magnetic circuit which virtually represents two horseshoe magnets<br> -placed with their like poles in contact. It is used for field magnets,<br> -the armatures occupying a place between the consequent poles.<br> -<br> -<br> -<img style="width: 606px; height: 547px;" alt="" - src="images/340F221.jpg"><br> -Fig. 221. ONE-HALF PORTION OF A DOUBLE MAGNETIC CIRCUIT.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Concentration of Ores.</span><br> -The concentration of ores or the freeing them from their gangue by<br> -magnetic attraction. It is only applicable to those cases in which<br> -either the ore itself or the gangue is attracted by the magnet. Its<br> -principal application is to the concentration of magnetic iron sands.<br> -(See Magnetic Concentration.)<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Concentrator.</span><br> -An apparatus similar to a magnetic separator, q. v., but used to<br> -concentrate magnetic iron sands. By the action of electro-magnets the<br> -magnetic iron sand (magnetite) is separated from the sand with which it<br> -is mixed.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Conductivity and Conductance.</span><br> -The first notion of permeance and of the magnetic circuit included the<br> -idea of magnetic conductivity, which conducted lines of force urged by<br> -magneto-motive force through a magnetic circuit. The terms are displaced<br> -by permeability and permeance.<br> -<br> -<br> -341 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Continuity.</span><br> -The completeness of a magnetic circuit, as when the armature of a<br> -horseshoe magnet is in contact with both poles. It is an attribute of a<br> -paramagnetic substance only and is identical for permanent magnets or<br> -for electro-magnets. An air space intervening between armature and<br> -magnet poles, or a space filled with any diamagnetic substance prevents<br> -continuity, although the lines of force to some extent still find their<br> -way around. The leakage is increased by discontinuity.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Control.</span><br> -Control of a magnetic needle, magnet, iron index or armature, in a<br> -galvanometer, ammeter or voltmeter by a magnetic field; the restitutive<br> -force being derived from a permanent magnet.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Couple.</span><br> -The couple of magnetic force which tends to bring the magnetic needle<br> -into the plane of the magnetic meridian. One force is represented by the<br> -imaginary pull upon the north pole, and the other by the opposite pull<br> -upon the south pole of the needle. The moment of the couple varies from<br> -a maximum when the needle is at right angles to the plane of the<br> -magnetic meridian to zero when it is in such plane.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Creeping.</span><br> -Viscous hysteresis; the slow increase of magnetism in a paramagnetic<br> -body when exposed to induction.<br> -<br> -<br> -<img style="width: 536px; height: 580px;" alt="" - src="images/341F222.jpg"><br> -Fig. 222. MAGNETIC CURVES OR FIGURES.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Curves.</span><br> -The pictorial representation of magnetic lines of force. It is generally<br> -produced by scattering filings on a sheet of paper or pane of glass held<br> -over a magnet. The filings arrange themselves in characteristic curves.<br> -Tapping the paper or pane of glass facilitates the arrangement, or<br> -jarring the filings off a smaller magnet, so that they fall polarized<br> -upon the paper, is thought by some to improve the effect. The group of<br> -curves forms what are termed magnetic figures, q. v.<br> -<br> -<br> -342 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Declination.</span><br> -The angular deviation of the magnetic needle, causing it to rest at an<br> -angle with the true meridian; the variation of the compass. (See<br> -Magnetic Elements.)<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Density.</span><br> -The intensity of magnetization expressed in lines of force per stated<br> -area of cross-section in a plane at right angles to the lines of force.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Dip.</span><br> -The inclination from the horizontal assumed by a magnetic needle free to<br> -move in the vertical plane. (See Magnetic Elements.) The angle of dip or<br> -inclination is entirely a function of the earth, not of the needle.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Discontinuity.</span><br> -A break or gap in a magnetic circuit. To make a complete circuit the<br> -iron or other core must be continuous. If the armature of a horseshoe<br> -magnet is in contact with both poles the continuity is complete. If the<br> -armature is not in contact magnetic continuity gives place to<br> -discontinuity. It is an attribute of a paramagnetic substance only, and<br> -is identical for permanent magnets, or for electro-magnets.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Elements.</span><br> -The qualities of the terrestrial magnetism at any place as expressed in<br> -its action upon the magnetic needle. Three data are involved.<br> -<br> -I. The Declination or Variation.<br> -II. The Inclination or Dip.<br> -III. The Force or Intensity.<br> -<br> -I. The Declination is the variation expressed in angular degrees of the<br> -magnetic needle from the true north and south, or is the angle which the<br> -plane of the magnetic meridian makes with that of the geographical<br> -meridian. It is expressed as east or west variation according to the<br> -position of the north pole; east when the north pole of the needle is to<br> -the east of the true meridian, and vice versa. Declination is different<br> -for different places; it is at present west in Europe and Africa, and<br> -east in Asia and the greater part of North and South America. The<br> -declination is subject to (a) secular, (b) annual and (c) diurnal<br> -variations. These are classed as regular; others due to magnetic storms<br> -are transitory and are classed as irregular, (a) Secular variations. The<br> -following table shows the secular variations during some three hundred<br> -years at Paris. These changes are termed secular, because they require<br> -centuries for their completion.<br> -<br> -<br> -</big></big><big><big>343 </big></big><big><big> - STANDARD ELECTRICAL DICTIONARY. <br> -<br> -<br> -Table of Declination or Variation at Paris.<br> -Year. Declination.<br> -1580 11º 30' E.<br> -1663 0°<br> -1700 8° 10' W.<br> -1780 19º 55' W.<br> -1785 22º 00' W.<br> -1805 22º 5' W.<br> -1814 22º 34' W.<br> -1825 22° 22' W.<br> -1830 22º 12' W.<br> -1835 22º 4' W.<br> -1850 20º 30' W.<br> -1855 19º 57' W.<br> -1860 19º 32' W.<br> -1865 18º 44' W.<br> -1875 17º 21' W.<br> -1878 17º 00' W.<br> -[Transcriber's note The value for 2008 is about 0° 48' W, -changing by<br> -0° 7' E/year.]<br> -<br> -On scrutinizing these figures it will be seen that there is part of a<br> -cycle represented and that the declination is slowly returning to the<br> -zero point after having reached its maximum western variation in 1814.<br> -Upwards of 300 years would be required for its completion on the basis<br> -of what is known. In other places, notably the coast of Newfoundland,<br> -the Gulf of the St. Lawrence and the rest of the North American seaboard<br> -and in the British Channel, the secular variations are much more rapid<br> -in progress. (b) Annual variations--These were first discovered in 1780<br> -by Cassini. They represent a cycle of annual change of small extent,<br> -from 15' to 18' only. In Paris and London the annual variation is<br> -greatest about the vernal equinox, or March 21st, and diminishes for the<br> -next three months, and slowly increases again during the nine following<br> -months. It varies during different epochs. (c) Diurnal variations were<br> -discovered in 1722 by Graham. A long needle has to be employed, or the<br> -reflection of a ray of light, as in the reflecting galvanometer, has to<br> -be used to observe them. In England the north pole of the magnetic<br> -needle moves every day from east to west from sunrise until 1 or 2 P.<br> -M.; it then tends towards the east and recovers its original position by<br> -10 P. M. During the night the needle is almost stationary. As regards<br> -range the mean amplitude of diurnal variations at Paris is from April to<br> -September 13' to 15'; for the other months from 8' to 10'. On some days<br> -it amounts to 25' and sometimes is no more than 5'. The amplitude of<br> -diurnal variations decreases from the poles to the equator. Irregular<br> -variations accompany earthquakes, the aurora borealis and volcanic<br> -eruptions. In Polar regions the auroral variations may be very great;<br> -even at 40° latitude they may be 1° or 2°. Simultaneous -irregularities<br> -sometimes extend over large areas. Such are attributed to magnetic<br> -storms. II. The Inclination is the angle which the magnetic needle makes<br> -with the horizon, when the vertical plane in which the needle is assumed<br> -to be free to move coincides with the magnetic meridian. It is sometimes<br> -called the dip of the needle. It varies as does the declination, as<br> -shown in the following table of inclinations of London.<br> -<br> -<br> -344 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Table of Inclination or Dip at London<br> -Year. Inclination.<br> -1576 71° 50'<br> -1600 72°<br> -1676 73° 30'<br> -1723 74° 42'<br> -1773 72° 19'<br> -1780 72° 8'<br> -1790 71° 33'<br> -1800 70° 35'<br> -1821 70° 31'<br> -1828 69° 47'<br> -1838 69° 17'<br> -1854 68° 31'<br> -1859 68° 21'<br> -1874 67° 43'<br> -1876 67° 39'<br> -1878 67° 36'<br> -1880 67° 35'<br> -1881 67° 35'<br> -<br> -III. Force or Intensity is the directive force of the earth. It varies<br> -with the squares of the number of oscillations the magnetic needle will<br> -make if caused to oscillate from a determined initial range. The<br> -intensity is supposed to be subject to secular change. According to<br> -Gauss the total magnetic intensity of the earth is equal to that which<br> -would be exerted if in each cubic yard there were eight bar magnets,<br> -each weighing one pound. This is, of course, a rough way of expressing<br> -the degree of intensity. Intensity is least near the magnetic equator<br> -and greatest near the magnetic poles; the places of maximum intensity<br> -are termed the magnetic foci. It varies with the time of day and<br> -possibly with changes in altitude.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Elongation.</span><br> -The elongation a bar of iron or steel undergoes when magnetized. By<br> -magnetization it becomes a little longer and thinner, there being no<br> -perceptible change in volume. The change is accompanied by a slight<br> -sound--the magnetic tick. An exceedingly delicate adjustment of<br> -apparatus is required for its observation.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Equator.</span><br> -A locus of the earth's surface where the magnet has no tendency to dip.<br> -It is, approximately speaking, a line equally distant from the magnetic<br> -poles, and is called also the aclinic line. It is not a great circle of<br> -the earth.<br> -<br> -<br> -345 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Field of Force.</span><br> -The field of force established by a magnet pole. The attractions and<br> -repulsions exercised by such a field follow the course of the electro-<br> -magnetic lines of force. (See also Field of Force.) Thus the tendency of<br> -a polarized needle attracted or repelled is to follow, always keeping<br> -tangential to curved lines, the direction of the lines of force, however<br> -sweeping they may be. The direction of magnetic lines of force is<br> -assumed to be the direction in which a positive pole is repelled or a<br> -negative one attracted; in other words, from the north pole of a magnet<br> -to its south pole in the outer circuit. The direction of lines of force<br> -at any point, and the intensity or strength of the field at that point,<br> -express the conditions there. The intensity may bc expressed in terms of<br> -that which a unit pole at unit distance would produce. This intensity as<br> -unitary it has been proposed to term a Gauss. (See Weber.)<br> -<br> -The direction of the lines of force in a magnetic field are shown by the<br> -time-honored experiment of sprinkling filings of iron upon a sheet of<br> -paper held over a magnet pole or poles. They arrange themselves, if the<br> -paper is tapped, in more or less curved lines tending to reach from one<br> -pole of the magnet to the other. Many figures may be produced by<br> -different conditions. Two near poles of like name produce lines of force<br> -which repel each other. (See Magnetic Curves.)<br> -<br> -A magnetic and an electro-magnetic field are identical in all essential<br> -respects; the magnetic field may be regarded as a special form of the<br> -electro-magnetic field, but only special as regards its production and<br> -its defined north and south polar regions.<br> -<br> -Synonyms--Magnetic Spin (not much used).<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Field, Uniform.</span><br> -A field of identical strength in all parts, such as the earth's magnetic<br> -field. If artificially produced, which can only be approximately done,<br> -it implies large cross-section of magnet pole in proportion to the<br> -length of the magnetic needle affected by it, which is used in<br> -determining its uniformity.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Figures.</span><br> -The figures produced by iron filings upon paper or glass held near<br> -magnetic poles. By these figures the direction of lines of force is<br> -approximately given, and a species of map of the field is shown. (See<br> -Magnetic Field of Force--Magnetic Curves.)<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Filament.</span><br> -The successive rows of polarized molecules assumed to exist in<br> -magnetized iron. Each molecule represents an infinitely small magnet,<br> -and its north pole points to the south pole of the next molecule. Such a<br> -string or row is a theoretical conception based on the idea that the<br> -molecules in a magnet are all swung in to parallelism in the magnetizing<br> -process. A magnetic filament may be termed the longitudinal element of a<br> -magnet. (See Magnetism, Hughes' Theory of.)<br> -<br> -[Transcriber's note: This description parallels the modern<br> -notion of electron spin as the basis of magnetism in materials.]<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Fluids.</span><br> -A two-fluid theory of magnetism has been evolved, analogous to the<br> -two-fluid theory of electricity. It assumes north fluid or "red<br> -magnetism" and a south fluid or "blue magnetism." Each magnetism is<br> -supposed to predominate at its own pole and to attract its opposite.<br> -Before magnetization the fluids are supposed to neutralize each other<br> -about each molecule; magnetization is assumed to separate them,<br> -accumulating quantities of them at the poles.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Flux.</span><br> -Magnetic induction; the number of lines of force that pass through a<br> -magnetic circuit.<br> -<br> -Synonym--Magnetic Flow.<br> -<br> -<br> -346 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Force.</span><br> -The forces of attraction and repulsion exercised by a magnet. By<br> -Ampere's theory it is identical with the forces of attraction and<br> -repulsion of electric currents.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Friction.</span><br> -The damping effect produced on the movements of a mass of metal by<br> -proximity to a magnet; the phenomenon illustrated in Arago's wheel, q.<br> -v. When a mass of metal moves in the vicinity of a magnet it cuts the<br> -lines of force emanating from its poles, thereby producing currents in<br> -its mass; as the production of these currents absorbs energy a damping<br> -effect is produced upon the movements of the mass.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Gear.</span><br> -Friction gear in which electro-magnetic adherence is employed to draw<br> -the wheels together. (See Adherence, Electro-magnetic--Electro-magnetic<br> -Friction Gear.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Inclination.</span><br> -The inclination from the horizontal of a magnetic needle placed in the<br> -magnetic meridian. (See Magnetic Element--Inclination Map.)<br> -<br> -Synonym--Magnetic Dip.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Induction.</span><br> -The force of magnetization within an induced magnet. It is in part due<br> -to the action of the surrounding particles of polarized material; in<br> -part to the magnetic field. (See Magnetic Induction, Coefficient of.)<br> -<br> -In a more general way it is the action of a magnet upon bodies in its<br> -field of force. In some cases the magnetism induced causes the north<br> -pole of the induced magnet to place itself as far as possible from the<br> -north pole of the inducing magnet and the same for the south poles. Such<br> -substances are called paramagnetic or ferromagnetic. They lie parallel<br> -or tangential to the lines of force. In other cases the bodies lie at<br> -right angles or normal to the lines of force. Such bodies are called<br> -diamagnetic.<br> -<br> -Some bodies are crystalline or not homogeneous in structure, and in them<br> -the lines of magnetic induction may take irregular or eccentric paths.<br> -(See AEolotropic.)<br> -<br> -Synonym--Magnetic Influence.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Induction, Apparent -Coefficient of.</span><br> -The apparent permeability of a paramagnetic body as affected by the<br> -presence of Foucault currents in the material itself. These currents act<br> -exactly as do the currents in the coils surrounding the cores of<br> -electro-magnets. They produce lines of force which may exhaust the<br> -permeability of the iron, or may, if in an opposite direction, add to<br> -its apparent permeability.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Induction, Coefficient of.</span><br> -The number, obtained by dividing the magnetization of a body, expressed<br> -in lines of force produced in it, by the magnetizing force which has<br> -produced such magnetization, expressed in lines of force producible by<br> -the force in question in air. It always exceeds unity for iron, nickel<br> -and cobalt. It is also obtained by multiplying the coefficient of<br> -induced magnetization by 4 PI (4 * 3.14159) and adding 1. (See Magnetic<br> -Susceptibility--Magnetization, Coefficient of Induced.)<br> -<br> -<br> -347 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The coefficient of magnetic induction varies with the material of the<br> -induced mass, and varies with the intensity of the magnetizing force.<br> -This variation is due to the fact that as the induced magnetism in a<br> -body increases, the magnetizing force required to maintain such<br> -induction, increases in a more rapid ratio. The coefficient of magnetic<br> -induction is the same as magnetic permeability, and in a certain sense<br> -is the analogue of conductivity. It is also termed the multiplying power<br> -of the body or core magnetized. It is the coefficient of induced<br> -magnetization (see Magnetization, Coefficient of Induced) referred to a<br> -mass of matter. For diamagnetic bodies the coefficient has a negative<br> -sign; for paramagnetic bodies it has a positive sign.<br> -<br> -Synonyms--Permeability--Multiplying Power--Magnetic Inductive Capacity.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Induction, Dynamic.</span><br> -The induction produced by a magnetic field which moves with respect to a<br> -body, or where the body if moving moves at a different rate, or where<br> -the body moves and the field is stationary. In the case where both move,<br> -part of the induction may be dynamic and part static. (See Magnetic<br> -Induction, Static.)<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Induction, Static.</span><br> -Magnetic induction produced by a stationary field acting upon a<br> -stationary body.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Induction, Tube of.</span><br> -An approximate cylinder or frustrum of a cone whose sides are formed of<br> -lines of magnetic induction. (See Magnetic Induction, Lines of.) The<br> -term tube is very curiously applied in this case, because the element or<br> -portion of a magnetic field thus designated is in no sense hollow or<br> -tubular.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Inertia.</span><br> -A sensible time is required to magnetize iron, or for it to part with<br> -its magnetism, however soft it may be. This is due to its magnetic<br> -inertia and is termed the lag. Permanent or residual magnetism is a<br> -phase of it. It is analogous to self-induction of an electric circuit,<br> -or to the residual capacity of a dielectric.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Insulation.</span><br> -Only approximate insulation of magnetism is possible. There is no<br> -perfect insulator. The best ones are only 10,000 times less permeable<br> -than iron. Hence lines of force find their way through air and all other<br> -substance, being simply crowded together more in paths of iron or other<br> -paramagnetic substance.<br> -<br> -<br> -348 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Intensity.</span><br> -The intensity of the magnetization of a body. It is measured by the<br> -magnetic lines of force passing through a unit area of the body, such<br> -area being at right angles to the direction of the lines of force.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Lag.</span><br> -In magnetism the tendency of hard iron or steel especially to take up<br> -magnetism slowly, and to part with it slowly. (See Magnetic Inertia.)<br> -The lag affects the action of a dynamo, and is a minor cause of those<br> -necessitating the lead of the brushes.<br> -<br> -Synonym--Magnetic Retardation.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Latitude.</span><br> -Latitude referred to the magnetic equator and isoclinic lines.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Leakage.</span><br> -The lines of force in a field magnet which pass through the air and not<br> -through the armature are useless and represent a waste of field. Such<br> -lines constitute magnetic leakage.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Limit.</span><br> -The temperature beyond which a paramagnetic metal cannot be magnetized.<br> -The magnetic limit of iron is from a red to a white heat; of cobalt, far<br> -beyond a white heat; of chromium, below a red heat; of nickel at about<br> -350° C. (662°F.) of manganese, from 15° C. to 20° C. -(59° to 68° F.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Lines of Force.</span><br> -Lines of force indicating the distribution of magnetic force, which is<br> -due presumably to whirls of the ether. A wire or conductor through which<br> -a current is passing is surrounded by an electro-magnetic field of<br> -force, q. v., whose lines of force form circles surrounding the<br> -conductor in question. A magnet marks the existence of a similar<br> -electro-magnetic field of force whose lines form circuits comprising<br> -part of and in some places all of the body of the magnet, and which are<br> -completed through the air or any surrounding paramagnetic or diamagnetic<br> -body. They may be thought of as formed by the Ampérian sheet of -current,<br> -and analogous to those just mentioned as surrounding a conductor.<br> -<br> -<br> -<img style="width: 723px; height: 287px;" alt="" - src="images/348F223.jpg"><br> -Fig. 223. MAGNETIC LINES OF FORCE, DIRECTION OF.<br> -<br> -<br> -A magnetic line of force may be thought of as a set of vortices or<br> -whirls, parallel to each other, and strung along the line of force which<br> -is the locus of their centres.<br> -<br> -If as many lines are drawn per square centimeter as there are dynes (per<br> -unit pole) of force at the point in question, each such line will be a<br> -unitary c. g. s. line of force.<br> -<br> -<br> -349 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Mass.</span><br> -A term for a quantity of magnetism. Unit mass is the quantity which at<br> -unit distance exercises unit force.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Matter.</span><br> -Imaginary matter assumed as a cause of magnetism. Two kinds, one<br> -positive and one negative, may be assumed as in the two fluid theory of<br> -electricity, or only one kind, as in the single fluid theory of<br> -electricity. Various theories of magnetic matter have been presented<br> -whose value is only in their convenience.<br> -<br> -[Transcriber's note: See "magnet" and Edward Purcell's explanation of<br> -magnetism using general relativity.]<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Memory.</span><br> -The property of retaining magnetism; coercive force; magnetic inertia;<br> -residual magnetism.<br> -<br> -[Transcriber's note: Small ferrite magnetic donuts were used as computer<br> -main memory from 1950 to 1970.]<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Meridian.</span><br> -A line formed on the earth's surface by the intersection therewith of a<br> -plane passing through the magnetic axis. It is a line determined by the<br> -direction of the compass needle. The meridians constantly change in<br> -direction and correspond in a general way to the geographical meridians.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Moment.</span><br> -The statical couple with which a magnet would be acted on by a uniform<br> -magnetic field of unit intensity if placed with its magnetic axis at<br> -right angles to the lines of force of the field. (Emtage.) A uniformly<br> -and longitudinally magnetized bar has a magnetic moment equal to the<br> -product of its length by the strength of its positive pole.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Needle.</span><br> -A magnet with a cup or small depression at its centre and poised upon a<br> -sharp pin so as to be free to rotate or oscillate in a horizontal plane.<br> -The cup is often made of agate. Left free to take any position, it<br> -places its magnetic axis in the magnetic meridian.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Parallels.</span><br> -Lines roughly parallel to the magnetic equator on all parts of each of<br> -which the dip of the magnetic needle is the same; also called Isoclinic<br> -Lines. These lines mark the places of the intersection of equipotential<br> -surfaces with the earth's surface. They are not true circles, and near<br> -the poles are irregular ellipses; the magnet there points toward their<br> -centres of curvature. They correspond in a general way with the<br> -Geographical Parallels of Latitude.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Permeability.</span><br> -The specific susceptibility of any substance, existing in a mass, for<br> -magnetic induction. (See Magnetic Induction, Coefficient of, synonym for<br> -Magnetic Permeability and Magnetization, Coefficient of Induced.)<br> -<br> -Synonyms--Magnetic Inductive Capacity--Multiplying Power--Coefficient of<br> -Magnetic Induction.<br> -<br> -<br> -350 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Perturbations.</span><br> -Irregular disturbances of the terrestrial magnetism, as by the aurora<br> -and in electric storms.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Poles.</span><br> -The points where the equipotential surfaces of the terrestrial field of<br> -force graze the earth's surface; the points toward which the north or<br> -south poles of the magnetic needle is attracted. Over a magnetic pole<br> -the magnetic needle tends to stand in a vertical position. There are two<br> -poles, Arctic or negative, and Antarctic or positive. Magnetic needles<br> -surrounding them do not necessarily point toward them, as they point to<br> -the centres of curvature of their respective magnetic parallels. The<br> -poles constantly change in position. The line joining them does not<br> -coincide with anything which may be termed the magnetic axis of the<br> -earth.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Poles, False.</span><br> -Poles on the earth's surface other than the two regular magnetic poles.<br> -There seem by observation to be several such poles, while analogy would<br> -limit true magnetic poles to two in number.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Potential.</span><br> -The potential at any point of a magnetic field is the work which would<br> -be done by the magnetic forces of the field upon a positive unit of<br> -magnetism as it moves from that point to an infinite distance. (Emtage.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Proof Piece.</span><br> -A piece of iron used for testing magnets and the distribution of<br> -magnetism in bars, by suspending or supporting above or near the magnet,<br> -by detaching after adherence, and in other ways.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Proof Plane.</span><br> -An exploring coil used for testing the distribution of magnetism. It is<br> -connected in circuit with a galvanometer, and exposed to alternation of<br> -current, or to other disturbing action produced by the magnet or field<br> -under examination. This affects the galvanometer, and from its movements<br> -the current produced in the coil, and thence the magnetic induction to<br> -which it was exposed, are calculated.<br> -<br> -Synonym--Exploring Coil.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Quantity.</span><br> -The magnetism possessed by a body; it is proportional to the action of<br> -similar poles upon each other, or to the field produced by the pole in<br> -question. It is also called the strength of a pole.<br> -<br> -The force exercised by two similar poles upon each other varies with<br> -their product and inversely with the square of the distance separating<br> -them; or it may be expressed thus (m * m) / (L^2). This is a force, and<br> -the dimensions of a force are ML/(T^2). Therefore, (m^2)/(L^2) =<br> -ML/(T^2) or m = (M^.5)*(L^1.5)/T.<br> -<br> -<br> -351 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Reluctance.</span><br> -The reciprocal of permeance; magnetic resistance; the relative<br> -resistance to the passage of lines of force offered by different<br> -substances. The idea is derived from treating the magnetic circuit like<br> -an electric one, and basing its action on magneto-motive force acting<br> -through a circuit possessing magnetic reluctance.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Reluctivity.</span><br> -The reciprocal of magnetic permeability, q. v.<br> -<br> -Synonym--Magnetic Resistance.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Retentivity.</span><br> -The property of steel or hard iron by which it slowly takes up and<br> -slowly parts with a magnetic condition--traditionally (Daniell) called<br> -coercitive force.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Rotary Polarization.</span><br> -If a plane polarized beam of light is sent through a transparent medium<br> -in a magnetic field its plane of polarization is rotated, and this<br> -phenomenon is denoted as above. (Compare Refraction, Electric, and see<br> -Electro-magnetic Stress.) This has been made the basis of a method for<br> -measuring current. A field of force varies with the current; the<br> -polarization produced by such field is therefore proportional to the<br> -current. (Becquerel & Rayleigh.)<br> -<br> -A plane polarized beam of light passing through the transparent medium<br> -in the magnetic field by the retardation or acceleration of one of its<br> -circular components has its plane of polarization rotated as described.<br> -The direction of the lines of force and the nature of the medium<br> -determine the sense of the rotation; the amount depends upon the<br> -intensity of the field resolved in the direction of the ray, and on the<br> -thickness and nature of the medium.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Saturation.</span><br> -The maximum magnetic force which can be permanently imparted to a steel<br> -bar. A bar may be magnetized beyond this point, but soon sinks to it.<br> -The magnetism produced in a bar is prevented from depolarization by the<br> -retentivity or coercive force of the bar. The higher the degree of<br> -magnetization the greater the tendency to depolarization.<br> -<br> -It is also defined as the maximum intensity of magnetism produced in a<br> -paramagnetic substance by a magnetic field as far as affected by the<br> -permeability of the substance in question. The more lines of force<br> -passed through such a substance the lower is its residual permeability.<br> -It is assumed that this becomes zero after a certain point, and then the<br> -point of saturation is reached. After this point is reached the addition<br> -of any lines of force is referred entirely to the field and not at all<br> -to the permeability of the substance. But such a zero is only definable<br> -approximately.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Screen.</span><br> -A box or case of soft iron, as thick as practicable, for protecting<br> -bodies within it from the action of a magnetic field. The lines of force<br> -to a great extent keep within the metal of the box on account of its<br> -permeability, and but a comparatively few of them cross the space within<br> -it.<br> -<br> -Such screens are used to prevent watches from being magnetized, and are<br> -a part of Sir William Thomson's Marine galvanometer.<br> -<br> -A magnetic screen may be a sphere, an infinite or very large plane, or<br> -of the shape of any equipotential surface.<br> -<br> -Synonym--Magnetic Shield.<br> -<br> -<br> -352 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Self-induction.</span><br> -The cause of a magnet weakening is on account of this quality, which is<br> -due to the direction of the lines of force within a magnet from the<br> -positive towards the negative pole. "A magnet thus tends to repel its<br> -own magnetism and to weaken itself by self-induction." (Daniell.)<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Separator.</span><br> -An apparatus for separating magnetic substances from mixtures. Such<br> -separators depend on the action of electro-magnets. In one form the<br> -material falls upon an iron drum, magnetized by coils. Any magnetic<br> -substance adheres to the drum and is thereby separated. They are used by<br> -porcelain makers for withdrawing iron particles from clay, by machinists<br> -to separate iron filings and chips from brass, and for similar purposes.<br> -<br> -<br> -<img style="width: 481px; height: 574px;" alt="" - src="images/352F224.jpg"><br> -Fig. 224. MAGNETIC SEPARATOR.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Shell.</span><br> -A theoretical conception of a cause of a magnetic field or of a<br> -distribution of magnetism. If we imagine a quantity of very short<br> -magnets arranged in contact with their like poles all pointing in the<br> -same direction so as to make a metal sheet, we have a magnetic shell.<br> -Its magnetic moment is equal to the sum of the magnetic moment of all<br> -its parts. If the shell is of uniform strength the magnetic moment of a<br> -unit area gives the strength of the shell; it is equal to the magnetic<br> -quantity per unit of area, multiplied by the thickness of the shell.<br> -<br> -If its strength is uniform throughout a magnetic shell is called simple;<br> -if its strength varies it is termed complex.<br> -<br> -Emtage thus defines it: A magnetic shell is an indefinitely thin sheet<br> -magnetized everywhere in the direction normal to itself.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Shell, Strength of.</span><br> -The magnetic quantity per unit of area of the shell multiplied by the<br> -thickness of the shell.<br> -<br> -<br> -353 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Shield.</span><br> -In general a magnetic screen, q. v. Sometimes a strong local field is<br> -made to act as a shield, by its predominance overcoming any local or<br> -terrestrial field to which the needle to be protected may be exposed.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Shunt.</span><br> -The conception of a magnetic circuit being formed, the shunt is a<br> -corollary of the theory. It is any piece of iron which connects points<br> -of a magnet differing in polarity, so as to divert part of the lines of<br> -force from the armature or yoke. The shunt is especially applicable in<br> -the case of horseshoe magnets. Thus a bar of iron placed across from<br> -limb to limb a short distance back from the poles would act as a shunt<br> -to the armature and would divert to itself part of the lines of force<br> -which would otherwise go through the armature and would weaken the<br> -attraction of the magnet for the latter. In dynamos a bar of iron used<br> -as a magnetic shunt has been used to diminish the lines of force going<br> -through the armature and hence to weaken the field and diminish the<br> -electro-motive force. By moving the shunt nearer or further from the<br> -poles the dynamo is regulated.<br> -<br> -In the cut the projections between the yoke and poles of the magnet<br> -shown act as a shunt to the yoke, taking some lines of force therefrom.<br> -<br> -<br> -<img style="width: 507px; height: 728px;" alt="" - src="images/353F225.jpg"><br> -Fig. 225. MAGNETIC SHUNT.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Storms.</span><br> -Terrestrial magnetic disturbances sometimes covering very wide areas,<br> -and affecting the magnetic declination and inclination. One such<br> -disturbance was felt simultaneously at Toronto, Canada, the Cape of Good<br> -Hope, Prague and Van Diemen's Land. (Sabine.)<br> -<br> -<br> -354 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Strain.</span><br> -The strain produced by magnetic lines of force in substances exposed to<br> -their action. It is observed in substances placed between the poles of a<br> -strong electro-magnet, and evinces itself in the alteration of the<br> -optical properties of transparent substances.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Stress.</span><br> -The stress produced by magnetic lines of force on substances through<br> -which they pass, evidenced in alteration of the optical properties of<br> -transparent bodies thus treated.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Susceptibility.</span><br> -The specific intrinsic susceptibility of any material for magnetic<br> -induction. It refers to the particle of matter, and not to the mass, as<br> -in the latter its own particles react on each other and bring about what<br> -is termed permeability, q. v. (See also Magnetization, Coefficient of<br> -Induced, and Magnetic Induction, Coefficient of.)<br> -<br> -Synonym--Coefficient of Induced Magnetization.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Tick.</span><br> -When a bar of iron is suddenly magnetized or demagnetized it emits a<br> -slight sound, called the Page sound, or the magnetic tick. This has been<br> -utilized in a telephone by Reiss. The telephone will receive sound, but<br> -is very weak. It consists of a bar surrounded with a coil of insulated<br> -wire. Variations in current produce sounds, which may be articulate if<br> -the currents are produced by a telephonic transmitter.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetic Twist.</span><br> -A bar of iron held in the magnetic meridian and pointing to the pole and<br> -twisted becomes to some extent permanently magnetized. Conversely a bar<br> -when magnetized seems to have a twist set up in it. The latter is<br> -magnetic twist.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Variations.</span><br> -Changes in the value of magnetic declination or inclination. (See<br> -Magnetic Elements.)<br> -<br> -<br> -<span style="font-weight: bold;">Magnetism, Ampére's Theory of.</span><br> -A theory accounting for magnetic phenomena by assuming the existence of<br> -currents circulating around the molecules of permanent magnets. If such<br> -currents so circulate and all in the same direction, the result is the<br> -same as if the body of the magnet was enveloped in currents representing<br> -those of an electro-magnet or solenoid. This is because in the interior<br> -the current around one molecule would counteract the current around its<br> -neighboring ones in part, so that the only virtual currents left would<br> -be represented by those on the outer surfaces of the outer shell of<br> -molecules, and these virtually resolve themselves into one general<br> -current sheet, surrounding the magnet and coinciding with its surface.<br> -<br> -The theory assumes that such currents permanently circulate around the<br> -molecules of paramagnetic substances. Under ordinary conditions there is<br> -no coincidence in their direction and no resultant current is produced.<br> -When magnetized or polarized the molecules are brought into order, so<br> -that the direction of their current coincides and the body becomes a<br> -magnet.<br> -<br> -<br> -355 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 607px; height: 469px;" alt="" - src="images/355F226.jpg"><br> -Fig. 226. AMPÉRIAN CURRENTS IN MAGNETS.<br> -<br> -<br> -At the north pole of the magnet the direction of the Ampérian -currents<br> -is the reverse of that of a watch when the observer faces the pole; the<br> -reverse obtains for the south pole.<br> -<br> -The attraction of opposite and repulsion of similar poles is explained<br> -by the actions of the Ampérian currents upon each other. If -north and<br> -south pole are placed together these currents will coincide in direction<br> -and hence will attract each other. If two like poles are put together<br> -the currents will have opposite directions and will repel each other.<br> -<br> -No energy is supposed to be required to maintain currents around or in a<br> -single molecule.<br> -<br> -<br> -<img style="width: 683px; height: 320px;" alt="" - src="images/355F227.jpg"><br> -Fig. 227. NORTH AND SOUTH POLES OF A MAGNET <br> -SHOWING DIRECTION OF AMPÉRIAN CURRENTS.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetism, Blue.</span><br> -A term arising from the two fluid theory of magnetism; the magnetism of<br> -the south pole of a magnet. (See Magnetic Fluids.) The magnetism of the<br> -north pole is termed red magnetism. Both terms originated presumably in<br> -the painting of magnets, and are little used.<br> -<br> -Synonym--South Magnetic Fluid.<br> -<br> -<br> -356 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetism, Components of Earth's.</span><br> -The magnetic force of the earth acts in the plane of the magnetic<br> -meridian and in direction generally lies oblique to the plane of the<br> -horizon. It can be resolved into two components, one vertical, which has<br> -no directive effect upon the magnetic needle, the other horizontal,<br> -which represents the directive element for the usual compass needle. For<br> -the dipping needle, q. v., the vertical component is the only active<br> -one. A magnetic needle mounted on a universal joint at its centre of<br> -gravity would be acted on by both components.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetism, Creeping of.</span><br> -The gradual increase of magnetism when a magnetic force is applied with<br> -absolute steadiness to a piece of iron. It is a form of magnetic lag. It<br> -may last for half an hour and involve an increase of several per cent.<br> -of the total magnetism.<br> -<br> -Synonym--Viscous Hysteresis.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Iron Clad.</span><br> -A magnet with a casing of iron connected at one end to the core. The<br> -term is generally applied to electromagnets of this form.<br> -<br> -Synonyms--Tubular Magnet--Jacketed Magnet.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetism, Decay of.</span><br> -The gradual loss of magnetism by permanent magnets, due to accidental<br> -shocks, changes of temperature, slow spontaneous annealing of the iron<br> -and other similar causes.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetism, Discharge of.</span><br> -The loosing of magnetization. Thus in a shunt-wound dynamo there is a<br> -critical resistance for the outer circuit, below which the field ceases<br> -to be magnetized, as enough current ceases to be shunted into it to<br> -magnetize it. The machine is said to unbuild itself, and a discharge of<br> -magnetism occurs from the field magnet.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetism, Ewing's Theory of.</span><br> -Ewing found by a model consisting of a number of pivoted magnetic<br> -needles that the observed phenomena of magnetization could be<br> -represented thereby. Thus there would be no need of assuming internal<br> -frictional forces of Maxwell, nor the closed rings or chains of Hughes.<br> -The theory retains the notion, however, of paramagnetic matter,<br> -consisting of an assemblage of molecular magnets. The loss of energy by<br> -hysteresis is represented in the model by the energy lost by the needles<br> -in beating against the air.<br> -<br> -<br> -357 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetism, Free.</span><br> -The magnetism or magnetic field outside of a magnetic circuit. It is due<br> -to escape of lines of force and to the magnetic leakage through the air.<br> -The lines of force are never, under the most favorable circumstances,<br> -confined to the metallic circuit of the magnet and armature. In a simple<br> -magnet without armature all the lines of force have to follow an air<br> -path, and the field is at its strongest. As the magnetism is strongest<br> -at the surface near the poles, the term is sometimes understood as<br> -applying to the surface attraction. In such case it is defined as the<br> -distribution, on a magnetized bar or mass, of magnetic lines of force as<br> -they emerge from its surface.<br> -<br> -Synonym--Surface Magnetization.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetism, Hughes' Theory of.</span><br> -A theory accounting for magnetic phenomena by assuming that each<br> -molecule is a magnet, and that in a polarized or magnetized body they<br> -are all arranged with their poles in the same direction, while in an<br> -unmagnetized body their poles, alternating in direction, neutralize each<br> -other.<br> -<br> -Magnetization consists in a partial rotation of the molecules so as to<br> -make them agree in position, thus, as a resultant developing north and<br> -south poles at the ends of the bar.<br> -<br> -The theory is in a certain sense simpler than Ampere's theory, but is<br> -not so generally adopted.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetism, Lamellar Distribution of.</span><br> -The distribution of magnetism in thin and uniform or "simple magnetic<br> -shells," q. v. A given distribution is termed lamellar if the substance<br> -in which it exists can be divided into simple magnetic shells, which<br> -either form closed surfaces, or have their edges in the surface of the<br> -substance. In lamellar distribution the polar area is very large<br> -compared with the distance between opposite poles.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetism of Gases.</span><br> -Faraday experimented on this point by coloring gases with a little vapor<br> -of iodine or other colored gas, and letting them flow between the two<br> -poles of a powerful electromagnet. In this way he found some are<br> -repelled, some attracted, and in the case of oxygen, it is attracted at<br> -one temperature and repelled at another. At ordinary temperatures a<br> -cubic yard of oxygen possesses the magnetism of 5.5 grains of iron and<br> -when liquefied it is strongly attracted.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetism or Magnetization, Temporary.</span><br> -When a mass of iron is magnetized by a current, when the current ceases<br> -the portion of its magnetism which disappears is the temporary<br> -magnetism; the portion retained is the residual or permanent magnetism.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetism, Red.</span><br> -A term arising from the two fluid theory of magnetism; the magnetism of<br> -the north pole of a magnet. (See Magnetic Fluids.) The magnetism of the<br> -south pole is termed blue magnetism. Both terms originated in the<br> -painting of magnets. They are but little used.<br> -<br> -Synonym--North Magnetic Fluid.<br> -<br> -<br> -358 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetic Remanence.</span><br> -The residual magnetism left in a bar of steel or other paramagnetic<br> -material after the application of a powerful magnet. It is distinguished<br> -from coercive force, as the latter is the amount of negative magnetizing<br> -or of demagnetizing force required to reduce the remanent magnetism to<br> -zero.<br> -<br> -Synonym--Remanence--Residual Magnetism.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetism, Solenoidal Distribution of.</span><br> -The distribution of magnetism in such a way that the poles are very far<br> -apart in proportion to their area. The magnetization of a long thin bar<br> -of steel illustrates solenoidal distribution.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetism Sub-permanent.</span><br> -The magnetism of a paramagnetic substance which presents a considerable<br> -degree of permanency, but which gradually disappears, leaving the<br> -permanent magnetism present. It is noticeable in iron or steel ships<br> -whose magnetism gradually reduced in quantity, eventually becomes fully<br> -permanent.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetism, Weber's Theory of.</span><br> -The molecules of a magnetizable material by this theory are supposed to<br> -be magnets with their poles lying in every direction, and hence<br> -neutralizing each other. By magnetization these are supposed to be<br> -turned with their similar poles in the same direction, and their axis<br> -parallel, hence acting like a group of magnets. It is practically<br> -identical with Hughes' theory.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetism, Terrestrial.</span><br> -The magnetism of the earth. (See Magnetic Elements.)<br> -<br> -<br> -<img style="width: 676px; height: 230px;" alt="" - src="images/358F228.jpg"><br> -Fig. 228. MAGNETIZATION BY DOUBLE TOUCH.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetization by Double Touch.</span><br> -The process of magnetizing a steel bar by simultaneously stroking it<br> -with two poles of a horseshoe magnet or with two opposite poles of two<br> -bar magnets. The poles must be close but not touching. A block of wood<br> -may be placed between the ends if single magnets are used. The poles are<br> -placed on the middle of the bar and carried back and forth to one end,<br> -then to the other, and so on, ending at the middle of the bar in such<br> -direction as to give each end the same number of strokes. The poles must<br> -be close together or consequent poles will be produced. If bar magnets<br> -are used they may be held inclined at an angle of 15º to 20º -with the<br> -horizontal bar to be magnetized. The ends of the latter may rest on<br> -poles of two other magnets, each end on a pole of the same name as that<br> -of the magnetizing magnet on its side. (See Magnetization, Hoffer's<br> -Method.)<br> -<br> -<br> -359 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetization by Separate Touch.</span><br> -A method of magnetization. Two magnets are used. Held in an inclined<br> -position two opposite poles are touched to the bar near its centre, and<br> -are drawn off to the two ends. They are returned through the air and the<br> -process is repeated.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetization by Single Touch.</span><br> -A method of polarizing or magnetizing steel bars, by stroking them<br> -always in one direction with one pole of a magnet, returning it through<br> -the air. The stroking is best done on both sides. The stroking may begin<br> -at one end and end at the other, or it may be commenced in the center of<br> -the bar and be carried to one end with one pole, and the same done for<br> -the other half with the other pole.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetization by the Earth.</span><br> -The earth imparts magnetism to iron masses. If a rod of steel is held<br> -parallel to the inclination and in the magnetic meridian it exhibits<br> -polarity, which by jarring or hammering, can be made to some extent<br> -permanent. A piece of soft iron held vertically, or still better in the<br> -line of the dip as above, and which is twisted when in that position,<br> -becomes magnetized with some degree of permanence. Many other instances<br> -are cited, such as fire-irons, lamp-posts, iron gates, lathe turnings,<br> -all of which often exhibit polarity, having been magnetized by the<br> -earth's field.<br> -<br> -[Transcriber's note: The earth's magnetic field is believed to originate<br> -it electric currents in the moving molten core.]<br> -<br> -<br> -<span style="font-weight: bold;">Magnetization, Coefficient of Induced.</span><br> -The coefficient (q. v.) expressing the relation between the specific<br> -intensity of magnetization of a particle and the magnetizing force. The<br> -magnetizing force is measured by the lines of force it can produce in a<br> -field of air. The coefficient of induced magnetization is the factor by<br> -which the intensity of a magnetizing field must be multiplied to produce<br> -the magnetization imparted by it to a particle of any substance. This<br> -coefficient varies for different substances, and is also called magnetic<br> -susceptibility. It is distinguished from permeability as referring only<br> -to a particle isolated from influence of a mass of surrounding particles<br> -of its own kind. It is definable as the intensity of the magnetization<br> -assumed by an exceedingly long and exceedingly thin bar placed in a unit<br> -field. If a mass of metal were placed in such a field all its particles<br> -would become affected and within the mass no unit field could exist.<br> -Hence magnetic susceptibility (another name for this coefficient) does<br> -not apply to the case of large cores of electro-magnets and<br> -dynamo-armatures, but is really a theoretical rather than a practical<br> -figure.<br> -<br> -The sign of the coefficient of diamagnetic bodies is negative; of<br> -paramagnetic bodies is positive.<br> -<br> -Synonym--Magnetic Susceptibility. \<br> -<br> -<br> -360 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetization, Cycle of.</span><br> -A cycle of positive or of positive and negative magnetization represents<br> -the application of a magnetizing force beginning at a fixed value,<br> -generally zero, rising to a maximum, or to a value of maximum distance<br> -from the initial and then returning to the original basis. It is<br> -virtually a full wave of magnetization and may extend on both sides of a<br> -zero line giving positive and negative values.<br> -<br> -Cycles of magnetization apply especially to transformers and other<br> -apparatus of that character used with the alternating current system.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetization, Hoffer's Method.</span><br> -For horseshoe bars an armature is placed against the poles of the magnet<br> -bar to be treated. The poles of a strong horseshoe magnet are stroked<br> -over it from poles to bend and returned through the air, or vice versa.<br> -In the first case the poles will be the same as those of the inducing<br> -magnet; in the second case they will be opposite. A maximum effect is<br> -produced in ten strokes. The stroking should be applied to both sides.<br> -An electro-magnet may be used as inducer as shown, but an armature<br> -should be used; in the cut it is omitted.<br> -<br> -<br> -<img style="width: 635px; height: 293px;" alt="" - src="images/360F229.jpg"><br> -Fig. 229. MAGNETIZING A HORSESHOE MAGNET.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetization, Intensity of.</span><br> -The amount of magnetism induced in or present in a body. It is expressed<br> -in Magnetic Lines of Force, q. v., per cross-sectional area.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetization, Isthmus Method of.</span><br> -A method used by Ewing in a research on the magnetization of iron in<br> -very strong fields. He used samples of iron turned down in the centre to<br> -a narrow neck, and thus concentrated the lines of force greatly.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetization, Elias' Method.</span><br> -The bar to be magnetized is surrounded by a magnetizing coil, q. v. A<br> -strong current is passed through it, and the coil is moved back and<br> -forth a few times.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetization, Jacobi's Method.</span><br> -For horseshoe bars. The bar is placed with its poles against those of a<br> -horseshoe magnet. A bar of soft iron, long enough to reach from outside<br> -to outside of the legs, is laid across near the junction and is drawn<br> -along towards the bend of the new bar and away from it. This is repeated<br> -a few times on both sides.<br> -<br> -<br> -361 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetization, Limit of.</span><br> -As the induction of magnetizing force increases, magnetization of<br> -paramagnetic metals tends towards a limit, the increase in magnetization<br> -being continually less and less as the metal becomes more highly<br> -magnetized. In diamagnetic substances no limit is discernible.<br> -<br> -Synonym--Maximum Magnetization.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetization, Specific.</span> <br> -The magnetic moment per gram of a substance.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnet-keeper.</span><br> -A bar of iron connecting the two poles of a permanent magnet. Often the<br> -same bar serves as armature and keeper.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Lamination of.</span><br> -It is advantageous to make magnets of laminated construction, or of thin<br> -plates of steel. The thin metal can be better tempered or hardened than<br> -thick metal. A slight separation of the plates is advantageous from some<br> -points of view. If in actual contact there is some danger that the<br> -weaker members will have their polarity reversed by the stronger ones.<br> -This is counteracted to some extent by separation.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Long Coil.</span><br> -A high resistance electro-magnet; one whose coil is of thin wire of<br> -considerable length.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnet, Natural.</span><br> -The lodestone, q. v.; a variety of magnetite or magnetic oxide of iron,<br> -exhibiting permanent magnetism, attracting iron, and possessing north<br> -and south poles.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnet, Neutral Line of.</span><br> -A line at right angles to the magnetic axis of a magnet, q.v., and<br> -nearly or quite at the centre, so situated with reference to the poles<br> -on either end that it marks the locus of no polarity. It has been called<br> -the equator of the magnet. It is defined by the intersection of the<br> -plane of no magnetism with the surface of the bar.<br> -<br> -Synonym--Magnetic Equator.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Normal.</span><br> -A bar or compound bar magnet, magnetized to such an extent that the<br> -curves of the lines of force run into each other in the middle, is thus<br> -termed by Jamin.<br> -<br> -<br> -<span style="font-weight: bold;">Magneto.</span><br> -Abbreviation for Magneto-electric Generator. (See Magneto-electric<br> -Generator.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magneto Call Bell.</span><br> -A call operated by current from a magneto-electric generator. It is very<br> -generally used in telephone systems.<br> -<br> -<br> -362 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Magneto-electric. adj.</span><br> -Relating to induced electric effects due to the cutting of true magnetic<br> -lines of force by, or equivalent action of or upon a conductor. These<br> -effects are identical with electro-magnetic effects and are only<br> -distinguished from them by the field being due to a permanent magnet<br> -instead of an electromagnet.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magneto-electric Brake.</span><br> -A device for bringing to rest an oscillating galvanometer needle. It<br> -consists essentially of a coil in circuit with a key and with the<br> -galvanometer. On opening the circuit an inverse current is established<br> -by induction, tending to bring the needle to rest.<br> -<br> -<br> -<span style="font-weight: bold;">Magneto-electric Generator.</span><br> -A current generator operating by maintaining a potential difference at<br> -its terminals, by reactions in a field of force, which field is<br> -established by a permanent magnet.<br> -<br> -The cut, Fig. 230, shows the general principle of construction of a<br> -direct current generator. The armature is rotated between the poles of a<br> -permanent magnet. Any of the regular types of dynamo armature can be<br> -used. From its commutator the current is taken by brushes.<br> -<br> -<br> -<img style="width: 685px; height: 399px;" alt="" - src="images/362F230.jpg"><br> -Fig. 230. MAGNETO-ELECTRIC GENERATOR.<br> -<br> -<br> -<img style="width: 594px; height: 370px;" alt="" - src="images/362F231.jpg"><br> -Fig. 231. MAGNETO-ELECTRIC GENERATOR.<br> -<br> -<br> -363 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The cut, Fig. 231, shows an alternating current machine. In it a pair of<br> -bobbins, wound in series, and both either right-handed or left-handed,<br> -are rotated between permanent magnet poles. The current may be taken off<br> -by two brushes bearing on two collecting rings on the axis of the<br> -bobbins, the ends of the wire being connected thereto. Or if a shocking<br> -current is desired, one of the brushes or springs may strike a series of<br> -pins forming virtually a broken or interrupted collecting ring. This<br> -gives a current for medical purposes.<br> -<br> -Synonyms--Magneto-dynamo--Magneto-electric Machine.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetograph.</span><br> -An apparatus for recording variations in magnetic elements. One type<br> -includes a magnetic needle to which a concave mirror is attached. The<br> -light ray from the mirror is reflected upon sensitized paper where its<br> -movements are photographically reproduced. The movements of the spot are<br> -due to the movements of the needle and act as the record of the same.<br> -<br> -<br> -<span style="font-weight: bold;">Magneto-Inductor.</span><br> -An instrument for use with a ballistic galvanometer to reproduce a<br> -definite current impulse. Two magnets are fastened together in one<br> -straight line, the north poles almost touching. This is mounted at the<br> -end of a rod like a pendulum, the axis of the magnets transverse to the<br> -rod. The magnets are carried by a frame and oscillate at the end of the<br> -rod, back and forth within a fixed coil, which is one-half the length<br> -of the double magnet. A bob is attached to the bottom of the frame by<br> -which the whole can be swung. As the magnets are of fixed value, their<br> -time of oscillation constant, and the coil fixed in size, the apparatus<br> -provides a means of getting a definite instantaneous current of<br> -identical value whenever needed.<br> -<br> -<br> -<img style="width: 358px; height: 655px;" alt="" - src="images/363F232.jpg"><br> -Fig. 232. MAGNETO-INDUCTOR.<br> -<br> -<br> -364 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetometer.</span><br> -(a) A reflecting galvanometer, with heavy magnetic needle, dampened by a<br> -copper frame. It was devised by Weber.<br> -<br> -(b) An apparatus for measuring the intensity of magnetic force. It may<br> -consist of a magnet suspended by bifilar or by torsion suspension. A<br> -reflecting mirror and scale as in the reflecting galvanometer may be<br> -used to act as indicator of its motions. It is used in investigations of<br> -the intensity of the earth's field.<br> -<br> -If the motions of the spot of light are received on a moving strip of<br> -sensitized paper and are thereby reproduced photographically, the<br> -instrument is self-recording. Such an apparatus is used in the Kew<br> -Observatory, Eng., for recording the terrestrial magnetic elements.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetometry.</span><br> -The determination of the magnetic moment of a magnet.<br> -<br> -It involves the determination by experiment of--( a) the product of the<br> -magnetic moment, M, of the magnet by the horizontal component, H, of the<br> -earth's magnetism; (b) the quotient of M divided by H. Knowing these two<br> -quantities, M is given by the formula M = SquareRoot( )M * H) * (M/H) )<br> -and if desired H is given by the formula H = SquareRoot( (M*H) / (M/H)).<br> -<br> -M*H is determined by the method of vibrations. A very long, thin magnet<br> -suspended by a torsion filament is caused to oscillate, and its period<br> -is determined. Calling such period T and the moment of inertia of the<br> -magnet I, we have the formula T= 2* PI * SquareRoot( I / (H*M) ) -(a),<br> -whence H*M is calculated, I of course being known or separately<br> -determined.<br> -<br> -<br> -<img style="width: 623px; height: 430px;" alt="" - src="images/364F233.jpg"><br> -Fig. 233 END-ON METHOD.<br> -<br> -<br> -<img style="width: 414px; height: 619px;" alt="" - src="images/364F234.jpg"><br> -Fig. 234. BROADSIDE METHOD.<br> -<br> -<br> -M/H is determined by the End-on deflection method, or the Broadside<br> -deflection method. In both cases the deflection of a compass needle by<br> -the magnet in question is the basis of the work.<br> -<br> -In the end-on method AB is the magnet under examination; DE the compass<br> -needle; a the angle of deflection; d the distance between C and -the<br> -middle of AB, which should be considerable compared with the length of<br> -DE; 2l, the length of AB. We then have the formula<br> - tan a = (M/H) * (2d / (d^2 - l^2)^2),<br> -which if 2l is small compared to d reduces to<br> - tan a = M/Hd 3<br> -<br> -(b), which gives M/H, a and d being known.<br> -<br> -<br> -365 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -In the broadside method the line d is the magnetic meridian, and the<br> -diagram shows the relative positions. We then have the formula<br> - tan a = (M/H) / (d2 + l2)^1.5;<br> -which if 1 is relatively small reduces to<br> - tan a = M/(H * d3 )(C.)<br> -<br> -<br> -<img style="width: 644px; height: 226px;" alt="" src="images/365PIC.jpg"><br> -[Transcriber's note: The image of the above paragraphs is included -here.]<br> -<br> -a and c or a and b can be combined giving M and H in C.G.S. measurement.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetometer, Differential.</span><br> -An apparatus, invented by Eickemeyer, for testing the magnetic qualities<br> -of different samples of iron. It is very similar in construction and<br> -principle to the magnetic bridge, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Magneto-motive Force.</span><br> -The force producing a magnetic field or forcing lines of force around a<br> -magnetic circuit. It is usually applied only to electro-magnets and is<br> -expressible in turns of the wire winding multiplied by amperes of<br> -current, or in ampere-turns.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet Operation.</span><br> -A term in surgery; the use of the electro-magnet or permanent magnet for<br> -removing particles of iron from the eye.<br> -<br> -<br> -<span style="font-weight: bold;">Magnetoscope.</span><br> -An apparatus for detecting the presence of magnetism, without measuring<br> -its intensity. A simple magneto-scope consists of a magnetized bit of<br> -watch-spring suspended in a vertical glass tube by a fine filament. A<br> -bit of unmagnetized soft iron wire may be used in the same way. The<br> -first has the advantage of indicating polarity; the latter merely shows<br> -magnetic attraction. A cork may be used as base of the instrument.<br> -<br> -<br> -<img style="width: 362px; height: 724px;" alt="" - src="images/365F235.jpg"><br> -Fig. 235. MAGNETOSCOPE.<br> -<br> -<br> -366 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Permanent.</span><br> -A bar of steel charged with residual magnetism. Steel possesses high<br> -coercive force in virtue of which when once magnetized it retains part<br> -of the magnetization.<br> -<br> -Permanent magnets are generally straight bars or U shaped; they are<br> -termed bar magnets, magnetic needles, horseshoe magnets, machine magnets<br> -and otherwise, according to their shape or uses.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet Pole.</span><br> -The part of a magnet showing strongest polarity; the part which attracts<br> -iron the most powerfully, and acts as the starting point for lines of<br> -force.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet Poles, Secondary.</span><br> -Magnet poles are often not situated at the ends. Owing to inequality of<br> -the material or other causes they may occupy intermediate positions on<br> -the magnet. Such poles are called secondary poles.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet Pole, Unit.</span><br> -A unit magnet pole is one which exerts unit force on another unit pole<br> -placed at unit distance from it. Unit force is the dyne; unit distance<br> -is one centimeter.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Portative Power of.</span><br> -The power of sustaining a weight by attraction of its armature possessed<br> -by a magnet. In general terms the adherence of the armature of a magnet<br> -to the pole varies with the square of the number of lines of force which<br> -pass through the point of contact. Hence an increased adherence of the<br> -armature to a horseshoe electro-magnet is sometimes obtained by<br> -diminishing the area of contact of one pole which concentrates the lines<br> -of force. Steel magnets were frequently made with rounded ends to<br> -increase the portative power.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Simple.</span><br> -A magnet made of one piece of metal, or at least magnetized as such; the<br> -reverse of a compound magnet, which is magnetized piece by piece and<br> -then fastened together.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Solenoidal.</span><br> -A magnet which is so uniformly magnetized and is so long in proportion<br> -to its other dimensions that it virtually establishes two magnetic<br> -poles, one at either end. It is a long thin bar so magnetized that all<br> -its molecules would, considered as magnets, be absolutely equal.<br> -(Daniell.) It acts like a solenoid, except that it is longer in<br> -proportion than the solenoid generally is constructed.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Sucking.</span><br> -A magnet coil with movable or loose axial bar of soft iron.<br> -<br> -The whole is usually mounted vertically. When a strong enough current is<br> -passed the bar is drawn up into the coil as if by suction, whence the<br> -name.<br> -<br> -<br> -367 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Magnet, Unipolar.</span><br> -No such thing as a unipolar magnet is possible. The name is given to<br> -poised or suspended magnets, one of whose poles lies in the axis of<br> -suspension. It is obvious that such a magnet will act, as far as its<br> -directive tendency and rotatory movements are concerned, as if it had<br> -only one pole. As shown in the cut, the pole s in both magnets lies in<br> -the axis of suspension or directly under the filament by which they are<br> -suspended, while the other pole n is the active pole in causing rotation<br> -or directive tendency; c c are counterweights or counterpoises.<br> -<br> -<br> -<img style="width: 422px; height: 373px;" alt="" - src="images/367F236.jpg"><br> -Fig. 236. UNIPOLAR MAGNETS.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Magnetophone.</span><br> -An apparatus for producing a loud sound, involving the principles of the<br> -telephone. A rapidly alternating or make and break current being<br> -produced by any means and being transmitted through the telephone gives<br> -a loud note of pitch dependent on the current producing it. Sometimes a<br> -perforated metallic disc is rotated in a magnetic field, and produces<br> -the requisite type of current.<br> -<br> -<br> -<span style="font-weight: bold;">Magnus' Law.</span><br> -A law of thermo-electricity. In a homogeneous circuit, however, the<br> -temperature varies from point to point; there is no current.<br> -<br> -Whatever potential differences may be established by the variations in<br> -temperature it is evident that they must counteract each other and<br> -reduce to zero.<br> -<br> -<br> -<span style="font-weight: bold;">Mains, Electric.</span><br> -The larger conductors in a system of electric light or power<br> -distribution.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Make. v.</span><br> -To complete a circuit, as by closing a switch.<br> -<br> -<br> -<span style="font-weight: bold;">Make and Break Current.</span><br> -A current which is continually broken or interrupted and started again.<br> -It is applied only where the "makes" and "breaks" succeed each other<br> -with great rapidity, as in the action of an induction coil or pole<br> -changer, etc. It has had considerable importance in litigation affecting<br> -the Bell telephone patents, the courts holding that the original Bell<br> -patent (No. 174,465, of 1876,) covered the undulating current, for the<br> -transmission of speech. Many efforts have been made by litigants to<br> -prove that specific telephones have transmitted articulate speech by the<br> -make and break current, but without success. If this could have been<br> -proved the assumption is that the courts would have sustained the use of<br> -such device as not infringing upon the claims of the Bell patent.<br> -<br> -<br> -<span style="font-weight: bold;">Malapterurus.</span><br> -A fish, sometimes called the thunder fish, an inhabitant of African<br> -rivers, occurring in the Nile and Senegal. It possesses considerable<br> -electric power, similar to that of the gymnotus and torpedo, although<br> -inferior in amount.<br> -<br> -<br> -368 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 563px; height: 233px;" alt="" - src="images/368F237.jpg"><br> -Fig. 237. MALAPTERURUS.<br> -<br> -<br> -<span style="font-weight: bold;">Man-hole.</span><br> -The cistern-like depression in the ground for giving access to the ends<br> -of tubes in electric conduits. (See Conduit, Electric Subway.)<br> -<br> -<br> -<span style="font-weight: bold;">Marked End or Pole.</span><br> -The north pole or north seeking pole of a magnet, so called because it<br> -is usually marked with a notch or scratch by the maker. The south pole<br> -is called the unmarked end.<br> -<br> -<br> -<span style="font-weight: bold;">Mass.</span><br> -The quantity of matter in a body. The C. G. S. unit of mass is the<br> -quantity of matter in a gram. While weight varies with latitude and<br> -other circumstances, mass is invariable.<br> -<br> -The unit of mass is also defined as the quantity of matter which in a<br> -balance will counterpoise a standard mass, the gram or pound. As the<br> -gram is intended to be the mass of one cubic centimeter of water at<br> -3.09º C. (39º F.), the C. G. S. unit of mass is really -1.000013 gram.<br> -<br> -As a primary unit its dimensions are indicated by M.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Mass, Electric.</span><br> -A term for quantity of electricity. The unit mass is such a quantity as<br> -at unit distance will act with unit force.<br> -<br> -<br> -<span style="font-weight: bold;">Matter, Electric.</span><br> -The imaginary substance constituting electricity; a conception used<br> -purely as a matter of convenience.<br> -<br> -[Transcriber's note: The electron was discovered five years after this<br> -publication.]<br> -<br> -<br> -<span style="font-weight: bold;">Matter, Radiant.</span><br> -Matter in the ultra-gaseous or so-called fourth state. In the gaseous<br> -state the molecules of a gas are in perpetual kinetic motion, colliding<br> -actually or virtually with each other, rebounding from such approach,<br> -and striking also the walls of the containing vessel. But except for<br> -these deflections, which are of enormous frequency, the paths of the<br> -molecules would be perfectly straight.<br> -<br> -In the radiant state matter exists in so high a vacuum that collisions<br> -of the molecules rarely occur, and the molecules simply beat back and<br> -forth in straight lines from side to side of the containing vessel.<br> -<br> -A layer of gas in this condition is termed a Crookes' layer, from Prof.<br> -William Crookes, who discovered and investigated these phenomena.<br> -<br> -<br> -369 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Luminous streams of the molecules are produced by electric high<br> -potential discharges between electrodes. The course of the discharge is<br> -normal, in general terms, to the surfaces of the electrodes, and reaches<br> -from one to the other in a curve or straight line, as the case may be.<br> -<br> -These luminous streams are deflected by a magnetic field; if brought to<br> -a focus can heat refractory material in that focus to a full white heat,<br> -and can develop phosphorescence. The latter is termed electric<br> -phosphorescence. A great variety of experiments have been devised to<br> -illustrate the phenomena of radiant matter. The vacuum is generally<br> -produced in a hermetically sealed glass vessel into which the electrodes<br> -are sealed, and which contain the phosphorescent substances or other<br> -essentials for the experiments. The vessels are termed Crookes' Tubes.<br> -<br> -[Transcriber's note: Crookes reported on "radiant matter" in 1879. It is<br> -actually electrons, but he failed to distinguish them from ordinary<br> -atoms. Thompson properly described electrons in 1897.]<br> -<br> -<br> -<span style="font-weight: bold;">Matteueci's Experiment.</span><br> -An experiment for showing the inductive effect of the discharge of a<br> -Leyden jar. Two glass plates are supported on standards in a vertical<br> -position. Flat coils of wire are wound or coiled and secured to one<br> -surface of each plate. One plate has much finer and longer wire than the<br> -other. Metal handles are connected to the ends of the coarser wire coil.<br> -The plates are placed with their coils facing each other. A Leyden jar<br> -is discharged through the coarser coil, while the handles are grasped by<br> -a person. The shock of the discharge is felt by him.<br> -<br> -<br> -<span style="font-weight: bold;">Matting, Electric Floor.</span><br> -Matting or floor covering underlaid with burglar alarm contacts, so<br> -arranged as to be closed by anyone walking on the matting. The contacts<br> -are connected to a burglar alarm system. The object is to provide an<br> -alarm if a burglar enters a house, in case he should enter a door or<br> -window without sounding the bell. The latter can be done by cutting out<br> -the window or part of the door instead of opening it.<br> -<br> -<br> -<span style="font-weight: bold;">Maxwell's Theory of Light.</span><br> -A theory of light. It is due to J. Clerk Maxwell.<br> -<br> -It supposes the phenomena of electric induction to be due to the ether,<br> -q. v. It supposes the condition of the ether when conveying light to be<br> -the same as if exposed to the induction of rapidly alternating currents<br> -or discharges (in this case synonymous). It therefore is an<br> -electro-magnetic effect if the theory is correct.<br> -<br> -An electric stress such as one due to the induction of an<br> -electrostatically charged body is not a wave-creating element or factor,<br> -but is a simple stress. But let this stress be stopped and renewed and<br> -at once it appears as a wave-forming agency.<br> -<br> -This stoppage and renewal represents evidently a discharge succeeded by<br> -a charge, or if repeated is equivalent to an intermittent current or an<br> -alternating one.<br> -<br> -<br> -370 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Again the electrostatic stress kept constant may by being carried<br> -through space carry with it a wave, just as a moving projectile carries<br> -a wave of air in advance of itself.<br> -<br> -Admitting this much the following consequences follow:<br> -<br> -Since in non-conductors the displacement produces a restitution force,<br> -which varies as the displacement which is requisite or is a criterion<br> -for the propagation of waves, while in conductors no such force is<br> -manifested and the electric energy appears as heat, it follows that<br> -light vibrations are not possible in conductors, because<br> -electro-magnetic waves do not exist in them when they are in circuit,<br> -and conductors should be opaque, while the reverse is true for<br> -non-conductors. (Daniell.)<br> -<br> -This is carried out often enough to make a striking evidence in favor of<br> -Maxwell's theory.<br> -<br> -The velocity of propagation of an electro-magnetic disturbance in a<br> -non-conductor should be equal to that of light. This constant is proved<br> -by mathematical considerations, to be approximately the same as the<br> -ratio of the electrostatic to the electromagnetic unit of intensity or<br> -quantity. This ratio is 3E10 (30,000,000,000), which is almost exactly<br> -the velocity of light.<br> -<br> -It also follows from what has been said that if an electrostatically<br> -charged body were whirled around a galvanometer needle at the rate of<br> -3E10 revolutions per second it should affect it like a circulating<br> -current. This rate of rotation cannot be attained, but Rowland has made<br> -manifest the effect of a rotating statically charged body upon a<br> -magnetic needle.<br> -<br> -The above is the merest outline of Maxwell's theory. The full<br> -development must be studied in his own and succeeding works.<br> -<br> -<br> -<span style="font-weight: bold;">Mayer's Floating Magnets.</span><br> -An experiment due to Prof. Mayer. A number of sewing needles are<br> -magnetized and thrust into bits of cork, almost all the way through,<br> -with their like poles projecting. They are floated in a basin of water<br> -and take, under the effects of attraction and repulsion, when approached<br> -by a magnet pole, regular geometric positions, marking out the positions<br> -of angles of polygons.<br> -<br> -<br> -<span style="font-weight: bold;">Measurements.</span><br> -The determination of the value of quantities; determination of the<br> -factor by which the unitary value must be multiplied to produce the<br> -quantity under examination. Such are the measurement of the voltage of a<br> -galvanic battery, or of the ohms of resistance of a conductor.<br> -Electricity has been termed the science of measurement.<br> -<br> -<br> -<span style="font-weight: bold;">Meg or Mega.</span><br> -A prefix, meaning one million times. A megohm is one million ohms; a<br> -megerg is one million ergs; a megadyne is one million dynes.<br> -<br> -<br> -371 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<img style="width: 664px; height: 574px;" alt="" - src="images/371F238.jpg"><br> -Fig. 238. MAYER'S FLOATING MAGNETS.<br> -<br> -<br> -<span style="font-weight: bold;">Mercury.</span><br> -A metal; one of the elements; symbol, Hg; atomic weight, 200 ;<br> -equivalent, 200 or 100; valency, 1 and 2.<br> -It is a conductor of electricity.<br> -The following data are 0º C. (32º F.)<br> - R<small><span style="font-family: monospace;">elative -Resistance, 62.73</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Specific -Resistance, 94.32 microhms.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Resistance of a wire,</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> (a) 1 foot long, weighing -1 grain, -18.51 ohms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> (b) 1 foot long, 1/1000 -inch thick, -572.3 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> (c) 1 meter long, weighing -1 gram, -12.91 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> (d) I meter long, 1 -millimeter thick -1.211 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Resistance of a 1 -inch cube, 37.15 -microhms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Percentage increase of -resistance per degree C. 1.8° F.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> at about -20° C. (68° F.), -.72 per cent.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Electro-chemical -equivalent (Hydrogen = .0105), -2.10 mgs.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -1.05 "</span></small><br> -<br> -372 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Mercury Cup.</span><br> -A cup of iron, wood or some material that does not amalgamate or is<br> -unattacked by mercury, which is filled with mercury and made an<br> -electrode of a circuit. By dipping the other terminal of the circuit<br> -into the mercury a very good contact is obtained. It is well to cover<br> -the mercury with alcohol. The cup may be filled so that the mercury<br> -rises in a meniscus or semi-globule above its edges.<br> -<br> -For some purposes this form is useful, as for contacts with the end of a<br> -swinging wire or pendulum, because in such cases the contact can be made<br> -without the contact point entering the cup. The point swings through the<br> -projecting meniscus without touching the edges of the cup. A mercury cup<br> -and contact constitute a mercury break.<br> -<br> -<br> -<span style="font-weight: bold;">Meridian, Astronomical.</span><br> -The great circle passing through the north and south poles of the<br> -celestial sphere. It lies in a plane with the corresponding geographical<br> -or terrestrial meridian.<br> -<br> -<br> -<span style="font-weight: bold;">Meridian, Geographic.</span><br> -The true north and south meridian; the approximate great circle formed<br> -by the intersection of a plane passing through north and south poles of<br> -the earth with the earth's surface.<br> -<br> -<br> -373 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 494px; height: 671px;" alt="" - src="images/372F239.jpg"><br> -Fig. 239. SCHALLENBERG'S ALTERNATING CURRENT METER.<br> -<br> -<br> -<span style="font-weight: bold;">Meter, Alternating Current.</span><br> -A meter for measuring alternating current, as supplied to consumers,<br> -from an alternating current system. Like most commercial meters its only<br> -function is the measurement of quantity; the potential difference is<br> -maintained at a constant figure by the generating plant.<br> -<br> -The cut shows the Schallenberg meter. It is simply an alternating<br> -current motor (see Motor, Alternating Current), with air vanes mounted<br> -on its spindle. A main coil passes all the current. Within this is a<br> -second coil complete in itself, and not touching or connecting with the<br> -other. The latter is built up of copper rings. Within the two coils, and<br> -concentric with both is a disc of copper carried by a vertical spindle.<br> -The same spindle carries air vanes, and is free to rotate. As it does so<br> -it moves the indicating machinery.<br> -<br> -The current in the outer coil induces one in the inner coil. Owing to<br> -lag, the current in the inner one differs in phase from that in the<br> -outer one, and a rotatory field is produced. The copper disc acquires<br> -induced polarity, and rotates with speed which normally would be in<br> -proportion to the square of the current. But the object of the meter is<br> -to register the current only. The air vanes effect this. The resistance<br> -of the air to their motion causes the rate of rotation to vary directly<br> -as the speed.<br> -<br> -<br> -<span style="font-weight: bold;">Meter Bridge.</span><br> -A form of Wheatstone's bridge in which one lateral pair of arms is<br> -represented by a straight wire. The other pair comprise a known<br> -resistance, and the resistance to be determined. The galvanometer is<br> -connected on one side between the known and unknown resistance. On the<br> -other side its connection is moved back and forth along the straight<br> -wire until the balance is secured and the galvanometer reads zero.<br> -<br> -The relative lengths of wire intercepted between the two ends thereof<br> -and the movable galvanometer connection are proportional to the<br> -resistance of these parts and give the necessary data with the one known<br> -resistance for determining the unknown resistance.<br> -<br> -<br> -374 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -In the original meter bridge the wire was one meter long, whence its<br> -name, and was stretched straight. In more recent examples the wire<br> -varies in length and in one form is bent into a circle or spiral, so as<br> -to make the instrument more compact.<br> -<br> -The contact is not a sliding one, but is adjusted by trial. The contact<br> -piece is slid along, but not touching the wire, and from time to time is<br> -pressed down against the wire. This prevents wear of the wire. The wire<br> -may be made of platinum or of platinum-iridium alloy. The latter is<br> -very hard and not easily worn out.<br> -<br> -Sometimes, as shown in the cut, three parallel wires are stretched along<br> -the baseboard of the instrument, and arranged so that a single wire, two<br> -wires or three wires in series can be used for the proportional sides of<br> -the bridge, thus making it a two-meter or three-meter bridge as desired.<br> -On the other hand some are made of restricted length, as a half or<br> -quarter meter only.<br> -<br> -<br> -<img style="width: 612px; height: 395px;" alt="" - src="images/374F240.jpg"><br> -Fig. 240. METER BRIDGE.<br> -<br> -<br> -In the cut J K is the wire, traversed by the contact key. By moving the<br> -contact C back and forth in the slot it can be brought over any of the<br> -three divisions of the wire. H is the handle for depressing the key. S<br> -is a flat spring, carrying the contact piece and holding it up from the<br> -wires, except when pressed downwards. As shown in the cut, it is in use<br> -for calibrating a voltmeter V, by Poggendorff's method, G being the<br> -galvanometer and r1 and r2 being resistances.<br> -<br> -Synonyms--Slide Bridge--Slide Balance.<br> -<br> -<br> -<span style="font-weight: bold;">Meter Candle.</span> <br> -A unit of illuminating power; the light given by one standard candle at -<br> -a distance of one meter. The ordinary units of illuminating power are <br> -altogether relative; this one is definite.<br> -<br> -<br> -375 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Meter, Chemical Electric.</span><br> -A current meter in which the current is determined by the amount of<br> -chemical decomposition which it can effect. In the Edison meter the<br> -solution is one of zinc sulphate. Two electrodes of zinc are immersed in<br> -it, and a fractional part of the current is passed through it. The gain<br> -in weight of one electrode and the loss in the other are proportional to<br> -the current. Both electrodes are weighed periodically, one acting as<br> -check upon the other.<br> -<br> -<br> -<span style="font-weight: bold;">Meter, Current.</span><br> -An instrument for measuring the quantity of electricity in current form<br> -supplied to consumers. It may be of various types. The general principle<br> -involved is that in commercial installations for incandescent light and<br> -power supply a fixed potential is usually maintained, the multiple arc<br> -system being employed. Hence all that is requisite is to measure the<br> -coulombs or the ampere-hours to know what quantity of energy has been<br> -supplied.<br> -<br> -<br> -<span style="font-weight: bold;">Meter, Electro-magnetic.</span><br> -A current meter in which the current is measured by its electro-magnetic<br> -effects.<br> -<br> -<br> -<span style="font-weight: bold;">Meter-millimeter.</span><br> -A unit of resistance. (See Resistance, Meter-millimeter.)<br> -<br> -<br> -<span style="font-weight: bold;">Meter, Thermal Electric.</span><br> -A current meter in which the current is measured by the heat it imparts<br> -to a conductor. In one meter a very light helix of mica is poised<br> -horizontally over a conductor, and the whole is enclosed in a case. As<br> -the wire is heated it causes an ascending current of air which rotates<br> -the vane, and the latter moves delicate clockwork which moves indicating<br> -hands. The hotter the wire the more rapidly the air ascends, and<br> -consequently the speed of the vane is proportional to the current,<br> -because the heat of the conductor is proportional thereto.<br> -<br> -<br> -<span style="font-weight: bold;">Meter, Time Electric.</span><br> -An electric meter which measures the length of time during which current<br> -is used. It assumes a constant current and potential. It is virtually a<br> -clock, which is turned on when the current passes, and is turned off<br> -with the current.<br> -<br> -<br> -<span style="font-weight: bold;">Meter, Watt.</span><br> -A combined current and potential meter. It is constructed on the general<br> -lines of a Siemens' Electro Dynamometer. If in it one coil is made of<br> -coarse wire and is placed in series with the current conductor, and if<br> -the other is wound with fine wire and is connected as a shunt from point<br> -to point whose potential difference is to be determined, the instrument<br> -becomes a watt meter.<br> -<br> -Synonym--Energy Meter.<br> -<br> -<br> -<span style="font-weight: bold;">Methven Standard or Screen.</span><br> -A standard of illuminating power. It is the light emitted by a<br> -three-inch Argand gas flame through a rectangular aperture in a silver<br> -plate carried by a screen. The aperture is of such size and so far<br> -distant from the flame as to permit the passage of exactly two candles<br> -illuminating power.<br> -<br> -<br> -<img style="width: 346px; height: 844px;" alt="" - src="images/376F241.jpg"><br> -</big></big><big><big>Fig. 241. METHVEN SCREEN<br> -<br> -<br> -</big></big><big><big>376 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Mho.</span><br> -A unit of conductance, not in very general use. It is the reciprocal of<br> -the ohm. Thus a resistance of ten ohms is a conductance of one-tenth<br> -mho.<br> -<br> -<br> -<span style="font-weight: bold;">Mica.</span><br> -A natural mineral, a silicate of several oxides; muscovite. It is used<br> -as an insulator and dielectric. Its resistance per centimeter cube after<br> -several minutes electrification at 20º C. (68º F.) is 8.4E13 -ohms<br> -(Ayrton). Its specific inductive capacity is 5, air being taken at 1.<br> -<br> -<br> -<span style="font-weight: bold;">Mica, Moulded.</span><br> -An insulating material, whose body is made of mica pulverized and<br> -cemented together with heat and pressure and some suitable cement.<br> -Shellac is often used as the cement.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Micro.</span><br> -A prefix meaning "one-millionth of;" a micro-farad is one-millionth of a<br> -farad.<br> -<br> -<br> -<span style="font-weight: bold;">Micrometer.</span><br> -An instrument for measuring small distances or small differences. It<br> -generally is based upon an accurate screw which may have a worm wheel<br> -for head, actuated by a worm or helix with graduated head, so that<br> -exceedingly small advances of the screw may be produced. The pitch of<br> -the screw being known its actual advance is known.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Micrometer, Arc.</span><br> -A micrometer for measuring the distance between voltaic arc electrodes.<br> -<br> -<br> -<span style="font-weight: bold;">Micron.</span><br> -A unit of length. It is one-millionth of a meter or four<br> -one-hundred-thousandths of an inch.<br> -<br> -<br> -377 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Microphone.</span><br> -An apparatus which includes a contact of variable resistance; such<br> -resistance can be varied in amount by slight vibrations, such as those<br> -produced by sound waves. The apparatus in use forms part of a circuit<br> -including a telephone and current generator. As the contact is varied<br> -the resistance of the circuit and consequently the current intensity<br> -changes and sounds are emitted by the telephone corresponding to such<br> -changes. If the microphone is spoken to, the telephone will emit<br> -corresponding sounds, reproducing the voice.<br> -<br> -It has been found in practice that carbon gives the best microphone<br> -contact. One of the simplest and earliest forms is shown in the cut. A<br> -short rod or pencil of carbon, A, such as used in batteries, is<br> -sharpened at the ends and rests loosely in a vertical position between<br> -two blocks of carbon, C C, in each of which a hole is drilled to receive<br> -one of the points. The blocks are carried on a standard and base D. The<br> -blocks are connected with two terminals x, y, of a circuit, including a<br> -telephone and battery. There are two contacts to be disturbed.<br> -<br> -If delicately adjusted a fly walking over the base-board will disturb<br> -the contacts enough to produce sounds in the telephone. These sounds are<br> -possibly not due only to sound waves, but in part to absolute mechanical<br> -disturbances.<br> -<br> -The various forms of telephone transmitter are generally microphones.<br> -<br> -<br> -<img style="width: 805px; height: 675px;" alt="" - src="images/377F242.jpg"><br> -Fig. 242. MICROPHONE.<br> -<br> -<br> -<span style="font-weight: bold;">Microphone Relay.</span><br> -A combined microphone and telephone. A microphone is placed close to the<br> -diaphragm of a telephone. The slight sound waves emitted by the<br> -telephone affect the microphone and are repeated in its circuit. The<br> -microphone circuit includes a local battery and telephone.<br> -<br> -<br> -<span style="font-weight: bold;">Microtasimeter.</span><br> -An apparatus for indicating minute changes in temperature or atmospheric<br> -moisture.<br> -<br> -<br> -378 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -A button of compressed lampblack is placed in series with a battery and<br> -galvanometer. A strip of some substance, affected in its length either<br> -by heat or by moisture, is held pressing against the button. A slight<br> -change in length of the strip varies the resistance of the button and<br> -hence affects the galvanometer. In this way exceedingly slight changes<br> -in heat or moisture may be indicated.<br> -<br> -For heat indications vulcanite may be used. The heat of the hand held<br> -near it is enough to affect the galvanometer. For moisture a slip of<br> -gelatine is used. The moisture of a damp slip of paper two or three<br> -inches distant is sufficient to affect the galvanometer.<br> -<br> -In the cut, Fig. 2, shows the general distribution of the apparatus in<br> -circuit with a battery and galvanometer. C is the base of the apparatus,<br> -from which the standard, B, with adjusting screw, H, rises. The strip of<br> -vulcanite is held between I and G. Within D is the carbon button (F in<br> -Fig. 3) pressed between G and E; A is a standard to carry the parts last<br> -described. In Fig. I it is shown as part of a Wheatstone bridge, a, b<br> -and c being resistance coils; l the tasimeter, and g the galvanometer.<br> -If a balance is secured, any variation in the resistance of the<br> -tasimeter will disturb the galvanometer.<br> -<br> -Synonym--Tasimeter.<br> -<br> -<br> -<img style="width: 482px; height: 693px;" alt="" - src="images/378F243.jpg"><br> -Fig. 243. MICROTASIMETER.<br> -<br> -<br> -379 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Mil.</span><br> -A unit of length; one-thousandth part of a lineal inch.<br> -<br> -It is equal to<br> -.025399 millimeter;<br> -.000083 foot;<br> -.001000 inch.<br> -<br> -<br> -<span style="font-weight: bold;">Mil, Circular.</span><br> -A unit of area; employed in designating the cross-sectional area of<br> -wires and other circular conductors.<br> -<br> -It is equal to<br> - .78540 square mil;<br> - .000507 square millimeter;<br> - 7.8E-7 (.00000078) square inch.<br> -<br> -If the diameter of a wire is given in mils, the square of its diameter<br> -gives its cross-sectional area in circular mils.<br> -<br> -<br> -<span style="font-weight: bold;">Mil-foot.</span><br> -A unit of resistance. (See Resistance, Mil-foot, Unit of).<br> -<br> -<br> -<span style="font-weight: bold;">Mil, Square.</span><br> -A unit of area; one-millionth of a square inch.<br> -<br> -It is equal to<br> - .000645 square millimeter;<br> - 1.2733 circular mil;<br> - .000001 square inch.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Milli.</span><br> -A prefix; one-thousandth. Thus a milligram is one-thousandth of a gram;<br> -a millimeter is one thousandth of a meter.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Milligram.</span><br> -A unit of weight ; one-thousandth of a gram, q. v.<br> -<br> -It is equal to<br> - .015432 grain;<br> - .000032 troy ounce.<br> -<br> -<br> -<span style="font-weight: bold;">Millimeter.</span><br> -A unit of length; one-thousandth of a meter.<br> -<br> -It is equal to<br> - 39.37079 mils;<br> - .03937 inch;<br> - .00109 yard.<br> -<br> -<br> -380 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Milli-oerstedt.</span><br> -A proposed but not adopted unit of current; one-thousandth of an<br> -oerstedt. It is equal to one-thousandth of an ampere.<br> -<br> -[Transcriber's note: oersted: 1. CGS unit of magnetic intensity, equal<br> -to the magnetic pole of unit strength when undergoing a force of one<br> -dyne in a vacuum. 2. Formerly, the unit of magnetic reluctance equal to<br> -the reluctance of a centimeter cube of vacuum between parallel<br> -surfaces.]<br> -<br> -<br> -<span style="font-weight: bold;">mm.</span><br> -Contraction for millimeters.<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Molar. </span><br> -Referring to phenomena of mass as gravitation. Mechanics<br> -generally treats of molar laws and phenomena.<br> -<br> -[Transcriber's note: Molar, or mole, often refers to a quantity of a<br> -substance containing an Avagadro number (6.02E23) of molecules--a weight<br> -equal to the atomic weight of the molecule. For example, a mole of<br> -hydrogen (H2) is 2.015 grams; sodium chloride (NaCl) is 58.443 grams.]<br> -<br> -<br> -<span style="font-weight: bold;">Molar Attraction.</span><br> -The attraction of mass for mass; gravitation. Synonyms--Mass<br> -Attraction--Gravitation.<br> -<br> -<br> -<span style="font-weight: bold;">Molecular Affinity.</span><br> -The attraction of molecules for each other as seen in the formation of<br> -double salts, the combining of water of crystallization with a salt, and<br> -in other cases; a phase of affinity belonging to chemistry, although<br> -outside of true atomic attraction.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Molecular Attraction.</span><br> -The attraction of molecules; physical affinity. Cohesion, the attraction<br> -of similar molecules for each other, and adhesion, that of dissimilar<br> -molecules, are examples. This should be distinguished from molecular<br> -affinity, a phase of chemical force.<br> -<br> -<br> -<span style="font-weight: bold;">Molecular Bombardment.</span><br> -When a gas contained in a vessel is brought to a sufficient state of<br> -rarefaction the molecules cease to be subject to the laws of diffusion,<br> -but move back and forth in straight lines from side to side of the<br> -vessel. Their courses can be affected by electric discharge, which can<br> -cause them to all impinge upon one of the electrodes, the positive one,<br> -producing luminous effects. The path, if referred to the negative<br> -electrode, tends to be normal to its surface, so that the resultant path<br> -may be curved, as the stream of molecules go to the positive electrode.<br> -The fanciful name of molecular bombardment is given to the phenomenon,<br> -the luminous effect being attributed to the impinging of the molecules<br> -against the positive electrode as they are projected from the positive.<br> -The course of the molecules is comparable to the stream of carbon<br> -particles from the positive to the negative electrode in an arc lamp.<br> -(See Matter, Radiant.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Molecular Chain.</span><br> -The theoretical rows of molecules supposed to extend from anode to<br> -cathode in an electrolytic cell (see Cell, Electric--Grothüss'<br> -Hypothesis) are called molecular chains.<br> -<br> -<br> -381 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Molecular Rigidity.</span><br> -The tendency of the molecules of a mass to retain their position in a<br> -mass in resistance to polarizing or depolarizing force, the first being<br> -the effect of a magnetic field. It is the theoretical cause of coercive<br> -force, q. v., and of residual magnetism. (See Magnetism, Residual.)<br> -<br> -<br> -<span style="font-weight: bold;">Molecule</span>.<br> -The smallest particle of matter that can exist alone. It is made up of<br> -atoms, but an atom can never exist alone, but only, with one or two<br> -possible exceptions, combined with one or more other atoms as a<br> -molecule. The molecules under present conditions are not in constant<br> -contact with each other, but are perpetually vibrating through paths, in<br> -solids probably in defined paths, in liquids and gases in perpetually<br> -new paths. The molecules collide with each other and rebound. This<br> -motion is the kinetic motion termed heat. At the absolute zero--minus<br> -273.72° C. (-460.7° F.) the molecules would be in contact and -quiescent.<br> -In the gaseous state the molecules of most substances occupy the same<br> -volume; those of a few elements occupy one-half and of others twice the<br> -normal volume. The mean free path of the molecule of hydrogen is about<br> -1/20,000 mm. (1/508,000 inch) (Maxwell) or twice this length (Crookes),<br> -the collisions in hydrogen are about 17,750 millions per second; the<br> -diameter is about 8/10,000,000 mm. (8/254,000,000 inch) ; A particle of<br> -matter 1/4,000 mm. (1/102,000 inch) contains, it is supposed, about<br> -40,000 molecules. The results of different authorities vary so widely as<br> -to deprive the subject of much of its interest. A Sprengel pump, such as<br> -used for exhausting Geissler tubes, or incandescent lamp bulbs, may<br> -leave only one hundred-millionth (1/100,000,000,) of an atmosphere<br> -present, giving the molecules a capability of an average free path of<br> -vibration 33 feet long.<br> -<br> -<br> -<span style="font-weight: bold;">Moment.</span><br> -When a force is applied so as to tend to produce rotation around a<br> -point, the product of the force by the shortest distance from the point<br> -of rotation to the extension of the line of the force. Such distance is<br> -the perpendicular to the extension of the line through the point of<br> -rotation.<br> -<br> -<br> -<span style="font-weight: bold;">Mordey Effect.</span><br> -A phenomenon observed in dynamo armatures. At full loads the hysteresis<br> -decreases. The effect is thus expressed by S. P. Thompson. "When an<br> -armature core is rotated in a strong magnetic field, the magnetization<br> -of the iron is being continually carried through a cycle, but in a<br> -manner quite different from that in which it is carried when the<br> -magnetizing force is periodically reversed, as in the core of a<br> -transformer. Mordey has found the losses by hysteresis to be somewhat<br> -smaller in the former case than in the latter."<br> -<br> -<br> -<span style="font-weight: bold;">Morse Receiver.</span><br> -The receiving instrument formerly universally used in the Morse system.<br> -It is now but little employed, the sounder having displaced it. Several<br> -types were invented.<br> -<br> -It consists of machinery which carries a reel of paper ribbon arranged<br> -to be fed over a roller by clockwork. A pencil, inking roller, or<br> -embossing stylus (for the latter the roller must have a groove) is<br> -carried by an arm with restricted range of vibration just over the paper<br> -and roller. The armature of an electro-magnet is attached to the arm.<br> -When the magnet is excited the armature is attracted and the marking<br> -device is pressed on the paper. If the clockwork is in operation the<br> -marker will make a line as long as the armature is attracted. When<br> -released no mark will be produced. In this way the dots and dashes of<br> -the Morse code are made on a ribbon of paper.<br> -<br> -As an inking arrangement a small roller is carried by the end of the<br> -vibrating arm. The embosser, or dry point stylus, was very extensively<br> -used. The clockwork was generally driven by descending weights.<br> -<br> -Synonym--Morse Recorder.<br> -<br> -<br> -382 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Mortar, Electric.</span><br> -An electric toy which may have various modifications. In the cut a<br> -wooden mortar with recess to receive a ball is shown. Two wires enter<br> -the base but do not touch. On placing the ball in position and passing a<br> -spark from a Leyden jar across the interval between the wires, the heat<br> -and disturbance are enough to project the ball. Gunpowder may be used,<br> -the discharge being passed through a wet string to prolong the spark.<br> -<br> -<br> -<img style="width: 362px; height: 423px;" alt="" - src="images/382F244.jpg"><br> -Fig. 244. ELECTRIC MORTAR.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Motor, Compound or Compound Wound.</span><br> -A motor which has two windings on the field magnets, one in parallel<br> -with that on the armature, the other in series therewith, exactly as in<br> -a compound dynamo. (See Dynamo, Compound.)<br> -<br> -<br> -<span style="font-weight: bold;">Motor, Differential.</span><br> -A differentially wound motor; with a compound wound field, whose series<br> -coil and shunt coil are wound in opposition to each other. It is<br> -virtually a compound wound dynamo. (See Dynamo, Compound Wound.)<br> -<br> -<br> -<span style="font-weight: bold;">Motor, Electric.</span><br> -A machine or apparatus for converting electric energy into mechanical<br> -kinetic energy. The electric energy is generally of the dynamic or<br> -current type, that is to say, of comparatively low potential and<br> -continuous or virtually continuous flow. Some electrostatic motors have,<br> -however, been made, and an influence machine can often be operated as a<br> -static motor.<br> -<br> -Electric motors of the current type may be divided into two<br> -classes--direct current and alternating current motors.<br> -<br> -Direct current motors are generally based on the same lines of<br> -construction as dynamos. One of the great discoveries in modern<br> -electricity was that if a current is passed through a dynamo, the<br> -armature will rotate. This fact constitutes the principle of the<br> -reversibility of the dynamo.<br> -<br> -<br> -383 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Motors built on the dynamo model may be series wound, shunt wound, or<br> -compound wound, or of the magneto type, in the latter case having a<br> -fixed field irrespective of any current sent through them. The field may<br> -be produced by an electro-magnet separately excited and unaffected by<br> -the current sent through the motor.<br> -<br> -A current passed through a magneto or motor with separately excited<br> -field will turn it in the direction opposite to that required to produce<br> -the same current from it were it worked as a generator.<br> -<br> -A current passed through a series wound motor acts exactly as above.<br> -<br> -Both these facts follow from Lenz's law, q. v.<br> -<br> -A current passed through a shunt wound motor acts oppositely to the<br> -above. The direction of rotation is the same as that required to produce<br> -a current of the same direction. This is because the field being in<br> -parallel with the armature the motor current goes through the magnet<br> -coils in the direction the reverse of that of the current produced in<br> -the armature when it is used as a dynamo. Hence this also carries out<br> -Lenz's law.<br> -<br> -The compound wound motor acts one way or the other according as its<br> -shunt or series winding preponderates. The two may exactly balance each<br> -other, when there will be no motion at all. The series connections of a<br> -compound wound dynamo should therefore be reversed, making both series<br> -and shunt work in unison, if the dynamo is to be used as a motor.<br> -<br> -The general principles of the electric motor of the dynamo, or<br> -continuous rotation type, can only be outlined here. The current passing<br> -through the field magnets polarizes them and creates a field. Entering<br> -the armature by the brushes and commutators it polarizes its core, but<br> -in such a way that the north pole is away from the south pole of the<br> -field magnet, and the same for the south pole. Hence the armature<br> -rotates. As it does this the brushes connect with other commutator<br> -sections, and the poles of the armature are shifted back. This action<br> -continues indefinitely.<br> -<br> -Another class of motors is of the reciprocating type. These are now very<br> -little used. (See Motor, Reciprocating.)<br> -<br> -One valuable feature of continuous rotation electric motors is the fact<br> -that they absorb energy, to a great extent proportional in amount to the<br> -work they have to do. The rotation of the armature in the field of the<br> -motor involves the cutting of lines of force by its coils. This<br> -generates an electro-motive force contrary in direction to that<br> -producing the actuating current. The more rapid the rotation the greater<br> -is this counter-electro-motive force. The motor armature naturally<br> -revolves faster with diminished resistance to the motion of the<br> -armature. This increases the counter-electromotive force, so that less<br> -energy is absorbed. When the motor is called on to do work, the armature<br> -rotates more slowly, and the counter-electro-motive force diminishes, so<br> -that the machine absorbs more energy. (See Jacobi's Law.)<br> -<br> -<br> -384 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Motor Electro-motive Force.</span><br> -The counter-electro-motive force of a motor. (F. J. Sprague.)<br> -<br> -A motor rotates in virtue of the pull of the field magnet upon the poles<br> -of the core of its armature. In responding to this pull the windings of<br> -the armature cuts lines of force and hence generates a<br> -counter-electro-motive force, for which the above term was suggested.<br> -<br> -<br> -<span style="font-weight: bold;">Motor-Generator.</span><br> -A combined motor and generator used to lower the potential difference in<br> -a portion of a circuit, e. g., that part within a building.<br> -<br> -A motor-generator is a dynamo whose armature carries two commutators,<br> -with two separate windings, one of fine wire of many turns, the other of<br> -coarse wire of few turns. If the potential of the system is to be<br> -lowered, the main current is passed through the fine winding. This<br> -causes the armature to turn motor-fashion, and a potential difference is<br> -generated by the rotation of the large coils in the field. This<br> -potential difference is comparatively low and by properly proportioning<br> -the windings may be lowered to as great a degree as required.<br> -<br> -The same apparatus may be inverted so as to raise potential difference.<br> -It acts for continuous current systems as the induction coil transformer<br> -does for alternating current systems.<br> -<br> -Synonym--Continuous Current Transformer.<br> -<br> -<br> -<span style="font-weight: bold;">Motor, Multiphase.</span><br> -A motor driven by multiphase currents. It is arranged in general terms<br> -for distribution of the multi phase currents in coils symmetrically<br> -arranged around the circle of the field. These coils are wound on cores<br> -of soft iron. A rotating field is thus produced, and a permanent magnet<br> -or a polarized armature pivoted in such a field will rotate with the<br> -field, its poles following the poles of the rotatory field.<br> -<br> -The cut, Fig. 245, illustrates the principles of action of a four phase<br> -current motor, connected to a four phase current dynamo or generator.<br> -The generator is shown on the left hand of the cut and the motor on the<br> -right hand. In the generator the armature N S is supposed to be turned<br> -by power in the direction shown by the arrow. Each one of the pair of<br> -coils is wound in the reverse sense of the one opposite to it, and the<br> -two are connected in series with each other, and with a corresponding<br> -pair in the motor. The connection can be readily traced by the letters A<br> -A', a a' for one set of coils and B B' b b' for the other set.<br> -<br> -<br> -385 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -For each rotation of the armature two currents, each in opposite<br> -direction, are produced in A A', and the same is the case for B B'.<br> -These currents which have an absolutely constant relation of phase, and<br> -which it will be seen alternate four times for each rotation of the<br> -armature, regulate the polarity of the field of the motor. The resultant<br> -of their action is to keep the poles of the field magnet of the motor<br> -constantly traveling around its circle. Hence the armature N S of the<br> -motor, seen on the right hand of the cut, tends to travel around also<br> -its north and south poles, following the south and north poles of the<br> -rotatory field respectively.<br> -<br> -<br> -<img style="width: 635px; height: 398px;" alt="" - src="images/385F245.jpg"><br> -Fig. 245. FOUR-PHASE CURRENT GENERATOR AND MOTOR.<br> -<br> -<br> -It is not essential that the armature should be a magnet or polarized.<br> -Any mass of soft iron will by induction be polarized and will be<br> -rotated, although not necessarily synchronously, with the rotatory<br> -field. Any mass of copper, such as a disc or cylinder, will have<br> -Foucault currents induced in it and will also rotate. The only<br> -components of such currents which are useful in driving the motor are<br> -those which are at right angles to the lines of force and to the<br> -direction of motion. A very good type of armature based on these<br> -considerations is a core of soft iron wound with insulated copper wire<br> -in one or more closed coils; and so wound as to develop the currents of<br> -proper direction.<br> -<br> -Such an armature is used in the Tesla alternating current motor. An<br> -efficiency of 85 per cent. has been attained with some of the Tesla<br> -motors.<br> -<br> -<br> -<span style="font-weight: bold;">Motor, Prime.</span><br> -A machine used for producing mechanical motion against resistance. It<br> -may operate by converting heat or any other form of kinetic or potential<br> -energy into mechanical energy of the moving type. A steam-engine and a<br> -water-wheel are examples of prime motors.<br> -<br> -<br> -<span style="font-weight: bold;">Motor, Reciprocating.</span><br> -The early type of motor depending upon reciprocating motion, such as the<br> -motion of a coil in a solenoid. These were based upon the lines of a<br> -steam engine, and have been abandoned except for special purposes where<br> -reciprocating motion is especially required, as in the case of rock<br> -drills.<br> -<br> -<br> -386 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 573px; height: 517px;" alt="" - src="images/386F246.jpg"><br> -Fig. 246. RICORDON'S RECIPROCATING MOTOR.<br> -<br> -<br> -In the cut, B is an electro-magnet; A is an armature; E a pole piece.<br> -The current enters by the springs, b b, and by commutation is supplied<br> -and cut off alternately, thus maintaining a reciprocating movement of<br> -the armature and rotation of the fly-wheel.<br> -<br> -Synonym--Pulsating Motor.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Motor, Series.</span><br> -A motor whose winding on the armature is in series with the winding on<br> -the field. It is similar to a series dynamo. (See Dynamo, Series.)<br> -<br> -<br> -<span style="font-weight: bold;">Motor, Shunt.</span><br> -A motor whose winding on the armature is in parallel with the winding on<br> -the field magnets. It is similar to a shunt wound dynamo. (See Dynamo,<br> -Shunt.)<br> -<br> -<br> -<img style="width: 592px; height: 210px;" alt="" - src="images/386F247.jpg"><br> -Fig. 247. MULTIPLE ARC CONNECTION.<br> -<br> -<br> -<span style="font-weight: bold;">Multiple.</span><br> -A term expressing connection of electric apparatus such as battery<br> -couples, or lamps in parallel with each other. In the ordinary<br> -incandescent lamp circuits the lamps are connected in multiple.<br> -<br> -Synonym--Multiple Arc.<br> -<br> -<br> -387 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Multiple Arc Box.</span><br> -A resistance box arranged so that the coils may be plugged in multiple<br> -instead of in series. Such can be used as a rheostat, as the resistance<br> -can be very gradually changed by putting the coils one by one into<br> -parallel with each other. Thus by adding in parallel with a 10 ohm coil<br> -a 10,000 ohm coil the resistance is decreased to 9.999001 ohms, and thus<br> -the resistance can be very slowly changed without sudden stops or abrupt<br> -changes.<br> -<br> -[Transcriber's note: The correct value is 9.99001]<br> -<br> -<br> -<span style="font-weight: bold;">Multiple Series.</span><br> -Arrangements of electric apparatus in a circuit in a number of series,<br> -which minor series are then arranged in parallel. The term may be used<br> -as a noun, as "arranged in multiple-series," or as an adjective, as "a<br> -multiple-series circuit."<br> -<br> -<br> -Fig. 248. MULTIPLE SERIES CONNECTION.<br> -<br> -<br> -<span style="font-weight: bold;">Multiple Switch Board.</span><br> -A switch board on whose face connecting spring jacks or other devices<br> -are repeated for the same circuits, so that different operators have<br> -each the entire set of connections repeated on the section of the board<br> -immediately in front of and within their reach. This multiplication of<br> -the same set of connections, giving one complete set to each operator,<br> -gives the title "multiple" to the type of switch board in question. The<br> -typical multiple switch board used in telephone exchanges is the best<br> -example of this construction. The calling annunciators of the<br> -subscribers are distributed along the bottom of the board extending its<br> -full length. To each operator a given number is assigned, all within<br> -reach of the right or left hand. This gives five or six feet length of<br> -board to each, and an operator only responds to those subscribers within<br> -his range. But anyone of his subscribers may want to connect with any of<br> -the others in the entire central station. Accordingly in front of each<br> -operator spring jacks are arranged, one for each of the entire set of<br> -subscribers connected in that office. The operator connects as required<br> -any of the calling subscribers, who are comparatively few, to any one of<br> -the large number served by the central station. Thus the entire set of<br> -subscribers' spring jacks are multiplied over and over again so as to<br> -give one set to each operator.<br> -<br> -<br> -388 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Multiple Wire Method for Working -Electro-magnets.</span><br> -A method for suppressing sparking in working electro-magnets<br> -intermittently. The magnet core is wound with a number (from four to<br> -twenty) of separate layers of fine wire. A separate wire is taken for<br> -each layer and all are wound in the same direction, from one end to the<br> -other of the space or bobbin without returning. The ends are then joined<br> -so as to bring all the wires in parallel. The effect of this is that as<br> -the coils vary in diameter the time constants of each is different from<br> -that of the others, the coefficient of self-induction being less, and<br> -the resistance being greater for the coils farthest from the central<br> -axis. Thus the extra currents run differently in the different coils,<br> -and only a comparatively small spark can be produced owing to the<br> -division of forces thus brought about.<br> -<br> -<br> -<img style="width: 677px; height: 207px;" alt="" - src="images/388F249.jpg"><br> -Fig. 249. DIAGRAM ILLUSTRATING MULTIPLE WIRE WORKING.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Multiplex Telegraphy.</span><br> -Any system of telegraphy transmitting more than four messages<br> -simultaneously over a single wire. Properly it should apply to all<br> -transmitting more than one, but conventionally has the above restricted<br> -meaning, distinguishing it from duplex and quadruplex telegraphy.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Multiplying Power of a Shunt.</span><br> -When a resistance is placed in parallel with a galvanometer on a circuit<br> -the following relation obtains. Let s and g equal the resistances of the<br> -shunt and galvanometer respectively, S and G the currents in amperes<br> -passing through them, V the potential difference between their common<br> -terminals, and A the whole current in amperes. Then we have<br> - A = ( (s + g ) / s ) * G<br> -and ( (s + g ) / s ) is termed the multiplying power of the shunt, as it<br> -is the factor by which the current passing through the galvanometer must<br> -be multiplied by to produce the total current.<br> -<br> -<br> -<span style="font-weight: bold;">Muscular Pile.</span><br> -A species of voltaic battery, often termed Matteueci's pile, made up of<br> -alternate pieces of muscle cut longitudinally and transversely<br> -respectively. The different pieces represent the elements of a battery,<br> -and their difference of potential is naturally possessed by the pieces.<br> -<br> -<br> -<span style="font-weight: bold;">Myria.</span><br> -A prefix; one million times. Thus myriavolt means one million volts.<br> -<br> -[Transcriber's note: Contemporary usage is mega, as in megavolt.]<br> -</big></big><br> -<big><big><br> -389 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">N.</span><br> -(a) Symbol for north pole or north-seeking pole of a magnet.<br> -<br> -(b) Symbol for the number of lines of force in a magnetic circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Nairne's Electrical Machine.</span><br> -The cylinder electrical machine, q.v.<br> -<br> -<br> -<span style="font-weight: bold;">Napierian Logarithms.</span><br> -A series of logarithms the base of whose system is 2.72818. They are<br> -also called hyperbolic logarithms.<br> -<br> -<br> -<span style="font-weight: bold;">Nascent State.</span><br> -An element just separating from a combination possesses at that time<br> -higher affinities than after separation, and can effect more powerful<br> -chemical changes.<br> -<br> -It is sometimes attributed to a differential time of existence in the<br> -atomic modification, before the freed atoms have united to form<br> -molecules.<br> -<br> -<br> -<span style="font-weight: bold;">Natural Currents.</span><br> -A term for earth currents. (See Current, Earth.)<br> -<br> -<br> -<span style="font-weight: bold;">Needle.</span><br> -(a) A term applied to a bar magnet poised horizontally upon a vertical<br> -point, or suspended in a horizontal position by a filament. Thus the<br> -magnet in a mariner's compass, which may be a substantial bar magnet, is<br> -called a magnetic needle.<br> -<br> -(b) An indicator in general shape like the hand of a clock. (Sec<br> -Annunciator, Needle- Telegraph, Needle.)<br> -<br> -<br> -<span style="font-weight: bold;">Needle of Oscillation.</span><br> -The magnetic needle poised horizontally, and used for measuring the<br> -intensity of the earth's magnetic field, or of an artificial magnetic<br> -field, by the method of oscillations. The intensities of the field is<br> -inversely as the square of the number of oscillations performed in a<br> -given time.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Needle, Telegraphic.</span><br> -The index in needle telegraphy (see Telegraph, Needle), whose motions<br> -indicate the characters it is desired to transmit.<br> -<br> -<br> -<span style="font-weight: bold;">Negative Charge.</span><br> -One of the two kinds of electric charges. The other is the positive.<br> -<br> -By the double fluid hypothesis this is assumed to be a charge of a<br> -particular kind of electricity--negative electricity.<br> -<br> -By the single fluid hypothesis it is supposed to be caused by the<br> -absence of part of the normal electricity of a surface. The reverse is<br> -held by some theorists.<br> -<br> -The subject is so purely theoretical that neither of the two hypotheses<br> -is accepted as final.<br> -<br> -[Transcriber's note: Current is a wire is the motion of negative<br> -electrons. Current in a electrolyte is the motion of positive ions and<br> -negative ions. Current in a plasma is the motion of electrons and<br> -positive ions.]<br> -<br> -<br> -390 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Negative Electricity.</span><br> -The kind of electricity with which a piece of amber is charged by<br> -friction with flannel; resinous electricity. (See Electrostatic Series.)<br> -<br> -<br> -In a galvanic battery the surface of the zinc plate is charged with<br> -negative electricity.<br> -<br> -According to the single fluid theory negative electrification consists<br> -in a deficiency of electricity.<br> -<br> -[Transcriber's note: Negative electrification is an excess of<br> -electrons.]<br> -<br> -<br> -<span style="font-weight: bold;">Negative Element.</span><br> -In a voltaic cell the plate not dissolved by the solution; the one which<br> -is positively charged; the copper, platinum, or carbon plate in the<br> -usual type of battery.<br> -<br> -The current is assumed to flow from negative element to positive element<br> -(the zinc plate) through the wire or other external conductor.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Nerve Currents.</span><br> -Currents of electricity obtained from nerves. They are much more feeble<br> -than those obtained from muscle, but are produced in the same general<br> -ways.<br> -<br> -<br> -<span style="font-weight: bold;">Network.</span><br> -Conductors in parallel and crossing each other, with connections at the<br> -junctions.<br> -<br> -The term is sometimes so loosely applied as to include parallel<br> -conductors.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Neutral Line of Commutator.</span><br> -The diameter of a commutator which connects its Neutral Points, q. v.;<br> -sometimes termed the diameter of commutation; the diameter approximately<br> -at right angles with the lines of force. The commutator brushes are<br> -applied at the extremities of this diameter.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Neutral Point of a Commutator.</span><br> -The points of a commutator at which no lines of force are cut; the<br> -points at the extremities of a diameter which, except for the lag, would<br> -be at right angles to the lines of force; the points at which the<br> -brushes touch the commutator.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Neutral Point, Thermo-electric.</span><br> -A temperature marking a point of no thermo-electric difference of<br> -potential. If the junctions of a thermo-electric couple are at<br> -temperatures, one a little over and the other an equal amount under the<br> -neutral point, no current will be developed. At the neutral point the<br> -thermo-electric polarities are reversed. Differences of temperature<br> -above it give currents of reverse direction to those given by<br> -corresponding differences below it. For an iron-copper couple the<br> -neutral point is 274.5° C. (526° F.)<br> -<br> -Synonym--Neutral Temperature.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Neutral Relay Armature.</span><br> -An unpolarizable armature for use with a relay; an armature of soft iron<br> -or iron wire; as distinguished from a polarized armature.<br> -<br> -<br> -391 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Neutral Wire.</span><br> -The central wire in the three wire system, q. v., of electric<br> -distribution; the wire connected to a point between the two dynamos, or<br> -otherwise to the central point of the current generator.<br> -<br> -<br> -<img style="width: 713px; height: 223px;" alt="" - src="images/391F250.jpg"><br> -Fig. 250. DIAGRAM OF THREE WIRE SYSTEM SHOWING NEUTRAL WIRE.<br> -<br> -<br> -<span style="font-weight: bold;">Neutral Wire Ampere Meter.</span><br> -An ampere meter connected in the circuit of the neutral wire to<br> -determine the current passing through it. Such determination is for the<br> -purpose of ascertaining how much more work is being done by one of the<br> -lateral leads than by the other.<br> -<br> -Synonym--Balance Ampere Meter.<br> -<br> -<br> -<span style="font-weight: bold;">N. H. P.</span><br> -Symbol or contraction for "nominal horse power." This is a basis for<br> -rating the size of an engine.<br> -<br> -<br> -<span style="font-weight: bold;">Nickel.</span><br> -A metal; one of the elements; atomic weight, 58.8 ; equivalent, 29.4;<br> -valency, 2; specific gravity, 8.8. It is a conductor of electricity.<br> - <small><span style="font-family: monospace;">Relative -resistance, annealed (Silver = 1), 8.285</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Specific -Resistance, -12.47 microhms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Resistance of a wire</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> (a) 1 foot long, weighing -1 grain, 15.206 ohms.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> (b) 1 foot long, 1/1000 -inch thick, 74.963 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> (c) 1 meter long, weighing -1 gram, 1.060 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> (d) 1 meter long, 1 -millimeter thick, .1587 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Resistance of a 1-inch -cube, -4.907 microhms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Electro-chemical -equivalent, (Hydrogen = .0105) .3087 mgs.</span></small><br> -<br> -It is strongly paramagnetic, but loses this quality at 350º C. -(662º F.)<br> -<br> -It is important as a constituent of German silver, an alloy much used<br> -for resistance coils.<br> -<br> -<br> -<span style="font-weight: bold;">Nickel, Bath.</span> <br> -A bath for the electro-deposition of nickel. A great many<br> -formulae have been given. Metallic nickel is dissolved in 1 vol.<br> -sulphuric acid mixed with 2 vols. water. Neutralize with ammonia, and<br> -add of ammonium sulphate one-half the weight of metallic nickel<br> -originally used; 135 parts of nickel will be enough for a bath of 10,000<br> -parts.<br> -<br> -<br> -392 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Other formulae are as follows:<br style="font-family: monospace;"> -<span style="font-family: monospace;"> Double nickel-ammonium -sulphate, 4 parts.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Ammonium -carbonate, -3 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Water -100 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Nickel sulphate, nitrate -or chloride, 1 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Sodium -bisulphate, -1 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Water, -20 "</span><br> -<br> -Nickel anodes are used in the bath to maintain the strength. Too much<br> -care cannot be exercised in the absolute cleanliness of the articles to<br> -be plated. A too alkaline bath gives a disagreeable yellow color to the<br> -deposit; too acid a bath gives badly adhering deposits.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Night Bell.</span><br> -An alarm bell in a telegraph office, which bell is connected at night to<br> -give a loud signal to attract the operator's attention. It is used in<br> -telephone exchanges and is connected so as to ring as long as a<br> -subscriber remains unanswered after calling.<br> -<br> -<br> -<span style="font-weight: bold;">Nobili's Rings.</span><br> -When a dilute solution of copper acetate is placed on a bright silver<br> -plate and a strip of zinc is touched to the silver beneath the copper, a<br> -series of rings of copper are formed by electrolysis around the zinc.<br> -These are Nobili's rings.<br> -<br> -If for the copper acetate a solution of lead oxide in potassium hydrate<br> -solution is substituted, and if the polished plate which may be German<br> -silver is connected to the positive electrode of a battery, and a<br> -platinum wire connected to the negative pole is immersed in the liquid,<br> -it determines the formation of beautiful iridescent rings of lead<br> -binoxide. The platinum wire is sometimes sealed in glass so that only<br> -its point projects.<br> -<br> -The colors are due to interference of light, the layers of lead oxide<br> -being extremely thin.<br> -<br> -The lead binoxide is formed by secondary reaction. Metallic lead is<br> -first deposited on the negative pole. The oxygen which goes to the<br> -positive pole formed by the polished plate produces lead binoxide which<br> -is deposited there in rings. The reaction is comparable to that of a<br> -storage battery.<br> -<br> -Synonyms--Metallochromes--Electric Rings.<br> -<br> -<br> -<span style="font-weight: bold;">Nodular Deposit.</span><br> -A deposit obtained in electroplating, characterized by irregular<br> -thickness; due to too low density of current.<br> -<br> -<br> -<span style="font-weight: bold;">Non-conductor.</span><br> -A material that does not conduct electricity except with great<br> -difficulty; a substance of very high resistance.<br> -<br> -Synonym--Insulator--Dielectric.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">North Pole.</span><br> -(a) The north-seeking pole of a magnet; the pole of a magnet which tends<br> -to point to the north, and whence lines of force are assumed to issue on<br> -their course to the other pole of the magnet.<br> -<br> -(b) The North Pole of the earth. Treating the earth as a magnet, and<br> -accepting the above nomenclature the north pole should be termed the<br> -south pole. (See Austral Pole--Boreal Pole.)<br> -<br> -<br> -393 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">North-seeking Pole.</span><br> -The pole of a magnet which tends to point to the north; the north pole<br> -of a magnet.<br> -<br> -<br> -<span style="font-weight: bold;">Null Method.</span><br> -Any method of obtaining measurements or comparisons, in which the<br> -measurement is correct when the deflection of the galvanometer or other<br> -indicator is zero, nought or null. The Wheatstone Bridge (see Bridge,<br> -Wheatstone) is an example of a null method.<br> -<br> -Two obvious advantages attach to null methods in electric galvanometer<br> -work. One is that an uncalibrated galvanometer can be employed. The<br> -other is that a galvanometer of any high degree of sensitiveness can be<br> -employed, there being no restriction as to its fineness of winding or<br> -highness of resistance.<br> -<br> -</big></big><big><big><br> -393 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 634px; height: 86px;" alt="" - src="images/393Omega.jpg"><br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">"Upper case Omega Graphic".</span><br> -(Greek capital" Omega") symbol for megohm.<br> -[Transcriber's note: Now used for ohms.]<br> -<br> -<br> -<span style="font-weight: bold;">"Lower case Omega Graphic".</span><br> -(Greek omega) symbol for ohm.<br> -[Transcriber's note: Now used for angular velocity, 2*PI*frequency.]<br> -<br> -<br> -<span style="font-weight: bold;">Occlusion.</span><br> -An absorption of gases by metals. Palladium will, if used as the<br> -hydrogen evolving electrode in decomposing water, absorb 980 times its<br> -volume of hydrogen, which is said to be occluded. The metal may also be<br> -heated in hydrogen and allowed to cool therein, when occlusion occurs.<br> -Platinum will occlude 4 times its volume of hydrogen; iron, 4.15 times<br> -its volume of carbon-monoxide; silver, 7 times its volume of oxygen.<br> -Metals with occluded gases may serve as elements in a galvanic couple.<br> -(See Gas Battery.) A metal expands in occluding a gas.<br> -<br> -In the storage battery it is believed that occlusion plays a part,<br> -hydrogen and oxygen being respectively absorbed by the two sets of<br> -plates, and acting as they do in Groves' gas battery.<br> -<br> -<br> -<span style="font-weight: bold;">Oerstedt.</span><br> -Name proposed for the unit of current strength, but not adopted. The<br> -ampere is the accepted name.<br> -<br> -<br> -394 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Oerstedt's Discovery.</span><br> -Oerstedt discovered in 1820 that a magnetic needle tended to place<br> -itself at right angles to a current of electricity. This fundamental<br> -experiment is the basis of the galvanometer.<br> -<br> -<br> -<img style="width: 587px; height: 510px;" alt="" - src="images/393F251.jpg"><br> -Fig. 251. OERSTEDT'S DISCOVERY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Ohm.</span><br> -The practical unit of resistance; 1E9 C. G. S. electro-magnetic units.<br> -The legal ohm is the resistance of a mercury column 1 square millimeter<br> -in cross-sectional area and 106 centimeters in length. There has been<br> -considerable confusion, owing to inaccuracy in early determinations, in<br> -the valuation of the ohm. In this work the legal ohm is used. The<br> -different ohms will be found defined in their place. Resistance units of<br> -various names may also be consulted.<br> -<br> -The following table gives the relative values of the different ohms.<br> -<small><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Length of</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Mercury -Board of</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Column in True B. -A. Trade Legal</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -Centimetre. Ohm. Ohm. -Ohm. Ohm.</span><br - style="font-family: monospace;"> -<br style="font-family: monospace;"> -<span style="font-family: monospace;">True -Ohm, -106.24 1. -1.0128 .9994 1.0022</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">B. A. -Ohm, -104.9 .9874 -1. -.9868 .9889</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Board of Trade Ohm -106.3 1.00050 1.0133 -1. 1.0028</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Legal -Ohm, -106.0 .9977 -1.0112 .9971 1.</span></small><br> -<br> -<br> -<span style="font-weight: bold;">Ohmage.</span><br> -The Resistance of a circuit expressed in ohms.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Ohm, B. A.</span><br> -The British Association unit of resistance; the resistance of a column<br> -of mercury 1 square millimeter in cross sectional area and 104.9<br> -centimeters long; the B. A. Unit of Resistance.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Ohm, Board of Trade.</span><br> -The approximate ohm as recommended by the British Board of Trade on the<br> -advice of a committee (Sir W. Thomson, Dr. J. Hopkinson, Lord Rayleigh<br> -and others). It is the resistance of a mercury column one square<br> -millimeter in section, and 106.3 centimeters long at 0º C. -(32º F.)<br> -<br> -Synonym--New Ohm.<br> -<br> -<br> -395 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Ohmic Resistance.</span><br> -True resistance as distinguished from spurious resistance, or<br> -counter-electro-motive force.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Ohm, Legal.</span><br> -The practical unit of resistance. The resistance of a column of mercury<br> -one square millimeter in cross-sectional area and 106 centimetres long<br> -at 0º C. (32º F.) The ohm used previously to 1884 is the B. -A. Unit of<br> -Resistance, q. v.<br> -<br> -One legal ohm = 1.0112 B. A. Units, and I B. A. Unit = 0.9889 legal ohm.<br> -<br> -The resistance of a copper wire 1 foot long and 1/1000 inch in diameter<br> -is about 10 ohms. The resistance of 1 mile of iron wire 1/3 inch in<br> -diameter is about 10 ohms.<br> -<br> -Synonym--Congress Ohm.<br> -<br> -<br> -396 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 642px; height: 466px;" alt="" - src="images/395F252.jpg"><br> -Fig. 252. THEORY OF OHMMETER.<br> -<br> -<br> -<img style="width: 595px; height: 501px;" alt="" - src="images/395F253.jpg"><br> -Fig. 253. OHMMETER.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Ohmmeter.</span><br> -An instrument for measuring directly the resistance of a conductor or of<br> -any part of a circuit through which a strong current is passing. -It is<br> -the invention of Prof. W. E. Ayrton.<br> -<br> -It contains two fixed coils at right angles to each other acting on the<br> -same needle of soft iron. One coil is of thick wire and is placed in<br> -series with the resistance to be measured. The other is of very thin<br> -wire and is placed in parallel with the same resistance. One wire acts<br> -by the total current, the other by the potential difference between the<br> -ends of the resistance. The action on the soft iron needle is due to the<br> -ratio of potential difference to total currents, or to the resistance<br> -itself. By properly designing and proportioning the coils the angular<br> -deflections of the needle are made proportional to the resistance.<br> -<br> -In use the thick wire may be kept permanently in circuit. On connecting<br> -the binding posts of the thin wire coil to any two parts of the circuit<br> -its resistance is at once given by the deflection of the needle.<br> -<br> -When no current is passing the needle rests in any position. A current<br> -in the thick coil brings it to zero. A current simultaneously passing<br> -through the thin high resistance coil brings about the deflection.<br> -<br> -The instrument is a commercial rather than a scientific one.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Ohm's Law.</span><br> -The fundamental law expressing the relations between current,<br> -electro-motive force and resistance in an active electric circuit. It<br> -may be expressed thus:<br> -<br> -(a) The current strength is equal to the electro-motive force divided by<br> -the resistance.<br> -<br> -(b) The electro-motive force is equal to the current strength multiplied<br> -by the resistance.<br> -<br> -(c) The resistance is equal to the electro-motive force divided by the<br> -current strength. All these are different forms of the same statement.<br> -Algebraically the law is usually expressed thus, (a) C = E/R. It may<br> -also be expressed thus: (b) E = C*R and (c) R= E/C, in which R denotes<br> -resistance, C denotes current strength, and E denotes electro-motive<br> -force.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Ohm, True.</span><br> -The true ohm is the resistance of a column of mercury 1 square<br> -millimeter in cross-sectional area, and 106.24 centimeters long. (See<br> -Ohm.)<br> -<br> -Synonym-Rayleigh Ohm.<br> -<br> -<br> -<span style="font-weight: bold;">Oil Insulation.</span><br> -Oil insulation has received several applications in electrical work. It<br> -has been proposed for use in underground conduits. These it was proposed<br> -to fill with oil after the insertion of the conductors, the latter<br> -properly wrapped with cotton or other covering. For induction coils it<br> -has been very successfully used. Its principal utility depends on the<br> -fact that it is liquid, so that if pierced by a spark it at once closes<br> -again. A solid insulator if pierced is permanently injured. It is also<br> -used in telegraph insulators (see Insulator, Liquid) to prevent surface<br> -leakage.<br> -<br> -<br> -397 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Olefiant Gas.</span><br> -A compound gas; C2H4; composed of carbon, 24; hydrogen, 4; molecular<br> -weight, 28; specific gravity, .981.<br> -<br> -It is a dielectric of about the resistance of air. Its specific<br> -inductive capacity at atmospheric pressure is 1.000722 (Boltzman.)<br> -<br> -Synonym--Ethene; heavy carburetted hydrogen.<br> -<br> -[Transcriber's note: Also called ethylene. A primary use is polyethylene<br> -plastic.]<br> -<br> -<br> -<span style="font-weight: bold;">Open. adj.</span><br> -An electric circuit is said to be open when it is cut or broken so that<br> -no current can pass through it. The term may be recollected by thinking<br> -of a switch; when open no current can pass through it. The same<br> -adjective is applied to magnetic circuits, an air gap implying an open<br> -circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Open Circuit Oscillation.</span><br> -An oscillation of current in open circuit so that a spark discharge<br> -accompanies it. It is produced by electric resonance in a simple circle<br> -or loop of wire with ends placed near together but not touching, if the<br> -circuit is of such size that its period of oscillation corresponds with<br> -that of the inducing discharge. (See Resonance, Electric.) Its period<br> -depends entirely on the self-induction of the circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Ordinate.</span><br> -In a system of plane co-ordinates (see Co-ordinates), the distance of<br> -any point from the axis of abscissas measured parallel to the axis of<br> -ordinates.<br> -<br> -<br> -<span style="font-weight: bold;">Ordinates, Axis of.</span><br> -The vertical axis in a system of co-ordinates, q. v.<br> -<br> -Synonym--Axis of Y.<br> -<br> -<br> -<span style="font-weight: bold;">Organ, Electric.</span><br> -An organ in which the air blast is admitted or excluded from the<br> -different pipes by electric mechanism.<br> -<br> -The outlines of the system are a series of contacts worked by the keys<br> -and stops, which cause, when operated by the organist, a current to pass<br> -through electro-magnets, opening the valves of the different pipes. Thus<br> -the manual may be at any distance from the organ, and a number of organs<br> -may be worked upon the same manual. As many as five in a single<br> -cathedral are thus connected to a manual in the chancel.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Orientation of a Magnetic Needle.</span><br> -The acquirement by a magnetic needle of its position of rest, with its<br> -magnetic axis in the magnetic meridian.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Origin of Co-ordinates.</span><br> -In a system of linear co-ordinates the point of intersection of the<br> -axes; the point whose co-ordinates are both zero.<br> -<br> -<br> -398 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Oscillating Needle.</span><br> -A small light bar magnet suspended by a filament and employed in<br> -determining the intensity of a magnetic field by the oscillations it<br> -completes in a given time after a given disturbance.<br> -<br> -<br> -<span style="font-weight: bold;">Oscillations, Electric.</span><br> -In static electricity the sudden and very rapid alternations in the<br> -discharge of a static condenser. This discharge of the disruptive order<br> -seems a single one, but is really composed of a number of discharges<br> -alternating in direction and producing electro-magnetic ether waves,<br> -probably identical with light waves except that they are longer and far<br> -less rapid.<br> -<br> -<br> -<span style="font-weight: bold;">Oscillatory Electro-motive Force.</span><br> -Electro-motive force rapidly changing in sense or in direction, so that<br> -it presents an oscillatory character. The alternating current and the<br> -telephone current as used in practice are actuated by this type of<br> -electro-motive force.<br> -<br> -<br> -<span style="font-weight: bold;">Osmose, Electric.</span><br> -When two liquids are separated by a porous diaphragm, and a strong<br> -current of electricity is passed through from the liquid on one side,<br> -through the diaphragm, to the liquid on the other side, the liquid on<br> -the side towards which the current is passing rises in level. The<br> -process is termed electric osmose. When a liquid is forced through a<br> -diaphragm a current is produced; in other words electric osmose is<br> -reversible. The current thus produced is termed a diaphragm current.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Oscillation, Electric.</span><br> -The phase of discharge of a static condenser in one direction. It is<br> -usually followed by a discharge in the opposite direction constituting a<br> -second oscillation, and so on, so that a great number of exceedingly<br> -short oscillations are comprised. Thus, in the discharge of the Leyden<br> -jar a large number of oscillations of current back and forth are<br> -produced, the current alternating like the swings of a pendulum.<br> -<br> -These oscillations are supposed to affect the ether, producing waves in<br> -it identical with light waves, except that we have not been able yet to<br> -produce them short enough to affect the visual organs. The waves thus<br> -produced can be reflected or refracted; some substances are transparent<br> -for them and others opaque. There is a possibility that man may yet<br> -succeed in producing electric oscillations of sufficient frequency to<br> -bring about the direct production of light.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Oscillatory Displacement.</span><br> -Hypothetical displacement currents of rapidly alternating direction<br> -produced in the oscillatory discharge of a Leyden jar or static<br> -condenser.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Oscillatory Induction.</span><br> -Induction produced by sympathetic action of an oscillatory discharge or<br> -by electric resonance. (See Oscillations, Electric--Resonance,<br> -Electric--Resonator, Electric.)<br> -<br> -<br> -399 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Outlet.</span><br> -The part of an electrolier or electric light fixture out of which the<br> -wires are led for attachment of an incandescent light socket.<br> -<br> -<br> -<span style="font-weight: bold;">Output.</span><br> -The rate of energy delivered or of work done by a machine. In the case<br> -of a current generator it is the volt-coulombs per given second, or<br> -better the volt-amperes delivered at its outer circuit terminals.<br> -<br> -<br> -<span style="font-weight: bold;">Output, Magnetic.</span><br> -The analogue in a magnetic circuit of the output of an electric circuit.<br> -It is the product of the magnetizing force by the induced magnetism.<br> -<br> -<br> -<span style="font-weight: bold;">Output, Unit of.</span><br> -As a unit of output of a dynamo Prof. Sylvanus P. Thompson has proposed<br> -1,000 watts, or one kilowatt. This unit is now frequently used. To<br> -completely define the dynamo, however, the amperage or the voltage must<br> -also be given, as a 10 kilowatt--110 volt machine, or a 10 kilowatt--99<br> -ampere machine.<br> -<br> -[Transcriber's note: 10 kilowatt at 110 volts is 91 amperes.]<br> -<br> -<br> -<span style="font-weight: bold;">Over-Compounding.</span><br> -A proportioning of the series and shunt windings of a compound dynamo,<br> -so that the voltage of the terminals rises with the load or output<br> -enough to allow for the drop in mains, thus maintaining the potential<br> -for full load at distant points in a district. It is carried out by an<br> -increase of ampere-turns in the series winding.<br> -<br> -<br> -<span style="font-weight: bold;">Overload.</span><br> -In an electric motor a mechanical load put upon it so great as to<br> -prevent economical working. One effect of such a load is to make the<br> -armature run so slowly as to unduly reduce the counter-electro-motive<br> -force and hence to permit so much current to pass through the coils as<br> -to heat them, perhaps injuriously. In this case the production of heat<br> -implies the waste of energy.<br> -<br> -<br> -<span style="font-weight: bold;">Overtype Dynamo or Motor.</span><br> -A dynamo or motor whose armature is placed above or in the upper part of<br> -the field magnets, the yoke piece of the magnets being in or resting<br> -upon the base of the machine.<br> -<br> -<br> -<span style="font-weight: bold;">Ozone.</span><br> -An allotropic form of oxygen. It possesses much more energetic chemical<br> -properties than oxygen. It is supposed to contain three atoms of oxygen<br> -in its molecule, represented thus:<br> -<span style="font-family: monospace;"> O</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> / \</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> O---O</span><br> -<br> -It is produced by electric discharges and it is its peculiar odor which<br> -is noticed about an electric machine, and sometimes in a thunderstorm<br> -near the path of a lightning flash.<br> -<br> -In the electrolysis of water some ozone may be produced, thus<br> -diminishing the volume of the oxygen or of the mixed gases given off.<br> -This is a source of inaccuracy in a gas voltameter.<br> -<br> -</big></big><big><big><br> -400 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Pacinotti's Inductor.</span><br> -The Pacinotti or Gramme Ring. (See Pacinotti's Ring.)<br> -<br> -<br> -<span style="font-weight: bold;">Pacinotti's Ring.</span><br> -A ring of iron wire wound with coils of insulated wire at right angles<br> -to its circular axis, and used as the armature of a dynamo or motor. A<br> -number of connections are taken from the coils to a central commutator.<br> -<br> -<br> -<img style="width: 640px; height: 559px;" alt="" - src="images/400F254.jpg"><br> -Fig. 254. PACINOTTI'S MACHINE, WITH RING ARMATURE.<br> -<br> -<br> -If such a ring with its coils is rotated in a field, current can be<br> -taken from points of the commutator on a line at right angles to the<br> -lines of force entering the ring.<br> -<br> -The ring was discovered in 1862 by Pacinotti, and later was<br> -independently discovered by Gramme. It is often known as the Gramme<br> -ring.<br> -<br> -<br> -<span style="font-weight: bold;">Pacinotti Teeth.</span><br> -Projections on a cylindrical or drum armature, between which in the<br> -grooves formed thereby, the wire is wound. The teeth being of iron tend<br> -to diminish the reluctance or magnetic resistance of the interpolar<br> -space, or interval between the poles of the field magnet.<br> -<br> -Synonym--Pacinotti Projections.<br> -<br> -<br> -<span style="font-weight: bold;">Paillard Alloys.</span> <br> -Non-magnetic palladium alloys, invented by Paillard, of<br> -Switzerland, used in anti-magnetic watches. The following are given as<br> -the compositions of several such alloys:<br> -<small><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -I. -II.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Palladium, 60 to -75 parts 50 to 75 parts</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Copper, -I5 to 25 " 20 to -30 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Iron. -1 to 5 " 5 to -20 "</span></small><br> -<br> -<br> -401 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The following are more complex:<small><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -I. -II.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Palladium, 65 to -75 parts 45 to 50 parts</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Copper, -15 to 25 " 15 to -25 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Nickel, -1 to 5 " 2 -to 5 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Silver, -3 to 10 " 20 to -25 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Gold, -1 to 2-1/2 " 2 to -5 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Platinum, 1/2 to -2 " 2 to -5 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Steel, -1 to 5 " 2 -to 5 "</span></small><br> -<br> -These alloys are used for balance springs, as well as for the balance<br> -wheels and escapement parts of watches. The elasticity of recently<br> -produced springs has been found to be very satisfactory.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Page Effect.</span><br> -The sounds produced by magnetizing and demagnetizing a bar of iron or<br> -steel; the magnetic tick. The sounds are strong enough to produce a<br> -telephonic effect. (See Magnetic Tick.)<br> -<br> -<br> -<span style="font-weight: bold;">Palladium.</span><br> -A metal of the platinum series. It has the highest power of occlusion,<br> -q.v., of all metals. It is the characteristic ingredient of non-magnetic<br> -watch alloys.<br> -<br> -Palladium used as an electrode in the electrolysis of water will occlude<br> -936 volumes of hydrogen, and the hydrogen-palladium alloy will exceed in<br> -size the original electrode.<br> -<br> -<br> -<img style="width: 343px; height: 686px;" alt="" - src="images/365F235.jpg"><br> -Fig. 255. LUMINOUS PANE.<br> -<br> -<br> -<span style="font-weight: bold;">Pane, Luminous.</span><br> -A pane of glass, one side of which has pasted to it a long zigzag strip<br> -of tinfoil. A design is made by cutting through the strip. On<br> -discharging a Leyden jar or an electric machine through the strip sparks<br> -appear where the tinfoil is severed, thus producing the design in a<br> -luminous effect. Many variations can be employed in their construction.<br> -<br> -<br> -402 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Pantelegraphy.</span><br> -A system of telegraphy for transmitting designs, maps, drawing, and the<br> -like by telegraphy. (See Telegraphy, Facsimile.)<br> -<br> -<br> -<span style="font-weight: bold;">Paper Filaments.</span><br> -Filaments of carbon for incandescent lamps made from paper.<br> -<br> -This is one of the earliest materials practically used. The paper is cut<br> -out of proper shape, and is carbonized in a close vessel, while embedded<br> -in powdered charcoal or some other form of carbon to absolutely cut off<br> -access of air. It is then placed in the lamp chamber and flashed or<br> -subjected to the regular treatment.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Parabola.</span><br> -A curve; one of the conic sections. It is approximately represented by a<br> -small arc of a circle, but if extended becomes rapidly deeper than a<br> -half circle.<br> -<br> -If, from a point within called the focus, lines are drawn to the curve<br> -and then other lines are drawn from these points parallel to the axis,<br> -the angles of incidence will he equal to the angles of reflection as<br> -referred to tangents at the points where the lines touch the curve.<br> -<br> -[Transcriber's note; The general equation of a parabola is<br> - A*x^2 + B*x*y + C*y^2 + D*x + E*y + F = 0<br> -such that B^2 = 4*A*C, all of the coefficients are real, and A and C are<br> -not zero. A parabola positioned at the origin and symmetrical on the y<br> -axis is simplified to y = a*x^2 ]<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Parabolic Reflector.</span><br> -A reflector for a light, a paraboloid or surface of revolution whose<br> -section is a parabola. A light placed at its focus has its rays<br> -reflected parallel to each other.<br> -<br> -Examples of parabolic reflectors are seen in electric search lights and<br> -in locomotive head-lights. They are employed in electric search lights.<br> -The arc light must be of such construction as to maintain its ignited<br> -points always at the same point, the focus of the paraboloid.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Paraffine. v.</span><br> -To coat or saturate with paraffine wax. Paper may be paraffined by<br> -dipping in the wax, or by being sprinkled with fragments of wax,<br> -subsequently melted in with a hot iron or otherwise. The tops of battery<br> -carbons are often paraffined to prevent the acid from rising in the<br> -pores by capillary attraction and rusting the connections.<br> -<br> -<br> -</big></big><big><big>403 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -</big></big><big><big><span style="font-weight: bold;">Paraffine Wax.</span><br> -A hydro-carbon composed principally of mixtures of the higher members of<br> -the paraffine series C n H2 n + 2. It is made from cannel coal, coal<br> -tar, or petroleum by distillation. It is an insulator. Its resistance at<br> -46° C. (114.8° F.) per centimeter cube is 3.4E16 ohms, or about -the<br> -highest resistance known.<br> -<br> -Its specific inductive capacity (for milky wax) is 2.47 (Schiller). For<br> -clear wax it is given as follows by different authorities:<br> - 1.92 Ayrton.<br> - 1.96 Wüllner.<br> - 1.977 Gibson & Barclay.<br> - 2.32 Baltzmann.<br> -<br> -It is extensively used in condensers and other electric apparatus as a<br> -dielectric and insulator.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Paragrêles.</span><br> -Protectors against hail; lightning rods used to guard fields against<br> -hail; of little or no real utility.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Parallax.</span><br> -The apparent change in position of an object when looked at from two<br> -points of view. By looking at an object a few feet distant first with<br> -one eye and then with the other, the shifting in apparent position is<br> -seen.<br> -<br> -In reading the position of an indicator or needle over a scale parallax<br> -introduces an error unless the eye is held vertically over the needle.<br> -By making the dial of looking- glass and holding the eye so that the<br> -reflection of its pupil is bisected by the needle this verticality is<br> -ensured.<br> -<br> -<br> -<span style="font-weight: bold;">Parallel.</span><br> -(a) In the nomenclature of electric circuits two or more conductors<br> -leading from one point to another, are said to be in parallel.<br> -<br> -(b) When two or more conductors connect two main leads of comparatively<br> -large size and low resistance they are said to be in parallel or in<br> -multiple arc. This order is easiest pictured as the rungs of a ladder in<br> -parallel connecting its two sides representing the main leads.<br> -<br> -It may be used as a noun as "arranged in parallel," or as an adjective<br> -as "a parallel circuit," the opposite of series, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Paramagnetic. adj.</span><br> -Possessing paramagnetic properties; tending to occupy a position with<br> -the longer axis parallel to the lines of force of a magnetic field;<br> -having magnetism; attracted by a magnet.<br> -<br> -"If a homogeneous isotropic substance is placed in a magnetic field it<br> -becomes magnetized at every point in the direction of the magnetic<br> -intensity at that point, and with an intensity of magnetization<br> -proportional to the magnetic intensity. When the positive direction of<br> -the induced magnetization is the same as that of the magnetic intensity<br> -the substance is called Magnetic or Paramagnetic; when it is opposite,<br> -the substance is called Diamagnetic." (Emtage.)<br> -<br> -A paramagnetic substance has high permeability or multiplying power for<br> -lines of force, hence in a magnetic field a bar of iron, etc., is in<br> -unstable equilibrium unless its longer axis is parallel with the lines<br> -of force in order to reduce as much as possible the reluctance of the<br> -circuit.<br> -<br> -<br> -404 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Iron is the most paramagnetic of all substances. Other paramagnetic<br> -metals are: Nickel, cobalt, manganese, platinum, cerium, osmium,<br> -palladium. Diamagnetic metals are bismuth, antimony, zinc, tin, mercury,<br> -lead, silver, copper, gold, arsenic. Bismuth is the most diamagnetic of<br> -all metals.<br> -<br> -Of gases oxygen is most paramagnetic. Becquerel calculated that a cubic<br> -yard of oxygen condensed would act on a magnetic needle as powerfully as<br> -5.5 grains of metallic iron. Liquefied oxygen will adhere to the poles<br> -of a magnet.<br> -<br> -Changes of temperature and of other conditions may affect a body's<br> -magnetism. Thus hot oxygen is diamagnetic, and a substance paramagnetic<br> -in a vacuum may be diamagnetic in air.<br> -<br> -Of liquids, solutions of iron or cobalt are paramagnetic; water, blood,<br> -milk, alcohol, ether, oil of turpentine and most saline solutions are<br> -diamagnetic.<br> -<br> -<br> -<span style="font-weight: bold;">Paramagnetism.</span><br> -(a) The science or study of paramagnetic substances and phenomena.<br> -<br> -(b) The magnetic property of a paramagnetic substance; that of being<br> -attracted by a magnet, and of arranging itself with its longer axis<br> -parallel with the lines of force of a magnetic field.<br> -<br> -<br> -<span style="font-weight: bold;">Parchmentizing.</span><br> -If cellulose is treated with a mixture of two parts of sulphuric acid<br> -and one part of water perfectly cold, it becomes like parchment. It<br> -should at once be washed with water, and then with ammonia and water.<br> -The Swan incandescent light fibres are made of parchmentized cotton<br> -thread, which is afterward carbonized.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Partial Earth.</span><br> -A fault in a conductor caused by imperfect connection with the earth,<br> -where insulation from the earth is desired.<br> -<br> -<br> -<span style="font-weight: bold;">Passive State.</span><br> -A state of a substance in virtue of which it is unattacked by a solvent<br> -which ordinarily would dissolve or attack it. Iron in strong nitric acid<br> -is unattacked or assumes the passive state. This particular case is<br> -supposed to be due to a coating of magnetic oxide, so that there would<br> -be properly speaking no question of a passive state, but only one of<br> -superficial protection.<br> -<br> -The existence of a true passive state of any substance is very doubtful.<br> -<br> -<br> -<span style="font-weight: bold;">P. D.</span><br> -Abbreviation for potential difference or difference of potential, or for<br> -electro-motive force.<br> -<br> -<br> -405 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Peltier Effect.</span><br> -The thermal effect produced by the passage of a current through the<br> -junction of two unlike conductors. Such junction is generally the seat<br> -of thermo-electric effects, and a current is generally produced by<br> -heating such a junction. If an independent current is passed in the same<br> -direction as that of the thermoelectric current, it cools the junction,<br> -and warms it if passed in the other direction. In general terms,<br> -referring to thermo-electric couples, if passed through them it tends to<br> -cool the hot and heat the cool junction. The phenomenon does not occur<br> -in zinc-copper junctions.<br> -<br> -<br> -<span style="font-weight: bold;">Peltier's Cross.</span><br> -A bar of bismuth and a bar of antimony soldered centre to centre at<br> -right angles, being notched or halved there to receive or to set into<br> -each other. It is used to demonstrate the Peltier effect, q. v. To one<br> -pair of ends are connected the terminals of a battery circuit; to the<br> -other pair are connected the terminals of a galvanometer.<br> -<br> -The galvanometer by its deflections in one and then in the other<br> -direction indicates that the junction is heated when the current passes<br> -from antimony to bismuth and vice versa. It thus illustrates the heating<br> -and cooling of a thermo-electric junction by a current of electricity.<br> -The current from the battery by the Peltier effect either heats or cools<br> -the junction, as the case may be. This heating or cooling them produces<br> -a thermo-electric current in the galvanometer circuit. The battery has<br> -no direct influence on the galvanometer.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Pendant Cord.</span><br> -A double conductor or pair of conductors, insulated from each other and<br> -covered with a worsted, silk, or cotton covering and used to suspend<br> -incandescent lamps and at the same time to conduct the current to them.<br> -It is also used for other similar service, such as acting as conductors<br> -for small motors. Often each conductor is composed of a number of thin<br> -wires laid together. This gives flexibility to the cord.<br> -<br> -Synonym--Flexible Cord.<br> -<br> -<br> -<span style="font-weight: bold;">Pendulum, Electric.</span><br> -(a) A pendulum operated by the intermittent action of an electro-magnet,<br> -whose circuit is opened and closed by the pendulum itself. A point at<br> -the lower end of the pendulum swinging through a globule of mercury may<br> -close and open the circuit. Various other methods of accomplishing the<br> -same end are employed ..<br> -<br> -(b) A pith ball suspended by a thread from an insulating stand. It is<br> -used to show the attraction exercised by a piece of sealing wax or other<br> -substance excited by rubbing.<br> -<br> -<br> -406 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Pen, Electric.</span><br> -A stylus for producing a series of perforations in paper, so that the<br> -paper may act as a stencil for the reproduction of a great number of<br> -copies of the original matter. Various kinds of electric pens have been<br> -invented. One kind, invented by Edison, consists of a handle carrying an<br> -electric motor actuating a needle, which is driven in and out of the<br> -other end of the handle with high rapidity. It is used by being held<br> -vertically on the paper with the needle end downward, and is moved so as<br> -to describe perforated letters or designs. The paper is then used as a<br> -stencil with an ink roller to reproduce the writing or design ad<br> -libitum. A simpler kind dispenses with the motor and depends on the<br> -perforations produced by the electric spark. As shown in the cut the<br> -stylus is one terminal of an induction coil circuit. The support on<br> -which the paper rests is the other terminal and must be a conductor. In<br> -use the induction coil is started, and the stylus is moved over the<br> -paper; a series of sparks pass through the paper from stylus to the<br> -supporting tablet, perforating the paper and producing a stencil to be<br> -used for reproduction.<br> -<br> -<br> -<img style="width: 681px; height: 631px;" alt="" - src="images/406F256.jpg"><br> -Fig. 256. ELECTRIC PEN.<br> -<br> -<br> -<span style="font-weight: bold;">Pentane Standard, Harcourt's.</span><br> -A standard of illuminating power; in it the combustible substance is a<br> -gas made by mixing one cubic foot of air with three cubic inches of<br> -liquid pentane, measured at 60° F. or, if measured as gases, 20 -volumes<br> -of air to 7 of pentane. It is burned at the rate of 0.5 cubic foot per<br> -hour from a cylindrical tube one inch in diameter, closed at the top by<br> -a disc 0.5 inch thick with a hole 0.25 inch in diameter, through which<br> -the gas issues. It gives a flame 2.5 inches high.<br> -<br> -The pentane used is the distillate of petroleum which boils at 50° -C.<br> -(122° F.) ; it has a specific gravity at 15° C. (60° F.) of -from 0.628<br> -to 0.631. It is almost pure pentane (C5H12).<br> -<br> -As long as the rate of consumption is between 0.48 and 0.52 cubic foot<br> -per hour the flame gives practically the same light.<br> -<br> -<br> -407 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Perforator.</span><br> -An apparatus used in automatic high speed telegraphy for perforating<br> -strips of paper. These are then used by drawing between a roller and<br> -contact spring for making and breaking the telegraphic circuit for the<br> -production of a record, such as the Morse record, at the distant<br> -receiving station.<br> -<br> -The perforated strip has different classes of holes punched in it to<br> -represent dots or dashes. It is fed by machinery very rapidly, so that<br> -the message is transmitted with the highest speed. Several operators may<br> -simultaneously prepare the paper strips, and thus in conjunction with<br> -its rapid feeding in the transmitter, far surpass the time of ordinary<br> -direct transmission.<br> -<br> -<br> -<img style="width: 539px; height: 530px;" alt="" - src="images/407F257.jpg"><br> -Fig. 257. PERFORATOR FOR <br> -WHEATSTONE'S AUTOMATIC TELEGRAPH.<br> -<br> -<br> -Perforators may be entirely mechanical but are sometimes pneumatic,<br> -compressed air being used to operate them. The holes they make are on<br> -different levels of the paper strip, as shown in the cut.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Period.</span><br> -The time required for the completion of one complete element of periodic<br> -motion. This may be a complete alternation (See Alternation, Complete)<br> -of an alternating current, or of an oscillatory discharge.<br> -<br> -<br> -<span style="font-weight: bold;">Periodicity.</span><br> -The rate of succession of alternations or of other fixed phases; the<br> -rate of recurrence of phenomena.<br> -<br> -<br> -408 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Permanency.</span><br> -In electric current conductors the property of possessing conductivity<br> -unaffected by lapse of time. Generally the permanency of conductors is<br> -very high. In some cases a slow annealing takes place which causes a<br> -gradual change with the lapse of time. Annealed German silver wire has<br> -been found to increase in conductivity at about .02 per cent. in a year.<br> -(Matthiessen.) Wire, whether annealed or not, is left in a strained<br> -condition after the drawing operations, and such a change is consonant<br> -with this fact. The figure only applies to the samples tested by<br> -Matthiessen.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Permanent State.</span><br> -In a telegraph line or other current conductor, the condition when a<br> -uniform current strength obtains over the whole line. When a current is<br> -started it advances through the line with a sort of wave front gradually<br> -increasing in strength. At the further end some time may elapse before<br> -it attains its full intensity. When its does the permanent state<br> -prevails. Until then the variable state, q. v., exists in the line.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Permeameter.</span><br> -An apparatus for determining the permeability of samples of iron. It<br> -consists of a large slotted block of iron. A coil is placed within the<br> -slot. A hole is drilled through one end, and a rod of the iron to be<br> -tested is passed through this hole and through the coil to the bottom of<br> -the slot. The lower end of the rod must be accurately faced off. The<br> -current is turned on, upon which the rod adheres to the bottom of the<br> -slot. The force required to detach it is determined with a spring<br> -balance. The permeation through its face is proportional to the square<br> -of the force required.<br> -<br> -<br> -<img style="width: 407px; height: 659px;" alt="" - src="images/408F258.jpg"><br> -Fig. 258. PERMEAMETER.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Permeance.</span><br> -The multiplying or the conducting power for magnetic lines of force<br> -possessed by a given mass of material. It varies with the shape and size<br> -of the substance as well as with the inducing force. It is distinguished<br> -from permeability, as the latter is a specific quality proper to the<br> -material, and expressed as such; the permeance is the permeability as<br> -affected by size and shape of the object as well as by its material.<br> -<br> -<br> -409 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Pflüger's Law.</span><br> -A law of electro-therapeutics. It states that stimulation of a nerve is<br> -only produced by successive appearance of the kathelectrotonic state,<br> -and disappearance of the anelectrotonic state.<br> -<br> -<br> -<span style="font-weight: bold;">Phantom Wires.</span><br> -The extra transmission circuits obtained in multiplex telegraph systems.<br> -A single line arranged for four separate simultaneous transmissions by<br> -quadruplex apparatus is said to establish three phantom wires.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Phase.</span><br> -In wave motion, oscillating motion, simple harmonic motion, or similar<br> -periodic phenomena, the interval of time passed from the time the moving<br> -particle moved through the middle point of its course to the instant<br> -when the phase is to be stated.<br> -<br> -<br> -<span style="font-weight: bold;">Pherope.</span><br> -An apparatus for the electric transmission of pictures. (See Telephote.)<br> -<br> -[Transcriber's note: Precursor of the contemporary Fax and scanner.]<br> -<br> -<br> -<span style="font-weight: bold;">Philosopher's Egg.</span><br> -An ellipsoidal vessel mounted with its long axis vertical and with two<br> -vertical electrodes, the upper one sliding, and arranged to be attached<br> -to an air pump. A discharge through it when the air is exhausted takes<br> -the general shape of an egg.<br> -<br> -<br> -<span style="font-weight: bold;">Phonautograph.</span><br> -An apparatus for registering the vibrations of a stylus, which is<br> -mounted on a diaphragm and is acted on by sound waves.<br> -<br> -It is virtually a resonating chamber, over one of whose ends a parchment<br> -diaphragm is stretched. To the centre of the parchment a needle or<br> -stylus is attached. A cylinder covered with soot is rotated in contact<br> -with the point of the stylus. As the chamber is spoken into the<br> -diaphragm and stylus vibrate and the vibrations are marked on the<br> -cylinder. It is of some electric interest in connection with telephony.<br> -<br> -<br> -<span style="font-weight: bold;">Phone.</span> <br> -Colloquial abbreviation for telephone.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Phonic Wheel.</span><br> -A form of small motor of very simple construction. It consists of a<br> -toothed wheel of soft iron. A bar electro-magnet is fixed with one pole<br> -facing the teeth of the wheel. By a tuning fork make and break a<br> -succession of impulses of rapid frequency and short duration are sent<br> -through the magnet. The teeth act as armatures and are successively<br> -attracted by the magnet. The regulated speed is one tooth for each<br> -impulse, but it may rotate at one-half the speed, giving two teeth for<br> -each impulse, or at certain other sub-multiples of its regular speed. It<br> -is the invention of Paul Lecour.<br> -<br> -<br> -410 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Phonograph.</span><br> -An apparatus for reproducing articulate speech. It is not electric,<br> -except as it may be driven by electricity.<br> -<br> -It consists of a cylinder of wax-like material which is rotated and<br> -moved slowly, longitudinally, screw fashion, at an even speed. A glass<br> -diaphragm carrying a needle point is supported with the point barely<br> -touching the wax. If the diaphragm is agitated, as by being spoken<br> -against, the needle is driven back and forwards cutting a broken line or<br> -groove following the direction of the thread of a screw in the wax, the<br> -depth of which line or groove continually varies.<br> -<br> -This imprints the message. If the needle is set back and the cylinder is<br> -rotated so as to carry the needle point over the line thus impressed,<br> -the varying depth throws the needle and diaphragm into motion and the<br> -sound is reproduced.<br> -<br> -The cylinder is rotated often by an electric motor, with a centrifugal<br> -governor.<br> -<br> -[Transcriber's note; Due to T. A. Edison, 1877, fifteen years before<br> -this book.]<br> -<br> -<br> -<span style="font-weight: bold;">Phonozenograph.</span><br> -An apparatus for indicating the direction of the point where a sound is<br> -produced. It operates by a microphone and telephone in conjunction with<br> -a Wheatstone bridge to determine the locality.<br> -<br> -<br> -<span style="font-weight: bold;">Phosphorescence.</span><br> -The emission of light rays by a substance not heated, but whose<br> -luminosity is due to the persistence of luminous vibration after light<br> -has fallen upon it.<br> -<br> -A phosphorescent body, after exposure to light, is luminous itself.<br> -Phosphorescence may be induced by rubbing or friction, by heat, by<br> -molecular bombardment, as in Crookes' tubes, and by static discharge of<br> -electricity, as well as by simple exposure to light.<br> -<br> -Another form of phosphorescence may be due to slow chemical combustion.<br> -This is the cause of the luminosity of phosphorous.<br> -<br> -<br> -<span style="font-weight: bold;">Phosphorous, Electrical Reduction of.</span><br> -Phosphorous is reduced from bone phosphate by the heat of the electric<br> -arc. The phosphate mixed with charcoal is exposed to the heat of the<br> -voltaic are, and reduction of the phosphorous with its volatilization at<br> -once ensues. The phosphorous as it volatilizes is condensed and<br> -collected.<br> -<br> -<br> -<span style="font-weight: bold;">Photo-electricity.</span><br> -The development of electrical properties by exposure to light. Crystals<br> -of fluor spar are electrified not only by heat (see Pyro-electricity)<br> -but also by exposure to sunlight or to the light of the voltaic arc.<br> -<br> -[Transcribers note: Although first observed in 1839 by Becquerel, it<br> -was not explained until 1905 by Albert Einstein with the introduction of<br> -photons.]<br> -<br> -<br> -<span style="font-weight: bold;">Photo-electric Microscope.</span><br> -A projection, solar or magic-lantern microscope worked by the electric<br> -light.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Photo-electro-motive Force.</span><br> -Electro-motive force produced in a substance by the action of light.<br> -<br> -<br> -411 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Photometer.</span><br> -An apparatus for measuring the intensity of light emitted by a given<br> -lamp or other source of illuminating power. They may be classified into<br> -several types.<br> -<br> -Calorimetric or Heat Photometers act by measuring relatively the heat<br> -produced by the ether waves (so-called radiant heat) emitted by the<br> -source. The accuracy of the instrument is increased by passing the rays<br> -through an alum solution. A thermopile, or an air thermometer, may be<br> -used to receive the rays.<br> -<br> -Chemical Photometers. In these the light falls upon sensitized<br> -photographic paper. The depth of coloration is used as the index of<br> -illuminating power.<br> -<br> -Direct Visual Photometers. These include Rumford's Shadow Photometer,<br> -Bunsen's Bar Photometer, and Wheatstone's Bead Photometer, in which the<br> -light is estimated by direct visual comparison of its effects.<br> -<br> -Optical Photometers. These include Polarization Photometers, in which<br> -the light is polarized; Dispersion Photometers, in which a diverging<br> -lens is placed in the path of the rays of light so as to reduce the<br> -illuminating power in more rapid ratio than that of the square of the<br> -distance.<br> -<br> -Selenium Photometers, in which the variations in resistance of selenium<br> -as light of varying intensity falls upon it is used as the indicator of<br> -the intensity of the light.<br> -<br> -Jet Photometers, for gas only, in which the height of a flame under<br> -given conditions, or the conditions requisite to maintain a flame of<br> -given height, is used to indicate the illuminating power.<br> -<br> -The subject of photometers has acquired more importance than ever in<br> -view of the extensive introduction of the electric light. (See Candle,<br> -Standard--Carcel--Violé's Standard--and Photometers of various -kinds.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Photometer, Actinic.</span><br> -A photometer whose registrations are produced by the action of the light<br> -being tested upon sensitized paper or plates, such as used in<br> -photography. Some efforts at self-registering photometers have been<br> -based on actinic registration of the height of a flame of the gas to be<br> -tested.<br> -<br> -<br> -<span style="font-weight: bold;">Photometer, Bar.</span><br> -A photometer in which the two lights to be compared are fixed at or<br> -opposite to the ends of a bar or scale of known length, generally 60 or<br> -100 inches. The bar is divided by the rule of the inverse square of the<br> -distances, so that if a screen is placed on any part of the bar where it<br> -receives an equal amount of light from both sources, the figure on the<br> -bar will indicate the relative illuminating power of the larger lamp or<br> -light in terms of the smaller. The divisions of the bar are laid out on<br> -the principle that the illuminating power of the two sources of light<br> -will vary inversely with the square of their distance from the screen.<br> -<br> -<br> -412 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The screen used is sometimes the Bunsen disc. This is a disc of paper<br> -with a spot of paraffine wax in the centre melted thoroughly into the<br> -paper or with a ring of paraffine wax surrounding the untouched centre.<br> -When this disc is equally illuminated on both sides the spot is nearly<br> -invisible. Inequality of illumination brings it out more visibly.<br> -Sometimes a Leeson disc is used. This consists of three pieces of paper,<br> -two thin ones between which a thicker piece, out of which a star is cut,<br> -is laid. When equally illuminated on both sides the star appears equally<br> -bright on both sides.<br> -<br> -The bar photometer is the standard form. A candle or pair of candles may<br> -be burned at one end and an incandescent lamp at the other, or a gas<br> -flame may first be rated by candles and used as a standard.<br> -<br> -Synonyms--Bunsen's Photometer--Translucent Disc Photometer.<br> -<br> -<br> -<img style="width: 588px; height: 261px;" alt="" - src="images/412F259.jpg"><br> -Fig. 259. BAR PHOTOMETER.<br> -<br> -<br> -<span style="font-weight: bold;">Photometer. Calorimetric.</span><br> -A photometer in which the radiant energy, so called radiant heat, is<br> -used as the measurer of the light.<br> -<br> -In one type a differential air thermometer is used, one of whose bulbs<br> -is blackened. On exposing this bulb to a source of light it will become<br> -heated, and if lights of the same character are used the heating will be<br> -in proportion to their illuminating power quite closely. The heating is<br> -shown by the movements of the index. By careful calibration the<br> -instrument may be made quite reliable.<br> -<br> -<br> -<span style="font-weight: bold;">Photometer, Dispersion.</span><br> -A photometer in which the rays from one of the lights under comparison<br> -are made more divergent by a concave lens. In this way a strong light,<br> -such as all arc lamp can be photometered more readily than where only<br> -the natural divergence of the beam exists. The law of the variation of<br> -the intensity of light with the square of the distance is abrogated for<br> -a law of more rapid variation by the use of a concave lens.<br> -<br> -The diagram, Fig. 260, illustrates the principle. E represents a<br> -powerful light, an arc light, to be tested. Its distance from the screen<br> -is e. Its light goes through the concave lens L and is dispersed as<br> -shown over an area A1, instead of the much smaller area A, which the<br> -same rays would otherwise cover. Calling l the distance of the lens from<br> -the screen, f its focus, and c the distance of the standard candle from<br> -the screen when the shadows are of equal intensity, we have the<br> -proportion.<br> -<br> -</big></big><big><big> -Illuminating power of lamps: ditto of standard candle::<br> - (l (e-l) + fe)2 : (c f)2<br> -<br> -<br> -</big></big><big><big>413 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="border: 2px solid ; width: 638px; height: 328px;" alt="" - src="images/413F260.jpg"><br> -Fig. 260. DIAGRAM OF PRINCIPLE <br> -OF THE DISPERSION PHOTOMETER.<br> -<br> -<br> -The cut, Fig. 261, gives a perspective view of Ayrton's Dispersion<br> -Photometer. C is the standard candle, L the concave lens, R the rod for<br> -producing the two shadows on the screen S.<br> -<br> -<br> -<img style="width: 583px; height: 425px;" alt="" - src="images/413F261.jpg"><br> -Fig. 261. AYRTON'S DISPERSION PHOTOMETER.<br> -<br> -<br> -The mirror M is fixed at an angle of 45° with the stem on which it<br> -rotates. The light of the arc lamp is received by the mirror and is<br> -reflected through the lens. The candle holder slides along a graduated<br> -bar C, and at D is an index plate to show the angle at which the spindle<br> -carrying the mirror is set.<br> -<br> -<br> -414 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Dr. J. Hopkinson in his dispersion photometer uses a double convex lens.<br> -This gives a focal image of the arc-lamp between the lens and screen,<br> -whence the rays diverge very rapidly, thus giving the desired dispersion<br> -effect.<br> -<br> -It is principally for arc lamps that dispersion photometers are used.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Photometer, Shadow.</span><br> -A photometer in which the relative intensity of the two lights is<br> -estimated by the intensity or strength of shadows of the same object<br> -which they respectively cast.<br> -<br> -<br> -<img style="width: 686px; height: 430px;" alt="" - src="images/414F262.jpg"><br> -Fig. 262. RUMFORD'S SHADOW PHOTOMETER.<br> -<br> -<br> -<img style="width: 634px; height: 519px;" alt="" - src="images/414F263.jpg"><br> -Fig. 263. RUMFORD'S SHADOW PHOTOMETER ARRANGED FOR TESTING<br> -INCANDESCENT LAMPS.<br> -<br> -<br> -415 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -A rod is supported in a vertical position. Back of it is a screen of<br> -white paper. The two lights to be compared are arranged in front of the<br> -rod and at a little distance from each other. They are shifted about<br> -until the two shadows appear of equal darkness. The relative intensity<br> -of the lights varies inversely with the square of their distances from<br> -the shadows cast respectively by them on the screen.<br> -<br> -The cut, Fig. 262, shows the simplest type of the shadow photometer. In<br> -the cut, Fig. 263, a shadow photometer for testing incandescent lamps is<br> -shown. In it E is the lamp under trial supported by a clamp H. A is an<br> -ampere meter in circuit with the lamp, and V is a voltmeter. A candle C<br> -can be moved along a graduated scale G G. R is the vertical rod, and S<br> -is the screen on which the shadows fall.<br> -<br> -<br> -<span style="font-weight: bold;">Photophore.</span><br> -An instrument for medical examination of the cavities of the body. It<br> -includes an incandescent lamp mounted in a tube with a concave mirror<br> -and convex lens.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Photo-voltaic Effect.</span><br> -The change in resistance of some substances effected by light. Selenium,<br> -of all substances, is most susceptible to this effect. (See Selenium.)<br> -<br> -<br> -<span style="font-weight: bold;">Piano, Electric.</span><br> -A piano whose manual or key-board operates to close electric circuits,<br> -whereby electro-magnets are caused to operate to drive the hammers<br> -against the strings.<br> -<br> -<br> -<span style="font-weight: bold;">Pickle.</span><br> -An acid solution for cleaning metal surfaces before electro-plating,<br> -galvanizing or other deposition of metal upon them.<br> -<br> -<br> -<span style="font-weight: bold;">Picture, Electric.</span><br> -A picture produced by passing a strong discharge through a piece of gold<br> -leaf clamped or firmly pressed upon a sheet of paper. The gold leaf is<br> -cut out of the desired shape, or else a stencil of paper overlays it.<br> -The discharge dissipates the gold, and produces a purple colored<br> -reproduction of the design upon the paper. The design is due to the<br> -deposition of an exceedingly thin film of metallic gold.<br> -<br> -Synonym--Electric Portrait.<br> -<br> -<br> -<span style="font-weight: bold;">Pile.</span><br> -A galvanic or voltaic battery. It is sometimes restricted to a number of<br> -voltaic couples connected. It should be only applied to batteries with<br> -superimposed plates and no containing vessel such as the Dry Pile, q.<br> -v., or Volta's Pile, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Pilot Transformer.</span><br> -In alternating current distribution a small transformer placed at any<br> -part of the system and connected to a voltmeter in the central station,<br> -to indicate the potential difference of the leads.<br> -<br> -<br> -<span style="font-weight: bold;">Pilot Wires.</span><br> -Wires brought from distant parts of electric light or power mains, and<br> -leading to voltmeters at the central station, so that the potential of<br> -distant parts of the system can be watched. The wires can be very small,<br> -as they have but little current to transmit.<br> -<br> -<br> -416 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Pistol, Electric.</span><br> -An experimental apparatus for exhibiting the power of electric<br> -incandescence or of the electric spark. A tube is mounted with a handle<br> -like a pistol. A plug is provided to screw in and out of its side. The<br> -plug carries two wires connected on its inner side by a fine platinum<br> -wire, or else disconnected but with their ends brought near together to<br> -act as terminals for the production of a spark. To use it the tube is<br> -filled with a mixture of air and gas, the latter either hydrogen,<br> -hydro-carbon or other combustible gas. The tube when full is corked. The<br> -wire is heated to incandescence by a current, or a spark is passed from<br> -a Leyden jar or other source of electrostatic excitation. The mixture,<br> -if properly proportioned, explodes and expels the cork violently.<br> -<br> -<br> -<img style="width: 611px; height: 450px;" alt="" - src="images/416F264.jpg"><br> -Fig. 264. ELECTRIC PISTOL.<br> -<br> -<br> -<span style="font-weight: bold;">Pith.</span><br> -A light and soft cellular tissue forming the central core of exogenous<br> -trees and plants. In the older parts of the tree the woody tissue often<br> -encroaches in and partly obliterates it.<br> -<br> -For electrical pith-balls, the pith of the elder, of corn, or, best of<br> -all, of sun-flower stems is used.<br> -<br> -<br> -<span style="font-weight: bold;">Pith-balls.</span><br> -Ball made of pith. They are used in the construction of electroscopes<br> -and for other experiments in static electricity.<br> -<br> -They are cut out with a sharp knife and their shape may be improved by<br> -gentle rolling in the hand or between the fingers.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Pivot Suspension.</span><br> -Suspension poising or supporting of an object on a sharp pivot. This is<br> -used for the needle in the ordinary compass. A cavity or inverted cup,<br> -which may be made of agate, is attached to the middle of the needle<br> -which has a hole for its reception. The centre of gravity of the needle<br> -comes below the bottom of the cup.<br> -<br> -Pivot suspension is not perfect, as it has considerable friction. There<br> -is no restitution force, as with torsion filaments.<br> -<br> -<br> -417 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Plant.</span><br> -The apparatus for commercial manufacturing or technical works. An<br> -electric lighting plant includes the boilers, engines and dynamos for<br> -producing the current, and the electric mains and subsidiary apparatus.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Plant Electricity.</span><br> -Electricity manifested by plant life. By means of a galvanometer<br> -potential differences are found to exist in different parts of trees or<br> -fruits. The roots and interior portions are negative, and the flowers,<br> -smaller branches and fruit are positive.<br> -<br> -In some cases a contraction of the tissue of plants can be produced by<br> -an electric current. The sensitive plant and others exhibit this<br> -phenomenon, exactly analogous to the action of muscular tissue.<br> -<br> -<br> -<span style="font-weight: bold;">Plate, Arrester.</span><br> -In a lightning arrester the plate connected to the circuit. Sometimes<br> -both plates are designated arrester plates.<br> -<br> -<br> -<span style="font-weight: bold;">Plate Condenser.</span><br> -A static condenser having a flat plate of glass for dielectric. (See<br> -Epinus' Condenser.)<br> -<br> -<br> -<span style="font-weight: bold;">Plate Electrical Machine.</span><br> -A frictional electric machine, in which a circular plate of glass is<br> -excited by friction with the cushions. It is the most recent type of<br> -frictional machine and has superseded the old cylinder machines. In its<br> -turn it is superseded by influence machines, really plate machines, but<br> -not so termed in practice.<br> -<br> -<br> -<span style="font-weight: bold;">Plate, Ground.</span><br> -In a lightning arrester, the plate connected to the earth.<br> -<br> -<br> -<span style="font-weight: bold;">Plate, Negative.</span><br> -In a voltaic battery, either primary or secondary, the plate which is<br> -unattacked by the oxygen or negative radical or element of the fluid. It<br> -corresponds to the carbon plate in the ordinary voltaic battery, and is<br> -the one charged with positive electricity.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Plate, Positive.</span><br> -In a voltaic battery, either primary or secondary, the plate which is<br> -dissolved or attacked by the oxygen or negative radical or element of<br> -the fluid. It is the plate corresponding to the zinc plate in the<br> -ordinary voltaic battery, and is the one charged with negative<br> -electricity.<br> -<br> -<br> -<span style="font-weight: bold;">Plating Balance.</span><br> -A balance or scales to which articles in an electroplater's bath are<br> -suspended. A weight exceeding by a known amount that of the article as<br> -immersed overbalances the article. When the plating is being deposited<br> -as soon as it exceeds the excess of weight of the counterpoise the<br> -balance tips, the article descends a little, the electric circuit is<br> -broken and the plating ceases. Thus the plating is automatically stopped<br> -when a predetermined amount of metal is deposited.<br> -<br> -<br> -418 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Plating Bath.</span><br> -A vessel of solution for the deposition of metal by electrolysis as used<br> -in electro-plating.<br> -<br> -<br> -<span style="font-weight: bold;">Plating, Electro-.</span><br> -The deposition of metal by electrolysis so as to coat the conducting<br> -surface of objects therewith. The full details of the many processes are<br> -very lengthy and cannot be given here.<br> -<br> -The general principle includes a battery or source of electric current.<br> -The object to be plated is connected to the negative terminal and is<br> -immersed in the solution. Thus with a battery the object is in<br> -electrical connection with the zinc plate. To the other terminal a<br> -metallic plate is connected. The object and the plate termed the anode<br> -being introduced into a suitable bath, the metal whose solution is in<br> -the bath is deposited upon the surface of the object.<br> -<br> -The bath is a solution of the metal in some form that will lend itself<br> -to the electrolytic action. The anode is often a plate of the metal of<br> -the bath, so that it dissolves as fast as metal is deposited on the<br> -object, thus keeping up the strength of the solution.<br> -<br> -The objects to be plated must be scrupulously clean, and great care must<br> -be taken to keep the bath uncontaminated.<br> -<br> -When the object has a non-conducting surface, it is made conducting by<br> -being brushed over with plumbago q.v. In addition iron dust is sometimes<br> -dusted over it. This acts by precipitating the metal of the bath<br> -directly and thus giving a conducting basis for the metal to deposit on.<br> -To avoid getting iron in a bath the object may be dipped in copper<br> -sulphate solution. This precipitates copper in place of the iron and<br> -leaves the article in good shape for silver or other plating.<br> -<br> -Electro-plating, if made thick enough, gives a reverse of the article<br> -when separated therefrom. A direct copy can be got by a second plating,<br> -on the first plating after separation, or a wax impression can be<br> -employed.<br> -<br> -Under the different metals, formulae for the baths will be found. (See<br> -also Quicking--<br> -Steeling--Plating Balance.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Platinoid.</span><br> -An alloy of copper, nickel, zinc in the proportions of German silver<br> -with 1 or 2 per cent of tungsten. It is used for resistances. It has a<br> -specific resistance (or resistance per centimeter cube) of about 34<br> -microhms. Its percentage variation in resistance per degree C. -(1.8° F.)<br> -is only about .021 per cent., or less than half that of German silver.<br> -This is its most valuable feature.<br> -<br> -<br> -419 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Platinum. </span><br> -A metal; one of the elements; symbol, Pt; atomic weight, -197.4;<br> -equivalent, 49.35; valency, 4; specific gravity, 21.5.<br> -It is a conductor of electricity.<br> -The following data refer to the annealed metal at 0° C. (32° F.)<br> -<small><span style="font-family: monospace;"> Relative Resistance -(Silver annealed = 1), 6.022</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Specific -Resistance, 9.057 microhms.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Resistance of a wire,</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> (a) 1 foot long, weighing -1 grain, -2.779 ohms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> (b) 1 foot long, 1/1000 -inch thick, -54.49 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> (c) 1 meter long, weighing -1 gram, -1.938 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> (d) 1 meter long, 1 -millimeter thick, -.1153 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Resistance of a 1 inch -cube, 3.565</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Electro-chemical equivalent -(Hydrogen = .0105), 0.5181.</span></small><br> -<br> -The coefficient of expansion by heat is almost the same as that of<br> -glass. It can be passed through holes in glass and the latter can be<br> -melted about it so as to hermetically seal its place of passage through<br> -the glass. It is used in incandescent lamps for leading-in wires and<br> -other similar uses.<br> -<br> -<br> -<span style="font-weight: bold;">Platinum Black.</span><br> -Finely divided platinum. It is made by boiling a solution of platinic<br> -chloride with excess of sodium carbonate and a quantity of sugar, until<br> -the precipitate is perfectly black and the supernatant liquid is<br> -colorless. It seems to possess a great power of occluding oxygen gas.<br> -When heated to redness it becomes spongy platinum. The negative plates<br> -of a Smee battery are coated with platinum black.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Platinum-silver Alloy.</span><br> -An alloy of 1 part platinum and 2 parts silver, used for resistance -coils.<br> -<br> - <small><span style="font-family: monospace;">Relative -Resistance (silver annealed = 1 ), -16.21 microhms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Specific Resistance at -0°C. (32° F.), 24.39</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Resistance of a wire,</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> (a) 1 foot long, weighing -1 -grain, -4.197 ohms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> (b) 1 foot long, 1/1000 -inch diameter, -146.70 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> (c) 1 meter long -weighing 1 -gram, -2.924 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> (d) 1 meter long, 1 -millimeter diameter, -0.3106 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Resistance of a 1 inch -cube, 9.603 -microhms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Percentage Variation per -degree C. (1.8° F.)</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> at about -20° C. (68° F.), 0.031 per cent.</span></small><br> -<br> -Synonym--Platinum Alloy.<br> -<br> -<br> -<span style="font-weight: bold;">Platinum Sponge.</span><br> -Finely divided platinum obtained by igniting platinum black, q.v., and<br> -also by igniting salts of platinum. It has considerable power of<br> -condensing or occluding oxygen. It will, if in good condition, set fire<br> -to a jet of hydrogen impinging upon it.<br> -<br> -<br> -<span style="font-weight: bold;">Plow.</span><br> -Contact arms projecting downwards from the motors, trucks, or bodies of<br> -electric street cars, which enter the underground conduit through the<br> -slot and carry contact pieces or brushes, to take the current for<br> -driving the motors from the leads within the conduit.<br> -<br> -<br> -420 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Plücker Tubes.</span><br> -A special form of Geissler tube designed for the production of<br> -stratification and for observing the effects produced in the space<br> -surrounding the negative electrode.<br> -<br> -<br> -<span style="font-weight: bold;">Plug.</span><br> -(a) A piece of metal with a handle and a somewhat tapered end, used to<br> -make connections by insertions between two plates or blocks of metal<br> -slightly separated and with grooves to receive it.<br> -<br> -(b) A plug or wedge with two metallic faces, insulated from each other<br> -with a separate wire connected to each one. It is used in spring-jacks<br> -q. v., to introduce a loop in a circuit.<br> -<br> -Synonym--Wedge.<br> -<br> -<br> -<span style="font-weight: bold;">Plug. v.</span><br> -To connect by inserting a plug, as in a resistance box.<br> -<br> -<br> -<img style="width: 504px; height: 552px;" alt="" - src="images/420F265.jpg"><br> -Fig. 265. PLUGS FOR RESISTANCE COIL BOX.<br> -<br> -<br> -<img style="width: 277px; height: 289px;" alt="" - src="images/420F266.jpg"><br> -Fig. 266. PLUG SWITCH.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Plug, Double.</span><br> -A spring-jack plug or wedge with two pairs of insulated faces, one<br> -behind the other, so as to simultaneously introduce two loops into a<br> -circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Plug, Grid.</span><br> -A piece or mass of lead oxide, inserted into the holes in the lead<br> -plates of storage batteries. The holes are often dovetailed or of uneven<br> -section to better retain the plugs.<br> -<br> -<br> -<span style="font-weight: bold;">Plug Infinity.</span><br> -In a box-bridge or resistance box, a plug whose removal from between two<br> -disconnected discs opens the circuit. All the other discs are connected<br> -by resistance coils of various resistance.<br> -<br> -<br> -<span style="font-weight: bold;">Plug Switch.</span><br> -A switch composed of two contact blocks, not touching each other and<br> -brought into electrical connection by the insertion of a metallic plug.<br> -The latter is usually provided with an insulating handle, and a seat is<br> -reamed out for it in the two faces of the contact blocks.<br> -<br> -<br> -421 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Plumbago.</span><br> -Soft lustrous graphite, a native form of carbon; sometimes chemically<br> -purified. It is used in electro-plating to give a conducting surface to<br> -non-conducting objects, such as wax moulds. The surface, after coating<br> -with plumbago, is sometimes dusted over with iron dust, which<br> -precipitates the metal of the bath and starts the plating. It is<br> -sometimes plated with copper, silver or gold, and is then termed<br> -coppered, silvered, or gilt plumbago. It is gilded by moistening with<br> -etherial solution of gold chloride and exposing to the air, and drying<br> -and igniting.<br> -<br> -<br> -<span style="font-weight: bold;">Plunger.</span><br> -A movable core which is used in connection with a so-called solenoid<br> -coil, to be drawn in when the coil is excited. (See Coil and Plunger.)<br> -<br> -<br> -<img style="width: 224px; height: 668px;" alt="" - src="images/421F267.jpg"><br> -Fig. 267 COIL AND PLUNGER WITH <br> -SCALES TO SHOW ATTRACTION.<br> -<br> -<br> -<span style="font-weight: bold;">P. O.</span><br> -Abbreviation for Post Office, q.v.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Poggendorf's Solution.</span><br> -An acid depolarizing and exciting fluid for zinc-carbon batteries. The<br> -following is its formula: Water, 100 parts; potassium bichromate, 12<br> -parts; concentrated sulphuric acid, 25 parts. All parts by weight. Use<br> -cold.<br> -<br> -<br> -<span style="font-weight: bold;">Point, Neutral.</span><br> -(a) On a commutator of a dynamo the points at the ends of the diameter<br> -of commutation, or where the brushes rest upon the surface of the<br> -commutator, are termed neutral points. At these points there is no<br> -generation of potential, they marking the union of currents of opposite<br> -direction flowing from the two sides of the armature into the brushes.<br> -<br> -(b) In electro-therapeutics, a place in the intra-polar region of a<br> -nerve so situated with reference to the kathode and electrode as applied<br> -in treatment, that its condition is unaffected.<br> -<br> -Synonym--Indifferent Point.<br> -<br> -(c) In a magnet the point of no attraction, situated between the two<br> -poles, at about an equal distance from each, so as to mark the centre of<br> -a magnet of even distribution of polarity.<br> -<br> -(d) In thermo-electricity the point of temperature where the<br> -thermo-electric powers of two metals are zero; in a diagram the point<br> -where the lines representing their thermo-electric relations cross each<br> -other; if the metals are arranged in a thermo-electric couple, one end<br> -at a temperature a given amount above, the other at a temperature the<br> -same amount below the neutral point, no current or potential difference<br> -will be produced.<br> -<br> -<br> -422 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Point, Null.</span><br> -A nodal point in electrical resonators; a point where in a system of<br> -waves or oscillations, there is rest, the zero of motion being the<br> -resultant of oppositely directed and equal forces. In electrical<br> -resonators it is to be sought for in a point symmetrically situated,<br> -with reference to the spark gap, or in a pair of points, which pair is<br> -symmetrically placed.<br> -<br> -The null point in resonators is found by connecting a lead from one of<br> -the secondary terminals of an induction coil to different parts of the<br> -resonator. The null point is one where the connection does not give rise<br> -to any sparks between the micrometer knobs or spark gap, or where the<br> -sparks are of diminished size.<br> -<br> -The whole is exactly comparable to loops and nodes in a vibrating string<br> -or in a Chladni plate as described in treatises on sound and acoustics.<br> -(See Resonance, Electrical--Resonator, Electrical.)<br> -<br> -Synonym--Nodal Point.<br> -<br> -<br> -<span style="font-weight: bold;">Point Poles.</span><br> -Magnet poles that are virtually points, or of no magnitude. A long thin<br> -magnet with little leakage except close to the ends may be supposed to<br> -have point poles within itself a short distance back from the ends.<br> -<br> -<br> -<span style="font-weight: bold;">Points, Consequent.</span><br> -In a magnet with consequent poles, the points where such poles are<br> -situated.<br> -<br> -<br> -<span style="font-weight: bold;">Points, Corresponding.</span><br> -In bound electrostatic charges the points of equal charges of opposite<br> -potentials; the points at opposite extremities of electrostatic lines of<br> -force. This definition implies that the bound charges shall be on equal<br> -facing areas of conductors, as otherwise the spread or concentration of<br> -the lines of force would necessitate the use of areas of size<br> -proportionate to the spreading or concentrating of the lines of force.<br> -At the same time it may figuratively be applied to these cases, the<br> -penetration of the surface by a single line of force including the area<br> -fixed by its relation to the surrounding lines.<br> -<br> -<br> -<span style="font-weight: bold;">Points, Isoelectric.</span><br> -In electro-therapeutics, points of equal potential in a circuit.<br> -<br> -<br> -423 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Points of Derivation.</span><br> -The point where a single conductor branches into two or more conductors,<br> -operating or acting in parallel with each other.<br> -<br> -<br> -<span style="font-weight: bold;">Polar Angle.</span><br> -The angle subtended by one of the faces of the pole pieces of the field-<br> -magnet of a dynamo or motor. The centre of the circle of the angle lies<br> -in the axis of the armature.<br> -<br> -Synonym--Angle of Polar Span.<br> -<br> -<br> -<span style="font-weight: bold;">Polar Extension.</span><br> -An addition made of iron to the poles of magnets. Various forms have<br> -been experimented with. The pole pieces of dynamo field magnets are<br> -polar extensions.<br> -<br> -Synonyms--Pole Piece--Polar Tips.<br> -<br> -<br> -<span style="font-weight: bold;">Polarity, Diamagnetic.</span><br> -The induced polarity of diamagnetic substances; it is the reverse of<br> -paramagnetic polarity, or of the polarity of iron. A bar of diamagnetic<br> -material held parallel with the lines of force in a magnetic field has a<br> -like pole induced in the end nearest a given pole of the field magnet,<br> -and vice versa. This theory accounts for the repulsion by a magnet of a<br> -diamagnetic substance. The existence of this polarity is rather an<br> -assumption. It originated with Faraday.<br> -<br> -<br> -<span style="font-weight: bold;">Polarity, Paramagnetic.</span><br> -The induced polarity of paramagnetic substances, such as iron, nickel,<br> -or cobalt.<br> -<br> -When such a substance is brought into a magnetic field the part nearest<br> -a specific pole of a magnet acquires polarity opposite to that of such<br> -pole and is thereby attracted.<br> -<br> -Another way of expressing it, in which the existence of a pole in or<br> -near to the field is not implied, is founded on the conventional<br> -direction of lines of force. Where these enter the substance a south<br> -pole is formed and where they emerge a north pole is formed.<br> -<br> -Such polarity tends always to be established in the direction of<br> -greatest length, if the body is free to rotate.<br> -<br> -<br> -424 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Polarization.</span><br> -(a) The depriving of a voltaic cell of its proper electro-motive force.<br> -Polarization may be due to various causes. The solution may become<br> -exhausted, as in a Smee battery, when the acid is saturated with zinc<br> -and thus a species of polarization follows. But the best definition of<br> -polarization restricts it to the development of counter-electro-motive<br> -force in the battery by the accumulation of hydrogen on the negative<br> -(carbon or copper) plate. To overcome this difficulty many methods are<br> -employed. Oxidizing solutions or solids are used, such as solution of<br> -chromic acid or powdered manganese dioxide, as in the Bunsen and<br> -Leclanché batteries respectively; a roughened surface of -platinum black<br> -is used, as in the Smee battery; air is blown through the solution to<br> -carry off the hydrogen, or the plates themselves are moved about in the<br> -solution.<br> -<br> -(b) Imparting magnetization to a bar of iron or steel, thus making a<br> -permanent magnet, is the polarization of the steel of which it is made.<br> -Polarization may be permanent, as in steel, or only temporary, as in<br> -soft iron.<br> -<br> -(c) The strain upon a dielectric when it separates two oppositely<br> -charged surfaces. The secondary discharge of a Leyden jar, and its<br> -alteration in volume testify to the strain put upon it by charging.<br> -<br> -(d) The alteration of arrangement of the molecules of an electrolyte by<br> -a decomposing current. All the molecules are supposed to be arranged<br> -with like ends pointing in the same direction, positive ends facing the<br> -positively-charged plate and negative ends the negatively-charged one.<br> -<br> -(e) The production of counter-electro-motive force in a secondary<br> -battery, or in any combination capable of acting as the seat of such<br> -counter-electro-motive force. (See Battery, Secondary--Battery, Gas.)<br> -The same can be found often in organized cellular tissue such as that of<br> -muscles, nerves, or of plants. If a current is passed through this in<br> -one direction, it often establishes a polarization or potential<br> -difference that is susceptible of giving a return current in the<br> -opposite direction when the charging battery is replaced by a conductor.<br> -<br> -<br> -<span style="font-weight: bold;">Polarization Capacity.</span><br> -A voltaic cell in use becomes polarized by its negative plate<br> -accumulating hydrogen, or other cause. This gradually gives the plate a<br> -positive value, or goes to set up a counter-electro-motive force. The<br> -quantity of electricity required to produce the polarization of a<br> -battery is termed its Polarization Capacity or Capacity of Polarization.<br> -<br> -<br> -<span style="font-weight: bold;">Polarization of the Medium.</span><br> -The dielectric polarization, q. v., of a dielectric, implying the<br> -arrangement of its molecules in chains or filaments; a term due to<br> -Faraday. He illustrated it by placing filaments of silk in spirits of<br> -turpentine, and introduced into the liquid two conductors. On<br> -electrifying one and grounding (or connecting to earth) the other one,<br> -the silk filaments arranged themselves in a chain or string connecting<br> -the points of the conductors.<br> -<br> -<br> -<span style="font-weight: bold;">Polar Region.</span><br> -That part of the surface of a magnet whence the internal magnetic lines<br> -emerge into the air. (S. P. Thompson.) As such lines may emerge from<br> -virtually all parts of its surface, the polar regions are indefinite<br> -areas, and are properly restricted to the parts whence the lines emerge<br> -in greatest quantity.<br> -<br> -<br> -<span style="font-weight: bold;">Polar Span.</span><br> -A proportion of the circle which represents the transverse section of<br> -the armature space between the pole pieces of the field magnet in a<br> -dynamo or motor; it is the proportion which is filled by the faces of<br> -the pole pieces.<br> -<br> -<br> -425 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Pole, Analogous.</span><br> -The end of a crystal of a pyroelectric substance, such as tourmaline,<br> -which end when heated become positively electrified. On reduction of<br> -temperature the reverse effect obtains.<br> -<br> -<br> -<span style="font-weight: bold;">Pole, Antilogous.</span><br> -The end of a crystal of a pyroelectric substance, such as tourmaline,<br> -which end, while increasing in temperature, becomes negatively<br> -electrified. During reduction of its temperature the reverse effect<br> -obtains.<br> -<br> -<br> -<span style="font-weight: bold;">Pole Changer.</span><br> -(a) An automatic oscillating or vibrating switch or contact-breaker<br> -which in each movement reverses the direction of a current from a<br> -battery or other source of current of fixed direction, as such current<br> -goes through a conductor.<br> -<br> -(b) A switch moved by hand which for each movement effects the above<br> -result.<br> -<br> -<br> -<span style="font-weight: bold;">Pole, Negative.</span><br> -(a) In a magnet the south pole; the pole into which the lines of force<br> -are assumed to enter from the air or outer circuit.<br> -<br> -(b) In a current generator the pole or terminal into which the current<br> -is assumed to flow from the external circuit. It is the negatively<br> -charged terminal and in the ordinary voltaic battery is the terminal<br> -connected to the zinc or positive plate.<br> -<br> -<br> -<span style="font-weight: bold;">Pole Pieces.</span><br> -The terminations of the cores of field or other electro-magnets, or of<br> -permanent magnets. These terminations are variously shaped, sometimes<br> -being quite large compared to the core proper of the magnet.<br> -<br> -They are calculated so as to produce a proper distribution of and<br> -direction of the lines of force from pole to pole. As a general rule the<br> -active field should be of uniform strength and the pole pieces may be of<br> -contour calculated to attain this end.<br> -<br> -<br> -<span style="font-weight: bold;">Pole, Positive.</span><br> -(a) In a magnet the north pole; the pole from which lines of force are<br> -assumed to emerge into the air.<br> -<br> -(b) In a current generator the pole or terminal whence the current is<br> -assumed to issue into the outer circuit. It is the positively charged<br> -terminal, and in the ordinary voltaic battery is the terminal connected<br> -to the copper or carbon plate, termed the negative plate.<br> -<br> -<br> -<span style="font-weight: bold;">Poles.</span><br> -(a) The terminals of an open electric circuit, at which there<br> -necessarily exists a potential difference, produced by the generator or<br> -source of electro-motive force in the circuit.<br> -<br> -(b) The terminals of an open magnetic circuit; the ends of a magnetized<br> -mass of steel, iron or other paramagnetic substance.<br> -<br> -(c) The ends in general of any body or mass which show electric or<br> -magnetic properties more developed than those of the central sections of<br> -the body.<br> -<br> -<br> -426 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Pole, Salient.</span><br> -In dynamo and motor field magnets, salient poles are those projecting<br> -from the base or main body of the field magnet, as distinguished from<br> -consequent poles formed by coils wound on the main body itself.<br> -<br> -<br> -<img style="width: 615px; height: 644px;" alt="" - src="images/426F268.jpg"><br> -Fig. 268. SALIENT POLES OF FIELD MAGNET.<br> -<br> -<br> -<span style="font-weight: bold;">Poles, Compensating.</span><br> -A device for avoiding the cross-magnetizing effect on the commutator<br> -core due to the lead of the brushes. It consists in maintaining a small<br> -bar electro-magnet perpendicularly between the pole pieces. This<br> -compensates the cross-magnetizing effect.<br> -<br> -<br> -<span style="font-weight: bold;">Poles of Intensity.</span><br> -The locus of highest magnetic force on the earth's surface. One such<br> -pole is in Siberia, another is about lat. 52° N., long. 92° W.<br> -<br> -[Transcriber's note: 52° N., long. 92° W is about 250 miles -Northeast of<br> -Winnipeg.]<br> -<br> -<br> -<span style="font-weight: bold;">Poles of Verticity.</span><br> -The magnetic poles of the earth. (See Magnetic Poles.)<br> -<br> -<span style="font-weight: bold;">Pole Tips.</span><br> -The extreme ends of the expanded poles of a field magnet. In some<br> -machines some of the pole tips are made of cast iron, to alter the<br> -distribution of the lines of force and resulting magnetic pull upon the<br> -armatures. This is done to take off the weight of the armature from its<br> -bearings.<br> -<br> -<br> -<span style="font-weight: bold;">Pole, Traveling.</span><br> -A term applied to the poles produced in the action of a rotatory field,<br> -whose poles constantly rotate around the circle of the field. (See<br> -Field, Rotatory.)<br> -<br> -<br> -417 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Porous Cup.</span><br> -A cup of pipe clay, unglazed earthenware or other equivalent material<br> -used in voltaic cells to keep two liquids separate and yet to permit<br> -electrolysis and electrolytic conduction.<br> -<br> -They are necessarily only an expedient, as their porous nature permits<br> -considerable diffusion, and were they not porous electrolytic action<br> -would be impossible.<br> -<br> -Synonym--Porous Cell.<br> -<br> -<br> -<span style="font-weight: bold;">Porret's Phenomenon.</span><br> -In electro-physiology, an increase in the diameter of a nerve produced<br> -by the positive pole of a voltaic circuit, when placed in contact with<br> -the tissue and near to the nerve in question, the other pole being<br> -connected to a more or less remote part of the body.<br> -<br> -<br> -<span style="font-weight: bold;">Portelectric Railroad.</span><br> -A railroad worked by solenoidal attraction, the car forming the core of<br> -the solenoids. It includes a series of solenoids or hollow coils of<br> -copper wire distributed all along the road and inclosing within<br> -themselves the track. On this a cylindrical car with pointed ends moves<br> -on wheels. Current is supplied to the solenoid in advance of the car,<br> -and attracts it. As it advances it breaks the contacts of the attracting<br> -solenoid and turns the current into the one next in advance. This<br> -operation is repeated as the car advances.<br> -<br> -The solenoids are placed close together, each including in the trial<br> -track 630 turns of No. 14 copper wire. The car was of wrought iron, 12<br> -feet long, 10 inches in diameter and weighing 500 lbs. It was proposed<br> -to employ the system for transportation of mail matter and similar uses.<br> -<br> -<br> -<span style="font-weight: bold;">Position Finder.</span><br> -An instrument for determining the position of objects which are to be<br> -fired at from forts. It is designed for use from forts situated on the<br> -water.<br> -<br> -Fiske's position finder may be thus generally described. On a chart the<br> -channel is divided into squares, and the position finder determines the<br> -square in which a vessel lies. For each square the direction and<br> -elevation of the guns is calculated beforehand. The enemy can therefore<br> -be continuously located and fired at, although from smoke or other cause<br> -the object may be quite invisible to the gunner.<br> -<br> -It comprises two telescopes situated at distant extremities of as long a<br> -base line as is obtainable. These telescopes are kept directed upon the<br> -object by two observers simultaneously. The observers are in constant<br> -telephonic communication. As each telescope moves, it carries a contact<br> -over an arc of conducting material. Below each telescope is an arm also<br> -moving over an arc of conducting material. These arcs enter into a<br> -Wheatstone bridge and are so connected that when the arm and the distant<br> -telescope are at the same angle or parallel a balance is obtained. Thus<br> -each observer has the power of establishing a balance. A chart is<br> -provided for each of them, and over it the arm connected with the<br> -distant telescope and an arm or indicator attached to the telescope at<br> -that station move so that as long as both telescopes point at the object<br> -and each observer maintains the electric balance, the intersection of<br> -the arms shows the position on the chart.<br> -<br> -The Position Finder is a simplification and amplification of the Range<br> -Finder, q. v. In practice the observers may be placed far from the<br> -forts, and may telephone their observations thereto. It has been found<br> -accurate within one-third of one per cent.<br> -<br> -<br> -428 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Positive Direction.</span><br> -The direction which lines of force are assumed to take in the air or<br> -outer circuit from a positive to a negative region. It applies to<br> -electrostatic, to magnetic and to electro-magnetic lines of force.<br> -<br> -<br> -<span style="font-weight: bold;">Positive Electricity.</span><br> -The kind of electricity with which a piece of glass is charged when<br> -rubbed with silk; vitreous electricity.<br> -<br> -In a galvanic cell the surface of the copper or carbon plate is charged<br> -with positive electricity. (See Electrostatic Series.)<br> -<br> -According to the single fluid theory positive electrification consists<br> -in a surplus of electricity.<br> -<br> -[Transcriber's note: "Positive electricity" is a deficiency of -electrons.]<br> -<br> -<br> -<span style="font-weight: bold;">Post Office. adj.</span><br> -Many pieces of electric apparatus of English manufacture are thus<br> -qualified, indicating that they are of the pattern of the apparatus used<br> -by the British Post Office in its telegraph department.<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Potential.</span><br> -Potential in general may be treated as an attribute of a point in space,<br> -and may express the potential energy which a unit mass would have if<br> -placed at that point.<br> -<br> -This conception of potential is that of a property attributable to a<br> -point in space, such that if a unit mass were placed there the forces<br> -acting upon it would supply the force factor of energy, while the body<br> -would supply the mass factor. This property is expressible in units,<br> -which produce, if the supposed mass is a unit mass, units of work or<br> -energy, but potential itself is neither.<br> -<br> -Thus taking gravitation, a pound mass on the surface of the earth<br> -(assuming it to be a sphere of 4,000 miles radius) would require the<br> -expenditure of 21,120,000 foot pounds to remove it to an infinite<br> -distance against gravity. The potential of a point in space upon the<br> -surface of the earth is therefore negative and is represented by<br> --21,120,000*32.2 foot poundals (32.2 = acceleration of gravity). (See<br> -Poundal.) In practice and conventionally all points on the earth's<br> -surface are taken as of zero potential.<br> -<br> -[Transcriber's note; 21,120,000 foot pounds is about 8 KWh.]<br> -<br> -<br> -429 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Potential, Absolute.</span><br> -The absolute electrical potential at a point possesses a numerical value<br> -and measures the tendency which the existing electric forces would have<br> -to drive an electrified particle away from or prevent its approach to<br> -the point, if such a particle, one unit in quantity, were brought up to<br> -or were situated at that point. It is numerically equal to the number of<br> -ergs of work which must be done to bring a positive unit of electricity<br> -from a region where there is absolutely no electric force up to the<br> -point in question. (Daniell.) Two suppositions are included in this. The<br> -region where there is an electric force has to be and only can be at an<br> -infinite distance from all electrified bodies. The moving of the<br> -particle must take place without any effect upon the distribution of<br> -electricity on other particles.<br> -<br> -<br> -<span style="font-weight: bold;">Potential, Constant.</span><br> -Unchanging potential or potential difference.<br> -<br> -The ordinary system of incandescent lighting is a constant potential<br> -system, an unvarying potential difference being maintained between the<br> -two leads, and the current varying according to requirements.<br> -<br> -<br> -<span style="font-weight: bold;">Potential Difference, Electric.</span><br> -If of any two points the absolute potentials are determined, the<br> -difference between such two expresses the potential difference.<br> -Numerically it expresses the quantity of work which must be done to<br> -remove a unit of electricity from one to the other against electric<br> -repulsion, or the energy which would be accumulated in moving it the<br> -other way.<br> -<br> -A positively charged particle is driven towards the point of lower<br> -potential. A negatively charged body is driven in the reverse direction.<br> -<br> -<br> -<span style="font-weight: bold;">Potential Difference, Electro-motive.</span><br> -A difference of potential in a circuit, or in part of a circuit, which<br> -difference produces or is capable of producing a current, or is due to<br> -the flow of such current.<br> -<br> -It may be expressed as the fall in potential or the electro-motive force<br> -included between any two points on a circuit. The current in an active<br> -circuit is due to the total electro-motive force in the circuit. This is<br> -distributed through the circuit in proportion to the resistance of its<br> -parts. Owing to the distribution of electro-motive force throughout a<br> -circuit including the generator, the terminals of a generator on closed<br> -circuit may show a difference of potential far lower than the<br> -electro-motive force of the generator on closed circuit. Hence potential<br> -difference in such a case has been termed available electro-motive<br> -force.<br> -<br> -<br> -<span style="font-weight: bold;">Potential, Electric Absolute.</span><br> -The mathematical expression of a property of a point in space, measuring<br> -the tendency which existing electric forces would have to drive an<br> -electrified unit particle away from or prevent its approach to the point<br> -in question, according to whether the point was situated at or was at a<br> -distance from the point in question.<br> -<br> -Potential is not the power of doing work, although, as it is expressed<br> -always with reference to a unit body, it is numerically equal to the<br> -number of ergs of work which must be done in order to bring a positive<br> -unit of electricity from a region where there is no electric<br> -force--which is a region at an infinite distance from all electrified<br> -bodies--up to the point in question. This includes the assumption that<br> -there is no alteration in the general distribution of electricity on<br> -neighboring bodies. (Daniell.)<br> -<br> -In practice the earth is arbitrarily taken as of zero electric -potential.<br> -<br> -<br> -430 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Potential, Fall of.</span><br> -The change in potential between any two points on an active circuit. The<br> -change in potential due to the maintenance of a current through a<br> -conductor.<br> -<br> -The fall in potential multiplied by the current gives work or energy<br> -units.<br> -<br> -The fall of potential in a circuit and its subsequent raising by the<br> -action of the generator is illustrated by the diagram of a helix. In it<br> -the potential fall in the outer circuit is shown by the descent of the<br> -helix. This represents at once the outer circuit and the fall of<br> -potential in it. The vertical axis represents the portion of the circuit<br> -within the battery or generator in which the potential by the action of<br> -the generator is again raised to its original height.<br> -<br> -In a circuit of even resistance the potential falls evenly throughout<br> -it.<br> -<br> -A mechanical illustration of the relation of fall of potential to<br> -current is shown in the cut Fig. 269. A vertical wire is supposed to be<br> -fixed at its upper end and a lever arm and cord at its lower end, with<br> -weight and pulley imparts a torsional strain to it. The dials and<br> -indexes show a uniform twisting corresponding to fall of potential. For<br> -each unit of length there is a definite loss of twisting, corresponding<br> -to fall of potential in a unit of length of a conductor of uniform<br> -resistance. The total twisting represents the total potential<br> -difference. The weight sustained by the twisting represents the current<br> -maintained by the potential difference. For a shorter wire less twisting<br> -would be needed to sustain the weight, as in a shorter piece of the<br> -conductor less potential difference would be needed to maintain the same<br> -current.<br> -<br> -<br> -<img style="width: 224px; height: 830px;" alt="" - src="images/430F269.jpg"><br> -Fig. 269. MECHANICAL ILLUSTRATION OF <br> -FALL OF POTENTIAL AND CURRENT STRENGTH.<br> -<br> -<br> -431 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 639px; height: 296px;" alt="" - src="images/431F270.jpg"><br> -Fig. 270. ILLUSTRATION OF THE FALL AND <br> -REDEVELOPMENT OF POTENTIAL IN AN ELECTRIC CIRCUIT.<br> -<br> -<br> -The fall of potential in a circuit in portions of it is proportional to<br> -the resistance of the portions in question. This is shown in the<br> -diagram. The narrow lines indicate high and the broad lines low<br> -resistance. The fall in different portions is shown as proportional to<br> -the resistance of each portion.<br> -<br> -<br> -<img style="width: 682px; height: 297px;" alt="" - src="images/431F271.jpg"><br> -Fig. 271. DIAGRAM OF FALL OF POTENTIAL IN A <br> -CONDUCTOR OF UNEVEN RESISTANCE.<br> -<br> -<br> -<span style="font-weight: bold;">Potential, Magnetic.</span><br> -The magnetic potential at any point of a magnetic field expresses the<br> -work which would be done by the magnetic forces of the field on a<br> -positive unit of magnetism as it moves from that point to an infinite<br> -distance therefrom. The converse applies to a negative unit.<br> -<br> -It is the exact analogue of absolute electric potential.<br> -<br> -The potential at any point due to a positive pole m at a distance r is<br> -m/r;. that due to a negative pole - m at a distance r' is equal to<br> --m/r';. that due to both is equal to m/r - m/r' or m(1/r - 1/r').<br> -<br> -Like electric potential and potential in general, magnetic potential<br> -while numerically expressing work or energy is neither, although often<br> -defined as such.<br> -<br> -<br> -432 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Potential, Negative.</span><br> -The reverse of positive potential. (See Potential, Positive.)<br> -<br> -<br> -<span style="font-weight: bold;">Potential, Positive.</span><br> -In general the higher potential. Taking the assumed direction of lines<br> -of force, they are assumed to be directed or to move from regions of<br> -positive to regions of negative potential. The copper or carbon plate of<br> -a voltaic battery is at positive potential compared to the zinc plate.<br> -<br> -<br> -<span style="font-weight: bold;">Potential, Unit of Electric.</span><br> -The arbitrary or conventional potential--or briefly, the potential of a<br> -point in an electric field of force--is, numerically, the number of ergs<br> -of work necessary to bring a unit of electricity up to the point in<br> -question from a region of nominal zero potential--i. e., from the<br> -surface of the earth. (Daniell.) This would give the erg as the unit of<br> -potential.<br> -<br> -<br> -<span style="font-weight: bold;">Potential, Zero.</span><br> -The potential of the earth is arbitrarily taken as the zero of electric<br> -potential.<br> -<br> -The theoretical zero is the potential of a point infinitely distant from<br> -all electrified bodies.<br> -<br> -<br> -<img style="width: 640px; height: 272px;" alt="" - src="images/432F272.jpg"><br> -Fig. 272. DIAGRAM OF POTENTIOMETER CONNECTIONS.<br> -<br> -<br> -<span style="font-weight: bold;">Potentiometer.</span><br> -An arrangement somewhat similar to the Wheatstone Bridge for determining<br> -potential difference, or the electro-motive force of a battery. In<br> -general principle connection is made so that the cell under trial would<br> -send a current in one direction through the galvanometer. Another<br> -battery is connected, and in shunt with its circuit the battery under<br> -trial and its galvanometer are connected, but so that its current is in<br> -opposition. By a graduated wire, like that of a meter bridge, the<br> -potential of the main battery shunt can be varied until no current<br> -passes. This gives the outline of the method only.<br> -<br> -<br> -433 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -In the cut A B is the graduated potentiometer wire through which a<br> -current is passed in the direction of the arrow. E is the battery under<br> -trial, placed in opposition to the other current, with a galvanometer<br> -next it. Under the conditions shown, if the galvanometer showed no<br> -deflection, the E. M. F. of the battery would be to the E. M. F. between<br> -the ends of the potentiometer wire, 1 . . . . .10, as 1.5 the distance<br> -between the points of connection, A and D of the battery circuit, is to<br> -10, the full length of the potentiometer wire.<br> -<br> -<br> -<span style="font-weight: bold;">Poundal.</span><br> -The British unit of force; the force which acting on a mass of one pound<br> -for one second produces an acceleration of one foot.<br> -<br> -[Transcriber's note: The force which acting on a mass of one pound<br> -produces an acceleration of ONE FOOT PER SECOND PER SECOND.]<br> -<br> -<br> -<span style="font-weight: bold;">Power. Activity;</span><br> -the rate of activity, of doing work, or of expending energy. The<br> -practical unit of electric power is the volt-ampere or watt, equal to<br> -1E7 ergs per second. The kilowatt, one thousand watts or volt-amperes,<br> -is a frequently adopted unit.<br> -<br> -<br> -<span style="font-weight: bold;">Power, Electric.</span><br> -As energy is the capacity for doing work, electric energy is -represented <br> -by electricity in motion against a resistance. This possesses a species -<br> -of inertia, which gives it a species of kinetic energy. To produce such -<br> -motion, electro- motive force is required. The product of E. M. F. by <br> -quantity is therefore electric energy. (See Energy, Electric.)<br> -<br> -Generally the rate of energy or power is used. Its dimensions are<br> - ( ( (M^.5)*(L^.5) ) / T ) * ( ( (M^.5) *(L^1.5) -)/( T^2) )<br> - (intensity or current rate) * -(electro-motive force or potential)<br> - = (M * (L^2) ) / (T^3),<br> -which are the dimensions of rate of work or activity. The practical unit<br> -of electric rate of energy or activity is the volt-ampere or watt. By<br> -Ohm's law, q. v., we have C = E/R (C = current; E = potential difference<br> -or electro-motive force; R = resistance.) The watt by definition = C*E.<br> -By substitution from Ohm's formula we deduce for it the following<br> -values: ((C^2) * R) and ((E^2) /R). From these three expressions the<br> -relations of electric energy to E.M.F., Resistance, and Current can be<br> -deduced.<br> -<br> -<br> -<span style="font-weight: bold;">Power of Periodic Current.</span><br> -The rate of energy in a circuit carrying a periodic current. In such a<br> -circuit the electro-motive force travels in advance of the current it<br> -produces on the circuit. Consequently at phases or intervals where,<br> -owing to the alternations of the current, the current is at zero, the<br> -electro-motive force may be quite high. At any time the energy rate is<br> -the product of the electro-motive force by the amperage. To obtain the<br> -power or average rate of energy, the product of the maximum<br> -electro-motive force and maximum current must be divided by two and<br> -multiplied by the cosine of the angle of lag, which is the angle<br> -expressing the difference of phase.<br> -<br> -[Transcriber's note; The voltage phase will lead if the load is<br> -inductive. The current phase will lead if the load is capacitive.<br> -Capacitors or inductors may be introduced into power lines to correct<br> -the phase offset introduced by customer loads.]<br> -<br> -<br> -434 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Pressel.</span><br> -A press-button often contained in a pear-shaped handle, arranged for<br> -attachment to the end of a flexible conductor, so as to hang thereby. By<br> -pressing the button a bell may be rung, or a distant lamp may be<br> -lighted.<br> -<br> -<br> -<span style="font-weight: bold;">Pressure.</span><br> -Force or stress exerted directly against any surface. Its dimensions are<br> -force/area or ((M*L)/(T^2)) / (L^2) = M/(L* (T^2)).<br> -<br> -<br> -<span style="font-weight: bold;">Pressure, Electric.</span><br> -Electro-motive force or potential difference; voltage. An expression of<br> -metaphorical nature, as the term is not accurate.<br> -<br> -<br> -<span style="font-weight: bold;">Pressure, Electrification by.</span><br> -A crystal of Iceland spar (calcium carbonate) pressed between the<br> -fingers becomes positively electrified and remains so for some time.<br> -Other minerals act in a similar way. Dissimilar substances pressed<br> -together and suddenly separated carry off opposite charges. This is<br> -really contact action, not pressure action.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Primary.</span><br> -A term used to designate the inducing coil in an induction coil or<br> -transformer; it is probably an abbreviation for primary coil.<br> -<br> -<br> -<span style="font-weight: bold;">Primary Battery.</span><br> -A voltaic cell or battery generating electric energy by direct<br> -consumption of material, and not regenerated by an electrolytic process.<br> -<br> -The ordinary voltaic cell or galvanic battery is a primary battery.<br> -<br> -<br> -<span style="font-weight: bold;">Prime. vb.</span><br> -To impart the first charge to one of the armatures of a Holtz or other<br> -influence machine.<br> -<br> -<br> -<img style="width: 662px; height: 468px;" alt="" - src="images/434F273.jpg"><br> -Fig. 273. PRIME CONDUCTOR AND PROOF PLANE.<br> -<br> -<br> -435 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Prime Conductor.</span><br> -A metal or metal coated sphere or cylinder or other solid with rounded<br> -ends mounted on insulating supports and used to collect electricity as<br> -generated by a frictional electric machine.<br> -<br> -According to whether the prime conductor or the cushions are grounded<br> -positive or negative electricity is taken from the ungrounded part.<br> -Generally the cushions are grounded, and the prime conductor yields<br> -positive electricity.<br> -<br> -<br> -<span style="font-weight: bold;">Probe, Electric.</span><br> -A surgeon's probe, designed to indicate by the closing of an electric<br> -circuit the presence of a bullet or metallic body in the body of a<br> -patient.<br> -<br> -Two insulated wires are carried to the end where their ends are exposed,<br> -still insulated from each other. In probing a wound for a bullet if the<br> -two ends touch it the circuit is closed and a bell rings. If a bone is<br> -touched no such effect is produced. The wires are in circuit with an<br> -electric bell and battery.<br> -<br> -<br> -<span style="font-weight: bold;">Projecting Power of a Magnet.</span><br> -The power of projecting its lines of force straight out from the poles.<br> -This is really a matter of magnetic power, rather than of shape of the<br> -magnet. In electromagnets the custom was followed by making them long to<br> -get this effect. Such length was really useful in the regard of getting<br> -room for a sufficient number of ampere turns.<br> -<br> -<br> -436 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 589px; height: 371px;" alt="" - src="images/435F274.jpg"><br> -Fig. 274. PRONY BRAKE.<br> -<br> -<br> -<span style="font-weight: bold;">Prony Brake.</span><br> -A device for measuring the power applied to a rotating shaft. It<br> -consists of a clamping device to be applied more or less rigidly to the<br> -shaft or to a pulley upon it. To the clamp is attached a lever carrying<br> -a weight. The cut shows a simple arrangement, the shaft A carries a<br> -pulley B to which the clamp B1 B2 is applied. The nuts C1 C2 are used<br> -for adjustment.<br> -<br> -A weight is placed in the pan E attached to the end of the lever D. The<br> -weight and clamp are so adjusted that the lever shall stand horizontally<br> -as shown by the index E. If we call r the radius of the pulley and F the<br> -friction between its surface and the clamp, it is evident that r F, the<br> -moment of resistance to the motion of the pulley, is equal to the weight<br> -multiplied by its lever arm or to W*R, where W indicates the weight and<br> -R the distance of its point of application from the centre of the pulley<br> -or r*F = R*W. The work represented by this friction is equal to the<br> -distance traveled by the surface of the wheel multiplied by the<br> -frictional resistance, or is 2*PI*r*n*F, in which n is the number of<br> -turns per minute. But this is equal to 2*PI*R*W. These data being known,<br> -the power is directly calculated therefrom in terms of weight and feet<br> -per minute.<br> -<br> -<br> -<span style="font-weight: bold;">Proof-plane.</span><br> -A small conductor, usually disc shaped, carried at the end of an<br> -insulating handle. It is used to collect electricity by contact, from<br> -objects electrostatically charged. The charge it has received is then<br> -measured (see Torsion Balance) or otherwise tested. (See Prime<br> -Conductor.)<br> -<br> -<br> -<span style="font-weight: bold;">Proof-sphere.</span><br> -A small sphere, coated with gold-leaf or other conductor, and mounted on<br> -an insulated handle. It is used instead of a proof-plane, for testing<br> -bodies whose curvature is small.<br> -<br> -<br> -<img style="width: 619px; height: 461px;" alt="" - src="images/436F275.jpg"><br> -Fig. 275. BOX BRIDGE.<br> -<br> -<br> -437 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Proportionate Arms. </span><br> -In general terms the arms of a Wheatstone bridge<br> -whose proportion has to be known to complete the measurement. There is a<br> -different system of naming them. Some designate by this title the two<br> -arms in parallel with each other branching at and running from one end<br> -of the bridge to the two galvanometer connections. In the cut of the Box<br> -Bridge, A C and A B are the proportionate arms. The third arm is then<br> -termed the Rheostat arm. (Stewart & Gee.)<br> -<br> -Others treat as proportionate arms the two side members of the bridge in<br> -parallel with the unknown resistance and third or rheostat arm.<br> -<br> -Synonym--Ratio Arms.<br> -<br> -<br> -<span style="font-weight: bold;">Prostration, Electric.</span><br> -Too great exposure to the voltaic arc in its more powerful forms causes<br> -symptoms resembling those of sunstroke. The skin is sometimes affected<br> -to such a degree as to come off after a few days. The throat, forehead<br> -and face suffer pains and the eyes are irritated. These effects only<br> -follow exposure to very intense sources of light, or for very long<br> -times.<br> -<br> -[Transcriber's note: Arcs emit ultraviolet rays.]<br> -<br> -<br> -<span style="font-weight: bold;">Protector, Comb.</span><br> -A lightning arrester, q. v., comprising two toothed plates nearly<br> -touching each other.<br> -<br> -<br> -<span style="font-weight: bold;">Protector, Electric.</span><br> -A protective device for guarding the human body against destructive or<br> -injurious electric shocks. In one system, Delany's, the wrists and<br> -ankles are encircled by conducting bands which by wires running along<br> -the arms, back and legs are connected. A discharge it is assumed<br> -received by the hands will thus be short circuited around the body and<br> -its vital organs. India rubber gloves and shoe soles have also been<br> -suggested; the gloves are still used to some extent.<br> -<br> -<br> -<span style="font-weight: bold;">Pull.</span><br> -A switch for closing a circuit when pulled. It is used instead of a push<br> -button, q.v., in exposed situations, as its contacts are better<br> -protected than those of the ordinary push button.<br> -<br> -<br> -<span style="font-weight: bold;">Pump, Geissler.</span><br> -A form of mercurial air pump. It is used for exhausting Geissler tubes,<br> -incandescent lamp bulbs and similar purposes.<br> -<br> -Referring to the cut, A is a reservoir of mercury with flexible tube C<br> -connected to a tube at its bottom, and raised and lowered by a windlass<br> -b, the cord from which passes over a pulley a. When raised the mercury<br> -tends to enter the chamber B, through the tube T. An arrangement of<br> -stopcocks surmounts this chamber, which arrangement is shown on a larger<br> -scale in the three figures X, Y and Z. To fill the bulb B, the cocks are<br> -set in the position Z; n is a two way cock and while it permits the<br> -escape of air below, it cuts off the tube, rising vertically from it.<br> -This tube, d in the full figure connects with a vessel o, pressure gauge<br> -p, and tube c, the latter connecting with the object to be exhausted.<br> -The bulb B being filled, the cock m is closed, giving the position Y and<br> -the vessel A is lowered until it is over 30 inches below B.<br> -<br> -<br> -438 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -This establishes a Torricellian vacuum in B. The cock n is now turned,<br> -giving the position X, when air is at once exhausted from the vessel<br> -connected to C. This process is repeated until full exhaustion is<br> -obtained. In practice the first exhaustion is often effected by a<br> -mechanical pump. By closing the cock on the outlet tube c but little air<br> -need ever find its way to the chambers o and B.<br> -<br> -<br> -<img style="width: 359px; height: 817px;" alt="" - src="images/438F276.jpg"><br> -Fig. 276. GEISSLER AIR PUMP.<br> -<br> -<br> -439 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Pumping.</span><br> -In incandescent lamps a periodical recurring change in intensity due to<br> -bad running of the dynamos, or in arc lamps to bad feeding of the<br> -carbons.<br> -<br> -<br> -<img style="width: 355px; height: 779px;" alt="" - src="images/439F277.jpg"><br> -Fig. 277. SPRENGEL AIR PUMP.<br> -<br> -<br> -<span style="font-weight: bold;">Pump, Sprengel.</span><br> -A form of mercurial air pump. A simple form is shown in the cut. Mercury<br> -is caused to flow from the funnel A, through c d to a vessel B. A side<br> -connection x leads to the vessel R to be exhausted. As the mercury<br> -passes x it breaks into short columns, and carries air down between<br> -them, in this way exhausting the vessel R. In practice it is more<br> -complicated. It is said to give a better vacuum than the Sprengel pump,<br> -but to be slower in action.<br> -<br> -<br> -440 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Pump, Swinburne.</span><br> -A form of mechanical air pump for exhausting incandescent lamp bulbs.<br> -Referring to the cut, A is a bulb on the upper part of a tube G; above A<br> -are two other bulbs C and D. From the upper end a tube runs to the bulb<br> -E. Through the cock L, and tube F connection is made with a mechanical<br> -air pump. The tube H leads to a drying chamber I, and by the tube J<br> -connects with the lamp bulbs or other objects to be exhausted. The tube<br> -G enters the bottle B through an airtight stopper, through which a<br> -second tube with stopcock K passes. In use a vacuum is produced by the<br> -mechanical pumps, exhausting the lamp bulbs to a half inch and drawing<br> -up the mercury in G. The bent neck in the bulb E, acts with the bulb as<br> -a trap to exclude mercury from F. When the mechanical pumps have<br> -produced a vacuum equal to one half inch of mercury, the cock L is<br> -closed and K is opened, and air at high pressure enters. This forces the<br> -mercury up to the vessel D, half filling it. The high pressure is now<br> -removed and the mercury descends. The valve in D closes it as the<br> -mercury falls to the level G. Further air from the lamps enters A, and<br> -by repetition of the ascent of the mercury, is expelled, through D. The<br> -mercury is again lowered, producing a further exhaustion, and the<br> -process is repeated as often as necessary.<br> -<br> -<br> -<img style="width: 239px; height: 678px;" alt="" - src="images/440F278.jpg"><br> -Fig. 278. SWINBURNE'S AIR PUMP.<br> -<br> -<br> -<span style="font-weight: bold;">Push-Button.</span><br> -A switch for closing a circuit by means of pressure applied to a button.<br> -The button is provided with a spring, so that when pushed in and<br> -released it springs back. Thus the circuit is closed only as long as the<br> -button is pressed. The electric connection may be made by pressing<br> -together two flat springs, each connected to one of the wires, or by the<br> -stem of the button going between two springs, not in contact, forcing<br> -them a little apart to secure good contact, and thereby bridging over<br> -the space between them.<br> -<br> -<br> -441 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Pyro-electricity.</span><br> -A phenomenon by which certain minerals when warmed acquire electrical<br> -properties. (Ganot.) The mineral tourmaline exhibits it strongly. It was<br> -originally observed in this mineral which was found to first attract and<br> -then to repel hot ashes.<br> -<br> -The phenomenon lasts while any change of temperature within certain<br> -limits is taking place. In the case of tourmaline the range is from<br> -about 10º C. (50º F.) to 150º C. (302º F.) Above or -below this range it<br> -shows no electrification.<br> -<br> -The effect of a changing of temperature is to develop poles, one<br> -positive and the other negative. As the temperature rises one end is<br> -positive and the other negative; as the temperature becomes constant the<br> -polarity disappears; as the temperature falls the poles are reversed.<br> -<br> -If a piece of tourmaline excited by pyro-electricity is broken, its<br> -broken ends develop new poles exactly like a magnet when broken.<br> -<br> -The following minerals are pyro-electric: Boracite, topaz, prehnite,<br> -zinc silicate, scolezite, axenite. The following compound substances are<br> -also so: Cane sugar, sodium- ammonium racemate and potassium tartrate.<br> -<br> -The list might be greatly extended.<br> -<br> -The phenomenon can be illustrated by sifting through a cotton sieve upon<br> -the excited crystal, a mixture of red lead and flowers of sulphur. By<br> -the friction of the sifting these become oppositely electrified; the<br> -sulphur adheres to the positively electrified end, and the red lead to<br> -the negatively electrified end. (See Analogous Pole-Antilogous Pole.)<br> -<br> -<br> -<span style="font-weight: bold;">Pyromagnetic Motor.</span><br> -A motor driven by the alternation of attraction and release of an<br> -armature or other moving part, as such part or a section of it is<br> -rendered more or less paramagnetic by heat.<br> -<br> -Thus imagine a cylinder of nickel at the end of a suspension rod, so<br> -mounted that it can swing like a pendulum. A magnet pole is placed to<br> -one side to which it is attracted. A flame is placed so as to heat it<br> -when in contact with the magnet pole. This destroys its paramagnetism<br> -and it swings away from the magnet and out of the flame. It cools,<br> -becomes paramagnetic, and as it swings back is reattracted, to be again<br> -released as it gets hot enough. This constitutes a simple motor.<br> -<br> -A rotary motor may be made on the same lines. Nickel is particularly<br> -available as losing its paramagnetic property easily.<br> -<br> -<br> -442 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Various motors have been constructed on this principle, but none have<br> -attained any practical importance. Owing to the low temperature at which<br> -it loses its paramagnetic properties nickel is the best metal for<br> -paramagnetic motors.<br> -<br> -In Edison's motor, between the pole pieces of an electro-magnet a<br> -cylinder made up of a bundle of nickel tubes is mounted, so as to be<br> -free to rotate. A screen is placed so as to close or obstruct the tubes<br> -farthest from the poles. On passing hot air or products of combustion of<br> -a fire or gas flame through the tubes, the unscreened ones are heated<br> -most and lose their paramagnetism. The screened tubes are then attracted<br> -and the armature rotates, bringing other tubes under the screen, which<br> -is stationary. Then the attracted tubes are heated while the others<br> -cool, and a continuous rotation is the result.<br> -<br> -<br> -<img style="width: 453px; height: 613px;" alt="" - src="images/442F279.jpg"><br> -Fig. 279. EDISON'S PYROMAGNETIC MOTOR.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Pyromagnetic Generator.</span><br> -A current generator producing electric energy directly from thermal<br> -energy by pyromagnetism.<br> -<br> -Edison's pyromagnetic generator has eight electro-magnets, lying on<br> -eight radii of a circle, their poles facing inward and their yokes<br> -vertical. Only two are shown in the cut. On a horizontal iron disc are<br> -mounted eight vertical rolls of corrugated nickel representing<br> -armatures. On each armature a coil of wire, insulated from the nickel by<br> -asbestus is wound. The coils are all in series, and have eight<br> -connections with a commutator as in a drum armature. There are two main<br> -divisions to the commutator. Each connects with an insulated collecting<br> -ring, and the commutator and collecting rings are mounted on a spindle<br> -rotated by power. Below the circle of vertical coils is a horizontal<br> -screen, mounted on the spindle and rotating with it.<br> -<br> -A source of heat, or a coal stove is directly below the machine and its<br> -hot products of combustion pass up through the coils, some of which are<br> -screened by the rotating screen. The effect is that the coils are<br> -subjecting to induction owing to the change in permeability of the<br> -nickel cores, according as they are heated, or as they cool when the<br> -screen is interposed. The two commutator segments are in constant<br> -relation to the screen, and current is collected therefrom and by the<br> -collecting rings is taken to the outside circuit.<br> -<br> -<br> -443 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Pyromagnetism.</span><br> -The development of new magnetic properties or alteration of magnetic<br> -sensibility in a body by heat. Nickel and iron are much affected as<br> -regards their paramagnetic power by rise of temperature.<br> -<br> -<br> -<img style="width: 481px; height: 646px;" alt="" - src="images/443F280.jpg"><br> -Fig. 280. PYROMAGNETIC GENERATOR.<br> -<br> -<br> -Pyrometer, Siemens' Electric.<br> -An instrument for measuring high temperatures by the variations in<br> -electric resistance in a platinum wire exposed to the heat which is to<br> -be measured.<br> -</big></big><big><big><br> -</big></big><big><big><br> -443 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Q.</span><br> -Symbol for electric quantity.<br> -<br> -<br> -<span style="font-weight: bold;">Quad.</span><br> -(a) A contraction for quadrant, used as the unit of inductance; the -henry.<br> -<br> -(b) A contraction for quadruplex in telegraphy.<br> -<br> -[Transcriber's note: A modern use of "quad" is a unit of energy equal to<br> -1E15 (one quadrillion) BTU, or 1.055E18 joules. Global energy<br> -production in 2004 was 446 quad.]<br> -<br> -<br> -<span style="font-weight: bold;">Quadrant.</span><br> -A length equal to an approximate earth quadrant, equal to 1E9<br> -centimeters. It has been used as the name for the unit of inductance,<br> -the henry, q. v.<br> -<br> -Synonym--Standard Quadrant.<br> -<br> -<br> -444 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Quadrant, Legal.</span><br> -The accepted length of the quadrant of the earth, 9.978E8 instead of 1E9<br> -centimeters; or to 9,978 kilometers instead of 10,000 kilometers.<br> -<br> -<br> -<span style="font-weight: bold;">Quadrature.</span><br> -Waves or periodic motions the angle of lag of one of which, with<br> -reference to one in advance of it, is 90°, are said to be in -quadrature<br> -with each other.<br> -<br> -[Transcriber's note: If the voltage and current of a power line are in<br> -quadrature, the power factor is zero (cos(90°) = 0) and no -real power<br> -is delivered to the load.]<br> -<br> -<br> -<span style="font-weight: bold;">Qualitative.</span><br> -Involving the determination only of the presence or absence of a<br> -substance or condition, without regard to quantity. Thus a compass held<br> -near a wire might determine qualitatively whether a current was passing<br> -through the wire, but would not be sufficient to determine its quantity.<br> -(See Quantitative.)<br> -<br> -<br> -<span style="font-weight: bold;">Quality of Sound.</span><br> -The distinguishing characteristic of a sound other than its pitch; the<br> -timbre.<br> -<br> -It is due to the presence with the main or fundamental sound of other<br> -minor sounds called overtones, the fundamental note prevailing and the<br> -other ones being superimposed upon it. The human voice is very rich in<br> -overtones; the telephone reproduces these, thus giving the personal<br> -peculiarities of every voice.<br> -<br> -Synonym--Timbre.<br> -<br> -<br> -<span style="font-weight: bold;">Quantitative.</span><br> -Involving the determination of quantities. Thus a simple test would<br> -indicate that a current was passing through a wire. This would be a<br> -qualitative test. If by proper apparatus the exact intensity of the<br> -current was determined, it would be a quantitative determination. (See<br> -Qualitative.)<br> -<br> -<br> -<span style="font-weight: bold;">Quantity.</span><br> -This term is used to express arrangements of electrical connections for<br> -giving the largest quantity of current, as a quantity armature, meaning<br> -one wound for low resistance.<br> -<br> -A battery is connected in quantity when the cells are all in parallel.<br> -It is the arrangement giving the largest current through a very small<br> -external resistance.<br> -<br> -The term is now virtually obsolete (Daniell); "in surface," "in<br> -parallel," or "in multiple arc" is used.<br> -<br> -<br> -<span style="font-weight: bold;">Quantity, Electric.</span><br> -Electricity may be measured as if it were a compressible gas, by<br> -determining the potential it produces when stored in a defined<br> -recipient. In this way the conception of a species of quantity is<br> -reached. It is also measured as the quantity of current passed by a<br> -conductor.<br> -<br> -Thus a body whose surface is more or less highly charged with<br> -electricity, is said to hold a greater or less quantity of electricity.<br> -<br> -It may be defined in electrostatic or electro-magnetic terms. (See<br> -Quantity, Electrostatic--Quantity, Electro-magnetic.)<br> -<br> -<br> -445 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Quantity.</span><br> -Electro-magnetic. Quantity is determined electro-magnetically by the<br> -measurement of current intensity for a second of time: its dimensions<br> -are therefore given by multiplying intensity or current strength by<br> -time. The dimensions of intensity are<br> - ( (M^.5) * (L^.5) ) / T<br> -therefore the dimensions of electro-magnetic quantity are<br> - ( ( (M^.5) * (L^.5) ) / T ) * T = ( (M^.5) * (L^.5) )<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Quantity, Electro-magnetic, Practical -Unit of.</span><br> -The quantity of electricity passed by a unit current in unit time; the<br> -quantity passed by one ampere in one second; the coulomb.<br> -<br> -It is equal to 3E9 electrostatic absolute units of quantity and to 0.1<br> -of the electro- magnetic absolute unit of quantity.<br> -<br> -One coulomb is represented by the deposit of<br> - .00111815 gram, or .017253 grain of silver,<br> - .00032959 gram, or .005804 grain of copper,<br> - .0003392 gram, or .005232 grain of zinc.<br> -<br> -If water is decomposed by a current each coulomb is represented by the<br> -cubic centimeters of the mixed gases (hydrogen and oxygen) given by the<br> -following formula.<br> - ( 0.1738 * 76 * (273 + Cº ) ) / ( h * 273 )<br> -in which Cº is the temperature of the mixed gases in degree -centigrade<br> -and h is the<br> -pressure in centimeters of mercury column; or by<br> - ( 0.01058 * 30 (491 + Fº - 32) ) / (h * 491 )<br> -for degrees Fahrenheit and inches of barometer.<br> -<br> -[Transcriber's note: 6.24150962915265E18 electrons is one coulomb.]<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Quantity, Electrostatic.</span><br> -Quantity is determined electro-statically by the repulsion a charge of<br> -given quantity exercises upon an identical charge at a known distance.<br> -The force evidently varies with the product of the two quantities, and<br> -by the law of radiant forces also inversely with the square of the<br> -distance. The dimensions given by these considerations is Q * Q/(L*L).<br> -This is the force of repulsion. The dimensions of a force are<br> -(M * L) /(T^2). Equating these two expressions we have:<br> - (Q^2)/(L^2) = (M*L)/(T^2)<br> - or<br> - Q = ((M^.5)*(L^1.5)) / T<br> -which are the dimensions of electrostatic quantity.<br> -<br> -<br> -<span style="font-weight: bold;">Quantity, Meter.</span><br> -An electric meter for determining the quantity of electricity which<br> -passes through it, expressible in coulombs or ampere hours. All<br> -commercial meters are quantity meters.<br> -<br> -<br> -446 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Quartz.</span><br> -A mineral, silica, SiO2. It has recently been used by C. V. Boys and<br> -since by others in the making of filaments for torsion suspensions. The<br> -mineral is melted, while attached to an arrow or other projectile. It is<br> -touched to another piece of quartz or some substance to which it adheres<br> -and the arrow is fired off from the bow. A very fine filament of<br> -surpassingly good qualities for galvanometer suspension filaments is<br> -produced.<br> -<br> -As a dielectric it is remarkable in possessing but one-ninth the<br> -residual capacity of glass.<br> -<br> -<br> -<span style="font-weight: bold;">Quicking.</span><br> -The amalgamating of a surface of a metallic object before silver<br> -plating. It secures better adhesion of the deposit. It is executed by<br> -dipping the article into a solution of a salt of mercury. A solution of<br> -mercuric nitrate 1 part, in water 100 parts, both by weight, is used.<br> -<br> -</big></big><br> -<big><big><br> -446 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">R.</span><br> -(a) Abbreviation and symbol for Reamur, as 10º R., meaning -10º by the<br> -Reamur thermometer. (See Reamur Scale.)<br> -<br> -(b) Symbol for resistance, as in the expression of Ohm's Law C=E/R.<br> -(rho, Greek r) Symbol for specific resistance.<br> -<br> -<br> -<span style="font-weight: bold;">Racing of Motors.</span><br> -The rapid acceleration of speed of a motor when the load upon it is<br> -removed. It is quickly checked by counter-electro-motive force. (See<br> -Motor, Electric.)<br> -<br> -<br> -<span style="font-weight: bold;">Radian.</span><br> -The angle whose arc is equal in length to the radius; the unit angle.<br> -<br> -<br> -<span style="font-weight: bold;">Radiant Energy.</span><br> -Energy, generally existing in the luminiferous ether, kinetic and<br> -exercised in wave transmission, and rendered sensible by conversion of<br> -its energy into some other form of energy, such as thermal energy.<br> -<br> -If the ether waves are sufficiently short and not too short, they<br> -directly affect the optic nerve and are known as light waves; they may<br> -be so short as to be inappreciable by the eye, yet possess the power of<br> -determining chemical change, when they are known as actinic waves; they<br> -may be also so long as to be inappreciable by the eye, when they may be<br> -heat-producing waves, or obscure waves.<br> -<br> -Other forms of energy may be radiant, as sound energy dispersed by the<br> -air, and gravitational energy, whose connection with the ether has not<br> -yet been demonstrated.<br> -<br> -<br> -<span style="font-weight: bold;">Radiation.</span><br> -The traveling or motion of ether waves through space.<br> -<br> -[Transcriber's note: The modern term corresponding to this definition is<br> -photons. The modern concept of radiation also includes particles--<br> -neutrons, protons, alpha (helium) and beta (electrons) rays and other<br> -exotic items.]<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Radicals.</span><br> -A portion of a molecule, possessing a free bond and hence free to<br> -combine directly. A radical never can exist alone, but is only<br> -hypothetical. An atom is a simple radical, an unsaturated group of atoms<br> -is a compound radical.<br> -<br> -<br> -447 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Radiometer.</span><br> -An instrument consisting of four vanes poised on an axis so as to be<br> -free to rotate, and contained in a sealed glass vessel almost perfectly<br> -exhausted. The vanes of mica are blackened on one side.<br> -<br> -On exposure to light or a source of heat (ether waves) the vanes rotate.<br> -The rotation is due to the beating back and forth of air molecules from<br> -the surface of the vanes to the inner surface of the glass globe.<br> -<br> -<br> -<span style="font-weight: bold;">Radiometer, Electric.</span><br> -A radiometer in which the motion of the molecules of air necessary for<br> -rotation of the vane is produced by electrification and not by heating.<br> -<br> -<br> -<span style="font-weight: bold;">Radio-micrometer.</span><br> -An instrument for detecting radiant energy of heat or light form. It<br> -consists of a minute thermopile with its terminals connected by a wire,<br> -the whole suspended between the poles of a magnet. A minute quantity of<br> -heat produces a current in the thermopile circuit, which, reacted on by<br> -the field, produces a deflection. A convex mirror reflecting light is<br> -attached so as to move with the thermopile. The instrument is of<br> -extraordinary sensitiveness. It responds to .5E-6 of a degree Centigrade<br> -or about 1E-6 degree Fahrenheit.<br> -<br> -<br> -<span style="font-weight: bold;">Radiophony.</span><br> -The production of sound by intermittent action of a beam of light upon a<br> -body. With possibly a few exceptions all matter may produce sound by<br> -radiophouy.<br> -<br> -<br> -<span style="font-weight: bold;">Range Finder.</span><br> -An apparatus for use on shipboard to determine the distance of another<br> -ship or object. It is designed for ships of war, to give the range of<br> -fire, so as to set the guns at the proper elevation. The general<br> -principle involved is the use of the length of the ship if possible, if<br> -not of its width, as a base line. Two telescopes are trained upon the<br> -object and kept trained continuously thereon. The following describes<br> -the Fiske range finder.<br> -<br> -The range finder comprises two fairly powerful telescopes, each mounted<br> -on a standard, which can be rotated round a vertical axis, corresponding<br> -with the center of the large disc shown in the engraving. One-half of<br> -the edge of this disc is graduated to 900 on either side of a zero<br> -point, and below the graduation is fixed a length of platinum silver<br> -wire. This wire only extends to a distance of 81.10 on either side of<br> -zero, and is intended to form two arms of a Wheatstone bridge. The<br> -sliding contact is carried by the same arm as the telescope standards,<br> -so that it moves with the telescope. The two instruments are mounted at<br> -a known distance apart on the ship, as shown diagrammatically in the<br> -cut. Here A and B are the centers of the two discs, C and D the arms<br> -carrying the telescopes, and E and F the platinum silver wires. Suppose<br> -the object is at T, such that A B T is a right angle, then<br> -AT=AB/sin(ATB).<br> -<br> -<br> -448 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -If the two sectors are coupled up as shown, with a battery, h, and a<br> -galvanometer, by the wires, a b and c d, then since the arm, e, on being<br> -aligned on the object takes the position c1 while d remains at zero, the<br> -Wheatstone bridge formed by these segments and their connections will be<br> -out of balance, and a current will flow through the galvanometer, which<br> -may be so graduated as to give the range by direct reading, since the<br> -current through it will increase with the angle A T B.<br> -<br> -<br> -<img style="width: 389px; height: 673px;" alt="" - src="images/448F281.jpg"><br> -Fig. 281. RANGE FINDER.<br> -<br> -<br> -In general, however, the angle A B T will not be a right angle, but some<br> -other angle. In this case AT = AB / sin(A T B) * sin( A B T), and hence<br> -it will only be necessary to multiply the range reading on the<br> -galvanometer by the sine of the angle A B T, which can be read directly<br> -by the observer at B. This multiplication is not difficult, but by<br> -suitably arranging his electrical appliances Lieutenant Fiske has<br> -succeeded in getting rid of it, so that the reading of the galvanometer<br> -always gives the range by direct reading, no matter what the angle at B<br> -may be. To explain this, consider the two telescopes shown in the cut in<br> -the positions C and D; the whole current then has a certain resistance.<br> -<br> -<br> -449 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Next suppose them, still remaining parallel, in the positions C1 and D1.<br> -The total resistance of the circuit is now less than before, and hence<br> -if C1, one of the telescopes, is moved out of parallel to the other,<br> -through a certain angle, the current through the galvanometer will be<br> -greater than if it were moved through an equal angle out of a parallel<br> -when the telescopes were in the positions C and D. The range indicated<br> -is, therefore, decreased, and by properly proportioning the various<br> -parts it is found that the range can always be read direct from the<br> -galvanometer, or in other words the multiplication of A B/sin( A T B )<br> -by sin( A B T ) is to all intents and purposes performed automatically.<br> -There is, it is true, a slight theoretical error; but by using a small<br> -storage battery and making the contents carefully it is said to be<br> -inappreciable. Each telescope is fitted with a telephone receiver and<br> -transmitter, so that both observers can without difficulty decide on<br> -what point to align their telescopes. It will be seen that it is<br> -necessary that the lines of sight of two telescopes should be parallel<br> -when the galvanometer indicates no current. It has been proposed to<br> -accomplish this by sighting both telescopes on a star near the horizon,<br> -which being practically an infinite distance away insures the<br> -parallelism of the lines of sight.<br> -<br> -<br> -<span style="font-weight: bold;">Rate Governor.</span><br> -An apparatus for securing a fixed rate of vibration of a vibrating reed.<br> -It is applied in simultaneous telegraphy and telephoning over one wire.<br> -The principle is that of the regular make and break mechanism, with the<br> -feature that the contact is maintained during exactly one-half of the<br> -swing of the reed. The contact exists during the farthest half of the<br> -swing of the reed away from the attracting pole.<br> -<br> -<br> -<img style="width: 648px; height: 375px;" alt="" - src="images/449F282.jpg"><br> -Fig. 282. LANGDON DAVIRS' RATE GOVERNOR.<br> -<br> -<br> -In the left hand figure of the cut, K is the key for closing the<br> -circuit. A is the base for attachment of the reed. V is the<br> -contact-spring limited in its play to the right by the screw S. C is the<br> -actuating magnet. By tracing the movements of the reed, shown on an<br> -exaggerated scale in the three right hand figures, it will be seen that<br> -the reed is in electric contact with the spring during about one-half<br> -its movement. The time of this connection is adjustable by the screw S.<br> -<br> -Synonym--Langdon Davies' Rate Governor or Phonophone.<br> -<br> -<br> -450 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Ray, Electric. Raia torpedo.</span><br> -The torpedo, a fish having the same power of giving electric shocks as<br> -that possessed by the electric eel, q. v. (See also Animal Electricity.)<br> -<br> -<br> -<img style="width: 390px; height: 593px;" alt="" - src="images/450F283.jpg"><br> -Fig. 283. TORPEDO OR ELECTRIC RAY<br> -<br> -<br> -<span style="font-weight: bold;">Reaction of Dynamo, Field and Armature.</span><br> -A principle of the dynamo current generator, discovered by Soren Hjorth<br> -of Denmark.<br> -<br> -When the armature is first rotated it moves in a field due to the<br> -residual magnetism of the field magnet core. This field is very weak,<br> -and a slight current only is produced. This passing in part or in whole<br> -through the field magnet cores slightly strengthens the field, whose<br> -increased strength reacts on the armature increasing its current, which<br> -again strengthens the field. In this way the current very soon reaches<br> -its full strength as due to its speed of rotation.<br> -<br> -The operation is sometimes termed building up.<br> -<br> -Sometimes, when there is but a trace of residual magnetism, it is very<br> -hard to start a dynamo.<br> -<br> -<br> -<span style="font-weight: bold;">Reading Telescope.</span><br> -A telescope for reading the deflections of a reflecting galvanometer.<br> -<br> -A long horizontal scale is mounted at a distance from the galvanometer<br> -and directly below or above the centre of the scale a telescope is<br> -mounted. The telescope is so directed that the mirror of the<br> -galvanometer is in its field of view, and the relative positions of<br> -mirror, scale and telescope are such that the image of the scale in the<br> -galvanometer mirror is seen by the observer looking through the<br> -telescope.<br> -<br> -Under these conditions it is obvious that the graduation of the scale<br> -reflected by the mirror corresponds to the deflection of the<br> -galvanometer needle.<br> -<br> -The scale may be straight or curved, with the galvanometer in the latter<br> -case, at its centre of curvature.<br> -<br> -<br> -<span style="font-weight: bold;">Reamur Scale.</span><br> -A thermometer scale in use in some countries of Continental Europe. The<br> -temperature of melting ice is 0°; the temperature of condensing -steam<br> -is 80°; the degrees are all equal in length. For conversion to<br> -centigrade degrees multiply degrees Reamur by 5/4. For conversion to<br> -Fahrenheit degrees multiply by 9/4 and add 32 if above 0° R., and if<br> -below subtract 32. Its symbol is R., as 10° R.<br> -<br> -<br> -451 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Recalescence.</span><br> -A phenomenon occurring during the cooling of a mass of steel, when it<br> -suddenly emits heat and grows more luminous for an instant. It is a<br> -phase of latent heat, and marks apparently the transition from a<br> -non-magnetizable to a magnetiz able condition.<br> -<br> -<br> -<span style="font-weight: bold;">Receiver.</span><br> -In telephony and telegraphy, an instrument for receiving a message as<br> -distinguished from one used for sending or transmitting one.<br> -<br> -Thus the Bell telephone applied to the ear is a receiver, while the<br> -microphone which is spoken into or against is the transmitter.<br> -<br> -<br> -<span style="font-weight: bold;">Receiver, Harmonic.</span><br> -A receiver including an electro-magnet whose armature is an elastic<br> -steel reed, vibrating to a particular note. Such a reed responds to a<br> -series of impulses succeeding each other with the exact frequency of its<br> -own natural vibrations, and does not respond to any other rapid series<br> -of impulses. (See Telegraph Harmonic.)<br> -<br> -<br> -<span style="font-weight: bold;">Reciprocal.</span><br> -The reciprocal of a number is the quotient obtained by dividing one by<br> -the number. Thus the reciprocal of 8 is 1/8.<br> -<br> -Applied to fractions the above operation is carried out by simply<br> -inverting the fraction. Thus the reciprocal of 3/4 is 4/3 or 1-1/3.<br> -<br> -<br> -<span style="font-weight: bold;">Record, Telephone.</span><br> -Attempts have been made to produce a record from the vibrations of a<br> -telephone disc, which could be interpreted by phonograph or otherwise.<br> -<br> -<br> -<img style="width: 684px; height: 489px;" alt="" - src="images/451F284.jpg"><br> -Fig. 284. MORSE RECORDER OR EMBOSSER.<br> -<br> -<br> -452 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Recorder, Morse.</span><br> -A telegraphic receiving apparatus for recording on a strip of paper the<br> -dots and lines forming Morse characters as received over a telegraph<br> -line. Its general features are as follows:<br> -<br> -A riband or strip of paper is drawn over a roller which is slightly<br> -indented around its centre. A stylus or blunt point carried by a<br> -vibrating arm nearly touches the paper. The arm normally is motionless<br> -and makes no mark on the paper. An armature is carried by the arm and an<br> -electro-magnet faces the armature. When a current is passed through the<br> -magnet the armature is attracted and the stylus is forced against the<br> -paper, depressing it into the groove, thus producing a mark. When the<br> -current ceases the stylus is drawn back by a spring.<br> -<br> -<br> -<img style="width: 710px; height: 462px;" alt="" - src="images/452F285.jpg"><br> -Fig. 285. INKING ROLLER MECHANISM OF MORSE RECORDER.<br> -<br> -<br> -In some instruments a small inking roller takes the place of the stylus,<br> -and the roller is smooth. The cut, Fig. 285, shows the plan view of the<br> -ink-roller mechanism. J is the roller, L is the ink well, Cl is the arm<br> -by which it is raised or lowered by the electro-magnet, as in the<br> -embosser. S S is the frame of the instrument, and B the arbor to which<br> -the arm carrying the armature is secured, projecting to the right. A<br> -spring is arranged to rub against the edge of the inking roller and<br> -remove the ink from it.<br> -<br> -The paper is fed through the apparatus by clockwork. At the present day<br> -sound reading has almost entirely replaced the sight reading of the<br> -recorder.<br> -<br> -<br> -<span style="font-weight: bold;">Recorder, Siphon.</span><br> -A recording apparatus in which the inked marks are made on a strip of<br> -paper, the ink being supplied by a siphon terminating in a capillary<br> -orifice.<br> -<br> -In the cut N S represents the poles of a powerful electro-magnet. A<br> -rectangular coil bb of wire is suspended between the coils. A stationary<br> -iron core a intensifies the field. The suspension wire f f 1 has its<br> -tension adjusted at h. This wire acts as conductor for the current.<br> -<br> -<br> -453 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The current is sent in one or the other direction or is cut off in<br> -practice to produce the desired oscillations of the coil b b. A glass<br> -siphon n l works upon a vertical axis l. One end l is immersed in an ink<br> -well m. Its longer end n touches a riband of paper o o. The thread k<br> -attached to one side of the coil pulls the siphon back and forth<br> -according to the direction of current going through the electro-magnet<br> -cores. A spiral spring adjusted by a hand-screw controls the siphon. In<br> -operation the siphon is drawn back and forth producing a zigzag line.<br> -The upward marks represent dots, the downward ones dashes. Thus the<br> -Telegraphic Code can be transmitted on it. To cause the ink to issue<br> -properly, electrification by a static machine has been used, when the<br> -stylus does not actually touch the paper, but the ink is ejected in a<br> -series of dots.<br> -<br> -<br> -<img style="width: 667px; height: 605px;" alt="" - src="images/453F286.jpg"><br> -Fig. 286. SIPHON RECORDER.<br> -<br> -<br> -<span style="font-weight: bold;">Reducteur for Ammeter.</span><br> -A resistance arranged as a shunt to diminish the total current passing<br> -through an ammeter. It is analogous to a galvanometer shunt. (See<br> -Multiplying Power of Shunt.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Reducteur for Voltmeter.</span><br> -A resistance coil connected in series with a Voltmeter to diminish the<br> -current passing through it. Its resistance being known in terms of the<br> -resistance of the voltmeter it increases the range of the instrument so<br> -that its readings may cover double or more than double their normal<br> -range.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Reduction of Ores, Electric.</span><br> -Treatment of ores by the electric furnace (see Furnace, Electric.) The<br> -ore mixed with carbon and flux is melted by the combined arc and<br> -incandescent effects of the current and the metal separates. In another<br> -type the metal is brought into a fusible compound which is electrolyzed<br> -while fused in a crucible. Finally processes in which a solution of a<br> -salt of the metal is obtained, from which the metal is obtained by<br> -electrolysis, may be included. Aluminum is the metal to whose extraction<br> -the first described processes are applied.<br> -<br> -<br> -454 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Refraction, Electric Double.</span><br> -Double refraction induced in some materials by the action of either an<br> -electrostatic, magnetic or an electro-magnetic field.<br> -<br> -The intensity or degree of refracting power is proportional to the<br> -square of the strength of field.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Refreshing Action.</span><br> -In electro-therapeutics the restoration of strength or of nerve force by<br> -the use of voltaic alternatives, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Region, Extra-polar.</span><br> -In electro-therapeutics the area or region of the body remote from the<br> -therapeutic electrode.<br> -<br> -<br> -<span style="font-weight: bold;">Region, Polar.</span><br> -In electro-therapeutics the area or region of the body near the<br> -therapeutic electrode.<br> -<br> -<br> -<span style="font-weight: bold;">Register, Electric.</span><br> -There are various kinds of electric registers, for registering the<br> -movements of watchmen and other service. Contact or press buttons may be<br> -distributed through a factory. Each one is connected so that when the<br> -circuit is closed thereby a mark is produced by the depression of a<br> -pencil upon a sheet or disc of paper by electro-magnetic mechanism. The<br> -paper is moved by clockwork, and is graduated into hours. For each<br> -push-button a special mark may be made on the paper. The watchman is<br> -required to press the button at specified times. This indicates his<br> -movements on the paper, and acts as a time detector to show whether he<br> -has been attending to his duty.<br> -<br> -<br> -<span style="font-weight: bold;">Register, Telegraphic.</span><br> -A term often applied to telegraph recorders, instruments for producing<br> -on paper the characters of the Morse or other alphabet.<br> -<br> -<br> -<span style="font-weight: bold;">Regulation, Constant Current.</span><br> -The regulation of a dynamo so that it shall give a constant current<br> -against any resistance in the outer circuits, within practical limits.<br> -It is carried out in direct current machines generally by independent<br> -regulators embodying a controlling coil with plunger or some equivalent<br> -electro-magnetic device inserted in the main circuit and necessarily of<br> -low resistance. In some regulators the work of moving the regulator is<br> -executed mechanically, but under electrical control; in others the<br> -entire work is done by the current.<br> -<br> -A typical regulator or governor (Golden's) of the first class comprises<br> -two driven friction wheels between which is a driving friction wheel,<br> -which can engage with one driven wheel only at once. It is brought into<br> -engagement with one or the other by a solenoid and plunger.<br> -<br> -<br> -455 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -As it touches one wheel it turns it in one direction. This moves a<br> -sliding contact in one direction so as to increase a resistance. This<br> -corresponds to a motion of the plunger in one direction. As the driving<br> -wheel moves in the opposite direction by a reverse action it diminishes<br> -the resistance. Thus the increase and decrease of resistance correspond<br> -to opposite movements of the solenoid plunger, and consequently to<br> -opposite variations in the current. The whole is so adjusted that the<br> -variations in resistance maintain a constant amperage. The resistance is<br> -in the exciting circuit of the dynamo.<br> -<br> -In Brush's regulator, which is purely mechanical, a series dynamo is<br> -made to give a constant current by introducing across the field magnets<br> -a shunt of variable resistance, whose resistance is changed by an<br> -electro-magnet, whose coils are in circuit with the main current. Carbon<br> -resistance discs are used which the electro-magnet by its attraction for<br> -its armature, presses with varying intensity. This alters the<br> -resistance, decreasing it as the current increases and the reverse. As<br> -the connection is in shunt this action goes to maintain a constant<br> -current.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Regulation, Constant Potential.</span><br> -The regulation of constant potential dynamos is executed on the same<br> -lines as that of constant current dynamos. If done by a controlling<br> -coil, it must for constant potential regulation be wound with fine wire<br> -and connected as a shunt for some part of the machine.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Regulation of Dynamos.</span><br> -The regulation of dynamos so that they shall maintain a constant<br> -potential difference in the leads of their circuit for multiple arc<br> -systems or shall deliver a constant current in series systems. Hence two<br> -different systems of regulation are required, (a) constant potential<br> -regulation--(b) constant current regulation. The first named is by far<br> -the more important, as it concerns multiple arc lighting, which is the<br> -system universally used for incandescent lighting.<br> -<br> -S. P. Thompson thus summarizes the methods of governing or regulating<br> -dynamos. Premising that alteration of the magnetic flux is the almost<br> -universal way of control, it can be done in two ways; first, by varying<br> -the excitation or ampere turns of the field, and second by varying the<br> -reluctance of the magnetic circuit. The excitation or magnetic flux may<br> -be varied<br> -<br> -(a) by hand, with the aid of rheostats and commutators in the exciting<br> -circuit;<br> -<br> -(b) automatically, by governors, taking the place of the hand;<br> -<br> -(c) by compound windings. The magnetic circuit may have its reluctance<br> -caused to vary in several ways;<br> -<br> -(d) by moving the pole pieces nearer to or further from the armature;<br> -<br> -(e) by opening or closing some gap in the magnetic circuit (field-magnet<br> -core);<br> -<br> -(f) by drawing the armature endways from between the pole pieces;<br> -<br> -(g) by shunting some of the magnetic lines away from the armature by a<br> -magnetic shunt.<br> -<br> -The latter magnetic circuit methods d, e, f, and g, have never met with<br> -much success except on small machines or motors. Method e is adopted in<br> -the Edison motor, the yoke being withdrawn or brought nearer the cores<br> -of the coils. (See Regulation, Constant Current-Regulation, constant<br> -Potential.)<br> -<br> -<br> -456 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Reguline. adj.</span><br> -Having the characteristics of a piece of metal, being flexible,<br> -adherent, continuous, and coherent. Applied to electrolytic deposits.<br> -<br> -<br> -<span style="font-weight: bold;">Relative.</span><br> -Indicating the relation between two or more things without reference to<br> -absolute value of any one of them. Thus one lamp may be of relatively<br> -double resistance compared to another, but this states nothing of the<br> -resistance in ohms of either lamp.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Relay.</span><br> -A receiving instrument which moves in accordance with impulses of<br> -currents received, and in so moving opens and closes a local circuit,<br> -which circuit may include as powerful a battery as required or<br> -desirable, while the relay may be on the other hand so delicate as to<br> -work with a very weak current.<br> -<br> -<br> -<img style="width: 607px; height: 318px;" alt="" - src="images/456F287.jpg"><br> -Fig. 287. RELAY.<br> -<br> -<br> -The typical relay includes an electro-magnet and armature. To the latter<br> -an arm is attached and the lower end of the arm works in pivots. As the<br> -armature is attracted the arm swings towards the magnet. When the<br> -current is cut off, the armature and arm are drawn back by a spring.<br> -When the arm swings towards the magnet its upper end touching a contact<br> -screw closes the local circuit. When it swings back it comes in contact<br> -with a second screw, with insulated point, and opens the circuit as it<br> -leaves the first named screw.<br> -<br> -One terminal connects with the arm through the pivots and frame. The<br> -other connects with the contact screw through the frame carrying it.<br> -<br> -Synonym--Relay Magnet.<br> -<br> -<br> -457 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Relay Bells.</span><br> -Bells connected by relay connection to a main line for acoustic<br> -telegraphy. A stroke on one bell indicates a dot and on the other a<br> -dash. The system is now nearly extinct.<br> -<br> -<br> -<span style="font-weight: bold;">Relay, Box-sounding.</span><br> -A relay which is surrounded by or mounted on a resonator or wooden box<br> -of such proportions and size as to reinforce the sound. This enables a<br> -relay to act as a sounder, its weak sounds being virtually magnified so<br> -as to be audible.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Relay Connection.</span><br> -A connection used in telegraphy, including a local battery, with a short<br> -circuit normally open, but closed by a switch and a sounder or other<br> -appliance. The latter is made very sensitive so as to be worked by a<br> -feeble current, and is connected to the main line. A very slight current<br> -closes the switch and the local battery comes into operation to work a<br> -sounder, etc. When the current ceases on the main line the switch opens<br> -and throws the local battery out of action. The switch is termed a<br> -relay, q. v. A long main line may thus produce strong effects at distant<br> -stations, the intensity of action depending on the local battery.<br> -<br> -<br> -<img style="width: 708px; height: 454px;" alt="" - src="images/457F288.jpg"><br> -Fig. 288. RELAY OR LOCAL CIRCUIT.<br> -<br> -<br> -<span style="font-weight: bold;">Relay, Differential.</span><br> -A relay containing two coils wound differentially, and of the same<br> -number of turns and resistance. If two equal currents pass through the<br> -coils they counteract each other and no action takes place. If there is<br> -a difference in the currents the relay acts as one coil preponderates.<br> -The coils may be wound for uneven currents with different resistance and<br> -number of turns.<br> -<br> -<br> -<span style="font-weight: bold;">Relay, Microphone.</span><br> -A relay connection applied to a telephone circuit. It consists of a<br> -microphone mounted in front of the diaphragm of a telephone receiver. In<br> -circuit with the microphone is a battery and second telephone receiver.<br> -The microphone is supposed to intensify the sounds of the first<br> -telephone.<br> -<br> -<br> -458 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Relay, Polarized.</span><br> -A relay whose armature is of steel, and polarized or permanently<br> -magnetized, or in which a permanent magnet is used as the basis for the<br> -electro-magnets. In the relay shown in the cut the coils shown are<br> -mounted on cores carried on the end of a powerful bent permanent magnet.<br> -Thus when no current passes their upper poles are both of the same sign,<br> -and the horizontally vibrating tongue is held by the magnetic attraction<br> -against one or the other pole piece. If a current is sent through the<br> -electro-magnet it gives opposite polarity to the two polar extensions.<br> -As the end of the vibrating tongue is of polarity determined by the<br> -permanent magnet it is attracted to one pole and repelled from the<br> -other. On cessation of current it remains attached by the permanent<br> -magnetism. If now a current is sent in the opposite direction the two<br> -poles again acquire opposite polarity, the reverse of the former, and<br> -the tongue flies across to the opposite side. On cessation of current it<br> -remains attached as before by the permanent magnetism.<br> -<br> -In its movements to and fro the relay tongue opens and closes a contact,<br> -so as to work a sounder or other apparatus. The polarized relay is of<br> -high sensibility, and requires little or no change of adjustment.<br> -<br> -<br> -<img style="width: 426px; height: 473px;" alt="" - src="images/458F288.jpg"><br> -Fig. 288. POLARIZED RELAY<br> -<br> -<br> -<span style="font-weight: bold;">Reluctance.</span><br> -In a magnetic circuit or portion thereof, the resistance offered to the<br> -flow of lines of force. The magnetic circuit as has already been stated<br> -is treated like an electric circuit, and in it reluctance occupies the<br> -place of resistance in the electric circuit. It is the reciprocal of<br> -permeance. S. P. Thompson expresses the law thus:<br> -<br> -Total number of magnetic lines = (magneto-motive force) / (magnetic<br> -reluctance)<br> -<br> -Synonyms--Magnetic Reluctance-Magnetic Resistance.<br> -<br> -<br> -<span style="font-weight: bold;">Reluctance, Unit of.</span><br> -The reluctance of a circuit through which unit magnetizing power<br> -(magneto-motive force) can produce a unit of induction or one line of<br> -force. This value is very high; the reluctance of ordinary magnetic<br> -circuits ranges from 1E-5 to 1E-8 unit of reluctance.<br> -<br> -<br> -<span style="font-weight: bold;">Reluctivity.</span><br> -Specific reluctance; the reluctance of a cube of material whose edge<br> -measures one centimeter in length. It is a quality bearing the same<br> -relation to reluctance that permeability does to permeance.<br> -<br> -It is defined as the reciprocal of magnetic permeability. (Kenelly.) If<br> -plotted as a curve for different values of the magnetizing force it is<br> -found to be nearly a straight line, a linear function of the magnetizing<br> -force, H with the equation a + b H. Reluctivity is the property of a<br> -substance; reluctance is the property of a circuit.<br> -<br> -<br> -459 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Remanence.</span><br> -The residual magnetism left after magnetic induction, expressed in lines<br> -of force per square centimeter.<br> -<br> -<br> -<span style="font-weight: bold;">Repeater.</span><br> -In telegraphy an instrument for repeating the signals through a second<br> -line. It is virtually a relay which is operated by the sender, and which<br> -in turn operates the rest of the main line, being situated itself at<br> -about the middle point of the distance covered. In the simpler forms of<br> -repeater two relays are used, one for transmission in one direction the<br> -other for transmission in the other. An attendant switches one or the<br> -other in as required.<br> -<br> -Thus a common relay is virtually a repeater for its local circuit. If<br> -such a relay is placed half way down a line, and if the line beyond it<br> -is connected as its local, it becomes a repeater.<br> -<br> -Some forms of repeaters are automatic, and repeat both ways without the<br> -need of an attendant.<br> -<br> -It is the practice to somewhat prolong the signals sent through a<br> -repeater.<br> -<br> -<br> -<span style="font-weight: bold;">Replenisher, Sir William Thomson's.</span><br> -A static accumulating influence machine contained in Thomson's quadrant<br> -electrometer and used to change the quadrants. The cut shows the<br> -horizontal section and construction of the apparatus.<br> -<br> -It contains two gilt brass inductors A B, and two eccentric sectors or<br> -carriers, C, D, which are mounted on an ebonite spindle, which is spun<br> -around by the fingers. The springs s s1 connect each with its inductor;<br> -the springs S S1 connect only each other, and touch the sectors as they<br> -turn around.<br> -<br> -One of the inductors may be always assumed to be of slightly higher<br> -potential than that of the other one. When the carriers are in contact<br> -with the springs S S1 they are each charged by induction with<br> -electricity opposite in sign to that of the nearest quadrant. As they<br> -leave the springs S S1 in their rotation, they next touch the springs s<br> -s1, but of the recently opposite inductor. They share each a portion of<br> -its charge with the inductors building up their charges. The action is<br> -repeated over and over again as they rotate.<br> -<br> -</big></big><big><big><img style="width: 574px; height: 594px;" alt="" - src="images/460F289.jpg"><br> -Fig. 289. DIAGRAM OF THOMSON'S REPLENISHER.<br> -<br> -</big></big><big><big><img style="width: 511px; height: 674px;" alt="" - src="images/461F290.jpg"><br> -Fig. 290. THOMSON'S REPLENISHER.<br> -<br> -<br> -460 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Reservoir, Common.</span><br> -A term applied to the earth, because all electrified bodies discharge<br> -into it if connected thereto.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Residual Atmosphere.</span><br> -The air left in a receiver after exhaustion by an air pump. The<br> -quantity, where good air pumps are used, is very minute.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Residue, Electric.</span><br> -The residual charge of a condenser. (See Charge, Residual.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Resin.</span><br> -(a) The product obtained by non-destructive distillation of the juice of<br> -the pitch pine. It is the solid residue left after the turpentine has<br> -been evaporated or distilled. It is a mixture of abietic acid C44 H64 O5<br> -and pinic acid C20 H30 O2. It is an insulator; its specific inductive<br> -capacity is 2.55. (Baltzmann.)<br> -<br> -Synonyms--Colophony--Rosin.<br> -<br> -(b) The name is also generally applied to similar substances obtained<br> -from the sap of other trees; thus shellac is a resin. The resins are a<br> -family of vegetable products; the solid portions of the sap of certain<br> -trees. Common resin, lac, dragons blood, are examples. They are all<br> -dielectrics and sources of resinous or negative electricity when rubbed<br> -with cotton, flannel, or silk. (See Electrostatic Series.)<br> -<br> -<br> -461 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Resinous Electricity.</span><br> -Negative electricity; the electricity produced upon the surface of a<br> -resinous body by rubbing it; such a body is shellac or sealing wax;<br> -flannel and other substances may be used as the rubbing material. (See<br> -Electrostatic Series.)<br> -<br> -<br> -<span style="font-weight: bold;">Resistance.</span><br> -(a) The quality of an electric conductor, in virtue of which it opposes<br> -the passage of an electric current, causing the disappearance of<br> -electro-motive force if a current passes through it, and converting<br> -electric energy into heat energy in the passage of a current through it.<br> -If a current passes through a conductor of uniform resistance there is a<br> -uniform fall of potential all along its length. If of uneven resistance<br> -the fall in potential varies with the resistance. (See Potential, Fall<br> -of.)<br> -<br> -The fall of potential is thus expressed by Daniell. "In a conductor, say<br> -a wire, along which a current is steadily and uniformly passing, there<br> -is no internal accumulation of electricity, no density of internal<br> -distribution; there is, on the other hand, an unequally distributed<br> -charge of electricity on the surface of the wire, which results in a<br> -potential diminishing within the wire from one end of the wire to the<br> -other."<br> -<br> -Resistance varies inversely with the cross section of a cylindrical or<br> -prismatic conductor, in general with the average cross-section of any<br> -conductor, and in the same sense directly with its true or average or<br> -virtual length. It varies for different substances, and for different<br> -conditions as of temperature and pressure for the same substance. A rise<br> -of temperature in metals increases the resistance, in some bad<br> -conductors a rise of temperature decreases the resistance.<br> -<br> -<br> -462 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Approximately, with the exception of iron and mercury, the resistance of<br> -a metallic conductor varies with the absolute temperature. This is very<br> -roughly approximate.<br> -<br> -Except for resistance energy would not be expended in maintaining a<br> -current through a circuit. The resistance of a conductor may be supposed<br> -to have its seat and cause in the jumps from molecule to molecule, which<br> -the current has to take in going through it. If so a current confined to<br> -a molecule would, if once started, persist because there would be no<br> -resistance in a molecule. Hence on this theory the Ampérian -currents<br> -(see Magnetism, Ampere's Theory of) would require no energy for their<br> -maintenance and Ampére's theory would become a possible truth.<br> -<br> -When metals melt their resistance suddenly increases.<br> -<br> -Light rays falling on some substances, notably selenium, q. v., vary the<br> -resistance.<br> -<br> -Longitudinal stretching of a conductor decreases it, it increases with<br> -longitudinal compression, and increases in iron and diminishes in tin<br> -and zinc when a transverse stress tends to widen the conductor.<br> -<br> -(b) The term resistance is used to express any object or conductor used<br> -in circuit to develop resistance.<br> -<br> -[Transcriber's note: At room temperatures, the thermal motion of ions in<br> -the conductor's crystal lattice scatters the electrons of the current.<br> -Imperfections of the lattice contribute slightly. At low temperatures<br> -superconductivity (zero resistance) can occur because an energy gap<br> -between the electrons and the crystal lattice prevents any interaction.<br> -At the time of this book, none of this was known. "Jumps from molecule<br> -to molecule" is a good guess.]<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Apparent.</span><br> -Impedance; the virtual resistance of a circuit including the spurious<br> -resistance due to counter-electromotive force. It may be made up of true<br> -resistance and partly of an inductive reaction, as it represents the net<br> -factor, the entire obstruction to the passage of a current, and not<br> -merely a superadded resistance or counter-electro-motive force.<br> -<br> -Synonym--Impedance.<br> -<br> -[Transcriber's note: Impedance can also have a component due to<br> -capacitance.]<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Asymmetrical.</span><br> -Resistance which varies in amount in different directions through a<br> -conductor. It implies a compound or composite conductor such as the<br> -human system. The presence of counter-electro-motive force in different<br> -parts of a conductor may bring about asymmetrical resistance.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, B. A. Unit of.</span><br> -The British Association Ohm. (See Ohm, B. A.)<br> -<br> -<br> -463 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance Box.</span><br> -A box filled with resistance coils. The coils are connected in series so<br> -that a circuit including any given number has their aggregate resistance<br> -added to its own. The terminals of consecutive coils are connected to<br> -short blocks of brass which are secured to the top of the box, lying<br> -flatwise upon it, nearly but not quite in contact with each other. Plugs<br> -of brass are supplied which can go in between pairs of blocks, which<br> -have a pair of grooves reamed out to receive them. Such plugs short<br> -circuit the coil below them when in position. The cut shows how such<br> -coils are connected and the use of plugs to short circuit them. The<br> -diagram shows the top of a Wheatstone bridge, q. v., resistance box with<br> -connections for determining resistances.<br> -<br> -<br> -<img style="width: 571px; height: 419px;" alt="" - src="images/463F291.jpg"><br> -Fig. 291. RESISTANCE BOX.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance Box, Sliding.</span><br> -A resistance box whose coils are set in a circle. Two metal arms with<br> -handles are pivoted at the centre of the circle and by moving them<br> -around they make and break contacts so as to throw the coils in and out<br> -of circuit. The object is to permit an operator to adjust resistance<br> -without looking at the box--an essential in duplex telegraphy.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Breguet Unit of.</span><br> -The same in origin as the Digney Unit. (See Resistance, Digney Unit of.)<br> -<br> -It is equal to 9.652 Legal Ohms.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Carbon.</span><br> -A resistance, a substitute for a resistance coil; it is made of carbon,<br> -and is of various construction. In the Brush dynamo regulator a set of<br> -four vertical piles of plates of retort carbon, q. v., is used as a<br> -resistance, whose resistance is made to vary by changing the pressure.<br> -This pressure automatically increases as the current strength increases,<br> -thus reducing the resistance.<br> -<br> -<br> -464 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance Coil, Standard.</span><br> -A standard or resistance issued by the Electric Standard Committee of<br> -Great Britain. The cut shows the standard ohm. It is formed either of<br> -German silver, or of an alloy of silver, 66.6 per cent. and platinum,<br> -33.4 per cent. The wire is insulated and doubled before winding as<br> -described before. (See Coil, Resistance.) The two ends of the wire are<br> -soldered, each one to a heavy copper wire or rod r. The whole coil is<br> -enclosed in a brass case, and is enclosed with paraffine melted in at A.<br> -A place for a thermometer is provided at t. By immersing the lower part<br> -of the case B in water of different degrees of heat any desired<br> -temperature can be attained.<br> -<br> -<br> -<img style="width: 398px; height: 577px;" alt="" - src="images/464F292.jpg"><br> -Fig. 292. STANDARD OHM COIL.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Combined.</span><br> -The actual resistance of several parallel conductors starting from the<br> -same point and ending at the same point. If the individual resistance be<br> -a b c d .. and the combined resistance be x then we have<br> -x = 1 / (( 1/a) + (1/b) + (1/c) + (1/d) + …)<br> -<br> -Synonym--Joint Resistance.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Critical.</span><br> -In a series wound dynamo the resistance of the outer circuit above which<br> -the machine will refuse to excite itself.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Dielectric.</span><br> -The mechanical resistance of a dielectric to the tendency to perforation<br> -or to the strains due to electrification. This is a phase of mechanical<br> -resistance, and is distinct from the electrical or ohmic resistance of<br> -the same substance.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Digney Unit of.</span><br> -The resistance of an iron wire, 1 kilometer long, 4 millimeters<br> -diameter, temperature unknown.<br> -<br> -It is equal to 9.163 legal ohms.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Electrolytic.</span><br> -The resistance of an electrolyte to the passage of a current decomposing<br> -it. It is almost entirely due to electrolysis and is added to by<br> -counter- electro-motive force, yet it is not treated specifically as<br> -such, but as an actual resistance. When a current of a circuit of too<br> -low voltage to decompose an electrolyte is caused by way of immersed<br> -terminals to pass through an electrolyte the resistance appears very<br> -high and sometimes almost infinite. If the voltage is increased until<br> -the electrolyte is decomposed the resistance suddenly drops, and what<br> -should be termed electrolytic resistance, far lower than the true<br> -resistance, appears.<br> -<br> -<br> -465 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, English Absolute or -Foot-Second Unit of.</span><br> -A unit based on the foot and second. It is equal to (( foot / second ) *<br> -1E7) , being based on these dimensions.<br> -<br> -It is equal to 0.30140 legal ohm.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Equivalent.</span><br> -A resistance equivalent to other resistances, which may include<br> -counter-electro-motive force.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Essential.</span><br> -The resistance of the generator in an electric circuit; the same as<br> -internal resistance.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, External.</span><br> -In an electric circuit the resistance of the circuit outside of the<br> -generator, or battery.<br> -<br> -Synonym--Non-essential Resistance.<br> -<br> -<br> -<img style="width: 361px; height: 553px;" alt="" - src="images/465F293.jpg"><br> -Fig. 293. RESISTANCE FRAME.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Resistance Frame.</span><br> -An open frame filled with resistance coils of iron, or German silver<br> -wire. It is used as a resistance for dynamos and the larger or working<br> -class of plant. The coils are sometimes connected so that by a switch<br> -moving over a row of studs one or more can be thrown into series<br> -according to the stud the switch is in contact with.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, German Mile Unit of.</span><br> -The resistance of 8,238 yards of iron wire 1/6 inch in diameter. It is<br> -equal to 56.81 legal ohms.<br> -<br> -<br> -466 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Hittorf's.</span><br> -A high resistance, often a megohm, composed of Hittorf's solution, q. v.<br> -It is contained in a vertical glass tube near whose upper and lower ends<br> -are electrodes of metallic cadmium attached to platinum wires. The<br> -cadmium is melted in glass tubes, the platinum wire is inserted into the<br> -melted metal and the tube is broken after all is solid. The resistance<br> -should show no polarization current.<br> -<br> -<br> -<img style="width: 310px; height: 570px;" alt="" - src="images/466F294.jpg"><br> -Fig. 294. HITTORF'S RESISTANCE<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Inductive.</span><br> -A resistance in which self-induction is present; such as a coil of<br> -insulated wire wound around an iron core.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Insulation.</span><br> -The resistance of the insulation of an insulated conductor. It is stated<br> -in ohms per mile. It is determined by immersing a section of the line in<br> -water and measuring the resistance between its conductor and the water.<br> -The section must be of known length, and its ends must both be above the<br> -liquid.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Resistance, Internal.</span><br> -The resistance of a battery, or generator in an electric circuit as<br> -distinguished from the resistance of the rest of the circuit, or the<br> -external resistance.<br> -<br> -Synonym--Essential Resistance.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Jacobi's Unit of.</span><br> -The resistance of a certain copper wire 25 feet long and weighing 345<br> -grains.<br> -<br> -It is equal to 0.6296 legal ohm.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Matthiessen's Meter-gram -Standard.</span><br> -The resistance of a pure hard drawn copper wire of such diameter that<br> -one meter of it weighs one gram. It is equal to .1434 Legal Ohms at -0º<br> -C. (32º F.)<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Matthiessen's Unit of.</span><br> -The resistance of a standard mile of pure annealed copper wire 1/16 inch<br> -diameter, at a temperature of 15.5º C. (60º F.).<br> -<br> -It is equal to 13.44 legal ohms.<br> -<br> -<br> -467 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Meter-millimeter Unit of.</span><br> -The resistance of a wire of copper one meter long and one square<br> -millimeter in section. It is equal to .02057 ohms at 0º C. -(32º F.) The<br> -term may also be applied to the resistance of similar sized wire of<br> -other metals.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Mil-foot Unit of.</span><br> -The resistance of a foot of copper wire one-thousandth of an inch in<br> -diameter. It is equal to 9.831 ohms at 0º C. (32º F.) The -term may also<br> -be applied to the resistance of similar sized wire of other metals.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Non-essential.</span><br> -The resistance of the portion of an electric circuit not within the<br> -generator; the same as external resistance.<br> -<br> -Synonym--External Resistance.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Non-inductive.</span><br> -A resistance with comparatively little or negligible self-induction.<br> -<br> -<span style="font-weight: bold;">Resistance of Human Body.</span><br> -The resistance of the human body is largely a matter of perfection of<br> -the contacts between its surface and the electrodes. It has been<br> -asserted that it is affected by disease. From 350 to 8,000 ohms have<br> -been determined as resistances, but so much depends on the contacts that<br> -little value attaches to the results.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Ohmic.</span><br> -True resistance measured in ohms as distinguished from<br> -counter-electro-motive force, q. v. The latter is called often spurious<br> -resistance.<br> -<br> -Synonym--True Resistance.<br> -<br> -[Transcriber's note: "True" vs. "spurious" are interesting terms,<br> -considering that today we define impedance as a combination of "real"<br> -resistance and "imaginary" capacitive and inductive reactance.]<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Reduced.</span><br> -The resistance of a conductor reduced to ohms, or to equivalent lengths<br> -of a column of mercury, 1 square millimeter in cross area.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Siemen's Unit of.</span><br> -The resistance of a column of mercury 1 meter long and 1 square<br> -millimeter cross-sectional area at 0º C. (32º F.)<br> -<br> -It is equal to .9431 legal ohm.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Resistance, Specific.</span><br> -The relative resistance of a substance. It is expressed as the actual<br> -resistance of a cube of the substance which is one centimeter on each<br> -edge. For metals it is usually expressed in microhms, for liquids in<br> -ohms.<br> -<br> -The resistances of a specified length of wire of specified diameter of<br> -different substances is often given, and is really a particular way of<br> -stating specific resistances.<br> -<br> -Synonym--Specific Conduction Resistance.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Resistance, Spurious.</span><br> -The counter-electro-motive force, q. v., operating to prevent a current<br> -being produced of what should be its full strength were the true<br> -resistance and actuating electro-motive force only concerned. Such<br> -counter-electro-motive force may be treated as a spurious resistance and<br> -such a value in ohms assigned to it as would correspond to its proper<br> -effect.<br> -<br> -<br> -468 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -In its effect on opposing a current and in resisting its formation it<br> -differs from true resistance. The latter in diminishing current strength<br> -absorbs energy and develops heat; spurious resistance opposes and<br> -diminishes a current without absorption of energy or production of heat.<br> -<br> -[Transcriber's note: "Spurious resistance" is now called reactance,<br> -consisting of capacitive reactance and inductive reactance. The<br> -combination of reactance and (Ohmic/true) resistance is called<br> -impedance. The calculation of impedance requires complex algebra, not<br> -just real values used in DC circuit analysis.]<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Steadying.</span><br> -When arc lamps are connected in parallel or multiple arc a small<br> -resistance coil is sometimes placed in series with each lamp for<br> -steadying purposes. It reduces the percentage of variation of resistance<br> -in each lamp, which may be caused by a change in the position of the<br> -carbons.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Resistance, Swiss Unit of.</span><br> -A unit constructed by the "Administration Suisse," based on the same<br> -data as the Breguet and the Digney Units. (See Resistance, Digney Unit<br> -of)<br> -<br> -It is equal to 10.30 legal ohms.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Thomson's Unit of.</span><br> -A unit of resistance based on the foot and second.<br> -<br> -It is equal to 0.3166 legal ohm.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Unit.</span><br> -Unit resistance is that of a conductor in which unit current is produced<br> -by unit electro-motive force.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Resistance, Varley's Unit of.</span><br> -The resistance of a standard mile of a special copper wire 1/16 inch<br> -diameter.<br> -<br> -It is equal to 25.33 ohms.<br> -<br> -<br> -<span style="font-weight: bold;">Resistance, Weber's Absolute Unit.</span><br> -A metric system unit; (meter / second) * 1E7<br> -<br> -It is equal to 0.9089 legal ohm.<br> -<br> -<br> -<span style="font-weight: bold;">Resonance, Electric.</span><br> -A set of phenomena known as the Hertz experiments are grouped under this<br> -title, which phenomena are incidents of and depend on the propagation of<br> -electric waves through wires or current conductors, as well as through<br> -the ether. Ordinarily a wire is only a seat of current, and is in its<br> -nature inconsistent with wave propagation through its mass. Such waves<br> -are virtually confined to the exterior of the wire. The point is that<br> -the current-producing force is supposed to enter the wire at all points<br> -from without, the current not being produced by an end-push. Hence in<br> -rapidly recurring waves which are produced by a rapidly pulsatory or<br> -alternating current, no time is afforded for the current-producing<br> -force, in this case the wave-producing force, to penetrate into the<br> -substance of the wire. In one of his experiments Dr. Hertz surrounded a<br> -wire by a glass tube chemically silvered. The coating was so thin as to<br> -be translucent. Through this metallic layer a current could be induced<br> -in the wire in its interior. Any mechanical layer of metal took up the<br> -induction itself, and protected the central wire. This gave a clue to<br> -the thickness of metal penetrated by the rapid induced waves used by Dr.<br> -Hertz.<br> -<br> -<br> -469 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 613px; height: 312px;" alt="" - src="images/469F295.jpg"><br> -Fig. 295. ELECTRICAL RESONANCE EXCITER.<br> -<br> -<br> -The method used for the production of rapid oscillations is the<br> -following. To the terminals of an induction coil two metal spheres AA1<br> -are connected as shown. This apparatus is termed the exciter; in its<br> -discharge a series of isochronous discharges takes place, alternating in<br> -direction. The period of duration T of a single one is given by the<br> -formula T= 2* PI * squareRoot( LC ), in which C is the capacity -and L<br> -is the self-induction. The spheres may be 30 centimeters (11.8 inches)<br> -in diameter, connected each to conductors 0.5 centimeter (.2 inch) in<br> -diameter and 40 centimeters (15.7 inches) long each. For the length of<br> -an undulation the formula gives for this apparatus 4.8 meters (15.75<br> -feet) as the length of a wave, assuming for them the velocity of<br> -propagation equal to that of light. The exciter may have 10,000 times<br> -the rate of oscillation possessed by the plain induction coil.<br> -<br> -When this apparatus is worked it produces induced waves in every<br> -neighboring conductor. The resonance effects appear in the size of the<br> -spark induced. Thus a wire bent into a circle with its ends nearly<br> -touching will give a spark, but if made of proper electrostatic<br> -capacity, corresponding with the particular waves employed, the spark<br> -will be very much larger. The ring, with its spark gap is termed a<br> -resonator. It is used as an explorer to trace the waves.<br> -<br> -Waves thus produced are transmitted by stone walls and nonconductors in<br> -general. A plate of zinc reflects part and transmits part. The reflected<br> -waves can be traced by the resonator, their angle of reflection being<br> -equal to their angle of incidence. They can be received by one parabolic<br> -reflector, reflected to another and brought to a focus. They can be<br> -reflected so as to produce interference or loops and nodes, and the<br> -loops and nodes can be traced by the resonator. By a prism of asphalt<br> -they are refracted exactly like light.<br> -<br> -From all this it is concluded that an additional proof is furnished of<br> -the identity of light and electro-magnetic waves, and a very strong<br> -experimental proof of Maxwell's theory of light is furnished.<br> -<br> -Synonym--Hertz's Experiments.<br> -<br> -<br> -470 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 640px; height: 297px;" alt="" - src="images/470F296.jpg"><br> -Fig. 296. ELECTRICAL RESONATOR.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Resonator, Electric.</span><br> -A small open electric circuit, with ends nearly touching. When exposed<br> -to electric resonance, or to a sympathetic electric oscillatory<br> -discharge, a spark passes from across the gap. The production of this<br> -spark is altogether a matter of the inductance of the resonator. The<br> -simplest form is a circle of copper wire with its ends nearly touching.<br> -The length of the gap is adjustable by bending. A screw adjustment may<br> -also be provided. Another form is shown in the cut, Fig. 296. Here<br> -sheets of tinfoil are used to regulate the electrostatic capacity, while<br> -at m is shown the finger piece for regulating the size of the spark gap<br> -a.<br> -<br> -Synonym--Spark Micrometer.<br> -<br> -<br> -<span style="font-weight: bold;">Resultant.</span><br> -The line indicating the result of the application of two or more forces<br> -to a point. Its direction and length give the elements of direction and<br> -intensity. (See Forces, Resolution of Forces, Composition of<br> -Components.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Resultant Polarity.</span><br> -The magnetic polarity imparted to a mass of iron acted on by two or more<br> -separate inducing forces or currents. It appears in dynamos and motors.<br> -The final polarity is the resultant of the inducing effect of the field<br> -magnet poles and of the windings.<br> -<br> -<br> -R<span style="font-weight: bold;">etardation.</span><br> -In telegraphy a retardation of the rate of transmission of signals. It<br> -is due to several causes.<br> -<br> -(a) The self-induction of the circuit, especially if it includes many<br> -electro-magnets, produces extra currents (see Currents, Extra.) These<br> -are opposed to the main current on closing it and hence retard the<br> -action. They are in the same direction on opening it and hence again<br> -retard the action.<br> -<br> -(b) Every line has a certain static capacity. This is affected by the<br> -proximity of the lines to the earth. For each signal electricity has to<br> -be charged upon the line until the line is charged to its end with a<br> -certain proportion of the initial density. This charging takes time and<br> -hence introduces retardation.<br> -<br> -(c) The cores of the electro-magnets of the relays or sounders are not<br> -instantly magnetized and demagnetized. This magnetic lag, q. v.,<br> -introduces retardation.<br> -<br> -<br> -471 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Retardation of Phase.</span><br> -The fractional lagging behind of waves or alternating currents; by<br> -lagging behind a portion of a wave length the corresponding phases, as<br> -of full amplitude, are kept back or retarded. The phase of current<br> -intensity may be retarded with reference to the electro-motive force by<br> -the introduction of transformers of high capacity with high resistance<br> -on open secondary circuits.<br> -<br> -[Transcriber's note: Capacitors are used to correct current phase lag.]<br> -<br> -<br> -<span style="font-weight: bold;">Retentivity.</span><br> -Coercitive or coercive force; by virtue of which steel retains its<br> -magnetism. It is the more modern name, "coercive force" as a term being<br> -rejected by many.<br> -<br> -Synonyms--Coercive Force--Coercitive Force.<br> -<br> -<br> -<span style="font-weight: bold;">Retort Carbon.</span><br> -Carbon deposited in coal gas retorts from decomposition of the<br> -hydrocarbons. It is a very hard, pure form, and is of graphitic<br> -modification. Owing to its great hardness it is little used for<br> -electrical purposes, the molded carbons being easier to make. The<br> -deposition occurs in the regular gas-making process, and is a<br> -disadvantage to the working.<br> -<br> -<br> -<span style="font-weight: bold;">Return.</span><br> -A line or conductor which is supposed to carry current back to its<br> -starting point, after it has traversed a line. It may be a wire or the<br> -grounding of the ends of a line [or] may make the earth act as a return,<br> -termed ground- or earth-return. The best distinction of a return is to<br> -so term the portion of a circuit on which no apparatus is placed.<br> -<br> -<br> -<span style="font-weight: bold;">Reversibility.</span><br> -The principal in virtue of which a device for producing a given form of<br> -energy can absorb the same and do work. The reversibility of the dynamo<br> -is its quality in virtue of which it can act as a current generator,<br> -thereby converting mechanical energy into electric energy, or if a<br> -current is passed through it, it rotates, doing work, and thereby<br> -converting electric energy into mechanical energy. The knowledge of this<br> -principle can be traced back to Jacobi in 1850.<br> -<br> -<br> -<span style="font-weight: bold;">Reversible Bridge.</span><br> -A form of Wheatstone's Bridge adapted for reversal of the positions or<br> -interchange of the proportionate arms, v., so that the accuracy of the<br> -coils can be tested.<br> -<br> -<br> -<span style="font-weight: bold;">Rheochord.</span><br> -An apparatus by means of which variable quantities of wire are thrown<br> -into the circuit; a rheostat using wire. (See Rheostat, Wheatstone's.)<br> -<br> -<br> -<span style="font-weight: bold;">Rheometer.</span><br> -A galvanometer. (Obsolete.)<br> -<br> -<br> -472 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Rheomotor.</span><br> -A source of current; a current generator; a producer of potential<br> -difference. (Obsolete.)<br> -<br> -<br> -<span style="font-weight: bold;">Rheophore.</span><br> -The portion of an active circuit capable of deflecting a magnetic<br> -needle. This properly includes all of the metallic conductor of a<br> -circuit. (Obsolete.)<br> -<br> -<br> -<span style="font-weight: bold;">Rheoscope.</span><br> -A galvanoscope; an instrument for qualitatively detecting potential<br> -difference, fall or rise. (See Galvanoscope.)<br> -<br> -<br> -<span style="font-weight: bold;">Rheostat.</span><br> -An adjustable resistance; an apparatus for changing the resistance<br> -without opening the circuit. Its action may depend on the introduction<br> -of variable lengths of mercury column, of some other liquid, or of wire<br> -into a circuit. (See Rheostat, Wheatstone's.)<br> -<br> -<br> -<span style="font-weight: bold;">Rheostat Arm.</span><br> -The third arm of known resistance in a Wheatstone bridge. (See<br> -Proportionate Arms.)<br> -<br> -<br> -<span style="font-weight: bold;">Rheostatic Machine.</span><br> -An apparatus for increasing potential difference. It consists of a<br> -number of static condensers. They are charged in multiple arc or in<br> -parallel, and are discharged in series. Secondary batteries may be used<br> -for the charging; thus a static effect is produced from a galvanic<br> -battery.<br> -<br> -<br> -<span style="font-weight: bold;">Rheostat, Wheatstone's.</span><br> -This apparatus consists of two cylinders, one, A, made of brass, the<br> -other, B, of wood, with a spiral groove. At its end is a copper ring a.<br> -A fine brass wire has one end attached to this ring. Its other end is<br> -fastened at e, and it is wound as shown; n and o are binding screws<br> -connected, one with the cylinder-ring a, the other with the brass<br> -cylinder, A. The current entering at o, traverses the wire on B, as<br> -there the windings are insulated by the grooves, thence it passes to m<br> -and by A, whose metal short circuits all the wire on it, to the<br> -binding-post n. The handle, d, is turned one way or the other to<br> -regulate the length of the wire through which the current must pass. On<br> -each cylinder there is a square head, one of which is shown at c, so<br> -that the handle can be shifted from one to the other as required; to A<br> -if the wire is to be wound on that cylinder, to B if the reverse is<br> -desired.<br> -<br> -<br> -<img style="width: 604px; height: 669px;" alt="" - src="images/473F297.jpg"><br> -Fig. 297. WHEATSTONE'S RHEOSTAT.<br> -<br> -<br> -473 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Rheotome.</span><br> -An automatic circuit breaker, one which rapidly opens and closes a<br> -circuit, as in the case of the primary of an induction coil an<br> -interrupter. (Obsolete.)<br> -<br> -<br> -<span style="font-weight: bold;">Rheotrope.</span><br> -A pole changer, current reverser, or commutator, g., such as the<br> -commutator of an induction coil. (Obsolete.)<br> -<br> -<br> -<span style="font-weight: bold;">Rhigolene.</span><br> -A petroleum product; a hydrocarbon of low boiling point. Its vapor is<br> -used in flashing (q. v.) carbon filaments for incandescent lamps.<br> -<br> -<br> -<span style="font-weight: bold;">Rhumbs.</span><br> -In a mariners' compass, the thirty-two points, designated, north, north<br> -by east, north north east, etc. (See Compass Mariner's-Compass, Points<br> -of the.)<br> -<br> -<br> -<span style="font-weight: bold;">Rhumkorff Coil.</span><br> -The induction coil, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Rigidity, Molecular.</span><br> -The tendency of molecules to resist rotation or change of position; the<br> -assumed cause of magnetic coercive force, or retentivity.<br> -<br> -<br> -<span style="font-weight: bold;">Ring Contact.</span><br> -A contact formed by a terminal clip in the shape of a ring, split or cut<br> -at one point so that its ends tend to spring together. The other<br> -terminal is a bar which passes into the cut and is tightly pressed by<br> -the elastic ring.<br> -<br> -<br> -<img style="width: 681px; height: 452px;" alt="" - src="images/474F298.jpg"><br> -Fig. 298. SWITCH WITH RING CONTACTS.<br> -<br> -<br> -474 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Ring, Faraday.</span><br> -A closed ring of iron used as the core of a transformer or induction<br> -coil. The term is derived from Faraday's classic experiment with such an<br> -apparatus when he produced a spark by induction in a secondary circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Roaring.</span><br> -A term applied to the noise sometimes produced in a voltaic arc, when<br> -the electrodes are close together and a heavy current is passing.<br> -<br> -<br> -<span style="font-weight: bold;">Rocker.</span><br> -In a dynamo the movable piece, mounted concentrically with the<br> -commutator, and carrying the rocker-arms and brush-holders. By moving it<br> -the brushes are adjusted for proper lead.<br> -<br> -<br> -<span style="font-weight: bold;">Rocker Arms.</span><br> -The arms projecting from a rocker and each carrying one of the<br> -brush-holders.<br> -<br> -<br> -<span style="font-weight: bold;">Roget's Spiral.</span><br> -An experimental apparatus for illustrating the mutual attraction of<br> -currents going in like direction. A cylindrical helix or spiral of wire<br> -is suspended by one end. Its lower end just dips into a mercury cup. An<br> -active circuit is connected, one terminal to the upper end, the other<br> -terminal to the mercury cup, bringing the apparatus in series into the<br> -circuit. The current as it passes causes the coil to shorten, each<br> -spiral attracting its neighbors. This breaks the circuit by drawing the<br> -lower end out of the mercury cup. The current being cut off the coils<br> -cease to attract each other, and the end dips into the mercury cup<br> -again. This closes the circuit, the coils again attract each other and<br> -the same sequence follows and is repeated over and over again. A bright<br> -spark is produced at each break of the mercury contact.<br> -<br> -<br> -<span style="font-weight: bold;">Rotation of Liquids, Electro-dynamic.</span><br> -By passing a current through a liquid, such as dilute sulphuric acid, it<br> -rotates if exposed to the induction of a current flowing at right angles<br> -to it. The condition resolves itself into a liquid traversed by<br> -horizontal currents from centre to circumference or vice versa, rotated<br> -by a current passing through a circular conductor below it.<br> -<br> -<br> -475 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Rotation of Liquids, Electro-magnetic.</span><br> -The rotation produced in a liquid carrying centripetal or centrifugal<br> -currents by an electromagnet. It is practically an intensification of<br> -electro-dynamic rotation. (See Rotation of Liquids, Electro-dynamic.)<br> -<br> -<br> -<span style="font-weight: bold;">Rubber.</span><br> -In a frictional electric machine the cushion of leather which is pressed<br> -against the plate as it rotates.<br> -</big></big><br> -<big><big><span style="text-decoration: underline;"><br> -</span></big></big><big><big><br> -475 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">S.</span><br> -(a) Symbol for second.<br> -<br> -(b) Symbol for space, or length; L is preferable.<br> -<br> -(c) Symbol for south-seeking pole of a magnet.<br> -<br> -<br> -<span style="font-weight: bold;">Saddle Bracket.</span><br> -A bracket carried on the top of telegraph poles, carrying an insulator<br> -for the upper wire.<br> -<br> -<br> -<span style="font-weight: bold;">Safety Device.</span><br> -(a) A device to prevent overheating of any portion of a circuit by<br> -excess of current. It generally consists of a slip of fusible metal<br> -which if the current attains too much strength melts and opens the<br> -circuit. To ensure its breaking a weight is sometimes suspended from the<br> -strip. In one form an insulated German silver wire is wrapped around the<br> -end of the fusible strip a number of times and its end is connected to<br> -it. The other end of the German silver wire connects with the main lead,<br> -so that all the current goes through both in series. If the German<br> -silver wire becomes heated from excess of current the coil wrapped<br> -tightly around the end of the fusible strip melts it and opens the<br> -circuit.<br> -<br> -(b) Lightning arresters, q. v., may be cited under this heading.<br> -<br> -Synonyms--Automatic Cut Out--Safety Fuse, Plug, or Strip.<br> -<br> -<br> -<img style="width: 474px; height: 314px;" alt="" - src="images/475F299.jpg"><br> -Fig. 299. COCKBURN SAFETY FUSE.<br> -<br> -<br> -<span style="font-weight: bold;">Safety Fuse.</span><br> -A strip of metal inserted so as to form part of a circuit and of such<br> -size that a smaller current [than] would heat the regular wire of the<br> -circuit dangerously, so as to cause a conflagration for instance, would<br> -melt the fuse and open the circuit. As it sometimes happens that a<br> -safety fuse melts without parting a weight is sometimes hung upon it, so<br> -as to break it as it softens.<br> -<br> -<br> -<span style="font-weight: bold;">Salt.</span><br> -A salt is a chemical compound containing two atoms of two radicals,.<br> -which saturate each other. One atom or radical is electro-positive<br> -referred to the other, which is electro-negative. By electrolysis salts<br> -are decomposed, the atoms or radicals separating and uniting to form new<br> -molecules.<br> -<br> -<br> -476 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Saturated. adj.</span><br> -A liquid is saturated with a substance when it has dissolved all that it<br> -can, while an excess is present in the liquid. It is possible, by<br> -dissolving some salts in hot water and allowing the solution to cool<br> -without access of air, to obtain a supersaturated solution. On<br> -introduction of a crystal of the salt, or often on mere access of air,<br> -the solution forms crystals and the liquid left is saturated.<br> -<br> -<br> -<span style="font-weight: bold;">Saw, Electric.</span><br> -A platinum coated steel wire mounted and connected to be raised to<br> -incandescence for cutting purposes.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Schweigger's Multiplier.</span><br> -An old term for the galvanometer as invented by Schweigger soon after<br> -Oerstedt's discovery.<br> -<br> -<br> -<span style="font-weight: bold;">Scratch Brushes.</span><br> -Brushes for cleaning the surface of articles to be electroplated to give<br> -a good metallic surface suitable for deposition. They have often wire<br> -instead of bristles.<br> -<br> -<br> -477 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 413px; height: 657px;" alt="" - src="images/476F300.jpg"><br> -Fig. 300. WIRE GAUZE ELECTRIC SCREEN.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Screen, Electric.</span><br> -A large plate or a hollow case or cage of conducting material connected<br> -with the earth, and used to protect any body placed within it from<br> -electrostatic influences.<br> -<br> -If within a hollow conducting sphere an electrified body is placed, the<br> -inner surface of the sphere will be charged with electricity of opposite<br> -kind to that of the sphere, and the outer surface with the same kind as<br> -that of the sphere. Thus the sum of the electricities called into action<br> -by induction is zero. The two inner charges are bound to each other. The<br> -induced charge on the outer surface of the sphere is all that has any<br> -effect on objects in the outer air.<br> -<br> -If the outer surface is connected to the earth it becomes discharged,<br> -and however highly electrified the body introduced into the sphere and<br> -the inner surface of such sphere may be, they produce no external<br> -effects, as they are bound one to the other.<br> -<br> -If the sphere is connected to the earth and an unelectrified object is<br> -placed within it, such object will be perfectly shielded from the<br> -effects of an outer electrostatic field. Perforated tinfoil or wire<br> -gauze has just as good a result. A large plate of metal connected to the<br> -earth has the same effect. The screen whether plane or hollow simply<br> -retains a bound charge due to the field of force, thereby neutralizing<br> -it, and the electricity of the opposite sign escapes to the earth. Thus<br> -a true shielding or screening effect is produced.<br> -<br> -In the cut an experiment is shown in which an electric screen is carried<br> -by a Leyden jar. Pith balls are suspended outside and inside of it. By<br> -the approach of an electrified body the outer pith balls will diverge,<br> -while no effect is produced upon the inner ones.<br> -<br> -<br> -<span style="font-weight: bold;">Secondary Actions.</span><br> -In electrolysis the direct products of the electrical decomposition are<br> -not always obtained at the electrodes, but products due to their<br> -reaction on the water and other chemicals may appear. These constitute<br> -secondary actions. Thus if a solution of copper sulphate is electrolyzed<br> -with platinum electrodes, metallic copper appears at one pole and<br> -sulphuric acid and oxygen gas at the other. But the products of<br> -electrolysis by the current are copper (Cu) and sulphion (SO4). The<br> -latter reacting on water sets free oxygen gas and forms sulphuric acid.<br> -The latter is a secondary action.<br> -<br> -<br> -<span style="font-weight: bold;">Secondary Generator.</span><br> -(a) An alternating current converter generating a so-called secondary<br> -current.<br> -<br> -(b) A secondary battery, q. v., may be thus termed.<br> -<br> -<br> -<span style="font-weight: bold;">Secondary, Movable.</span><br> -The term movable secondaries has been applied to rings, spheres and<br> -discs of conducting material, such as copper, whose behavior when near<br> -the pole of an electro-magnet traversed by an alternating current, have<br> -been studied by Elihu Thomson. Such masses are subjected to very<br> -peculiar movements and mutual reactions. As the phenomena are due to<br> -induced currents the above term has been applied to the masses in which<br> -the currents are induced.<br> -<br> -<br> -478 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Secondary Plates, Colors of.</span><br> -In a secondary battery of the lead plate type, the color of the plates<br> -is a good indication of the condition of the battery. The negative plate<br> -should be brown or deep-reddish, the other should be slate-colored.<br> -<br> -<br> -<span style="font-weight: bold;">Secondary Poles.</span><br> -Poles sometimes found in magnets existing in positions intermediate<br> -between the end or true poles.<br> -<br> -Synonym--Consequent Poles.<br> -<br> -<br> -<span style="font-weight: bold;">Seebeck Effect.</span><br> -The production of a current by heating the junction of two different<br> -metals forming part of a circuit, or the thermo-electric production of<br> -current, is stated as the Seebeck effect, having been discovered by that<br> -investigator.<br> -<br> -<br> -<span style="font-weight: bold;">Selenium.</span><br> -A non-metallic element. It is interesting electrically on account of the<br> -changes its electric resistance undergoes when it is subjected to light.<br> -<br> -In one set of experiments it was found that diffused light caused the<br> -resistance to fall in the ratio of 11 to 9. Full sunlight reduced it to<br> -one-half. Of the spectrum colors red was most powerful and the ultra red<br> -region still more strongly affected its resistance.<br> -<br> -The effect produced by exposure to light is instantaneous, but on<br> -removal to the dark only slowly disappears.<br> -<br> -A vessel of hot water was found to have no effect, showing that short<br> -ether waves are essential to the effect.<br> -<br> -<br> -<span style="font-weight: bold;">Selenium Cell.</span><br> -A selenium resistance box. Vitreous selenium is made by keeping ordinary<br> -selenium for some hours at a temperature of about 220º C. -(428º F.)<br> -after fusing. It is placed in an electric circuit as part of the<br> -conductor.<br> -<br> -Its resistance can then be determined. It decreases in sunlight to about<br> -one-half its resistance in the dark.<br> -<br> -The selenium cell is used in the Photophone, q. v. Otherwise it is<br> -little more than a subject of experiment.<br> -<br> -<br> -<span style="font-weight: bold;">Selenium Eye.</span><br> -A model eye in which selenium in circuit with a battery and galvanometer<br> -takes the place of the retina of the human eye.<br> -<br> -<br> -<span style="font-weight: bold;">Self-repulsion.</span><br> -When a body is electrified each molecule repels its neighbor and the<br> -condition in question is thus designated. An electrified soap-bubble<br> -expands in virtue of self-repulsion.<br> -<br> -<br> -<span style="font-weight: bold;">Semi-conductors.</span><br> -Substances which conduct static electricity poorly, but quite<br> -appreciably and beyond the extent of leakage. The following are<br> -examples: Alcohol and ether, powdered glass, flowers of sulphur, dry<br> -wood, paper, ice at 0º C. (32º F.)<br> -<br> -<br> -479 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Sensibility. </span><br> -The measure of the effect of a current upon a galvanometer,<br> -or any similar case.<br> -<br> -<br> -<span style="font-weight: bold;">Sensitiveness, Angle of Maximum.</span><br> -Every galvanometer has its angle of maximum sensitiveness, which is the<br> -angle of deflection at which a small increment of current will produce<br> -the greatest deflection. For every tangent galvanometer 45° is the -angle<br> -in question. In using a galvanometer for direct reading methods it is an<br> -object to have it work at its angle of maximum sensitiveness.<br> -<br> -<br> -<span style="font-weight: bold;">Separately Excited Dynamo.</span><br> -A dynamo-electric machine whose field magnet is excited from an outside<br> -source, which may be another dynamo or a battery. Alternating current<br> -dynamos are often of this description.<br> -<br> -<br> -<span style="font-weight: bold;">Separate Touch.</span><br> -In magnetism a method of inducing magnetism in a steel bar. The opposite<br> -poles of two magnets are applied at the center of the bar to be<br> -magnetized, but without touching each other, and are drawn apart to its<br> -ends. They are returned through the air and the process is repeated a<br> -number of times and on both sides of the bar if necessary.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Separation of Electricities.</span><br> -Under the double fluid theory of electricity the action of<br> -electrification in accumulating positive electricity in one conductor<br> -and negative on the other of the excited surfaces of two conductors.<br> -<br> -<br> -<span style="font-weight: bold;">Separator.</span><br> -India rubber bands or other forms used in batteries to keep the plates<br> -from touching in the cell; especially applied to secondary batteries,<br> -where the plates are so near together as to require separators to<br> -prevent short circuiting.<br> -<br> -<br> -<img style="width: 699px; height: 108px;" alt="" - src="images/479F301.jpg"><br> -Fig. 301. SERIES CONNECTION.<br> -<br> -<br> -<span style="font-weight: bold;">Series.</span><br> -(a) Arranged in succession as opposed to parallel. Thus if a set of<br> -battery jars are arranged with the zinc of one connected to the carbon<br> -of the next one for the entire number, it is said to be arranged in<br> -series. When incandescent lamps are arranged in succession so that the<br> -current goes through one after the other they are arranged in series.<br> -<br> -The opposite of parallel, q. v., or multiple arc, q. v.; it may be used<br> -as a noun or as an adjective.<br> -<br> -(b) See Electro-Chemical Series;<br> -<br> -(c) Thermo-Electric Series<br> -<br> -(d) Electrostatic Series;<br> -<br> -(e) Electro-motive Series.<br> -<br> -Synonym--Cascade Connection (but little used.)<br> -<br> -<br> -480 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<span style="font-weight: bold;">Series-multiple.</span><br> -Arrangement of electric apparatus, in which the parts are grouped in<br> -sets in parallel and these sets are connected in series. It is used as a<br> -noun, as "arranged in series-multiple," or as an adjective, as "a<br> -series-multiple circuit or system."<br> -<br> -<br> -<img style="width: 648px; height: 163px;" alt="" - src="images/480F302.jpg"><br> -Fig. 302. SERIES-MULTIPLE CONNECTION.<br> -<br> -<br> -<span style="font-weight: bold;">Service Conductors.</span><br> -In electric distribution the equivalents of service pipes in the<br> -distribution of gas; wires leading from the street mains to the houses,<br> -where current is to be supplied.<br> -<br> -<br> -<span style="font-weight: bold;">Serving.</span><br> -The wrapping or winding of a cable composed of small size wire, laid<br> -closely and smoothly with a tool called a serving mallet, or serving<br> -block, or by machinery. It serves to protect the cable from wear.<br> -<br> -<br> -<span style="font-weight: bold;">Shackle.</span><br> -In telegraph lines a swinging insulator bracket for use where wires make<br> -an angle with the pole. A journal box is attached to the pole, like half<br> -of a gate hinge. To this a short iron arm is pivoted so as to be free to<br> -swing through a considerable angle. At its end an insulator is carried<br> -to which the wire is attached. The shackle swings into line with the<br> -wire, or takes a position for two wires corresponding to the resultant<br> -of their directions of pull.<br> -<br> -<br> -<img style="width: 666px; height: 397px;" alt="" - src="images/480F303.jpg"><br> -Fig. 303. DOUBLE SHACKLE<br> -<br> -<br> -<span style="font-weight: bold;">Shadow. Electric.</span><br> -A term applied to a phenomenon of high vacua. If an electric discharge<br> -is maintained in a Crookes' tube the glass opposite the negative<br> -electrode tends to phosphoresce. A plate of aluminum, used also as the<br> -positive electrode, protects the glass directly behind it so as to<br> -produce the effect of a shadow.<br> -<br> -Synonym--Molecular Shadow.<br> -<br> -[Transcriber's note: The effect is due to the "shadowing" of the<br> -electrons streaming past the plate.]<br> -<br> -<br> -481 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Sheath for Magnet Coils.</span><br> -In 1867 C. E. Varley proposed the use of a copper sheath surrounding a<br> -magnet core to diminish self-induction. It has since been used by Brush<br> -and others. Sometimes metallic foil is laid between the successive coils<br> -of wire.<br> -<br> -Synonym--Mutual Induction Protector.<br> -<br> -<br> -<span style="font-weight: bold;">Sheath for Transformers.</span><br> -A protective sheath of copper, interposed between the primary and<br> -secondary circuits of an alternating current transformer. It is<br> -connected to the earth. If the primary coil loses its insulation before<br> -it can leak to the secondary it is grounded. This protects the secondary<br> -circuit from the high electro-motive force of the primary circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Shellac.</span><br> -A resin; produced as an exudation upon the branches of certain Asiatic<br> -trees, such as the banyan (Ficus religiosa). It is due to punctures in<br> -the bark of the trees in question, which punctures are made by the<br> -female of the insect coccus ficus or c. lacca.<br> -<br> -Commercial shellac contains about 90 per cent. of resinous material, the<br> -rest is made up of wax, gluten, coloring matter and other substances.<br> -<br> -Shellac is soluble in alcohol, and in aqueous solutions of ammonium<br> -chloride, of borax and in strong ammonia solution. Long standing is<br> -required in the case of the last named solvent. Dilute hydrochloric and<br> -acetic acids dissolve it readily; nitric acid slowly; strong sulphuric<br> -acid is without action on it. Alkalies dissolve it.<br> -<br> -In electric work it is used as an insulator and dielectric. Its<br> -alcoholic solution is used to varnish glass plates of influence<br> -machines, for the coils of induction coils and similar purposes.<br> -<br> -Resistance in ohms per centimeter cube at 28° C. (82.4 -F.)--(Ayrton),<br> -9.0E15<br> -<br> -Specific Inductive Capacity (Wüllner), 2.95 to 3.73<br> -<br> -The same substance in less pure forms occurs in commerce, as stick lac,<br> -lump lac, seed lac, button lac.<br> -<br> -<br> -<span style="font-weight: bold;">Shellac Varnish.</span><br> -Solution of shellac in alcohol; methylic alcohol (wood alcohol or wood<br> -naphtha) is often used as solvent.<br> -<br> -Dr. Muirhead recommends button lac, dissolved in absolute alcohol, and<br> -the top layers decanted. For highest insulation he dissolves the lac in<br> -ordinary alcohol, precipitates by dropping into water, collects the<br> -precipitate, dries and dissolves in absolute alcohol.<br> -<br> -<br> -<span style="font-weight: bold;">Shielded. adj.</span><br> -An electric measuring instrument of the galvanometer type is shielded<br> -when it is so constructed that its indications are not seriously<br> -affected by the presence of neighboring magnets or by fields of force.<br> -Shielding can be effected by using a very strong permanent magnet to<br> -produce a field within which the magnetic needle moves and which reacts<br> -upon it, or by enclosing the instrument in a thick iron box.<br> -<br> -<br> -482 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">S. H. M.</span><br> -Symbol or abbreviation for "simple harmonic motion."<br> -<br> -<br> -<span style="font-weight: bold;">Shock, Break.</span><br> -A term in electro-therapeutics; the shock received when an electric<br> -circuit, including the patient in series, is broken or opened.<br> -<br> -Synonym--Opening Shock.<br> -<br> -<br> -<span style="font-weight: bold;">Shock, Electric.</span><br> -The effect upon the animal system of the discharge through it of<br> -electricity with high potential difference. Pain, nervous shock, violent<br> -muscular contortions accompany it. Of currents, an alternating current<br> -is reputed worse than a direct current; intermediate is the pulsatory<br> -current.<br> -<br> -The voltage is the main element of shock, amperage has also some direct<br> -influence.<br> -<br> -<br> -<span style="font-weight: bold;">Shock, Static.</span><br> -A term in electro-therapeutics. The application of static discharges<br> -from small condensers or Leyden jars to a patient who is insulated from<br> -the ground with one electrode applied to the conducting surface on which<br> -he rests, while the other, a spherical electrode, is brought near the<br> -body so as to produce a disruptive or spark discharge.<br> -<br> -<br> -<span style="font-weight: bold;">Short Circuit.</span><br> -A connection between two parts of a circuit, which connection is of low<br> -resistance compared to the intercepted portion. The term is used also as<br> -a verb, as "to short circuit a lamp."<br> -<br> -<br> -<img style="width: 671px; height: 252px;" alt="" - src="images/482F304.jpg"><br> -Fig. 304. DIAGRAM ILLUSTRATING SHORT CIRCUIT WORKING.<br> -<br> -<br> -<span style="font-weight: bold;">Short Circuit Working.</span><br> -A method of working intermittently an electro-magnet so as to avoid<br> -sparking. It consists in providing a short circuit in parallel with the<br> -magnetic coils. This short circuit is of very low resistance. To throw<br> -the magnet into action the short circuit is opened; to throw it out of<br> -action the short circuit is closed. The shunt or short circuit must be<br> -of negligibly small resistance and inductance.<br> -<br> -<br> -483 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Shovel Electrodes.</span><br> -Large plate electrodes used in a medical bipolar bath. (See Bath,<br> -Bipolar.)<br> -<br> -<br> -<span style="font-weight: bold;">Shunt.</span><br> -In a current circuit a connection in parallel with a portion of the<br> -circuit. Thus in a dynamo a special winding for the field may have its<br> -ends connected to the bushes, from which the regular external circuit<br> -also starts. The field is then wound in shunt with the armature. In the<br> -case of a galvanometer a resistance coil may be put in parallel with it<br> -to prevent too much current going through the galvanometer; this<br> -connection is a shunt.<br> -<br> -The word is used as a noun, as "a shunt," or "a connection or apparatus<br> -in shunt with another," and as an adjective, as "a shunt connection," or<br> -as a verb, as "to shunt a battery."<br> -<br> -<br> -<span style="font-weight: bold;">Shunt Box.</span><br> -A resistance box designed for use as a galvanometer shunt. (See Shunt,<br> -Galvanometer.) The box contains a series of resistance coils which can<br> -be plugged in or out as required.<br> -<br> -<br> -<span style="font-weight: bold;">Shunt, Electro-magnetic.</span><br> -In telegraphy a shunt for the receiving relay consisting of the coils of<br> -an electro-magnet. It is placed in parallel with the relay. Its poles<br> -are permanently connected by an armature. Thus it has high<br> -self-induction.<br> -<br> -On opening and closing the circuit by the sending key, extra currents<br> -are produced in the shunt. The connections are so arranged that on<br> -making the circuit the extra current goes through the relay in the same<br> -direction as the principal current, while on breaking the circuit the<br> -induced current goes in the opposite direction.<br> -<br> -Thus the extra currents accelerate the production and also the cessation<br> -of signalling currents, tending to facilitate the operations of sending<br> -despatches.<br> -<br> -<br> -<span style="font-weight: bold;">Shunt, Galvanometer.</span><br> -A resistance placed in parallel with a galvanometer, so as to short<br> -circuit its coils and prevent enough current passing through it to<br> -injure it. By knowing the resistance of the shunt and of the<br> -galvanometer coils, the proportion of current affecting the galvanometer<br> -is known. This gives the requisite factor for calculation. (See<br> -Multiplying Power of Shunt.)<br> -<br> -<br> -<span style="font-weight: bold;">Shunt Ratio.</span><br> -The coefficient expressing the ratio existing between the current in a<br> -shunt and in the apparatus or conductor in parallel with it. (See<br> -Multiplying Power of/ Shunt.)<br> -<br> -<br> -<span style="font-weight: bold;">Shunt Winding.</span><br> -A dynamo or motor is shunt-wound when the field magnet winding is in<br> -shunt or in parallel with the winding of the armature.<br> -<br> -<br> -<span style="font-weight: bold;">Shuttle Current.</span><br> -A current alternating in direction; an alternating current.<br> -<br> -<br> -484 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Side-Flash.</span><br> -A bright flashing lateral discharge from a conductor conveying a current<br> -due to a static discharge.<br> -<br> -<br> -<span style="font-weight: bold;">Sighted Position.</span><br> -In an absolute electrometer (see Electrometer, Absolute) the position of<br> -the balanced arm carrying the movable disc or plate, when the disc and<br> -guard plate are in one plane. The cross-hair on the lever-end is then<br> -seen midway between two stops, or some other equivalent position is<br> -reached which is discerned by sighting through a magnifying glass or<br> -telescope.<br> -<br> -<br> -<span style="font-weight: bold;">Silver.</span><br> -A metal; one of the elements; symbol Ag.; atomic weight, 108; valency, -1;<br> -equivalent, 108; specific gravity, 10.5. It is a conductor of -electricity.<br> - <small style="font-family: monospace;">Relative resistance, -annealed, 1.0<br> - Specific Resistance, annealed, at 0° C. (32° -F.) 1.504 microhms.<br> - Resistance of a wire at 0° C. (32° F.), -Annealed. Hard Drawn.<br> - (a) 1 foot long, weighing 1 grain, -.2190 ohms .2389 ohms.<br> - (b) 1 foot long, 1/1000 inch thick, -9.048 " 9.826 "<br> - (c) 1 meter long, weighing 1 gram, -.1527 " .1662 "<br> - (d) 1 meter long, 1 millimeter thick, .01916 -" .02080 "</small><br - style="font-family: monospace;"> -<br style="font-family: monospace;"> -<span style="font-family: monospace;"> <small>Resistance -annealed of a 1-inch cube, at 0° C. (32°F.) -.5921 microhms.</small></span><small><br style="font-family: monospace;"> -<br style="font-family: monospace;"> -<span style="font-family: monospace;"> Percentage increase in -resistance per degree C.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> (1.8 F.) at about 20° -C. (68° F.), annealed, -0.377 per cent.</span><br style="font-family: monospace;"> -<br style="font-family: monospace;"> -<span style="font-family: monospace;"> Electro-chemical -equivalent, (Hydrogen = .0105) -.1134 mgs.</span></small> -<br style="font-family: monospace;"> -<br> -<br> -<span style="font-weight: bold;">Silver Bath.</span><br> -A solution of a salt of silver for deposition in the electroplating<br> -process.<br> -<br> -The following is a typical formula:<br> -<span style="font-family: monospace;"> -<small>Water, -10.0 parts by weight.</small></span><small><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Potassium -Cyanide, -5 -" "</span><br - style="font-family: monospace;"> -</small><span style="font-family: monospace;"><small> Metallic -Silver, -2.5 "</small> -"</span><br> -<br> -The silver is first dissolved as nitrate and converted into cyanide and<br> -added in that form, or for 2.5 parts metallic silver we may read:<br> - Silver cyanide, 3 parts by weight.<br> -<br> -While many other formulas have been published the above is<br> -representative of the majority. Other solvents for the silver than<br> -potassium cyanide have been suggested, such as sodium hyposulphite, but<br> -the cyanide solution remains the standard.<br> -<br> -<br> -<span style="font-weight: bold;">Silver Stripping Bath.</span><br> -Various baths are used to remove silver from old electroplated articles.<br> -Their composition depends upon the base on which the metal is deposited.<br> -Silvered iron articles are placed as anodes in a solution of 1 part<br> -potassium cyanide in 20 parts of water. As kathode a silver anode or a<br> -copper one lightly oiled may be used. From the latter the silver easily<br> -rubs off. For copper articles a mixture of fuming sulphuric acid and<br> -nitric acid (40º Beaumé) may be used. The presence of any -water in this<br> -mixture will bring about the solution of the copper. Or fuming sulphuric<br> -acid may be heated to between 300º and 400º F., some pinches -of dry<br> -pulverized potassium nitrate may be thrown in and the articles at once<br> -dipped. These methods effect the solution of the silver, leaving the<br> -copper unattacked.<br> -<br> -<br> -485 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Simple Substitution.</span><br> -A method of obtaining a resistance equal to that of a standard. The<br> -standard is put in circuit with a galvanometer and the deflection is<br> -noted. For the standard another wire is substituted and its length<br> -altered until the same deflection is produced. The two resistances are<br> -then evidently identical. The standard can be again substituted to<br> -confirm the result.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Sine Curve.</span><br> -If we imagine a point moved back and forth synchronously with a<br> -pendulum, and if such point made a mark upon paper, it would trace the<br> -same line over and over again. If now the paper were drawn steadily<br> -along at right angles to the line of motion of the point, then the point<br> -would trace upon it a line like the profile of a wave. Such line is a<br> -sine curve. It derives its name from the following construction. Let a<br> -straight line be drawn, and laid off in fractions, such as degrees, of<br> -the perimeter of a circle of given diameter. Then on each division of<br> -the line let a perpendicular be erected equal in height to the sine of<br> -the angle of the circle corresponding to that division; then if the<br> -extremities of such lines be united by a curve such curve will be a sine<br> -curve.<br> -<br> -In such a curve the abscissas are proportional to the times, while the<br> -ordinates are proportional to the sines of angles, which angles are<br> -themselves proportional to the times. The ordinates pass through<br> -positive and negative values alternately, while the abscissas are always<br> -positive.<br> -<br> -Any number of sine curves can be constructed by varying the diameter of<br> -the original circle, or by giving to the abscissas a value which is a<br> -multiple of the true length of the divisions of circle. If the pendulum<br> -method of construction were used this would be attained by giving a<br> -greater or less velocity to the paper as drawn under the pendulum.<br> -<br> -A species of equation for the curve is given as follows: y = sin( x )<br> -<br> -In this x really indicates the arc whose length is x, and reference<br> -should be made to the value of the radius of the circle from which the<br> -curve is described. It will also be noticed that the equation only<br> -covers the case in which the true divisions of the circle are laid off<br> -on the line. If a multiple of such divisions are used, say n times, or<br> -1-n times, then the equation should read <br> -y = n sin( x ) or y = sin( x ) / n<br> -<br> -Synonyms--Curve of Sines--Sinusoidal Curve--Harmonic Curve.<br> -<br> -<br> -486 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Sine Law.</span><br> -The force acting on a body is directly proportional to the sine of the<br> -angle of deflection when--<br> -<br> -I. The controlling force is constant in magnitude and direction; and<br> -<br> -II. The deflecting force, although variable in its direction in space,<br> -is fixed in direction relatively to the deflecting body.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Single Fluid Theory.</span><br> -A theory of electricity. Electricity, as has been said, being<br> -conveniently treated as a fluid or fluids, the single fluid theory<br> -attributes electrical phenomena to the presence or absence of a single<br> -fluid. The fluid repels itself but attracts matter; an excess creates<br> -positive, a deficiency, negative electrification; friction, contact<br> -action or other generating cause altering the distribution creates<br> -potential difference or electrification. The assumed direction (see<br> -Direction) of the current and of lines of force are based on the single<br> -fluid theory. Like the double fluid theory, q. v., it is merely a<br> -convenience and not the expression of a truth. (See Fluid, Electric, and<br> -Double Fluid Theory.)<br> -<br> -Synonym--Franklin's Theory.<br> -<br> -<br> -<span style="font-weight: bold;">Single Fluid Voltaic Cell.</span><br> -A galvanic couple using only a single fluid, such as the Smee or Volta<br> -cell.<br> -<br> -<br> -<span style="font-weight: bold;">Simple Harmonic Motion.</span><br> -Motion of a point or body back and forth along a line; the motion of a<br> -pendulum, as regards its successive swings back and forth, is an example<br> -of harmonic motion.<br> -<br> -<br> -<span style="font-weight: bold;">Sinistrotorsal. adj.</span><br> -The reverse of dextrotorsal, q. v. A helix with left-handed winding, the<br> -reverse of an ordinary screw, such as a wood-screw or corkscrew.<br> -<br> -<br> -<span style="font-weight: bold;">Skin Effect.</span><br> -A current of very brief duration does not penetrate the mass of a<br> -conductor. Alternating currents for this reason are mainly conducted by<br> -the outer layers of a conductor. The above is sometimes called the skin<br> -effect.<br> -<br> -<br> -<span style="font-weight: bold;">Sled.</span><br> -A contact for electric cars of the conduit system. It is identical with<br> -the plow, q.v., but is drawn after the cars instead of being pushed<br> -along with them.<br> -<br> -<br> -<span style="font-weight: bold;">Slide Meter Bridge.</span><br> -A name for a Slide Bridge one meter long. There are also slide half<br> -meter and slide quarter meter bridges and others. (See Meter Bridge.)<br> -<br> -<br> -<span style="font-weight: bold;">S. N. Code.</span><br> -Abbreviation for single needle code, the telegraphic alphabet used with<br> -the single needle system.<br> -<br> -<br> -<span style="font-weight: bold;">Soaking-in-and-out.</span><br> -A term for the phenomena of the residual electrostatic charge; the<br> -gradual acquirement or loss by a condenser of a portion of its<br> -electrostatic charge.<br> -<br> -<br> -487 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Soldering, Electric.</span><br> -(a) Soldering in which the solder is melted by means of electricity;<br> -either current incandescence or the voltaic arc may be used. It is<br> -identical in general with electric welding. (See Welding, Electric.)<br> -<br> -(b) The deposition by electric plating of a metal over the ends of two<br> -conductors held in contact. This secures them as if by soldering. It is<br> -used in connecting the carbon filament of an incandescent lamp with the<br> -platinum wires that pass through the glass. Copper is the metal usually<br> -deposited.<br> -<br> -<br> -<span style="font-weight: bold;">Solenoid.</span><br> -The ideal solenoid is a system of circular currents of uniform<br> -direction, equal, parallel, of equal diameter of circle, and with their<br> -centers lying on the same straight line, which line is perpendicular to<br> -their planes.<br> -<br> -<br> -<img style="width: 608px; height: 311px;" alt="" - src="images/487F305.jpg"><br> -Fig. 305. EXPERIMENTAL SOLENOID.<br> -<br> -<br> -The simple solenoid as constructed of wire, is a helical coil, of<br> -uniform diameter, so as to represent a cylinder. After completing the<br> -coil one end of the wire is bent back and carried through the centre of<br> -the coil, bringing thus both ends out at the same end. The object of<br> -doing this is to cause this straight return member to neutralize the<br> -longitudinal component of the helical turns. This it does approximately<br> -so as to cause the solenoid for its practical action to correspond with<br> -the ideal solenoid.<br> -<br> -Instead of carrying one end of the wire through the centre of the coil<br> -as just described, both ends may be bent back and brought together at<br> -the centre.<br> -<br> -A solenoid should always have this neutralization of the longitudinal<br> -component of the helices provided for; otherwise it is not a true<br> -solenoid.<br> -<br> -Solenoids are used in experiments to represent magnets and to study and<br> -illustrate their laws. When a current goes through them they acquire<br> -polarity, attract iron, develop lines of force and act in general like<br> -magnets.<br> -<br> -A solenoid is also defined as a coil of insulated wire whose length is<br> -not small as compared with its diameter.<br> -<br> -<br> -488 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Sonometer, Hughes'.</span><br> -A sound measurer; a modification of a portion of Hughes' induction<br> -balance, used for testing the delicacy of the ear or for determining the<br> -relative intensity of sounds. (See Hughes' Induction Balance.) It is the<br> -arrangement of three coils, two mounted one at each of the ends of a<br> -graduated bar, and the third one between them and free to slide back and<br> -forth thereon.<br> -<br> -<br> -<span style="font-weight: bold;">Sonorescence.</span><br> -The property of producing sounds under the influence of momentary light<br> -radiations rapidly succeeding each other. It is the property utilized in<br> -the photophone, q. v.<br> -<br> -<br> -<img style="width: 629px; height: 458px;" alt="" - src="images/488F306.jpg"><br> -Fig. 306. MORSE SOUNDER.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Sounder.</span><br> -In telegraphy an instrument consisting of an electromagnet with armature<br> -attached to an oscillating bar, the range of whose movements is<br> -restricted by adjusting screws. The armature is drawn away from the<br> -magnet by a spring. When a current is sent through the magnet the<br> -armature is drawn towards the poles and produces a sound as the bar<br> -strikes a striking piece or second adjusting screw. When the current<br> -ceases the bar and armature are drawn back, striking the first mentioned<br> -screw with a distinct sound, the back stroke.<br> -<br> -The sounder is used to receive Morse and analogous character messages.<br> -The forward strokes correspond to the beginnings of the dots or dashes<br> -of the code, the back strokes to beginnings of the intervals. The<br> -distinction between dots and dashes is made by observing the interval<br> -between forward and back stroke.<br> -<br> -Various devices are used to increase the sound. Sometimes a resonance<br> -box is used on which the sounder is mounted.<br> -<br> -In practice sounders are generally placed on local circuits and are<br> -actuated by relays.<br> -<br> -<br> -489 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Sound Reading.</span><br> -The art or method of receiving telegraph messages by ear. It is now<br> -universally used by all expert Morse operators. It can only be applied<br> -to telegraph systems producing audible sounds; in some cases, as in<br> -needle telegraphy, it may be quite inapplicable.<br> -<br> -<br> -<span style="font-weight: bold;">Space, Clearance.</span><br> -The space between faces of the pole pieces and the surface of the<br> -armature in a dynamo. It is really the air gap, but in calculating<br> -dynamo dimensions the thickness of the insulated copper wire windings of<br> -the commutator are counted in as part of the air gap, because copper is<br> -almost the same as air in impermeability. Clearance space is a<br> -mechanical factor; the air gap is an electric or magnetic factor.<br> -<br> -Synonym--Inter-air Space.<br> -<br> -<br> -<span style="font-weight: bold;">Space, Crookes' Dark.</span><br> -In an exhausted tube, through which an electric discharge is caused to<br> -pass, the space surrounding the negative electrode of the tube. This<br> -space is free from any luminous effect, and by contrast with the light<br> -of the discharge appears dark. The vacuum may be made so high that the<br> -dark space fills the whole space between the electrodes. It is less for<br> -a less vacuum and varies for other factors, such as the temperature of<br> -the negative electrode from which it originates, the kind of residual<br> -gas present, and the quality of the spark.<br> -<br> -<br> -<span style="font-weight: bold;">Space, Faraday's Dark.</span><br> -The space in an exhausted tube between the luminous glows about the two<br> -electrodes.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Space, Interferric.</span><br> -A term for the air-gap in a magnetic circuit. It is etymologically more<br> -correct than air-gap, for the latter is often two-thirds or more filled<br> -with the insulating material and copper wire of the armature windings.<br> -(See Space, Clearance.)<br> -<br> -<br> -<span style="font-weight: bold;">Spark Arrester.</span><br> -A screen of wire netting fitting around the carbons of an arc lamp above<br> -the globe to prevent the escape of sparks from the carbons.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Spark Coil.</span><br> -A coil for producing a spark from a source of comparatively low<br> -electro-motive force. It consists of insulated wire wound round a core<br> -of soft iron, best a bundle of short pieces of wire. Such a coil may be<br> -eight inches long and three inches thick, and made of No. 18-20 copper<br> -wire, with a core one inch in diameter. On connecting a battery<br> -therewith and opening or closing the circuit, a spark is produced by<br> -self-induction, q. v. It is used for lighting gas.<br> -<br> -<br> -490 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Spark, Duration of Electric.</span><br> -Wheatstone determined the duration of the spark given by a Leyden jar as<br> -1/24000 second. Feddersen by interposing a tube of water 9 millimeters<br> -(.36 inch) long in its path found that it lasted 14/10000 second, and<br> -with one 180 millimeters (7.2 inches) long, 188/10000 second. Lucas and<br> -Cazin for a 5 millimeter (.2 inch) spark, with different numbers of<br> -Leyden jars, found the following:<br> -<small><span style="font-family: monospace;">Number of -jars. Duration of Spark.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -2 .000026 -second</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -4 .000041 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -6 .000045 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -8 .000047 "</span></small><br> -<br> -The duration increases with the striking distance, and is independent of<br> -the diameter of the balls between which it is produced.<br> -<br> -<br> -<span style="font-weight: bold;">Spark Gap.</span><br> -The space left between the ends of an electric resonator (see Resonator,<br> -Electric) across which the spark springs. Its size may be adjustable by<br> -a screw, something like the arrangement of screw calipers.<br> -<br> -<br> -<span style="font-weight: bold;">Sparking.</span><br> -In dynamo-electric machines, the production of sparks at the commutator<br> -between the brushes and commutator sections. The sparks are often true<br> -voltaic arcs, and in all cases are injurious if in any quantity, wearing<br> -out the commutator and brushes.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Sparking, Line or Points of Least.</span><br> -In a dynamo or electric motor the diameter of the commutator<br> -determining, or the points on the commutator marking the position of the<br> -brushes where the sparking is a minimum. Field magnets powerful in<br> -proportion to the armature are a preventative cause. The direction of<br> -the line fixes the angle of lead to be given to the brushes.<br> -<br> -<br> -<span style="font-weight: bold;">Sparking, Resistance to.</span><br> -The resistance to disruptive discharge through its substance offered by<br> -a dielectric or insulator. It does not depend on its insulating<br> -qualities, but on its rigidity and strength.<br> -<br> -<br> -<span style="font-weight: bold;">Spark, Length of.</span><br> -The length of the spark accompanying the disruptive discharge is counted<br> -as the distance from one electrode to the other in a straight line. It<br> -is longer for an increased potential difference between the two<br> -electrodes. If the gas or air between the electrodes is exhausted the<br> -length increases, until the vacuum becomes too high, when the length<br> -begins to decrease, and for a perfect vacuum no spark however small can<br> -be produced. The shape of the conductor which is discharged, the<br> -material of the electrodes, and the direction of the current are all<br> -factors affecting the length of spark producible.<br> -<br> -<br> -491 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Spark Tube.</span><br> -A tube used as a gauge or test to determine when the exhaustion of the<br> -vacuum chamber or bulb of an incandescent lamp is sufficiently high.<br> -<br> -The interior of the tube is connected with the interior of the bulb or<br> -chamber of the lamps in process of exhaustion, and hence shares their<br> -degree of exhaustion. From time to time connections with an induction<br> -coil are made. When the exhaustion is carried far enough no discharge<br> -will take place through the vacuum. As long as the tube acts like a<br> -Geissler tube the exhaustion is not considered perfect.<br> -<br> -<br> -<span style="font-weight: bold;">Specific Heat of Electricity.</span><br> -The heat absorbed or given out by a fluid in passing from one<br> -temperature to another depends on its specific heat. In the Peltier and<br> -the Thomson effects. q. v., the electric current acts as the producer of<br> -a change of temperature, either an increase or decrease as the case may<br> -be. This suggests an absorption of and giving out of heat which amount<br> -of heat corresponding to a current of known amount is determinable, and<br> -may be referred to any unit of quantity such as the coulomb. This or<br> -some equivalent definite quantity of heat it has been proposed (Sir<br> -William Thomson) to term the Specific Heat of Electricity.<br> -<br> -<br> -<span style="font-weight: bold;">Spent Acid.</span><br> -Acid which has become exhausted. In a battery the acid becomes spent<br> -from combination with zinc. It also loses its depolarizing power, if it<br> -is a chromic acid solution or of that type, and then may be said to be<br> -spent.<br> -<br> -<br> -<span style="font-weight: bold;">Spent Liquor.</span><br> -The liquor of a plating bath which has become exhausted from use, the<br> -metal it contained being all or partly deposited.<br> -<br> -<br> -<span style="font-weight: bold;">Sphygmograph, Electric.</span><br> -An electric apparatus for recording the beat of the pulse, both as<br> -regards its rate and strength.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Sphygmophone.</span><br> -An apparatus for examination of the pulse by the microphone and<br> -telephone.<br> -<br> -<br> -<span style="font-weight: bold;">Spiders.</span><br> -Core-discs of a dynamo or motor armature are sometimes perforated with a<br> -large central aperture, are fastened together with insulated bolts, and<br> -the whole mass is secured to the shaft by three- or four-armed spiders.<br> -These are like rimless wheels, the ends of their arms being secured to<br> -the hollow cylinder constituting the armature core, and a central<br> -aperture in their hub receiving the shaft.<br> -<br> -<br> -492 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Spiral.</span><br> -This term is sometimes used instead of coil, as the primary spiral or<br> -secondary spiral of an induction coil or transformer.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Spiral Winding.</span><br> -The winding used on ring armatures. This may diagrammatically be<br> -represented by a spiral carried around the ring shaped core. With two<br> -field poles it gives two collecting points, positive and negative, with<br> -four field poles it gives four collecting points, alternately positive<br> -and negative.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Splice Box.</span><br> -A box in which the splices in underground cables and electric lines are<br> -contained. The splicing is generally done in the boxes with the cables<br> -in place. They may be two-way for straight lines, or be four-way for two<br> -side or lateral connections.<br> -<br> -<br> -<span style="font-weight: bold;">Spluttering.</span><br> -A term applied to a sound sometimes produced in a voltaic arc, perhaps<br> -caused by impure or insufficiently baked electrodes. (Elihu Thomson.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Spring Control.</span><br> -Control of or giving the restitutive force to the needle of a<br> -galvanometer, core of a solenoid ammeter or moving part of any similar<br> -instrument by a spring. As an example see Ammeter, Ayrton's.<br> -<br> -<br> -<img style="width: 604px; height: 358px;" alt="" - src="images/492F307.jpg"><br> -Fig. 307. SPRING JACKS.<br> -<br> -<br> -<span style="font-weight: bold;">Spring Jack.</span><br> -An arrangement for effecting, at one insertion of a species of plug, the<br> -opening or breaking of a circuit and for the simultaneous connection to<br> -the terminals formed by the breaking of two terminals of another system<br> -or loop. Thus let a line include in its circuit two springs pressing<br> -against each other, thereby completing the circuit. If a plug or wedge<br> -of insulating material were inserted between the springs so as to press<br> -them apart it would break the circuit and the whole would constitute a<br> -spring jack cut-out. If each side of the plug had a strip of brass or<br> -copper attached to it, and if the ends of another circuit were connected<br> -to these strips, then the insertion of the plug would throw the new line<br> -into the circuit of the other line.<br> -<br> -<br> -493 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Spring Jack Cut-out.</span><br> -A cut-out, of the general construction of a spring jack, q. v., except<br> -that a simple insulating plug or wedge is used in place of the<br> -metal-faced wedge with its connections of the regular spring jack. The<br> -insertion of an insulating wedge opens the circuit, which on its removal<br> -is closed. The regular spring jack wedge will operate in the same way,<br> -if its connections are kept open.<br> -<br> -<br> -<span style="font-weight: bold;">Spurious Voltage.</span><br> -The voltage in excess of that developed by a secondary battery which is<br> -required in the charging process. It is about .25 volt.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Square Wire.</span><br> -Wire whose cross-section is a square. It has been used of iron for<br> -building up the cores of armatures for dynamos or motors, for which it<br> -is peculiarly suitable, and also of copper as a winding for armatures.<br> -<br> -<br> -<span style="font-weight: bold;">Staggering. adj.</span><br> -When the brushes of a dynamo are set, one a little in advance of the<br> -other on the surface of the commutator, they are said to be set<br> -staggering. It is used to get over a break in the armature circuit.<br> -<br> -<br> -<span style="font-weight: bold;">State, Electrotonic.</span><br> -A term expressing an abandoned theory. Faraday at one time proposed the<br> -theory that a wire had to be in the electrotonic state to produce<br> -electro-motive force by movement through an electric field. Any such<br> -idea was ultimately abandoned by Faraday.<br> -<br> -<br> -<span style="font-weight: bold;">Static Breeze.</span><br> -The electric breeze obtained by the silent discharge of high tension<br> -electricity.<br> -<br> -<br> -<span style="font-weight: bold;">Static Electricity.</span><br> -Electricity at rest or not in the current form ordinarily speaking. The<br> -term is not very definite and at any rate only expresses a difference in<br> -degree, not in kind. The recognition of the difference in degree has now<br> -to a great extent also disappeared.<br> -<br> -<br> -<span style="font-weight: bold;">Station, Central.</span><br> -The building or place in which are placed electrical apparatus, steam<br> -engines and plant supplying a district with electric energy.<br> -<br> -<br> -<span style="font-weight: bold;">Station, Distant.</span><br> -The place at the further end of a telegraph line, as referred to the<br> -home station.<br> -<br> -<br> -<span style="font-weight: bold;">Station, Home.</span><br> -The end of a telegraph line where the operators using the expression are<br> -working.<br> -<br> -<br> -494 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Station, Transforming.</span><br> -In alternating current distribution, a building or place where a number<br> -of transformers are worked, so that low potential or secondary circuits<br> -are distributed therefrom.<br> -<br> -<br> -<span style="font-weight: bold;">Steel.</span><br> -A compound of iron with carbon. The carbon may range from a few<br> -hundredths of one per cent. up to two per cent. For magnets, tool steel<br> -drawn to a straw color or a little lower is good. All shaping and filing<br> -should be done before magnetization.<br> -<br> -<br> -<span style="font-weight: bold;">Steeling.</span><br> -The deposition of iron on copper plates by electrolysis. In<br> -electrotyping a thin deposit of iron is thus given the relief plates<br> -before printing from them. The deposit is very hard and exceedingly<br> -thin, so that it does not interfere with the perfection of the<br> -impression in the printing process. As the iron becomes worn it can be<br> -dissolved off with hydrochloric acid, which does not dissolve the<br> -copper, and a new deposit can be given it. Thus the plate may last for<br> -an indefinite number of impressions.<br> -<br> -The iron bath may be prepared by immersing in a solution of ammonium<br> -chloride, two plates of iron, connected as anode and kathode in a<br> -circuit. One plate dissolves while hydrogen is given off from the other.<br> -The solution thus produced is used for a bath.<br> -<br> -The hardness of the deposit, which is really pure iron, gives the name<br> -of "steeling."<br> -<br> -Synonym--Acierage.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">St. Elmo's Fire.</span><br> -Luminous static discharge effects sometimes seen on objects elevated in<br> -the air. They are especially noticed on ships' masts. The sailors term<br> -them corpusants (holy bodies). They resemble tongues or globes of fire.<br> -<br> -<br> -<span style="font-weight: bold;">Step-by-step Telegraphy.</span><br> -A system of telegraphy in which in the receiving instrument a hand is<br> -made to move step-by-step, with an escape movement around a dial. For<br> -each step there is a letter and the hand is made to stop at one or the<br> -other letter until the message is spelled out. (See Dial Telegraph.)<br> -<br> -<br> -<span style="font-weight: bold;">Step-down. adj.</span><br> -A qualification applied to a converter or transformer in the alternating<br> -current distribution, indicating that it lowers potential difference and<br> -increases current from the secondary.<br> -<br> -<br> -<span style="font-weight: bold;">Step-up. adj.</span><br> -The reverse of step-down; a qualification of a transformer or converter<br> -indicating that it raises the potential and decreases the current in the<br> -secondary.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Sticking.</span><br> -The adherence, after the current is cut off, of the armature to the<br> -poles of a magnet. In telegraphy it is a cause of annoyance and<br> -obstructs the working. It may, in telegraphy, be due to too weak a<br> -spring for drawing back the armature, or to imperfect breaking of the<br> -contact by the despatcher's key or by the receiver's relay.<br> -<br> -<br> -495 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Stopping Off.</span><br> -In electroplating the prevention of deposition of the plating metal on<br> -any desired portions of the object. It is effected by varnishing the<br> -places where no coating is desired. An article can be plated with<br> -silver, stopped off in any desired design, and the unvarnished portions<br> -may then be plated with gold in another bath. Various effects can be<br> -produced by such means.<br> -<br> -<br> -<span style="font-weight: bold;">Storage Capacity.</span><br> -A term for the ampere-hours of electricity, which can be taken in<br> -current form from a storage battery.<br> -<br> -<br> -<span style="font-weight: bold;">Storage of Electricity.</span><br> -Properly speaking electricity can only be stored statically or in static<br> -condensers, such as Leyden jars. The term has been popularly applied to<br> -the charging of secondary or storage batteries, in which there is really<br> -no such thing as a storage of electricity, but only a decomposition and<br> -opposite combination brought about, which leave the battery in a<br> -condition to give a current.<br> -<br> -<br> -<span style="font-weight: bold;">Storms, Electric.</span><br> -Wide-spread magnetic and electric disturbances, involving the<br> -disturbance of the magnetic elements and other similar phenomena. (See<br> -Magnetic Storms.)<br> -<br> -<br> -<span style="font-weight: bold;">Strain.</span><br> -The condition of a body when subjected to a stress. Various consequences<br> -may ensue from strain in the way of disturbance of electric and other<br> -qualities of the body strained.<br> -<br> -<br> -<span style="font-weight: bold;">Stratification Tube.</span><br> -A Geissler tube, q. v., for showing the stratification of the electric<br> -discharge through a high vacuum.<br> -<br> -The stratifications are greatly intensified by the presence of a little<br> -vapor of turpentine, alcohol, bisulphide of carbon and other substances.<br> -<br> -<br> -<span style="font-weight: bold;">Stray Field.</span><br> -In a dynamo or motor the portion of the field whose lines of force are<br> -not cut by the armature windings.<br> -<br> -<br> -<span style="font-weight: bold;">Stray Power.</span><br> -The proportion of the energy wasted in driving a dynamo, lost through<br> -friction and other hurtful resistances.<br> -<br> -<br> -<span style="font-weight: bold;">Streamlets, Current.</span><br> -A conception bearing the same relation to an electric current that lines<br> -of force do to a field of force; elementary currents. If evenly<br> -distributed the current is of uniform density; if unevenly distributed,<br> -as in alternating currents, the current density varies in different<br> -parts of the cross section of the conductor. This evenness or unevenness<br> -may be referred to the number of streamlets per unit of area of<br> -cross-section.<br> -<br> -[Transcriber's note: Streamlets per unit of area is redundant with<br> -current density.]<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Stress.</span><br> -Force exercised upon a solid tending to distort it, or to produce a<br> -strain.<br> -<br> -<br> -496 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Stress, Dielectric.</span><br> -The condition of a dielectric when maintaining a charge; its two<br> -extremities are in opposite states of polarity, or are under permanent<br> -potential difference. As the two opposite polarities tend to unite a<br> -condition of stress is implied in the medium which separates them.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Stress, Electro-magnetic.</span><br> -The stress produced upon transparent substances in an electro-magnetic<br> -field of force. It is shown in the modified optical properties of glass<br> -and similar substances placed between the poles of a strong<br> -electro-magnet.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Stress, Electrostatic.</span><br> -The stress produced upon substances in an electrostatic field of force;<br> -the exact analogue of electro-magnetic stress, and affecting transparent<br> -substances in the same general way.<br> -<br> -<br> -<span style="font-weight: bold;">Striae, Electric.</span><br> -In Geissler tubes the light produced by the electric discharge is filled<br> -with striae, bright bands alternating with dark spaces; these may be<br> -termed electric striae.<br> -<br> -<br> -<span style="font-weight: bold;">Striking Distance.</span><br> -The distance that separates two conductors charged with electricity of<br> -different potential, when a spark starts between them.<br> -<br> -<br> -<span style="font-weight: bold;">Striking Solution.</span><br> -In silver-plating a bath composed of a weak solution of silver<br> -cyanide-with a large proportion of free potassium cyanide. It is used<br> -with a strong current and a large silver anode. This gives an<br> -instantaneous deposition of metallic silver over the surface of the<br> -article which goes to insure a perfect coating in the silver bath<br> -proper. After a few seconds in the striking solution, the article is at<br> -once removed to the plating bath.<br> -<br> -<br> -<span style="font-weight: bold;">Stripping.</span><br> -The removal of electroplating from an object. It may be effected in<br> -several ways. An object whose plating is to be removed is placed in a<br> -plating bath of the solution of the metal with which it is coated. It is<br> -connected as the anode to the positive plate of the battery or<br> -corresponding terminal of the generator. A kathode connected to the<br> -other terminal being placed in the bath, the coating is dissolved by<br> -electrolytic action. Sometimes simple treatment with acid is employed.<br> -Different stripping baths are described under the heads of the different<br> -metals.<br> -<br> -<br> -<span style="font-weight: bold;">S. U.</span><br> -Symbol or abbreviation for Siemens' Unit of Resistance. (See Resistance,<br> -Siemens' Unit of.)<br> -<br> -<br> -<span style="font-weight: bold;">Sub-branch.</span><br> -A branch or lead of wire taken from a branch lead: a term used in<br> -electric distribution.<br> -<br> -<br> -<span style="font-weight: bold;">Sub-main.</span><br> -In electric distribution a conductor connected directly to a main; a<br> -branch.<br> -<br> -<br> -497 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Subway, Electric.</span><br> -A subterranean system of conduits for electric cables. As generally<br> -constructed in this country it includes manholes, q. v., at the street<br> -corners connected by ducts or pipes. These pipes are large enough to<br> -hold a cable. To introduce a cable into a duct, which latter may be two<br> -or three inches in diameter, and from two hundred to six or seven<br> -hundred feet long, a wire or rope is first passed through the duct. This<br> -is done by a set of short wooden rods with screws at the end so as to be<br> -screwed together. Each rod must be shorter than the diameter of the<br> -manhole. A rod is thrust in, another is screwed to it and thrust in, and<br> -thus a set of rods is made to extend as far as desired. In pulling them<br> -out a rope is attached and drawn through. This rope or a larger one is<br> -used in drawing the cable through the duct. A windlass is employed to<br> -draw the rope with cable attached through the ducts.<br> -<br> -<br> -<span style="font-weight: bold;">Sulphating.</span><br> -In storage battery cells, the formation of a hard white basic lead<br> -sulphate, Pb2 S05. Its formation is due to over-exhaustion of the cells.<br> -As long as the voltage is not allowed to fall below 1.90 volts per cell<br> -little of it forms. As it accumulates it is apt to drop off the plate<br> -and fall to the bottom, thus weakening the plate possibly, and depriving<br> -it of active material, and clogging up the cell. If it carries a film of<br> -metallic lead with it, there is danger of short circuiting the cell.<br> -<br> -The presence of some sodium sulphate in the solution is said to tend to<br> -prevent sulphating, or to diminish it.<br> -<br> -Sulphur Dioxide.<br> -A compound gas, S O2; composed of<br> -<small style="font-family: monospace;"><span - style="font-family: monospace;"> </span> -Sulphur, -32<br> - -Oxygen, -32<br> - Molecular weight, 64<br> - Specific gravity, 2.21.</small><br> -<br> -It is a dielectric of about the same resistance as air. Its specific<br> -inductive capacity at atmospheric pressure is: 1.0037 (Ayrton).<br> -<br> -Synonyms--Sulphurous Acid--Sulphurous Acid Gas.<br> -<br> -<br> -<span style="font-weight: bold;">Sunstroke, Electric.</span><br> -Exposure to the arc light sometimes produces the effects observed in<br> -cases of sunstroke. It is said that, in the case of workmen at electric<br> -furnaces, these effects are very noticeable. (See Prostration,<br> -Electric.)<br> -<br> -[Transcriber's note: Effects are due to ultraviolet light.]<br> -<br> -<br> -<span style="font-weight: bold;">Supersaturated. adj.</span><br> -A liquid is supersaturated when it has dissolved a substance at a<br> -temperature favorable to its solubility and its temperature has been<br> -allowed to change, the liquid being kept free from agitation or access<br> -of air, provided crystallization or precipitation has not taken place.<br> -It expresses the state of a liquid when it holds in solution more than<br> -the normal quantity of any substance soluble in it.<br> -<br> -<br> -<span style="font-weight: bold;">Surface.</span><br> -A galvanic battery is arranged in surface when all the positive plates<br> -are connected together and all the negative plates are also connected.<br> -This makes it equivalent to one large cell, the surface of whose plates<br> -would be equal to the aggregate surface of the plates of the battery. It<br> -is also used as an adjective, as "a surface arrangement of battery."<br> -<br> -<br> -498 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Surface Density.</span><br> -The relative quantity of an electric charge upon a surface.<br> -<br> -<br> -<span style="font-weight: bold;">Surface, Equipotential.</span><br> -A surface over all of which the potential is the same. In a general<br> -sense equipotential surfaces are given by planes or surfaces which cut<br> -lines of force at right angles thereto, or which are normal to lines of<br> -force. The conception applies to electrostatic and electro-magnetic<br> -fields of force, and for current conductors the planes normal to the<br> -direction of the current are equipotential surfaces.<br> -<br> -The contour of an equipotential surface of a field of force which is<br> -drawn or represented by delineations of its lines of force can be<br> -obtained by drawing a line normal thereto. This line will ordinarily be<br> -more or less curved, and will be a locus of identical potentials.<br> -<br> -An electric equipotential surface may be described as electro-static,<br> -electro- magnetic, or magnetic; or may be an equipotential surface of a<br> -current conductor. Besides these there are mechanical and physical<br> -equipotential surfaces, such as those of gravitation.<br> -<br> -<br> -<span style="font-weight: bold;">Surface Leakage.</span><br> -Leakage of current from one part of an insulating material to another by<br> -the film of moisture or dirt on the surface.<br> -<br> -<br> -<span style="font-weight: bold;">Suspension.</span><br> -This term is applied to methods of supporting galvanometer needles,<br> -balance beams, magnetic compass needles and similar objects which must<br> -be free to rotate. (See Suspension, Bifilar--Fibre and Spring<br> -Suspension--Fibre Suspension--Knife Edge Suspension--Pivot<br> -Suspension--Suspension, Torsion.)<br> -<br> -<br> -<img style="width: 284px; height: 631px;" alt="" - src="images/498F308.jpg"><br> -Fig. 308. DIAGRAM OF BIFILAR SUSPENSION.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Suspension, Bifilar.</span><br> -Suspension by two vertical parallel fibres, as of a galvanometer needle.<br> -The restitution force is gravity, the torsion being comparatively slight<br> -and negligible. Leaving torsion out of account the restitution force is<br> -(a) proportional to the distance between the threads;. (b) inversely<br> -proportional to their length; (c) proportional to weight of the needle<br> -or other object suspended; (d) proportional to the angle of<br> -displacement.<br> -<br> -<br> -499 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Assume two masses A and B at the end of a weightless rod, suspended by<br> -the parallel cords a A, b B. Let the rod be rotated through an angle<br> -theta. Consider the cord a A. Its lower end is swung through the angle<br> -theta, as referred to the center O; the cord is deflected from the<br> -vertical by an angle psi, such that a A tang(psi)= O A 2 sin (theta/2).<br> -The component of gravitation tending to restore A to A, acting towards A<br> -is equal to m g tan(psi). Its moment around O is equal to (m g tan(psi))<br> -* (O A cos(theta/2). The whole moment of the couple is 2 m g -tan(psi).<br> -0 A. cos(theta/2) = 2 m g (O A2/ a A) 2 sin(theta/2). Cos(theta/2) =<br> -2mgl(OA2/aA) sin(theta). The moment of the restoring force is thus<br> -proportional to the sine of the angle of deflection, and the<br> -oscillations of such a system are approximately simple harmonic.<br> -(Daniell.)<br> -<br> -If the twisting is carried so far as to cause the threads to cross and<br> -come in contact with each other the suspension ceases to be a bifilar<br> -suspension, but assumes the nature of a torsional suspension.<br> -<br> -<br> -<img style="width: 755px; height: 308px;" alt="" src="images/499Fig.jpg"><br> -[Transcriber's note: This is the image of the first paragraph.]<br> -<br> -<br> -<span style="font-weight: bold;">Swaging, Electric.</span><br> -Mechanical swaging in which the objects to be swaged are heated by an<br> -electric current as in electric welding.<br> -<br> -<br> -<span style="font-weight: bold;">S. W. G. </span><br> -Abbreviation for Standard Wire Gauge.<br> -<br> -<br> -<img style="width: 549px; height: 635px;" alt="" - src="images/499F309.jpg"><br> -Fig. 309. SIMPLE SWITCH.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Switch.</span><br> -A device for opening and closing an electric circuit.<br> -<br> -A simple type is the ordinary telegrapher's switch. A bar of metal is<br> -mounted horizontally by a pivot at one end, so as to be free to rotate<br> -through an arc of a circle. In one position its free end rests upon a<br> -stud of metal. One terminal of a circuit is attached to its journal, the<br> -other to the stud. Resting on the stud it closes the circuit, in other<br> -positions it opens the circuit.<br> -<br> -<br> -500 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Switch, Automatic.</span><br> -A switch opened and closed by the electric current. It is used for<br> -lighting distant incandescent lamps. It includes one or two<br> -electro-magnets operated by two push buttons. In the usual arrangement<br> -one button is black and the other white, for extinguishing and lighting<br> -respectively. When the white button is pushed it causes a current to<br> -pass through one of the electro-magnets. This attracts its armature,<br> -thereby making a contact and throwing the lamps into the lighting<br> -circuit. Then they remain lighted until the black button is pressed.<br> -This excites the other magnet, which attracts its armature, breaks the<br> -contact and extinguishes the lights.<br> -<br> -The object of the automatic switch is to enable distant lamps to be<br> -lighted without the necessity of carrying the electric leads or wires to<br> -the place whence the lighting is to be done. A very small wire will<br> -carry enough current to operate the magnets, and open circuit batteries,<br> -such as Leclanché batteries, may be used as the source of -current for<br> -the switch, but generally the lighting current is used for the purpose.<br> -<br> -A single magnet may do the work. When the lighting button is pressed the<br> -magnet is excited, attracts its armature and holds it attracted, until<br> -by pressing the black button the current is turned off from it. In this<br> -case the lighting current is used to excite the magnet.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Switch Board.</span><br> -A board or tablet to which wires are led connecting with cross bars or<br> -other switching devices, so as to enable connections among themselves or<br> -with other circuits to be made.<br> -<br> -<br> -<span style="font-weight: bold;">Switch, Circuit Changing.</span><br> -A switch whose arm in its swing breaks one contact and swinging over<br> -makes another. It is employed to change the connections of circuits from<br> -one dynamo to another.<br> -<br> -Synonyms--Changing Switch--Changing Over Switch.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Switch, Double Break.</span><br> -A form of switch in which double contact pieces are provided to give a<br> -better contact. One form consists of a hinged bar whose end swings down<br> -between two pairs of springs. Both pairs are connected to one terminal,<br> -and the bar to the other terminal of a circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Switch, Double Pole.</span><br> -A heavy switch for central station work, that connects and disconnects<br> -two leads simultaneously.<br> -<br> -<br> -<span style="font-weight: bold;">Switch, Feeder.</span><br> -A heavy switch, often of double contact type, for connecting and<br> -disconnecting feeders from bus bars in central stations.<br> -<br> -<br> -501 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Switch, Knife.</span><br> -A switch whose movable arm is a narrow, deep bar of copper or brass, and<br> -which in making contact is forced in edgeways between two springs<br> -connected to one terminal. The bar is connected to the other terminal.<br> -<br> -Synonyms--Knife Break Switch--Knife Edge Switch.<br> -<br> -<br> -<span style="font-weight: bold;">Switch, Multiple.</span><br> -A switch which in the swing of its bar connects one by one with a number<br> -of contacts so that ultimately the end of its bar is in contact with all<br> -at once. It is used to throw lights in and out in succession, and it<br> -can, if the multiple contacts connect with resistances, make them<br> -operate as a rheostat.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Switch, Pole Changing.</span><br> -A switch for changing the direction of the current in a circuit.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Switch, Reversing.</span><br> -A switch, often of the plug type (see Plug Switch) for changing the<br> -direction of current passing through a galvanometer.<br> -<br> -<br> -<span style="font-weight: bold;">Switch, Snap.</span><br> -A switch constructed to give a quick, sharp break. It has a spiral<br> -spring interposed between the handle and arm. As the handle is drawn<br> -back to open it the spring is first extended, the bar being held by the<br> -friction of the contacts, until the spring suddenly jerks it up, thus<br> -breaking the contact.<br> -<br> -<br> -<span style="font-weight: bold;">Switch, Storage Battery Changing.</span><br> -A switch for changing storage battery connections from series to<br> -multiple and back again.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Switch, Three Way.</span><br> -A switch, so constructed that by turning its handle connection can be<br> -made from one lead to either of two other leads, and also so that<br> -connection can be completely cut off.<br> -<br> -<br> -<span style="font-weight: bold;">Sympathetic Vibration.</span><br> -The establishment of periodic movement in one body by impulses of the<br> -same period communicated to it from another body in motion. Thus if two<br> -tuning forks are of the same pitch and one is sounded the other will<br> -begin to sound by sympathy, the sound waves communicating the necessary<br> -periodic impulses to it.<br> -<br> -Sympathetic vibrations are utilized in harmonic telegraphy. (See<br> -Harmonic Receiver--Telegraph, Harmonic.)<br> -</big></big><big><big><br> -<br> -501 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">T.</span><br> -Symbol of time.<br> -<br> -<br> -<span style="font-weight: bold;">Tailings.</span><br> -(a) In high speed transmission of telegraph signals by the automatic<br> -system, the definiteness of the signal marks is sometimes interfered<br> -with by retardation. Wrong marks are thus produced called tailings.<br> -<br> -(b) The prolongation of the current at the distant receiving station of<br> -a telegraph line due to the discharge of the line and to self-induction.<br> -<br> -Synonyms--Tailing--Tailing Current.<br> -<br> -<br> -502 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Tamidine.</span><br> -Reduced nitro-cellulose. Nitro-cellulose is dissolved in a proper<br> -solvent and is obtained by evaporation as a translucent solid mass. By<br> -ammonium sulphide or other reagent it is reduced so as to be virtually<br> -cellulose. It is cut into shape for filaments of incandescent lamps,<br> -which shapes are carbonized and flashed.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Tangent Law.</span><br> -In a galvanometer the tangents of the angles of deflection of the needle<br> -are proportional to the deflecting force--<br> -<br> -I. When the controlling force is unaltered in absolute magnitude -and<br> -direction by the motion of the needle.<br> -<br> -II. When the deflecting force acts at right angles always to the<br> -controlling force.<br> -<br> -These conditions are usually secured by having the actuating coil<br> -through which the current passes flat and of large diameter compared to<br> -the length of the needle; by using the uniform field of the earth as the<br> -control; by having a short needle; by placing the coil with its plane in<br> -the magnetic meridian.<br> -<br> -For best proportions of tangent galvanometer coils see Bobbins.<br> -<br> -<br> -<img style="width: 778px; height: 464px;" alt="" - src="images/502F310.jpg"><br> -Fig. 310. GRAPHIC CONSTRUCTION OF TANGENT SCALE.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Tangent Scale.</span><br> -An arc of a circle in which the number of graduations in any arc<br> -starting from zero are proportional to the tangent of the angle<br> -subtended by such arc. The system is for use with tangent galvanometers.<br> -Thus if for 45° a value of 100 is taken and marked on the scale -then for<br> -the arc 26° 33' + a value of 50 should be marked on the scale -because<br> -such are the relative values of the tangents.<br> -<br> -Thus the scale instead of being divided into degrees is divided into<br> -arcs of varying length, growing shorter as they are more distant from<br> -the zero point, of such length that the first division being subtended<br> -by a tangent of length 1, the first and second divisions added or taken<br> -together as one arc are subtended by a tangent of length 2, and so on.<br> -<br> -In the cut a simple method of graphically laying out a tangent scale is<br> -shown. In it C is the centre of the arc, and H the radius running to the<br> -zero of the instrument. From C a circle is described and on H a vertical<br> -line tangent to the arc is erected. Taking any part of the tangent, as<br> -the length shown ending at D, it is divided into any number of equal<br> -parts. Radii of the circle are now drawn whose prolongations pass<br> -through the divisions on the tangent. These radii, where they intersect<br> -the arc of the circle, determine equal divisions of the tangent scale,<br> -which, as is evident from the construction, are unequal angular<br> -divisions of the arc.<br> -<br> -<br> -503 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Tanning, Electric.</span><br> -The tanning of hides in the manufacture of leather by the aid of<br> -electrolysis. A current of electricity is maintained through the tanning<br> -vats in which regular tanning liquor is contained. Very extraordinary<br> -claims are made for the saving of time in the tanning process. What is<br> -ordinarily a process of several months, and sometimes of a year, is said<br> -to be reduced to one occupying a few days only. The action of<br> -electrolysis is the one relied on to explain the results.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Tapper.</span><br> -The key used in single needle telegraph transmitters. It comprises two<br> -flat springs L, E, each with a handle, normally pressed upward against<br> -one contact bar Z, and when pressed down by the operator making contact<br> -against a lower bar C when messages are to be transmitted. A double<br> -tapper, such as shown, is used for each instrument.<br> -<br> -Synonyms--Double Tapper Key--Pedal Key.<br> -<br> -<br> -<img style="width: 326px; height: 684px;" alt="" - src="images/503F311.jpg"><br> -Fig. 311. TAPPER.<br> -<br> -<br> -<span style="font-weight: bold;">Target, Electric.</span><br> -A target registering or indicating electrically upon an annunciator the<br> -point of impact of each bullet.<br> -<br> -<br> -<span style="font-weight: bold;">Taste, Galvanic.</span><br> -The effect produced upon the gustatory nerves by the passage of an<br> -electric current, or by the maintenance of potential difference between<br> -two portions of the tongue. It is very simply produced by placing a<br> -silver coin above, and a piece of zinc below the tongue, or the reverse,<br> -and touching their edges. A sour, peculiar taste is at once perceived.<br> -It cannot be due to any measurable quantity of current or of<br> -electrolytic decomposition, because the couple can do little more than<br> -establish a potential difference. With a strong current the taste<br> -becomes too strong for comfort, and if on a telegraph line the extra<br> -currents produced by the signaling make the operation of tasting the<br> -current a very unpleasant one. It is said that messages have been<br> -received in this way, the receiver placing one terminal of the line on<br> -his tongue, and a terminal attached to a grounded wire below it, and<br> -then receiving the Morse characters by taste.<br> -<br> -<br> -504 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Teazer.</span><br> -Originally a fine wire coil wound on the field magnets of a dynamo in<br> -shunt with the regular winding to maintain the magnetism. It was<br> -originally used in electroplating machines to prevent inversion of the<br> -magnetism, but has since developed into a component part of the winding<br> -of the compound dynamo. (See Dynamo, Compound.)<br> -<br> -<br> -<span style="font-weight: bold;">Tee, Lead.</span><br> -A lead pipe of T shape used for connecting branches to electric cables.<br> -The tee is soldered by wiped joints to the lead sheathings of the cable<br> -and branches after the wires have been connected, and the junctions<br> -coated with insulating tape or cement, or both.<br> -<br> -It is sometimes made in two halves, and is known as a split tee.<br> -<br> -<br> -<span style="font-weight: bold;">Tel-autograph.</span><br> -A telegraph for reproducing the hand-writing of the sender at the<br> -receiving end of the line. To save time a special spelling is sometimes<br> -used.<br> -<br> -<br> -<span style="font-weight: bold;">Teleautograph.</span><br> -The special spelling used with the Tel-Autograph telegraph.<br> -<br> -<br> -<span style="font-weight: bold;">Tele-barometer, Electric.</span><br> -A barometer with electric attachment for indicating or recording at a<br> -distance the barometric readings.<br> -<br> -<br> -<span style="font-weight: bold;">Telegraph, ABC.</span><br> -This term is applied to alphabet telegraphs indicating the message by<br> -the movements of a pointer on a dial marked with the characters to be<br> -sent. In England the Wheatstone ABC system is much employed.<br> -<br> -<br> -<span style="font-weight: bold;">Telegraph, Automatic.</span><br> -A telegraph system based on the operation of the transmitting instrument<br> -by a perforated strip of paper drawn through it. The perforations made<br> -by an apparatus termed a perforator, are so arranged as to give<br> -telegraphic characters of the Morse or International Code in the<br> -transmitting instrument. (See Perforator.) Bain in the year 1846 was the<br> -originator of the system. He punched a fillet of paper with dots and<br> -dashes, and drew it between two terminals of the line, thus sending over<br> -the line a corresponding series of short and long currents which were<br> -received by his chemical receiver. (See Chemical Receiver.) The method<br> -was not successful. Its modern development, the Wheatstone Automatic<br> -Telegraph, is highly so. The perforated paper by its perforations<br> -controls the reciprocating movement of two rods, which pass through each<br> -hole in two rows, corresponding to the two rods respectively as the<br> -holes come opposite to the ends of the rods. The rods are kept<br> -constantly moving up and down. If unperforated paper is above them their<br> -upward motion is limited. This gives three positions for the rods, (a)<br> -both down, (b) one up and the other down, (c) both up. These positions<br> -of the rods work a pole changing key by which dots, spaces, and dashes<br> -are transmitted to the receiving instrument, which is an exceedingly<br> -delicate ink-printer. The latter can have its speed adjusted to receive<br> -from 200 to 450 words per minute.<br> -<br> -<br> -505 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Telegraph, Dial.</span><br> -A telegraph in which as receiver a dial instrument is used. A pointer or<br> -index hand moves around a dial. The dial is marked with letters of the<br> -alphabet. The movements of the pointer are controlled by the<br> -transmitting operator at a distant station. He by the same actions moves<br> -a pointer on a duplicate instrument before him and the two are<br> -synchronized to give identical indications. Thus a message is spelled<br> -out letter by letter on both dials simultaneously. The motions of the<br> -index are generally produced by what is virtually a recoil escapement.<br> -The scape wheel is carried by the axle of the index, and a pallet or<br> -anchor is vibrated by an electro-magnet whose armature is attached to<br> -the stem of the pallet. As the pallet is vibrated it turns the wheel and<br> -index one tooth for each single movement. There are as many teeth in the<br> -wheel as there are characters on the dial. The two instruments being in<br> -duplicate and synchronized, the pallets move exactly in unison, so that<br> -identical readings of the dials are given. The pallets may be moved by<br> -any kind of make and break mechanism, such as an ordinary telegraph key.<br> -The index moves by steps or jerks, so that the system is sometimes<br> -called step-by-step telegraphy.<br> -<br> -<br> -<img style="width: 636px; height: 324px;" alt="" - src="images/505F312.JPG"><br> -Fig. 312. DIAL TELEGRAPH.<br> -<br> -<br> -In the cut the make and break transmitter is shown at v v, with its<br> -handle and contacts g and t. This mechanism sends impulses of current by<br> -F and Z to the receiving magnet l. This attracts and releases its<br> -armature K from contact into the position indicated by the dotted lines.<br> -This works the rocker n on the pin o, and actuates the double or anchor<br> -pawl s r, which turns the pallet or scrape wheel m.<br> -<br> -The system is dropping into disuse, being supplanted by the telephone.<br> -<br> -Synonym--Step-by-step Telegraph.<br> -<br> -<br> -506 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Telegraph, Double Needle.</span><br> -A telegraph system in which the message is read by the motions of two<br> -vertical needles on the face of the instrument in front of the receiving<br> -operator. An identical instrument faces the transmitting operator. By<br> -two handles, one for each hand, the needles are caused by electric<br> -impulses to swing to right and to left so as to give a telegraphic code.<br> -It has been generally superseded by the single needle telegraph.<br> -<br> -<br> -<span style="font-weight: bold;">Telegraph, Duplex.</span><br> -A telegraph capable of transmitting simultaneously two messages over one<br> -wire. The methods of effecting it are distinct from those of multiplex<br> -telegraphy. This term is used as a distinction from diode multiplex<br> -telegraphy, in which the work is done on other principles. There are two<br> -systems of duplex telegraphy, the differential and the bridge systems.<br> -<br> -<br> -<span style="font-weight: bold;">Telegraph, Duplex Bridge.</span><br> -A system of duplex telegraphy employing the principle of the Wheatstone<br> -bridge. The other or differential system depends on equality or<br> -difference of currents; the bridge method on equality or difference of<br> -potentials. The cut shows the system known as Steam's Plan.<br> -<br> -At the ends of the line wire are two cross connections like duplicate<br> -galvanometer connections in a Wheatstone bridge, each including a<br> -receiving relay. The rest of the connections are self-explanatory.<br> -<br> -When A depresses his key the current splits at the point indicating the<br> -beginning of the bridge. One portion goes through the line to B and to<br> -earth, the other goes to earth at A through the rheostats indicated by<br> -the corrugated lines.<br> -<br> -On reaching B's end the current divides at the cross-connection and part<br> -goes through the receiving relay shown in the center of that<br> -cross-connection.<br> -<br> -Thus if A sends to B or B to A it is without effect on the home<br> -receiving instrument. Now suppose that both simultaneously are sending<br> -in opposite directions. If the connections be studied it will be seen<br> -that every movement of the transmitting key will affect the balance of<br> -the distant or receiving end of the bridge and so its instrument will<br> -record the signals as they are sent.<br> -<br> -As shown in the cut the sending keys are on local circuits, and work<br> -what are known as duplex transmitters. These are instruments which send<br> -line signals without breaking the connection.<br> -<br> -<br> -<img style="width: 584px; height: 350px;" alt="" - src="images/507F313.jpg"><br> -Fig. 313. STEARN'S PLAN OF DUPLEX BRIDGE TELEGRAPHY.<br> -<br> -<br> -In Stearn's plan condensers are introduced as shown. By this plan<br> -different receiving instruments can be used. The inventor once worked a<br> -Morse instrument at one end of the line, and a Hughes' instrument at the<br> -other end.<br> -<br> -<br> -507 STANDARD ELECTRICAL DICTIONARY.<br> -<br style="font-weight: bold;"> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Telegraph, Duplex, Differential.</span><br> -A system of duplex telegraphy employing the differential action of two<br> -exciting or magnetizing coils. The general principles are the following.<br> -Suppose that at each of two stations, there is a magnet working as a<br> -sounder or relay. Each magnet is differentially wound, with two coils of<br> -opposite direction, of identical number of turns.<br> -<br> -When the sending key at a station A is depressed two exactly equal<br> -currents go through the magnet in opposite directions. One called the<br> -compensation current goes to the earth at the stations. The other called<br> -the line current goes through the line, through the line coil of the<br> -distant station E, thereby actuating the relay or sounder armature.<br> -<br> -The instrument of the sender A is unaffected because he is sending<br> -opposite and equal currents through its two coils. A special resistance<br> -is provided on the compensation circuit for keeping the currents exactly<br> -equal in effect. Nothing the sender at A does affects his own<br> -instrument.<br> -<br> -Now suppose E desires to telegraph back at the same time that A is<br> -telegraphing to his station. He works his key. This does not affect his<br> -own instrument except by sending the equal and opposite currents through<br> -its coils. When his key is depressed and A's key is untouched, he works<br> -A's receiving instrument.<br> -<br> -<br> -508 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -When A's key is depressed simultaneously with B's key, the two line<br> -currents are in opposition and neutralize each other. This throws out<br> -the balance in the instruments and both armatures are attracted by the<br> -compensation currents left free to act by the neutralization of the line<br> -currents.<br> -<br> -<br> -<img style="width: 652px; height: 379px;" alt="" - src="images/508F314.jpg"><br> -Fig. 314. DUPLEX TELEGRAPH, DIFFERENTIAL SYSTEM<br> -<br> -<br> -Suppose that B is sending a dash, and it begins while A's key is raised.<br> -The line and compensation currents in B's receiving instrument<br> -neutralize each other and no effect is produced, while A's receiving<br> -instrument begins to register or indicate a dash. Now suppose A starts<br> -to send a dash while B's is half over. He depresses his key. This sends<br> -the two opposite currents through his magnet. His line current<br> -neutralizes B's working current so that the compensation currents in<br> -both receiving instruments hold the armatures attracted for the two<br> -dashes. Meanwhile A's dash ends and he releases his key. At once his<br> -line current ceases to neutralize B's line current, his receiving<br> -instrument is actuated now by B's line current, while B's receiving<br> -instrument ceases to be actuated by the compensation current.<br> -<br> -Two assumptions are made in the above description. The line currents are<br> -assumed to be equal in strength and opposite in direction at each<br> -station. Neither of these is necessary. The line current received at a<br> -station is always weaker than the outgoing line current, and it is the<br> -preponderance of the compensation current over the partly neutralized<br> -line current that does the work. As this preponderance is very nearly<br> -equal to the line current received from the distant station, the signals<br> -are actuated by almost the same current, whether it is compensation or<br> -line current.<br> -<br> -<br> -509 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Both line currents may coincide in direction. Then when the two keys are<br> -depressed, a line current of double strength goes through both receiving<br> -instruments and both work by preponderance of the double line current<br> -over the compensation current. In other respects the operation is the<br> -same as before described.<br> -<br> -<br> -<img style="width: 596px; height: 343px;" alt="" - src="images/509F315.jpg"><br> -Fig. 315. DUPLEX TELEGRAPH, DIFFERENTIAL SYSTEM.<br> -<br> -<br> -<img style="width: 557px; height: 393px;" alt="" - src="images/509F316.jpg"><br> -Fig. 316. DIFFERENTIAL DUPLEX TELEGRAPH CONNECTIONS.<br> -<br> -<br> -The cut shows a diagram of the operation of one end of the line. R and R<br> -are resistances, E and E are earth contacts, and the two circles show<br> -the magnet of the receiving instrument wound with two coils in<br> -opposition. The battery and key are also shown. It also illustrates what<br> -happens if the key of the receiver is in the intermediate position<br> -breaking contact at both 1 and 2. The sender's line current then goes<br> -through both coils of the receiving instrument magnet, but this time in<br> -series, and in coincident direction. This actuates the instrument as<br> -before. Owing to the resistance only half the normal current passes, but<br> -this half goes through twice as many coils or turns as if the receiver's<br> -key was in either of the other two positions.<br> -<br> -In actual practice there are many refinements. To compensate for the<br> -varying resistance of the line a rheostat or resistance with sliding<br> -connection arm is connected in the compensation circuit so that the<br> -resistance can be instantly changed. As the electro-static capacity of<br> -the line varies sectional condensers are also connected in the<br> -compensation circuits.<br> -<br> -<br> -510 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Telegraph, Facsimile.</span><br> -A telegraph for transmitting facsimiles of drawing or writing. The<br> -methods employed involve the synchronous rotation of two metallic<br> -cylinders, one at the transmitting end, the other at the receiving end.<br> -<br> -On the transmitter the design is drawn with non-conducting ink. A tracer<br> -presses upon the surface of each cylinder and a circuit is completed<br> -through the two contacts. In operation a sheet of chemically prepared<br> -paper is placed over the surface of the receiving cylinder. The two<br> -cylinders are rotated in exact synchronism and the tracers are traversed<br> -longitudinally as the cylinders rotate. Thus a number of makes and<br> -breaks are produced by the transmitting cylinder, and on the receiving<br> -cylinder the chemicals in the paper are decomposed, producing marks on<br> -the paper exactly corresponding to those on the transmitting cylinder.<br> -<br> -Synonyms--Autographic Telegraph--Pantelegraphy.<br> -<br> -<br> -<span style="font-weight: bold;">Telegraph, Harmonic Multiplex.</span><br> -A telegraph utilizing sympathetic vibration for the transmission of<br> -several messages at once over the same line. It is the invention of<br> -Elisha Gray. The transmitting instrument comprises a series of vibrating<br> -reeds or tuning-forks, each one of a different note, kept in vibration<br> -each by its own electro-magnet. Each fork is in its own circuit, and all<br> -unite with the main line so as to send over it a make and break current<br> -containing as many notes superimposed as there are tuning forks. At the<br> -other end of the line there are corresponding tuning forks, each with<br> -its own magnet. Each fork at this end picks up its own note from the<br> -makes and breaks on the main line, by the principle of sympathetic<br> -vibration.<br> -<br> -To each pair of operators a pair of forks of identical notes are<br> -assigned. As many messages can be transmitted simultaneously as there<br> -are pairs of forks or reeds.<br> -<br> -The movements of a telegraph key in circuit with one of the transmitting<br> -reeds sends signals of the Morse alphabet, which are picked out by the<br> -tuning fork of identical note at the other end of the line.<br> -<br> -<br> -511 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Telegraph, Hughes'.</span><br> -A printing telegraph in very extensive use in continental Europe. Its<br> -general features are as follows:<br> -<br> -The instruments at each end of the line are identical. Each includes a<br> -keyboard like a piano manual, with a key for each letter or character.<br> -On each machine is a type wheel, which has the characters engraved in<br> -relief upon its face. With the wheel a "chariot" as it is termed also<br> -rotates. The type wheels at both stations are synchronized. When a key<br> -is depressed, a pin is thrown up which arrests the chariot, and sends a<br> -current to the distant station. This current causes a riband of paper to<br> -be pressed up against the face of both type wheels so as to receive the<br> -imprint of the character corresponding to the key. The faces of the<br> -wheels are inked by an inking roller.<br> -<br> -<br> -Fig. 317. ELECTRO-MAGNET OF HUGHES' PRINTING TELEGRAPH.<br> -<br> -<br> -The most characteristic feature is the fact that the current sent by<br> -depressing a key does not attract an armature, but releases one, which<br> -is then pulled back by a spring. The armature is restored to its<br> -position by the mechanical operation of the instrument. The magnet used<br> -is a polarized electro-magnet. Coils are carried on the ends of a strong<br> -powerful magnet. The coils are so connected that a current sent through<br> -them by depressing a key is in opposition to the magnetism of the<br> -permanent magnet so that it tends to release the armature, and in<br> -practice does so. This release permits the printing mechanism to act.<br> -The latter is driven by a descending weight, so that very slight<br> -electric currents can actuate the instruments.<br> -<br> -Synonym--Hughes' Type Printer.<br> -<br> -<br> -<span style="font-weight: bold;">Telegraphic Code.</span><br> -(a) The telegraphic alphabet, as of the Morse System. (See Alphabet,<br> -Telegraphic.)<br> -<br> -(b) A code for use in transmitting messages either secretly, or<br> -comprising several words or short sentences in one word, in order to<br> -economize in transmission. Such codes are extensively used in commercial<br> -cable messages.<br> -<br> -<br> -512 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Telegraph, Magneto-electric.</span><br> -A telegraph in which the current is produced by magneto-electric<br> -generators. It has been applied to a considerable extent in England. The<br> -Wheatstone ABC or dial telegraph is operated by a magneto-generator<br> -turned by hand.<br> -<br> -In this country the magneto-electric generator by which the calling bell<br> -of a telephone is rung is an example. The magneto-electric key (See Key,<br> -Magneto-electric) is for use in one kind of magneto-electric<br> -telegraphing.<br> -<br> -<br> -<span style="font-weight: bold;">Telegraph, Morse.</span><br> -A telegraph, characterized by the use of a relay, working a local<br> -circuit, which circuit contains a sounder, or recorder for giving dot<br> -and dash signals constituting the Morse alphabet. The signals are sent<br> -by a telegraph key, which when depressed closes the circuit, and when<br> -released opens it. The two underlying conceptions of the Morse Telegraph<br> -system are the use of the dot and dash alphabet, and the use of the<br> -local circuit, which circuit includes a receiving instrument, and is<br> -worked by a relay, actuating a local battery. It would be difficult to<br> -indicate any invention in telegraphy which has had such far-reaching<br> -consequences as the one known as the Morse telegraph.<br> -<br> -In other places the principal apparatus of the system will be found<br> -described. The cut Fig. 318, repeated here gives the general disposition<br> -of a Morse system. (See Circuit, Local.)<br> -<br> -<br> -<img style="width: 579px; height: 382px;" alt="" - src="images/512F318.jpg"><br> -Fig. 318. DIAGRAM OF MORSE SYSTEM.<br> -<br> -<br> -513 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The key by which the messages are transmitted is shown in Fig. 319. M is<br> -a base plate of brass. A is a brass lever, mounted on an arbor G carried<br> -between adjustable set screws D. C is the anvil where contact is made by<br> -depressing the key by the finger piece B of ebonite. E, Fl are adjusting<br> -screws for regulating the vertical play of the lever. H is the switch<br> -for opening or closing the circuit. It is opened for transmission, and<br> -closed for receiving. By screws, L L, with wing nuts, K K, the whole is<br> -screwed down to a table.<br> -<br> -<br> -<img style="width: 620px; height: 408px;" alt="" - src="images/513F319.jpg"><br> -Fig. 319. MORSE TELEGRAPH KEY.<br> -<br> -<br> -In the United States the simplest disposition of apparatus is generally<br> -used. The main line is kept on closed circuit. In it may be included a<br> -large number of relays at stations all along the line, each with its own<br> -local circuit. There may be fifty of such stations. Battery is generally<br> -placed at each end of the line. Very generally gravity batteries are<br> -used, although dynamos now tend to supplant them in important stations.<br> -<br> -As relays the ordinary relay is used. Its local circuit includes a<br> -sounder and local battery. The latter is very generally of the gravity<br> -type, but oxide of copper batteries (See Battery, Oxide of Copper) are<br> -now being introduced. At main or central offices, the terminals of the<br> -lines reach switch boards, where by spring-jacks and plugs, any desired<br> -circuits can be looped into the main circuit in series therewith.<br> -<br> -In European practise the main line is kept on open circuit. Polarized<br> -relays are used to work the local circuits. The currents for these have<br> -to be alternating in direction. When the line is not in use its ends are<br> -connected to earth at both ends, leaving the battery out of circuit.<br> -Each intermediate station has its own main, or line battery for use when<br> -it desires to send a message. In the American system as first described,<br> -it will be seen that the main batteries are at most two in number.<br> -<br> -For the details of the different apparatus, the following definitions<br> -may be consulted: Embosser, Telegraphic--Recorder, Morse--Relay--Relay<br> -Connection--Sounder.<br> -<br> -<br> -514 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Telegraph, Multiplex.</span><br> -A system of telegraphy by which a number of messages can be transmitted<br> -in both directions over a single wire. The principles underlying the<br> -systems are the following:<br> -<br> -Suppose that at the two extremities of a telegraph line two arms are<br> -kept in absolute synchronous rotation. Let the arms in their rotation,<br> -press upon as many conducting segments as there are to be transmissions<br> -over the line. A transmitting and receiving set of instruments may be<br> -connected to one segment at one end of the line, and another set to the<br> -corresponding segment at the distant station. For each pair of segments<br> -two sets can be thus connected. Then if the arm rotates so rapidly that<br> -the contacts succeed each other rapidly enough each pair of sets of<br> -instruments can be worked independently of the others. In practice this<br> -rapid succession is effected by having a number of contacts made for<br> -each pair during a single rotation of the arm or equivalent.<br> -<br> -The multiplex system has been perfected by the use of La Cour's phonic<br> -wheel (see Phonic Wheel), and brought into a practical success by<br> -Patrick B. Delany, of New York.<br> -<br> -Two phonic wheels rotate at each end of the line. They are kept in<br> -synchronous motion by two vibrating steel reeds of exactly the same<br> -fundamental note, and the axle of each wheel carries an arm whose end<br> -trails over the contacts or distributor segments already spoken of. The<br> -reeds are adjusted to vibrate at such speed that the trailer is in<br> -contact with each segment about 1/500 second. The number of groups of<br> -segments required for each working is determined by the retardation of<br> -the signals owing to the static capacity of the line. To convert the<br> -rapidly recurring impulses of current into practically a single current,<br> -condensers are connected across the coils of the relay. One battery<br> -serves for all the arms.<br> -<br> -Multiplex telegraphy can effect from two to six simultaneous<br> -transmissions over one wire. For two or four transmissions the method<br> -only distinguishes it from duplex or quadruplex telegraphy. The terms<br> -diode, triode, tetrode, pentode and hexode working are used to indicate<br> -respectively the simultaneous transmission of two, three, four, five, or<br> -six messages over one wire.<br> -<br> -It will be seen that the multiplex process really assigns to each<br> -transmission separate times, but divides these times into such short and<br> -quickly recurring intervals that the work is executed as if there was<br> -continuous contact. In no case is there the popular conception of the<br> -sending of several messages actually simultaneously over one wire. Each<br> -signal in reality has its own time assigned it, divided into short<br> -periods of high frequency, and only utilizes the line when it is free.<br> -<br> -<br> -515 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Telegraph, Over-house.</span><br> -An English term for telegraph lines led over houses and supported on<br> -standards on the roofs.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Telegraph Pole Brackets.</span><br> -Arms for carrying insulators, which arms are attached to telegraph poles<br> -or other support. They vary in style; sometimes they are straight bars<br> -of wood gained into and bolted or spiked in place; sometimes they are of<br> -iron.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Telegraph, Printing.</span><br> -Various telegraphs have been invented for printing in the ordinary<br> -alphabet the messages at the receiving end of the line.<br> -<br> -Representative instruments of this class are used for transmitting<br> -different market and stock reports to business offices from the<br> -exchanges. The type faces are carried on the periphery of a printing<br> -wheel, which is rotated like the hand of a dial telegraph, and against<br> -whose face a paper riband is pressed whenever the proper letter comes<br> -opposite to it. As each letter is printed the paper moves forward the<br> -space of one letter. Spacing between words is also provided for. In the<br> -recent instruments two lines of letters are printed on the paper one<br> -above the other.<br> -<br> -In England, and on the continent of Europe, printing instruments have<br> -received considerable use for ordinary telegraphic work. Hughes' type<br> -printer and Wheatstone's ABC telegraph meet with extensive use there for<br> -ordinary transmission.<br> -<br> -<br> -<span style="font-weight: bold;">Telegraph, Quadruplex.</span><br> -Duplex telegraphy is the sending of two messages in opposite directions<br> -simultaneously through the same wire. Duplex telegraphy is the sending<br> -of two messages simultaneously in the same direction. The two combined<br> -constitute quadruplex telegraphy. [SIC]<br> -<br> -The system was suggested by Stark of Vienna and Bosscha of Leyden in<br> -1855; the successful problem was solved by Edison in 1874.<br> -<br> -The principle is based on the two orders of difference in electric<br> -currents; they may vary in strength or in direction. Thus we may have<br> -one instrument which works with change of strength of current only, the<br> -other with change of direction only. The two can be worked together if<br> -the direction of the current can be altered without alteration of<br> -strength, and if strength can be altered without alteration of<br> -direction. Double current and single current working are so combined<br> -that one relay works by one system of currents and another relay by the<br> -other system. A current is constantly maintained through the line. The<br> -relay operated by change in direction is a simple polarized relay which<br> -works by change of direction of current. The relay operated by change in<br> -strength is the ordinary unpolarized relay.<br> -<br> -<br> -516 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -For the following description and the cuts illustrating it we are<br> -indebted to Preece and Sivewright. The cut shows the arrangement of the<br> -apparatus and connections for terminal offices.<br> -<br> -"Sufficient table room is provided to seat four clerks. The apparatus is<br> -arranged for the two senders to sit together in the centre, the messages<br> -to be forwarded being placed between them. The section on the left of<br> -the switch Q is known as the 'A' side, that on the right as the 'B' side<br> -of the apparatus.<br> -<br> -K1 the reversing key, reverses the direction of the current. K2 is a<br> -simple key, known as the increment key; it is used simply to increase<br> -the strength of the current.<br> -<br> -<br> -<img style="width: 635px; height: 455px;" alt="" - src="images/516F320.jpg"><br> -Fig. 320. QUADRUPLEX TELEGRAPH CONNECTIONS.<br> -<br> -<br> -The way in which the keys K1 and K2 combine their action is shown by<br> -Fig. 321. E1 and E2 are the line batteries, the one having two and<br> -one-third (2-1/3) the number of cells of the other, so that if E1 be the<br> -electro-motive force of the smaller, that of the whole combined battery<br> -will be 3.3 E1. The negative pole of E1 is connected to z and z1 -of K1<br> -and the positive pole of E2 to a of K2 through a resistance coil s. A<br> -wire, called the 'tap' wire, connects the positive pole of E1 and the<br> -negative pole of E2 to b of K2. This wire has in it a resistance coil<br> -r2. The springs c and c1 of Kl are connected to the lever L of K2. Now,<br> -when both keys are at rest, the negative pole of E1 is to line through<br> -z, and the positive pole of E1 to earth through b of K2 and c of K1; the<br> -positive pole of E2 being insulated at a of K2.<br> -<br> -<br> -517 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -There is thus a weak negative current flowing to line. When K1 alone is<br> -worked, the current of E1 is reversed. When K2 is worked alone, c of K1<br> -is transferred from b to a, and the strength of the negative current<br> -going to line is increased through the increase of the electro-motive<br> -force from E1 to 3.3 E1 for the whole battery is brought into play. When<br> -K1 and K2 are depressed together, then the negative pole of E1 goes to<br> -earth through Z1; and the positive pole of E2 to line through a of K2<br> -and c1 of K1 and a positive current, due to the whole electro-motive<br> -force 3.3 E1 goes to line. Hence the effect of working K1 is simply to<br> -reverse the current, whatever its strength, while that of K2 is to<br> -strengthen it, whatever its direction.<br> -<br> -The resistance coil s, of 100° resistance, is called a spark coil,<br> -because it prevents the high electro-motive force of the whole battery<br> -from damaging the points of contact by sparking or forming an arc across<br> -when signals are sent; and the resistance r2 is made approximately equal<br> -to the combined resistance of E2 and the spark coil, so that the total<br> -resistance of the circuit may not be altered by the working of the<br> -apparatus.<br> -<br> -<br> -<img style="width: 635px; height: 455px;" alt="" - src="images/516F320.jpg"><br> -Fig. 321. QUADRUPLEX TELEGRAPH.<br> -<br> -<br> -A1 and B1 (Fig. 320) are the relays which are used to respond to the<br> -changes in the currents sent by the keys K1 and K2 at the distant<br> -station.<br> -<br> -A, is a simple polarized relay wound differentially, each wire having a<br> -resistance of 200 [omega], and so connected up as to respond to the -working of<br> -the reversing key K1 of the distant station. It acts independently of<br> -the strength of the current, and is therefore not affected by the<br> -working of the increment key K2. It is connected up so as to complete<br> -the local circuit of the sounder S1 and the local battery l1 and forms<br> -the receiving portion of the 'A' side.<br> -<br> -B, is a non-polarized relay also wound differentially, each coil having -<br> -a resistance of 200 [omega]. It responds only to an increase in the <br> -strength of the current, and therefore only to the working of the <br> -increment key K2 of the distant station.<br> -<br> -[Transcriber's note: In current usage upper case omega indicates ohms -and<br> -lower case omega denotes angular frequency, 2*PI*f.]<br> -<br> -<br> -518 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The relay spring is so adjusted that the armatures are not actuated by<br> -the weak current sent from E by the key K1.<br> -<br> -In its normal position this relay completes the circuit of the local<br> -battery through the sounder S. This sounder S, called the uprighting<br> -sounder, acts as a relay to a second sounder, S2, called the reading<br> -sounder, which is worked by another local battery, l2. Of course,<br> -normally, the armature of S is held down and that of S2 is up, but when<br> -the tongue t moves, as it does when the increment key K2 is depressed so<br> -as to send the whole current to line, then the current from l is<br> -interrupted, and the circuit of l2 is completed by the rising of the<br> -armature of S, causing the reading sounder S2 to work. This is the 'B'<br> -side.<br> -<br> -R is a rheostat for balancing the resistance of the line, as used in<br> -duplex working.<br> -<br> -C is a condenser used for compensating the static charge of the line. It<br> -is provided with an adjustable retardation coil, R1, to prolong the<br> -effect of the compensating current from the condenser.<br> -<br> -G is a differential galvanometer, used for testing, and for facilitating<br> -adjustment and balancing.<br> -<br> -Q is a switch for putting the line to earth, either for balancing, or<br> -for any other purpose. There is on the earth wire leading from Q a<br> -resistance coil, r1, equalling approximately the resistance of the whole<br> -battery, 3.3 E1, and the resistance s.<br> -<br> -The connections shown in Fig. 321, are for an 'up' office. At a 'down'<br> -office it is necessary to reverse the wires on the two lower terminals<br> -of the galvanometer and the two battery wires on the reversing key K1.<br> -<br> -The keys K1 and K2 are, for repeaters, replaced by transmitters.<br> -<br> -The adjustment of this apparatus requires great care and great accuracy.<br> -Its good working depends essentially on technical skill that can only be<br> -acquired by patience and perseverance.<br> -<br> -Faults in working generally arise from careless adjustments, dirty<br> -contacts, loose connections, battery failures, and the ordinary line<br> -interruptions, but there are no troubles that are beyond the reach of<br> -ordinary skill, and it can be safely said that, within moderate<br> -distances, wherever and whenever duplex working is practicable, then<br> -quadruplex working is so too."<br> -<br> -The above is a typical quadruplex bridge system. There is also a<br> -differential system, the full description of which, in addition to what<br> -has been given, is outside of the scope of this work.<br> -<br> -<br> -519 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Telegraph Repeater.</span><br> -An extension of the relay system, adopted for long lines. A repeating<br> -station comprises in general terms duplicate repeating apparatus. One<br> -set is connected for messages in one direction, the other for messages<br> -in the opposite direction. The general operation of a repeating set is<br> -as follows. The signals as received actuate a relay which by its local<br> -circuit actuates a key, which in ordinary practise would be the sounder,<br> -but in the repeater its lever opens and closes a circuit comprising a<br> -battery and a further section of the line.<br> -<br> -Repeaters are placed at intervals along the line. Each repeater repeats<br> -the signals received for the next section of line with a new battery. It<br> -represents an operator who would receive and repeat the message, except<br> -that it works automatically.<br> -<br> -The Indo-European line from London to Teheran, 3,800 miles long, is<br> -worked directly without any hand retransmission, it being carried out by<br> -five repeaters. This gives an average of over 500 miles for each<br> -repeater.<br> -[Transcriber's note: … 650 miles for each repeater.]<br> -<br> -Repeaters introduce retardation, and each repeater involves a reduction<br> -in the rate of working. Yet in many cases they increase the speed of a<br> -line greatly, as its speed is about equal to that of its worst section,<br> -which may be far greater than that of the whole line in one.<br> -<br> -Synonym--Translater.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Telegraph Signal.</span><br> -In the telegraph alphabet, a dot, or dash; the signal or effect produced<br> -by one closing of the circuit. A dash is equal in length to three dots.<br> -The space between signals is equal to one dot; the space between letters<br> -to three dots; and the space between words to six dots.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Telegraph, Single Needle.</span><br> -A telegraph system in which the code is transmitted by the movements of<br> -a needle shaped index which oscillates to right and left, the left hand<br> -deflection corresponding to dots, the right hand deflection to dashes.<br> -The instruments for sending and receiving are combined into one. The<br> -needles are virtually the indexes of vertical galvanometers. In one form<br> -by a tapper key (see Tapper), in another form by a key worked by a<br> -drop-handle (the drop handle instrument), currents of opposite<br> -directions are sent down the line. These pass through both instruments,<br> -affecting both needles and causing them to swing to right or left, as<br> -the operator moves his key.<br> -<br> -As galvanometer needle or actuating needle a soft iron needle is<br> -employed, which is polarized by the proximity of two permanent magnets.<br> -This avoids danger of reversal of polarity from lightning, a trouble<br> -incident to the old system.<br> -<br> -<br> -520 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The cut, Fig. 322, shows a single needle telegraph instrument of the<br> -tapper form. The action of the tapper can be understood from the next<br> -cut.<br> -<br> -<br> -<img style="width: 480px; height: 683px;" alt="" - src="images/520F322.JPG"><br> -Fig. 322. SINGLE NEEDLE TELEGRAPH INSTRUMENT, DOUBLE<br> -TAPPER FORM.<br> -<br> -<br> -<img style="width: 269px; height: 587px;" alt="" - src="images/520F323.JPG"><br> -Fig. 323. DOUBLE TAPPER KEY FOR SINGLE NEEDLE TELEGRAPH.<br> -<br> -<br> -C and Z are two strips of metal to which the positive and negative poles<br> -of the battery are respectively connected. E and L are two metallic<br> -springs; E is connected to earth, L is connected to the line; at rest<br> -both press against Z. If L is depressed so as to touch C, the current<br> -from the battery goes to the line by the key L, goes through the coils<br> -of the distant instrument and deflects the needle to one side, and then<br> -goes to the earth. If the key E is depressed, L retaining its normal<br> -position, the direction of the current is reversed, for the other pole<br> -of the battery is connected to the earth and the reverse current going<br> -through the coils of the distant instrument deflects the galvanometer<br> -needle to the other side.<br> -<br> -In the drop-handle type an analogous form of commutator worked by a<br> -single handle produces the same effects.<br> -<br> -<br> -521 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Telegraph, Wheatstone, A. B. C.</span><br> -A magneto-electric telegraph of the dial system. An alternating current<br> -magneto-generator is turned by hand and by depressing keys its current<br> -is admitted to or cut off from the line and receiver's instrument. The<br> -message is received by a dial instrument working by the escapement<br> -motion described under Telegraph, Dial.<br> -<br> -<br> -<span style="font-weight: bold;">Telegraph, Writing.</span><br> -A telegraph in which the message is received in written characters. The<br> -transmitter includes a stylus which is held in the hand and whose point<br> -bears against the upper end of a vertical rod. The rod is susceptible of<br> -oscillation in all directions, having at its base a spring support<br> -equivalent to a universal joint.<br> -<br> -The stylus is moved about in the shape of letters. As it does this it<br> -throws a series of resistances in and out of the circuit.<br> -<br> -At the receiving end of the line the instrument for recording the<br> -message includes two electro-magnets with their cores at right angles to<br> -each other and their faces near together at the point of the angle. An<br> -armature is supported between the faces and through it a vertical rod<br> -carried by a spring at its bottom rises. These magnets receive current<br> -proportional to the resistances cut in and out by the motions of the<br> -other rod at the transmitting end of the line. These resistances are<br> -arranged in two series at right angles to each other, one for each<br> -magnet. Thus the movements of the transmitting stylus and rod are<br> -repeated by the end of the rod in the receiving instrument. A species of<br> -pen is carried at the end of the rod of the receiving instrument, which<br> -marks the letters upon a riband of paper which is fed beneath it.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Telemanometer. Electric.</span><br> -A pressure gauge with electric attachment for indicating or recording<br> -its indications at a distance.<br> -<br> -It is applicable to steam boilers, so as to give the steam pressure in<br> -any desired place.<br> -<br> -<br> -<span style="font-weight: bold;">Telemeter, Electric.</span><br> -An apparatus for electrically indicating or recording at a distance the<br> -indications of any instrument such as a pressure gauge, barometer or<br> -thermometer, or for similar work. The telemanometer applied to a boiler<br> -comes into this class of instrument.<br> -<br> -<br> -<span style="font-weight: bold;">Telephotography.</span><br> -The transmission of pictures by the electric current, the requisite<br> -changes in the current being effected by the action of light upon<br> -selenium. The picture is projected by a magic lantern. Its projection is<br> -traversed by a selenium resistance through which the current passes.<br> -This is moved systematically over its entire area, thus constituting the<br> -transmitter, and synchronously with the motion of the selenium a contact<br> -point at the other end of the line moves systematically over a sheet of<br> -chemically prepared paper. The paper, which may be saturated with a<br> -solution of potassium ferrocyanide and ammonium nitrate, is stained by<br> -the passage of the current, and by the variation in intensity of<br> -staining, which variation is due to variations in the current, produced<br> -by the effects of the light upon the selenium, the picture is<br> -reproduced.<br> -<br> -<br> -522 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Telepherage.</span><br> -An electric transportation system, hitherto only used for the carrying<br> -of ore, freight, etc. Its characteristic feature is that the electric<br> -conductors, suspended from poles, supply the way on which carriages<br> -provided with electric motors run. The motors take their current<br> -directly from the conductors.<br> -<br> -There are two conducting lines, running parallel with each other,<br> -supported at the opposite ends of transverse brackets on a row of<br> -supporting poles. At each pole the lines cross over so that right line<br> -alternates with left, between consecutive pairs of poles.<br> -<br> -The cars are suspended from pulleys running on one or the other of the<br> -conductors. A train of such cars are connected and the current is taken<br> -in near one end and leaves near the other end of the train. These<br> -current connections are so distant, their distance being regulated by<br> -the length of the train, that they are, for all but an instant at the<br> -time of passing each of the poles, in connection with segments of the<br> -line which are of opposite potential. To carry out this principle the<br> -distance between contacts is equal to the distance between poles. Owing<br> -to the crossing over of the lines the contacts are in connection as<br> -described and thereby the actuating current is caused to go through the<br> -motors.<br> -<br> -Cars running in one direction go on the electric conductors on the one<br> -side, those running in the other direction go on the other conductor.<br> -<br> -A great many refinements have been introduced, but the system has been<br> -very little used.<br> -<br> -<br> -<span style="font-weight: bold;">Telephone.</span><br> -An instrument for the transmission of articulate speech by the electric<br> -current. The current is defined as of the undulatory type. (See Current,<br> -Undulatory.)<br> -<br> -The cut shows what may be termed the fundamental telephone circuit. A<br> -line wire is shown terminating in ground plates and with a telephone in<br> -circuit at each end. The latter consists of a magnet N S with a coil of<br> -insulated wire H surrounding one end. Facing the pole of the magnet is a<br> -soft iron diaphragm D, held in a frame or mouthpiece T. Any change of<br> -current in the line affects the magnetism of the magnet, causing it to<br> -attract the diaphragm more or less. The magnet and diaphragm really<br> -constitute a little electric motor, the diaphragm vibrating back and<br> -forth through an exceedingly short range, for changes in the magnetic<br> -attraction.<br> -<br> -The principle of the reversibility of the dynamo applies here. If the<br> -magnet is subjected to no change in magnetism, and if the diaphragm is<br> -moved or vibrated in front of its poles, currents will be induced in the<br> -wire bobbin which surrounds its end. If two such magnets with bobbins<br> -and diaphragms are arranged as shown, vibrations imparted to one<br> -diaphragm will send currents through the line which, affecting the<br> -magnetism of the distant magnet, will cause its diaphragm to vibrate in<br> -exact accordance with the motions of the first or motor diaphragm. In<br> -the combination one telephone represents a dynamo, the other a motor.<br> -<br> -If the vibrations of the diaphragm are imparted by the voice, the voice<br> -with all its modulations will be reproduced by the telephone at the<br> -distant end of the line.<br> -<br> -<br> -523 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 605px; height: 202px;" alt="" - src="images/523F324.JPG"><br> -Fig. 324. DIAGRAM OF BELL TELEPHONES <br> -AND LINE WITH EARTH CONNECTIONS.<br> -<br> -<br> -<img style="width: 535px; height: 281px;" alt="" - src="images/523F325.JPG"><br> -Fig. 325. SECTION OF BELL TELEPHONE.<br> -<br> -<br> -The above gives the essential features of the Bell telephone. In<br> -practice the telephone is used only as the receiver. As transmitter a<br> -microphone is employed. To give the current a battery, generally of the<br> -open circuit type, is used, and the current in the line is an induced or<br> -secondary one.<br> -<br> -The microphone which is talked to, and which is the seat of the current<br> -variations which reproduce original sound, is termed the transmitter,<br> -the telephone in which the sounds are produced at the distant end of the<br> -line is termed the receiver.<br> -<br> -Fig. 325 shows the construction of the Bell telephone in universal use<br> -in this country as the receiver. M is a bar magnet, in a case L L. B B<br> -is a bobbin or coil of insulated wire surrounding one end of the magnet.<br> -D is the diaphragm of soft iron plate (ferrotype metal), and E is the<br> -mouthpiece. The terminals of the coil B B connect with the binding<br> -screws C C. The wire in the coil is No. 36, A. W. G., and is wound to a<br> -resistance of about 80 ohms.<br> -<br> -<br> -524 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -As typical transmitter the Blake instrument may be cited. It is a carbon<br> -microphone. It is shown in section in the cut; a is the mouthpiece and e<br> -is a diaphragm of iron plate, although other substances could be used; f<br> -is a steel spring, with a platinum contact piece at its end. One end<br> -bears against the diaphragm, the other against a carbon block k. The<br> -latter is carried by a brass block p, and pressure is maintained between<br> -these contacts by the spring g and weight of the piece c, which by<br> -gravity tends to press all together. The current passes by way of the<br> -spring f, carbon button k and spring g through the circuit indicated.<br> -<br> -A battery is in circuit with these parts. If a telephone is also in<br> -circuit, and the transmitter is spoken against, the diaphragm vibrating<br> -affects the resistance of the carbon-platinum contact, without even<br> -breaking the contact, and the telephone reproduces the sound. The heavy<br> -piece of metal C acts by its inertia to prevent breaking of the contact.<br> -The position of this piece c, which is carried by the brass plate m, is<br> -adjusted by the screw n.<br> -<br> -<br> -<img style="width: 279px; height: 752px;" alt="" - src="images/524F326.JPG"><br> -Fig. 326. SECTION OF BLAKE TRANSMITTER.<br> -<br> -<br> -In practice the transmitter and battery are usually on a local circuit,<br> -which includes the primary of an induction coil. The line and distant<br> -receiving telephone are in circuit with the secondary of the induction<br> -coil, without any battery.<br> -<br> -<span style="font-weight: bold;">Telephone, Bi-.</span><br> -A pair of telephones carried at the ends of a curved bar or spring so<br> -that they fit the head of a person using them. One telephone is held<br> -against each ear without the use of the hands.<br> -<br> -<br> -525 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Telephone, Capillary.</span><br> -A telephone utilizing electro-capillarity for the production of<br> -telephonic effects. The following describes the invention of Antoine<br> -Breguet.<br> -<br> -The point of a glass tube, drawn out at its lower end to a capillary<br> -opening dips vertically into a vessel. This vessel is partly filled with<br> -mercury, over which is a layer of dilute sulphuric acid. The end of the<br> -immersed tube dips into the acid, but does not reach the mercury. One<br> -line contact is with mercury in the tube, the other with the mercury in<br> -the vessel. The arrangement of tube and vessel is duplicated, giving one<br> -set for each end of the line. On introducing a battery in the circuit<br> -the level of the mercury is affected by electro-capillarity. The tubes<br> -are closed by plates or diaphragms at their tops, so as to enclose a<br> -column of air. It is evident that the pressure of this air will depend<br> -upon the level of the mercury in the tube, and this depends on the<br> -electro-motive force. On speaking against the diaphragm the sound waves<br> -affect the air pressure, and consequently the level, enough to cause<br> -potential differences which reproduce the sound in the other instrument.<br> -<br> -<br> -<img style="width: 598px; height: 385px;" alt="" - src="images/525F327.jpg"><br> -Fig. 327. BREGURT'S CAPILLARY TELEPHONE.<br> -<br> -<br> -<span style="font-weight: bold;">Telephone, Carbon.</span><br> -A telephone transmitter based on the use of carbon as a material whose<br> -resistance is varied by the degree of pressure brought to bear upon it.<br> -Undoubtedly the surface contact between the carbon and the other<br> -conducting material has much to do with the action. Many carbon<br> -telephones have been invented. Under Telephone the Blake transmitter is<br> -described, which is a carbon telephone transmitter. The Edison carbon<br> -transmitter is shown in section in the cut. E is the mouth piece and D<br> -the diaphragm. I is a carbon disc with adjusting screw V. A platinum<br> -plate B B, with ivory button b, is attached to the upper surface of the<br> -carbon disc. C C is an insulating ring. The wire connections shown bring<br> -the disc into circuit. It is connected like a Blake transmitter. It is<br> -now but little used.<br> -<br> -<br> -<img style="width: 730px; height: 518px;" alt="" - src="images/526F328.JPG"><br> -Fig. 328. SECTION OF EDISON CARBON TRANSMITTER.<br> -<br> -<br> -526 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Telephone, Chemical.</span><br> -A telephone utilizing chemical or electrolytic action in transmitting or<br> -receiving. The electro-motograph is an example of a chemical receiver.<br> -(See Electro-motograph.)<br> -<br> -<br> -<span style="font-weight: bold;">Telephone, Electrostatic.</span><br> -A telephone utilizing electrostatic disturbances for reproduction of the<br> -voice. In the cut D and C are highly charged electrophori. The<br> -diaphragms A and B when spoken to affect the potential of the<br> -electrophorus so as to produce current variations which will reproduce<br> -the sound. Dolbear and others have invented other forms of transmitters<br> -based on electrostatic action. Receivers have also been constructed. A<br> -simple condenser may be made to reproduce sound by being connected with<br> -a powerful telephone current.<br> -<br> -<br> -<img style="width: 550px; height: 197px;" alt="" - src="images/526F329.JPG"><br> -Fig. 329. DIAGRAM OF EDISON'S ELECTROSTATIC TELEPHONE.<br> -<br> -<br> -<span style="font-weight: bold;">Telephone Induction Coil.</span><br> -The induction coil used in telephone circuits for inducing current on<br> -the main line. It is simply a small coil wound with two separate<br> -circuits of insulated wire. In the Edison telephone the primary coil, in<br> -circuit with the transmitter, is of No. 18 to 24 wire and of 3 to 4 ohms<br> -resistance. The secondary in circuit with the line and receiving<br> -instrument is of No. 36 wire and of 250 ohms resistance. The Bell<br> -telephone induction coil has its primary of No. 18 to 24 wire wound to a<br> -resistance of 1/2 ohm, and its secondary of No. 36 wire, and of 80 ohms<br> -resistance.<br> -<br> -<br> -527 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Telephone, Reaction.</span><br> -A form of telephone containing two coils of insulated wire, one of which<br> -is mounted on the disc, and the other on the magnet pole in the usual<br> -way. These coils react upon each other so as to strengthen the effect.<br> -<br> -<br> -<span style="font-weight: bold;">Telephone, Thermo-electric.</span><br> -A telephone transmitter including a thermo-electric battery, placed in<br> -circuit with the line. A plate of vulcanite faces it. When the sound<br> -waves strike the vulcanite they move it backward and forward. These<br> -movements, owing to the elasticity of the vulcanite, produce minute<br> -changes of temperature in it, which affecting the thermo-electric pile<br> -produce in the circuit currents, which passing through a Bell telephone<br> -cause it to speak. This type of instrument has never been adopted in<br> -practice.<br> -<br> -<br> -<span style="font-weight: bold;">Telephote.</span><br> -An apparatus for transmitting pictures electrically, the properties of<br> -selenium being utilized for the purpose.<br> -<br> -Synonym--Pherope.<br> -<br> -<br> -<span style="font-weight: bold;">Teleseme.</span><br> -An annunciator, displaying on a dial the object wanted by the person<br> -using it. It is employed to transmit messages from rooms in a hotel to<br> -the office, or for similar functions.<br> -<br> -<br> -<span style="font-weight: bold;">Tele-thermometer.</span><br> -A thermometer with electric attachment for indicating or recording its<br> -indications at a distance.<br> -<br> -<br> -<span style="font-weight: bold;">Tempering, Electric.</span><br> -A process of tempering metals by electrically produced heat. The article<br> -is made part of an electric circuit. The current passing through it<br> -heats it, thereby tempering it. For wire the process can be made<br> -continuous. The wire is fed from one roll to another, and if required<br> -one roll may be immersed in a liquid bath or the wire between the rolls<br> -may be led therein. The current is brought to one roll and goes through<br> -the wire to the other. As it does this the wire is constantly fed from<br> -one roll to another. The bath may be used as described to cool it after<br> -the heating. The amount of heating may be regulated by the rate of<br> -motion of the wire.<br> -<br> -<br> -528 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Ten, Powers of.</span><br> -This adjunct to calculations has become almost indispensable in working<br> -with units of the C. G. S. system. It consists in using some power of 10<br> -as a multiplier which may be called the factor. The number multiplied<br> -may be called the characteristic. The following are the general<br> -principles.<br> -<br> -The power of 10 is shown by an exponent which indicates the number of<br> -ciphers in the multiplier. Thus 10^2 indicates 100; 10^3 indicates 1,000<br> -and so on.<br> -<br> -The exponent, if positive, denotes an integral number, as shown in the<br> -preceding paragraph. The exponent, if negative, denotes the reciprocal<br> -of the indicated power of 10. Thus 10^-2 indicates 1/100; 10^-3 -indicates<br> -1/1000 and so on.<br> -<br> -The compound numbers based on these are reduced by multiplication or<br> -division to simple expressions. Thus: 3.14 X 10^7 = 3.14 X 10,000,000 =<br> -31,400,000. 3.14 X 10^-7 = 3.14/10,000,000 or 314/1000000000. Regard -must<br> -be paid to the decimal point as is done here.<br> -<br> -To add two or more expressions in this notation if the exponents of the<br> -factors are alike in all respects, add the characteristics and preserve<br> -the same factor. Thus:<br> -<br> - (51X 10^6) + (54 X 10^6) = 105 X 10^6.<br> - (9.1 X 10^-9) + (8.7 X 10^-9) = 17.8 X 10^-9.<br> -<br> -To subtract one such expression from another, subtract the<br> -characteristics and preserve the same factor. Thus:<br> -<br> - (54 X 10^6) - (51 X 10^6) = 3 X 10^6.<br> -<br> -If the factors have different exponents of the same sign the factor or<br> -factors of larger exponent must be reduced to the smaller exponent, by<br> -factoring. The characteristic of the expression thus treated is<br> -multiplied by the odd factor. This gives a new expression whose<br> -characteristic is added to the other, and the factor of smaller exponent<br> -is preserved for both,<br> -<br> -Thus:<br> - (5 X 10^7) + (5 X10^9) = (5 X 10^7) + (5 X 100 X 10^7) = 505 X -10^7.<br> -<br> -The same applies to subtraction. Thus:<br> - (5 X 10^9) - (5 X 10^7) = (5 X 100 X 10^7) - (5 X 10^7) = 495 X -10^7.<br> -<br> -If the factors differ in sign, it is generally best to leave the<br> -addition or subtraction to be simply expressed. However, by following<br> -the above rule, it can be done. Thus:<br> -<br> -Add<br> - 5 X 10^-2 and 5 X 10^3.<br> - 5 X 10^3 = 5 X 10^5 X 10^-2<br> - (5 X 10^5 X 10^-2) + (5 X 10^-2) = 500005 X 10^-2<br> -<br> -This may be reduced to a fraction 500000/100 = 5000.05.<br> -<br> -To multiply add the exponents of the factors, for the new factor, and<br> -multiply the characteristics for a new characteristic. The exponents<br> -must be added algebraically; that is, if of different signs the<br> -numerically smaller one is subtracted from the other one, and its sign<br> -is given the new exponent.<br> -<br> -Thus;<br> - (25 X 10^6) X (9 X 10^8) = 225 X 10^14.<br> - (29 X 10^ -8) X (11 X 10^7) = 319 X 10^-1<br> - (9 X 10^8) X (98 X 10^2) = 882 X 10^1<br> -<br> -<br> -529 STANDARD ELECTRICAL DICTIONARY. <br> -<br> -<br> -To divide, subtract (algebraically) the exponent of the divisor from <br> -that of the dividend for the exponent of the new factor, and divide the -<br> -characteristics one by the other for the new characteristic. Algebraic <br> -subtraction is effected by changing the sign of the subtrahend, <br> -subtracting the numerically smaller number from the larger, and giving <br> -the result the sign of the larger number.<br> -(Thus to subtract 7 from 5 proceed thus; 5 - 7 = -2.)<br> -<br> -Thus;<br> - (25 X 10^6) / (5 X 10^8) = 5 X 10^-2<br> - (28 X 10^-8) / (5 X 10^3) = 5.6 X 10^-11<br> -<br> -[Transcriber's note: I have replaced ordinary exponential notation by<br> -the more compact and simpler "programming" representation. The last two<br> -example would be:<br> - 25E6 / 5E8 = 5E-2<br> - 28E-8 / 5E3 = 5.6E-11<br> -]<br> -<br> -<br> -<span style="font-weight: bold;">Tension.</span><br> -Electro-motive force or potential difference in a current system is<br> -often thus termed. It is to be distinguished from intensity or current<br> -strength, which word it too greatly resembles.<br> -<br> -<br> -<span style="font-weight: bold;">Tension, Electric.</span><br> -(a) The condition an electrified body is brought into by<br> -electrification, when each molecule repels its neighbor. The condition<br> -is described as one of self-repulsion.<br> -<br> -(b) The voltage or potential difference of a circuit is also thus<br> -termed.<br> -<br> -<br> -<span style="font-weight: bold;">Terminal.</span><br> -The end of any open electric circuit, or of any electric apparatus; as<br> -the terminals of a circuit, dynamo, or battery.<br> -<br> -<br> -<span style="font-weight: bold;">Terminal Pole.</span><br> -In telegraph line construction the last pole of a series; one beyond<br> -which the line is not carried. Such pole, as the pull of the wires is<br> -all in one direction, requires special staying or support. The regular<br> -line poles are free from this strain, as the wire pulls in both<br> -directions.<br> -<br> -<br> -<span style="font-weight: bold;">Tetanus, Acoustic.</span><br> -A term in electro-therapeutics. An effect produced on a nerve by very<br> -rapidly alternating induced currents. The currents are produced by an<br> -induction coil with a vibrator giving a musical note. This is a species<br> -of gauge of proper frequency of alternations.<br> -<br> -<br> -<span style="font-weight: bold;">Theatrophone.</span><br> -An apparatus worked by automatic paying machinery by which a telephone<br> -connection is made with a theatre or opera by the deposition of a coin<br> -in a slot.<br> -<br> -<br> -<span style="font-weight: bold;">Therm.</span><br> -A unit of heat. It has been proposed by the British Association and<br> -amounts to a redefinition of the smaller calorie. It is the amount of<br> -heat required to raise the temperature of one gram of water one degree<br> -centigrade, starting at the temperature of maximum density of water.<br> -<br> -<br> -530 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Thermaesthesiometer.</span><br> -An electro-therapeutic instrument for testing the sensitiveness of the<br> -surface of the body to changes of temperature. Vessels of mercury are<br> -provided with thermometers to indicate their temperature. One vessel is<br> -surrounded by an electric conductor wound in a number of turns. The<br> -temperature is raised by passing a current through this. By successive<br> -applications of the vessels to the same spot upon the skin the power of<br> -differentiating temperatures is determined.<br> -<br> -<br> -<span style="font-weight: bold;">Thermo Call.</span><br> -(a) An electric alarm or call bell operated by thermo-electric currents.<br> -It may serve as a fire alarm or heat indicator, always bearing in mind<br> -the fact that differential heat is the requisite in a thermo-electric<br> -couple.<br> -<br> -(b) See Thermo-electric Call.<br> -<br> -<br> -<span style="font-weight: bold;">Thermo-chemical Battery.</span><br> -A voltaic battery in which the electro-motive force is generated by<br> -chemical action induced by heat.<br> -<br> -The chemical used generally is sodium nitrate or potassium nitrate. The<br> -positive plate is carbon. On heating the battery the nitrate attacks the<br> -carbon, burning it and produces potential difference. For negative plate<br> -some metal unattacked by the nitrate may be employed.<br> -<br> -<br> -<img style="width: 504px; height: 289px;" alt="" - src="images/530F330.JPG"><br> -Fig. 330. POUILLET'S THERMO-ELECTRIC BATTERY.<br> -<br> -<br> -<span style="font-weight: bold;">Thermo-electric Battery or Pile.</span><br> -A number of thermo-electric couples q. v., connected generally in<br> -series.<br> -<br> -In Nobili's pile the metals are bismuth and antimony; paper bands<br> -covered with varnish are used to insulate where required. In Becquerel's<br> -pile copper sulphide (artificial) and German silver, (90 copper, 10<br> -nickel) are the two elements. The artificial copper sulphide is made<br> -into slabs 4 inches long, 3/4 inch wide, and 1/2 inch thick (about).<br> -Water is used to keep one set of junctions cool, and gas flames to heat<br> -the other set. In Fig. 331, c, d represent the binding screws. The<br> -couples are mounted on a vertical standard, with adjusting socket and<br> -screw B, so that its lower end can be immersed in cold water, or raised<br> -therefrom as desired.<br> -<br> -<br> -531 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 497px; height: 352px;" alt="" - src="images/531F331.JPG"><br> -FIG. 331. BECQUEREL'S THERMO-ELECTRIC BATTERIES.<br> -<br> -<br> -Fig. 332 shows one couple of the battery. S is artificial antimony<br> -sulphide; M is German silver; m is a protecting plate of German silver<br> -to save the sulphide from wasting in the flame.<br> -<br> -<br> -<img style="width: 322px; height: 412px;" alt="" - src="images/531F332.JPG"><br> -Fig. 332. ELEMENTS OF BECQUEREL'S THERMOELECTRIC BATTERIES.<br> -<br> -<br> -Clamond's pile has been used in practical work. The negative element is<br> -an alloy of antimony, 2 parts, zinc, 1 part. The positive element is tin<br> -plate. Mica in some parts, and a paste of soluble glass and asbestus in<br> -other parts are used as insulators. They are built up so as to form a<br> -cylinder within which the fire is maintained. The air is relied on to<br> -keep the outer junctions cool. The temperature does not exceed 200° -C.<br> -(392° F.)<br> -<br> -Sixty such elements have an electro-motive force of 300 volts and an<br> -internal resistance of 1.5 ohms. Such a battery requires the consumption<br> -of three cubic feet of gas per hour. (See Currents, Thermo-electric. )<br> -<br> -<br> -532 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Thermo-electric Call.</span><br> -A thermostat arranged to ring a bell or to give some indication when the<br> -temperature rises or falls beyond certain points. It may be a compound<br> -bar of brass and steel fixed at one end and free for the rest of its<br> -length. Its end comes between two adjustable contacts. As the<br> -temperature rises it bends one way (away from the brass side) and, if<br> -hot enough, touching a contact gives one signal. If the temperature<br> -falls it curves the other way, and if cold enough touches the other<br> -contact, giving another signal. (See Thermostat, Electric.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Thermo-electric Couple.</span><br> -If two dissimilar conductors form adjacent parts of a closed circuit,<br> -and their junction is at a different temperature than that of the rest<br> -of the circuit, a current will result. Such pair of conductors are<br> -called a thermo-electric couple. They may be joined in series so as to<br> -produce considerable electro-motive force. (See Thermo-electricity and<br> -other titles in thermo-electricity.)<br> -<br> -The efficiency of a thermo-electric couple according to the second law<br> -of thermo-dynamics is necessarily low--not over 10 per cent.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Thermo-electric Diagram.</span><br> -A diagram indicating the change in potential difference for a fixed<br> -difference of temperature between different metals at different<br> -temperatures. It is laid out with rectangular co-ordinates. On one axis<br> -temperatures are laid off, generally on the axis of abscissas. On the<br> -other axis potential differences are marked. Different lines are then<br> -drawn, one for each metal, which show the potential difference, say for<br> -one degree centigrade difference of temperature between their junctions,<br> -produced at the different temperatures marked on the axis of abscissas.<br> -<br> -<br> -<img style="width: 616px; height: 325px;" alt="" - src="images/532F333.JPG"><br> -Fig. 333. THERMO-ELECTRIC DIAGRAM, <br> -GIVING POTENTIAL DIFFERENCE IN C. G. S. UNITS.<br> -<br> -<br> -Thus taking copper and iron we find at the temperature 0° C. -(32° F.) a<br> -difference of one degree C. (1.8° F.) in their junctions will -produce a<br> -potential difference of 15.98 micro volts, while at 274.5° C. -(526.1°<br> -F.) the lines cross, and zero difference of potential is indicated.<br> -Taking the lead line on the same diagram it crosses the iron line a<br> -little above 350° C. (662° F.), indicating that if one junction -is<br> -heated slightly above and the other is heated slightly below this<br> -temperature no potential difference will be produced. Lead and copper<br> -lines, on the other hand, diverge more and more as the temperature<br> -rises.<br> -<br> -<br> -533 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Thermo-electric Inversion.</span><br> -The thermo-electric relations of two conductors vary at different<br> -temperatures. Sometimes at a definite point they have no electro-motive<br> -force and after passing this point the positive plate becomes a negative<br> -one and vice versa. This is inversion, or reversal. (See Thermo-electric<br> -Diagram.)<br> -<br> -Synonym-- Thermo-electric Reversal.<br> -<br> -<br> -<span style="font-weight: bold;">Thermo-electricity.</span><br> -Electric energy, electro-motive force or electrification produced from<br> -heat energy by direct conversion. It is generally produced in a circuit<br> -composed of two electric conductors of unlike material, which circuit<br> -must possess at least two junctions of the unlike substances. By heating<br> -one of these to a higher temperature than that of the other, or by<br> -maintaining one junction at a different temperature from that of the<br> -other a potential difference is created accompanied by an electric<br> -current.<br> -<br> -In many cases differential application of heat to an identical material<br> -will develop potential difference. This effect, the converse of the<br> -Thomson effect, is not used to produce currents, as in a closed circuit<br> -the potential differences due to differential heating would neutralize<br> -each other.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Thermo-electric Junction.</span><br> -A junction between two dissimilar conductors, which when heated or<br> -cooled so as to establish a differential temperature, as referred to the<br> -temperature of the other junction, produces potential difference and an<br> -electric current.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Thermo-electric Pile, Differential.</span><br> -A thermo-electric pile arranged to have opposite faces subjected to<br> -different sources of heat to determine the identity or difference of<br> -temperature of the two sources of heat. It corresponds in use to a<br> -differential air thermometer.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Thermo-electric Power.</span><br> -The coefficient which, multiplying the difference of temperature of the<br> -ends of a thermo-electric couple, gives the potential difference,<br> -expressed in micro-volts. It has always to be assigned to a mean or<br> -average temperature of the junctions, because the potential difference<br> -due to a fixed difference of temperature between two metals varies with<br> -the average temperature of the two junctions. (See Thermo-electric<br> -Diagram.)<br> -<br> -For bismuth and antimony at 19.5° C. (67.1° F.) it is 103 -microvolts per<br> -degree Centigrade (1.8° F.). This means that if one junction is -heated<br> -to 19° C. and the other to 20° C. (66.2° F. and 68.0° -F.) a potential<br> -difference of 103 micro-volts will be produced.<br> -<br> -The potential difference is approximately proportional to the difference<br> -of temperature of the two junctions if such difference is small. Hence<br> -for large differences of potential the thermo-electric power coefficient<br> -does not apply.<br> -<br> -As a differential function it is thus deduced by Sir William Thomson,<br> -for expressing the E. M. F. in a thermo-electric circuit: If a circuit<br> -is formed of two metals with the junctions at indefinitely near<br> -temperatures, t and t + dt, and dE is the E. M. F. of the circuit, then<br> -the differential coefficient dE/dt is called the thermo-electric power<br> -of the two metals for the temperature t.<br> -<br> -<br> -534 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Thermo-electric Series.</span><br> -The arrangement of possible thermoelectric elements, q. v., in a table<br> -in the order of their relative polarity. Bismuth and antimony form a<br> -couple in which when their junction is heated the bismuth acts as the<br> -positive or negatively charged element and antimony as the negative or<br> -positively charged. Between these two extremes according to Seebeck the<br> -series runs as follows:<br> -<br style="font-family: monospace;"> -<small><span style="font-family: monospace;"> -Antimony, Silver, -Copper,</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Arsenic, -Gold, Platinum,</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -Iron, Molybdenum, -Palladium,</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Steel, -Tin, Cobalt,</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Cadmium, -Lead, Nickel,</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Tungsten, -Mercury, Bismuth.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -Zinc, Manganese,</span></small><br> -<br> -A differential temperature of 1° C. (1.8° F.) in a -bismuth-antimony<br> -couple maintains a potential difference of 103 micro-volts.<br> -<br> -Matthiessen gives a different series; it is arranged in two columns; the<br> -first column has positive coefficients annexed the second has negative.<br> -On subtracting the greater one from the lesser, which, if the two<br> -elements are in different columns, of course amounts to adding after<br> -changing the negative sign, the relative potential difference due to the<br> -combination is obtained.<br> -<small><span style="font-family: monospace;"> - -+ --</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Bismuth -25 Gas -Coke 0.1</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -Cobalt -9 -Zinc -0.2</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Potassium -5.5 -Cadmium 0.3</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -Nickel -5 -Strontium 2.0</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -Sodium 3. -Arsenic 3.8</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -Lead 1.03 -Iron -5.2</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Tin -1 Red Phosphorous 9.6</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -Copper -1 -Antimony 9.8</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -Silver -1 -Tellurium 179.9</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Platinum -0.7 -Selenium 290</span></small><br> -<br> -Thus the relative E. M. F. of a bismuth-nickel couple, as both are in<br> -the + column, would be 25 - 5 = 20; that of a cobalt-iron couple, one<br> -being in the + column the other in the - column, would be 9 + 5.2 =<br> -14.2. Alloys are not always intermediate to their constituents, and<br> -small amounts of impurities affect the results largely. This may account<br> -for the discrepancies of different observers. Other compounds could be<br> -introduced into the series.<br> -<br> -Artificial silver sulphide has been used by Becquerel in a<br> -thermo-electric battery.<br> -<br> -<br> -535 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Thermo-electric Thermometer.</span><br> -A species of differential thermometer. It consists of two<br> -thermo-electric junctions connected in opposition with a galvanometer in<br> -the circuit. Any inequality of temperature in the two ends or junctions<br> -produces a current shown by the galvanometer. It may be used to<br> -determine the temperature of a distant place, one of the junctions being<br> -located there and the other being under control of the operator. If the<br> -latter junction is heated until no current is produced its temperature<br> -is evidently equal to that of the distant couple or junction. The<br> -heating may be done with hot water or mercury, or other melted metal.<br> -The temperature of the water, or other substance, gives the temperature<br> -of the distant place.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Thermolysis.</span><br> -Decomposition by heat; dissociation. All compound bodies are<br> -decomposable by heat if it is intense enough. Hence at very elevated<br> -temperatures there can be no combustion.<br> -<br> -Synonym--Dissociation.<br> -<br> -<br> -<span style="font-weight: bold;">Thermometer.</span><br> -An instrument for indicating the intensity of heat. Three scales of<br> -degrees of heat are used in practise, the Fahrenheit, Réamur, and<br> -Centigrade, each of which is described under its own title. (See Zero,<br> -Thermometric-Zero, Absolute.) The ordinary thermometer depends on the<br> -expansion of mercury; in some cases alcohol is used. Besides these the<br> -compound bar principle as used in the thermostat (see Thermostat,<br> -Electric) is employed.<br> -<br> -<br> -<span style="font-weight: bold;">Thermometer, Electric.</span><br> -(a) A thermometer whose indications are due to the change of resistance<br> -in conductors with change of temperature. Two exactly similar resistance<br> -coils maybe electrically balanced against each other. On exposing one to<br> -a source of heat, its resistance will change and it will disturb the<br> -balance. The balance is restored by heating the other coil in a vessel<br> -of water when the temperature of the water gives the temperature of both<br> -coils. The coils are enclosed in water-tight metallic cases.<br> -<br> -Synonym--Electric Resistance Thermometer.<br> -<br> -(b) A differential thermometer may be made by connecting with a pair of<br> -conductors, two thermo-electric couples in opposition to each other, and<br> -including a galvanometer in series. On heating the junction of one<br> -couple more than that of the other a current at once goes through the<br> -galvanometer.<br> -<br> -(c) (See Thermometer, Kinnersley's.)<br> -<br> -Synonym--Thermo-electrometer.<br> -<br> -<br> -536 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<img style="width: 449px; height: 601px;" alt="" - src="images/536F334.JPG"><br> -Fig. 334. KINNERSLEY'S THERMOMETER.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Thermometer, Kinnersley's.</span><br> -A thermo-electrometer. A large glass tube is mounted on a standard and<br> -communicates with a small tube parallel to it. Water is poured in so as<br> -to rise in the small tube. Two wires terminating in bulbs enter the<br> -large tube by its top and bottom. The upper wire can be adjusted by<br> -moving up and down through a stuffing box. On discharging a Leyden jar<br> -through the space between the knobs on the two wires the water for a<br> -moment rises in the small tube. There is little or no accuracy in the<br> -instrument. It is allied to the electric mortar (see Mortar, Electric)<br> -as a demonstrative apparatus.<br> -<br> -Synonyms--Electric Thermometer--Thermo-electrometer.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Thermo-multiplier.</span><br> -A thermo-electric battery including a number of couples. The term is<br> -generally applied to a small battery with its similar junctions facing<br> -in one direction and used for repeating Melloni's experiments on radiant<br> -energy, or so-called radiant heat.<br> -<br> -<br> -537 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Thermophone.</span><br> -An apparatus for reproducing sounds telephonically by the agency of<br> -heat; a receiving telephone actuated by heat. Thus a wire may be<br> -attached to the centre of a diaphragm and kept in tension therefrom, and<br> -the transmitting telephone current may be caused to pass through it. The<br> -wire changes in temperature and consequently in length with the pulses<br> -of current going through it and vibrates the diaphragm, reproducing the<br> -sound. It is to be distinguished from the thermo-electric telephone<br> -which involves the action of potential difference produced by<br> -thermo-electric action.<br> -<br> -<br> -<span style="font-weight: bold;">Thermostat, Electric.</span><br> -A thermostat or apparatus, similar to a thermometer in some cases, for<br> -closing an electric circuit when heated. It is used in connection with<br> -automatic fire alarms to give warning of fire. For this use a<br> -temperature of 52° C. (125° F.) is an approved one for setting -one at,<br> -to complete the circuit. It is also applied to regulation of<br> -temperature, as in incubators.<br> -<br> -(a) One kind of thermostat consists of a compound bar wound into a<br> -spiral and fastened at one end, to which a terminal of a circuit is<br> -connected. The bar may be made of two strips of brass and iron riveted<br> -together, and wound into a spiral. When such a bar is submitted to<br> -changes of temperature it bends in different directions, because brass<br> -expands and contracts more under changes of temperature than does iron.<br> -A contact point, to which the other terminal is connected, is arranged<br> -to make contact with the spiral at any desired degree of temperature,<br> -thus closing an electric circuit and ringing a bell, opening or closing<br> -a damper, or doing anything else to notify an attendant or to directly<br> -change the temperature.<br> -<br> -If the brass forms the outside of the spiral, increase of temperature<br> -makes the bending of the spiral bring the coils still closer. If the<br> -brass forms the inside, increase of temperature makes the spiral tend to<br> -become less close. As shown in the cut, the brass should lie along the<br> -inside of the spiral.<br> -<br> -Sometimes a straight compound bar is used, one of whose ends is fastened<br> -and the other is free. As the temperature changes such a bar curves more<br> -or less, its free end moving to and fro. Two contact screws are<br> -provided, one on each side of its free end. If the temperature falls it<br> -makes contact with one of these; if the temperature rises, it makes<br> -contact with the other. Thus it may close one of two circuits, one for a<br> -fall and the other for a rise in temperature.<br> -<br> -It is well to introduce a third bar between the brass and iron ones,<br> -made of some material of intermediate coefficient of expansion.<br> -<br> -(b) Another kind of thermostat comprises a vessel of air or other gas,<br> -which, expanding by heat, actuates a piston or other device and closes<br> -an electric circuit. Synonym--Electro-pneumatic Thermostat.<br> -<br> -(c) Another form utilizes the expansion of mercury. The mercury is made<br> -part of an open electric circuit. As it expands it comes in contact with<br> -the other terminal of the circuit, thus completing it, when the current<br> -gives an alarm or does as is provided for in the apparatus employed.<br> -<br> -Thermostats may be worked on either open or closed circuits; normally<br> -the circuit may be open as described and may close on rise of<br> -temperature, or it may be normally closed and open as the temperature<br> -rises.<br> -<br> -<br> -<img style="width: 378px; height: 644px;" alt="" - src="images/537F335.JPG"><br> -Fig. 335. ELECTRIC THERMOSTAT.<br> -<br> -<br> -538 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Thomson Effect.</span><br> -In an unequally heated conductor the differential heating is either<br> -increased as in iron, or diminished as in copper by a current. In lead<br> -the phenomenon does not occur. It is termed the Thomson effect. It is<br> -intimately related to the Peltier effect.<br> -<br> -In a thermo-electric couple a heated junction is the source of<br> -electro-motive force, if heated more than other parts of the circuit.<br> -The current in a copper-iron junction flows from the copper to the iron<br> -across the heated junction. A hot section of an iron conductor next to a<br> -cold section of the same is a source of thermoelectricity, in the sense<br> -that the hot section is negative to the colder. A current passing from<br> -the hot to the cold iron travels against rising potentials, and cools<br> -the iron in the cooler parts. As it passes to the hotter parts it<br> -travels against falling potentials and hence heats the iron in these<br> -parts. In this way a current intensifies differential heating in an iron<br> -conductor.<br> -<br> -In copper the reverse obtains. In it the thermo-electric relations of<br> -hot and cold copper are the reverse of those of iron, and a current<br> -tends to bring all parts of a differentially heated copper conductor to<br> -an identical temperature.<br> -<br> -As a current travels in iron from hot to cold it absorbs heat; in copper<br> -traveling from cold to hot it absorbs heat.<br> -<br> -The convection of heat by a current of electricity in unequally heated<br> -iron is negative, for it is opposed to that convection of heat which<br> -would be brought about by the flow of water through an unequally heated<br> -tube. In copper, on the other hand, the electric convection of heat is<br> -positive. (Daniell.)<br> -<br> -The above effects of the electric current upon an unequally heated<br> -conductor are termed the Thomson effects. In iron, at low red heat, they<br> -are reversed and are probably again reversed at higher temperatures.<br> -<br> -<br> -539 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Three Wire System.</span><br> -A system of distribution of electric current for multiple arc or<br> -constant potential service. It is the invention of Thomas A. Edison.<br> -<br> -It includes three main wires which start from the central station or<br> -generating plant, and ramify with corresponding reduction in size,<br> -everywhere through the district or building to be lighted. As ordinarily<br> -carried out when dynamos are used, the dynamos are arranged in groups of<br> -two. One lateral lead starts from the negative binding post of one<br> -dynamo. The positive terminal of this dynamo connects to the negative of<br> -the other. Between the two dynamos the central or neutral lead is<br> -connected. The other lateral lead starts from the positive binding post<br> -of the second dynamo.<br> -<br> -The lamps or other appliances are calculated for the potential<br> -difference of a single dynamo. They are arranged between the neutral<br> -wire and the laterals, giving as even a disposition as possible to the<br> -two laterals.<br> -<br> -<br> -<img style="width: 661px; height: 193px;" alt="" - src="images/539F336.JPG"><br> -Fig. 336. DIAGRAM OF THREE WIRE SYSTEM <br> -SHOWING NEUTRAL WIRE.<br> -<br> -<br> -If evenly arranged and all burning or using current, no current goes<br> -through the neutral wire. If all the lamps situated on one lateral are<br> -on open circuit all the current goes through the neutral wire. In other<br> -cases the neutral wire receives the excess of current only.<br> -<br> -The advantages of the system are that it uses smaller wire than the two<br> -wire system for lamps of the same voltage. If lamps of double the<br> -voltage were used the two wire system would be most economical.<br> -<br> -<br> -540 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Four wire and five wire systems have been more or less used, based on<br> -identical considerations, and involving in each case the coupling of<br> -three or of four dynamos respectively, or else employing a dynamo with<br> -special armature connections to give the requisite three-fold or<br> -four-fold division of total potential. In the five wire system the total<br> -voltage is four times that of a single lamp, the lamps are arranged four<br> -in series across the leads and the central wire is the only one that can<br> -be considered a neutral wire. When lamps are burning entirely from three<br> -side-leads they constitute a sort of three wire system by themselves,<br> -and their central wire may for the time be a neutral wire.<br> -<br> -In some of the three wire mains, especially in the larger sizes, the<br> -neutral wire is made of much smaller section than that of a lateral<br> -conductor, because in extensive districts it is practically impossible<br> -that the current should be concentrated in the neutral wire.<br> -<br> -<br> -<span style="font-weight: bold;">Throw.</span><br> -In a galvanometer the instantaneous deflection of the needle when the<br> -contact or closing of the circuit is instantaneous, or when the<br> -discharge is completed before the needle begins to move. The throw of<br> -the needle is the datum sought when the ballistic galvanometer is used.<br> -<br> -Synonym--Elongation.<br> -<br> -<br> -<span style="font-weight: bold;">Throw-back Indicator.</span><br> -A drop annunciator, whose shutter or drop is electrically replaced.<br> -<br> -<br> -<span style="font-weight: bold;">Thrust-bearings.</span><br> -Bearings to support the end-thrust or push of a shaft. In disc armatures<br> -where the field-magnets attract the armatures in the direction of their<br> -axis of rotation, thrust-bearings have to be provided. In ordinary<br> -cylinder or drum armatures end-thrust is not applied, as a little end<br> -motion to and fro is considered advantageous as causing more even wear<br> -of the commutator surface.<br> -<br> -<br> -<span style="font-weight: bold;">Thunder.</span><br> -The violent report which, as we hear it, succeeds the lightning flash in<br> -stormy weather. It is really produced simultaneously with the lightning<br> -and is supposed to arise from disturbance of the air by the discharge.<br> -The rolling noise has been attributed to successive reflections between<br> -clouds and earth, and to series of discharges reaching the ear from<br> -different distances and through air of varying density. The subject is<br> -obscure. By timing the interval from lightning flash to the report of<br> -the thunder an approximate estimate of the distance of the seat of<br> -discharge can be made. The first sound of the thunder should be timed.<br> -An almost concurrence of thunder and lightning indicates immediate<br> -proximity of the discharge.<br> -<br> -[Transcriber's note: The speed of sound at sea level is about 5 seconds<br> -per mile.]<br> -<br> -<br> -<span style="font-weight: bold;">Ticker.</span><br> -A colloquial name for a stock or market report automatic printing<br> -telegraph, which prints its quotations and messages on a long tape.<br> -<br> -<br> -541 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Time Constant.</span><br> -(a) When current is first turned into a circuit of considerable<br> -self-induction it is resisted rather by the inductance than by the<br> -resistance. It is governed by the ratio of resistance and self-induction<br> -and this factor represents the time which it takes for the current to<br> -reach a definite fraction of its final strength. This fraction is<br> -(2.7183 - 1)/2.7183 or 0.63. 2.7183 is the base of the Napierian -system<br> -of logarithms. Thus if in any circuit we divide the inductance in<br> -henries by the resistance in ohms, the ratio gives the time-constant of<br> -the circuit, or it expresses the time which it will take for the current<br> -to reach 0.63 of its final value.<br> -<br> -(b) In a static condenser the time required for the charge to fall to<br> -1/2.7183th part of its original value.<br> -<br> -<br> -<span style="font-weight: bold;">Time Cut-outs.</span><br> -Cut-outs which automatically cut storage batteries out of the charging<br> -circuit when they are sufficiently charged.<br> -<br> -<br> -<span style="font-weight: bold;">Time-fall.</span><br> -In a secondary battery the decrease with use of electromotive force<br> -maintained by a primary or secondary battery. As the battery becomes<br> -spent its voltage falls. The conditions of the fall are represented by<br> -its discharging curve. (See Curve, Discharging.)<br> -<br> -<br> -<span style="font-weight: bold;">Time-reaction.</span><br> -A term in electro-therapeutics; the period of time occupied in the<br> -passage of the effects of an electric current from nerve to muscle.<br> -<br> -<br> -<span style="font-weight: bold;">Time-rise.</span><br> -In a secondary battery the increase of electromotive force produced<br> -during the charging process. Its rate and conditions are graphically<br> -shown in the charging curve. (See Curve, Charging.)<br> -<br> -<br> -<span style="font-weight: bold;">Tin.</span><br> -A metal; one of the elements; symbol, Sn; atomic weight, 117.8;<br> -equivalent, 58.9 and 29.5; valency, 2 and 4; specific gravity, 7.3.<br> -It is a conductor of electricity.<br> -<small><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Relative resistance, -compressed, (Silver = 1) 8.784</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Specific resistance at -0° C. (32° F.), -13.21 microhms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Resistance of a wire at -0° C. (32° F.),</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> (a) 1 foot long, weighing -1 -grain, 1.380 ohms.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> (b) 1 foot long, 1/1000 -inch thick, -79.47 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> (c) 1 meter long, weighing -1 -gram, .9632 "</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> (d) 1 meter long, 1 -millimeter thick, -.1682 "</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Resistance of a 1 inch -cube at 0° C. (32° -F.), 5.202 microhms.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> Percentage of variation in -resistance</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> per degree C. -(1.8° F.), at about 20° C. -(68° F.), .0365</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> Electro-chemical -equivalent (hydrogen = .0105), -.619 mgs.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -.310 "</span></small><br> -<br> -542 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Tinnitus, Telephone.</span><br> -A nervous affection of the ear, of the order of professional cramp; it<br> -is attributed to too much use of the telephone.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Tin Sounders.</span><br> -A recent addition to the single needle telegraph. (See Telegraph, Single<br> -Needle.) It consists of small tin plates, cut and bent, and so fitted in<br> -pairs to the instrument, that the needle as deflected strikes one or the<br> -other on its right and left hand movements. The sounders can be made to<br> -give sufficiently distinctive sounds to make sound-reading, q. v.,<br> -possible. Commercial tin plate, which is really tinned iron, seems to<br> -give the best results.<br> -<br> -<br> -<img style="width: 424px; height: 454px;" alt="" - src="images/542F337.JPG"><br> -Fig. 337. TIN SOUNDERS.<br> -<br> -<br> -<span style="font-weight: bold;">Tissandier's Solution. </span><br> -A solution for bichromate batteries. It is composed as follows:<br - style="font-family: monospace;"> -<small><span style="font-family: monospace;"> -</span><span style="font-family: monospace;">Water, -100 parts by weight</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> potassium -bichromate, 16 parts</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> 66° sulphuric -acid, 37 parts.</span></small><br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Tongue of Polarized Relay.</span><br> -The German silver extension of the vibrating or oscillating member of a<br> -polarized relay, corresponding to the armature of an ordinary relay.<br> -<br> -<br> -<span style="font-weight: bold;">Tongue of Polarized Relay, Bias of.</span><br> -In a Siemens' polarized relay the pole pieces are adjustable so that<br> -they may be brought nearer to or withdrawn from the tongue. One of the<br> -poles is adjusted so as to be nearer the tongue. This one-sided<br> -adjustment is the bias. Its effect is that when the relay is unexcited<br> -this pole attracts the armature so that it normally is drawn towards it.<br> -This ensures the normal contact of the tongue either with the contact<br> -point, or with the insulated stop piece or adjustment screw. Without<br> -bias the armature remains in contact with or drawn towards whichever<br> -pole it was last attracted to. In its usual use a bias is given it.<br> -<br> -<br> -<span style="font-weight: bold;">Top, Magnetic.</span><br> -A toy illustrating magnetic attraction. It consists of a disc or body of<br> -lead or other material, through which a magnetized steel spindle pointed<br> -at its lower end is thrust. A number of short pieces of iron wire are<br> -used with it. It is spun like an ordinary top upon the point of the<br> -spindle and one of the pieces of iron wire is laid by the side of its<br> -point. As it turns the magnetic adherence causes the piece of wire to be<br> -carried along in one direction by the rotation of the spindle, until the<br> -end is reached, when it goes over to the other side of the spindle and<br> -travels back again.<br> -<br> -By using bent pieces of wire of various shapes the most curious effects<br> -are produced. Circles and S shaped pieces give good effects. To increase<br> -the mysterious effect covered iron wire (bonnet wire) may be employed.<br> -<br> -<br> -<img style="width: 605px; height: 462px;" alt="" - src="images/543F338.JPG"><br> -Fig. 338. MAGNETIC TOP.<br> -<br> -<br> -543 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Torpedo, Electric.</span><br> -(a) A fish, the Raia Torpedo, which possesses the power of giving<br> -electric shocks. (See Ray, Electric.)<br> -<br> -(b) An instrument of war; a torpedo whose operations include electrical<br> -discharge or other electric function or factor of operation.<br> -<br> -<br> -<span style="font-weight: bold;">Torpedo, Sims-Edison.</span><br> -A torpedo driven by an electric motor, and also steered by electricity.<br> -Its motions are all controlled from the shore. The torpedo proper is<br> -carried some distance below the surface of the water by a vessel<br> -immediately above it, from which it is suspended by two rigid bars. In<br> -the torpedo is a cable reel on which the conducting cable is disposed.<br> -An electric motor and controlling gear are also contained within the<br> -torpedo. In its front the explosive is placed. It is driven by a screw<br> -propeller actuated by the electric motor. As it moves it pays out cable<br> -so that it has no cable to draw after it through the water, the cable<br> -lying stationary in the water behind it. This avoids frictional<br> -resistance to its motion. The maintenance of the torpedo at a proper<br> -depth is one of the advantages of the system.<br> -<br> -<br> -544 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Torque.</span><br> -A force tending to produce torsion around an axis. An example is the<br> -pulling or turning moment of an armature of an electric motor upon its<br> -shaft. It is often expressed as pounds of pull excited at the end of a<br> -lever arm one foot long.<br> -<br> -The expression is due to Prof. James Thompson, then of the University of<br> -Glasgow.<br> -<br> -"Just as the Newtonian definition of force is that which produces or<br> -tends to produce motion (along a line), so torque may be defined as that<br> -which produces or tends to produce torsion (around an axis). It is<br> -better to use a term which treats this action as a single definite<br> -entity than to use terms like 'couple' and 'moment,' which suggest more<br> -complex ideas." (S. P. Thompson.)<br> -<br> -A force, acting with radius r gives a torque equal to f X r ; f -and r <br> -may be expressed in any units. S. P. Thompson gives the following <br> -equivalents :<br> -<br> -To reduce<br> - dyne-centimeters to gram centimeters, divide by 981<br> - dyne-centimeters to meter-kilograms divide -by 981E5<br> - dyne-centimeter, to -pound-feet divide -by 13.56E6<br> - pound-feet to -meter-kilograms divide -by 7.23<br> -<br> -In each of these compound units the first unit is the force and the<br> -second unit is the radius or lever arm of the torque.<br> -<br> -Synonyms--Turning Moment--Moment of Couple--Axial Couple--Angular<br> -Force--Axial Force.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Torsion Balance, Coulomb's.</span><br> -Originally an apparatus in which electrostatic attraction or repulsion<br> -is measured against the torsion of a filament, often of silk-worm cocoon<br> -fibre. It consists in one form of a cylindrical glass vessel in which a<br> -light shellac needle is suspended horizontally by a fibre. This needle<br> -carries at one end a gilded disc or sphere and is suspended by a fine<br> -wire, or filament. A proof plane, q. v., is excited by touching it to<br> -the body under trial; it is then inserted in the case. The disc on the<br> -needle is first attracted and then repelled. The position finally taken<br> -by the needle is noted. The force of torsion thus produced is determined<br> -by twisting the filament by the torsion head on the top of the apparatus<br> -so as to move the needle a certain distance towards the proof plane. The<br> -more the torsion-head has to be turned to carry the needle through a<br> -specified arc the greater is the torsion effected or the greater is the<br> -repulsion exerted, The torsional force of a wire is proportional to the<br> -angle of torsion; this gives the basis for the measurement.<br> -<br> -With magnetic needle it is used to measure magnetic repulsion and<br> -attraction. The best material for the filament is quartz, but the<br> -instrument is not very much used.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Torsion Galvanometer.</span><br> -A galvanometer in which the torsion required to bring the index back to<br> -zero, when the current tends to displace it, is made the measure of the<br> -current strength or of the electro-motive force. It involves the use of<br> -a torsion head, q. v., or its equivalent.<br> -<br> -<br> -545 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Torsion Head.</span><br> -The handle and disc from whose undersurface the filament depends to<br> -which the needle or magnet is attached. It is turned to measure the<br> -torsional effect, the edge of the disc being marked or graduated so as<br> -to give the angle of deflection required to overcome the effect of the<br> -torque of the needle.<br> -<br> -<br> -<span style="font-weight: bold;">Torsion Suspension.</span><br> -Suspension by one or more wires, fibres, or ribands, involving the<br> -restitutive force of torsion. Thus fibre suspension, q. v., is a variety<br> -of torsion suspension.<br> -<br> -Often a single riband of steel stretched horizontally and secured at<br> -both ends is used, the suspended object, e. g., a balance beam, being<br> -attached at its own centre to the centre of the stretched riband. Quite<br> -sensitive balances are constructed on this principle. It is peculiarly<br> -available where an electric current is to be transmitted, as absolute<br> -contact is secured, as in William Thomson's ampere balances.<br> -<br> -<br> -<span style="font-weight: bold;">Touch.</span><br> -A term applied to methods of magnetization, as "single touch," "double<br> -touch," or "separate touch," indicating how the poles of the inducing<br> -magnet or magnets are applied to the bar to be magnetized. Under the<br> -titles of Magnetization the different methods are described.<br> -<br> -<br> -<span style="font-weight: bold;">Tourmaline.</span><br> -A mineral; a subsilicate; characterized by the presence of boric<br> -trioxide, which replaces aluminum oxide. It is notable for possessing<br> -pyro-electric properties. (See Pyro-electricity.)<br> -<br> -<br> -<span style="font-weight: bold;">Tower, Electric.</span><br> -The tower used in the tower system, q. v., of arc light illumination.<br> -<br> -<br> -<span style="font-weight: bold;">Tower System.</span><br> -In electric lighting the system of lighting extended areas by powerful<br> -arc lamps placed on high towers, generally of iron or steel frame-work.<br> -The lights are thus maintained at a high elevation, giving greater<br> -uniformity of illumination than if they were lower, but at the expense<br> -of considerable light which is lost. Sometimes wooden masts are employed<br> -instead of towers.<br> -<br> -The principle involved is that the intensity of light at any place given<br> -by a source of illumination varies with the square of its distance from<br> -the place in question. Hence in using strong arc lights it is an object<br> -to have the distances of all parts of the area illuminated at as nearly<br> -uniform distances from the light as possible. An approximation to<br> -uniformity is secured by placing the lamps at a very high elevation.<br> -<br> -<br> -546 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Transformer.</span><br> -In alternate current lighting the induction coil by which the primary<br> -current with high initial electro-motive force is caused to produce a<br> -secondary current with low initial electromotive force.<br> -<br> -A typical transformer consists of a core of thin iron sheets. The<br> -primary is of comparatively thin wire and often of ten or more times as<br> -many turns as the secondary. The latter is of thicker wire. Where the<br> -ratio of 10 to 1 as regards number of turns in the primary and secondary<br> -obtains, the initial E. M. F. of the secondary is one-tenth that of the<br> -primary circuit.<br> -<br> -The cores are laminated, as described, to avoid the formation of<br> -Foucault currents.<br> -<br> -The counter-electro-motive force of the transformer when the secondary<br> -circuit is open, prevents any but the slightest current from passing<br> -through the primary. In proportion as the secondary is closed and its<br> -resistance diminished, as by lighting more lamps in parallel, the<br> -counter-electro-motive force of the transformer falls and more current<br> -passes through the primary.<br> -<br> -<br> -<img style="width: 532px; height: 712px;" alt="" - src="images/546F339.JPG"><br> -Fig. 339. FERRANTI'S TRANSFORMER.<br> -<br> -The economy of the apparatus is in the fact that counter-electromotive<br> -force reduces current through a conductor without absorbing any energy.<br> -A resistance coil cuts down a current, but absorbs energy equal to the<br> -current multiplied by the potential difference between the terminals of<br> -the coil. This electric energy is converted into heat energy and is<br> -wasted. But the counter-electromotive force of a transformer is exerted<br> -to reduce current without production of heat and with little waste of<br> -energy. This is one of the advantages of the alternating current system<br> -of distribution of electric energy.<br> -<br> -The object of a transformer being to secure safety to the person or to<br> -life by the separation of the high potential primary or street circuit,<br> -and the low potential house circuit, any contact of the two circuits in<br> -the converter is a source of danger. Special care should be taken to<br> -ensure absence of leakage, as it is termed. Mica or other insulation is<br> -sometimes employed to prevent the wires from coming in contact by<br> -piercing or sparking with the core and with each other.<br> -<br> -<br> -547 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Transformer, Commuting.</span><br> -A type of continuous current transformer, resembling a dynamo with<br> -armature and field both stationary, but with revolving commutator, by<br> -which the magnetic polarity of a double wound armature is made to<br> -rotate. This secures the desired action, of a change or lowering of<br> -potential.<br> -<br> -<br> -<span style="font-weight: bold;">Transformer, Continuous Alternating.</span><br> -An apparatus for transforming a continuous into an alternating current<br> -or the reverse. The combination of a continuous current dynamo with an<br> -alternating current one is sometimes employed. It is a form of motor<br> -dynamo.<br> -<br> -Another type is a regular dynamo with ordinary commutator and with, in<br> -addition thereto, two, three or four contact rings, connecting to as<br> -many symmetrically disposed points in the winding of the armature. This<br> -will give out or receive alternating currents of two, three or four<br> -phases according to the number of collecting rings. One winding serves<br> -for both alternating and continuous currents.<br> -<br> -<br> -<span style="font-weight: bold;">Transformer, Continuous Current.</span><br> -A machine of the dynamo type for changing the potential of a circuit. In<br> -one form two armatures are mounted on one shaft in a single field or in<br> -separate fields; one is a motor armature driven by the original current;<br> -the other generates the new current. This is a motor dynamo. In 1874<br> -Gramme constructed a machine with ring armature with two windings, of<br> -coarse and fine wire respectively, and with independent commutators.<br> -Such dynamo could transform currents up or down.<br> -<br> -Continuous current transformers have attained an efficiency of 83 per<br> -cent. at full load, and of 75 per cent. at half load. Owing to the<br> -balancing of the self-inductions of the two windings these machines do<br> -not spark. As the driven and driving parts are contained in one rotating<br> -part their friction is very slight.<br> -<br> -<br> -<span style="font-weight: bold;">Transformer, Core.</span><br> -A transformer wound upon an enclosed core, such as the hedgehog<br> -transformer (see Transformer, Hedgehog), or common induction coil.<br> -<br> -<br> -548 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Transformer, Hedgehog.</span><br> -An induction coil transformer whose iron core is composed of a bundle of<br> -iron wires, which after the wire windings are in place have their ends<br> -spread out to reduce to some extent the reluctance of the circuit, which<br> -at the best is high, as the air acts as the return circuit.<br> -<br> -This transformer has a low degree of hysteresis; and its efficiency for<br> -very small loads or for no load is superior to that of the closed<br> -magnetic circuit transformer.<br> -<br> -<br> -<img style="width: 326px; height: 758px;" alt="" - src="images/548F340.JPG"><br> -Fig. 340. SWINBURNE'S HEDGEHOG TRANSFORMER.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Transformer, Multiple.</span><br> -A transformer connected in parallel with others between the two leads of<br> -the primary circuit. The term refers to the connection only and not to<br> -any peculiarity of the transformer itself.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Transformer, Oil.</span><br> -A transformer with oil insulation. The advantage of this insulation is<br> -that if pierced it at once closes, so that no permanent injury ensues.<br> -It is a self-healing form of insulation.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Transformer, Series.</span><br> -Transformers connected in series upon the primary circuits. The term,<br> -like "multiple transformers," only applies to the connection, not to the<br> -transformer. Series transformers are but little used.<br> -<br> -<br> -<span style="font-weight: bold;">Transformer, Shell.</span><br> -A transformer with its iron core entirely outside of and enclosing the<br> -primary and secondary winding. It may be made by the use of outer iron<br> -wire windings as core.<br> -<br> -<br> -<span style="font-weight: bold;">Transformer, Welding.</span><br> -The transformer used for electric welding. (See Welding, Electric.) It<br> -is a transformer with very long primary and exceedingly short and thick<br> -secondary. It is used with the alternating current in the primary, and<br> -produces in the secondary circuit which includes the bars to be welded a<br> -very low potential difference.<br> -<br> -Owing to the very low resistance of the secondary circuit this low<br> -electro-motive force produces a very strong current, which develops the<br> -requisite heat. The same type of transformer is used for brazing and<br> -similar purposes.<br> -<br> -<br> -549 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Transmitter.</span><br> -In general electric phraseology, any instrument which produces signals<br> -to be transmitted through a line or circuit is a transmitter. Thus the<br> -Morse key in telegraphy or the Blake transmitter in telephony are<br> -examples of such.<br> -<br> -<br> -<span style="font-weight: bold;">Transmitter, Carbon.</span><br> -A form of microphone used as a telephone transmitter. (See Carbon<br> -Telephone.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Transposing.</span><br> -A method of laying metallic circuits for telephoning. The wires at short<br> -intervals are crossed so that alternate sections lie on opposite sides<br> -of each other. It is done to avoid induction.<br> -<br> -<br> -<span style="font-weight: bold;">Transverse Electro-motive Force.</span><br> -Electro-motive force in a substance in which electric displacement is<br> -taking place, produced by a magnetic field. It is sometimes assigned as<br> -the cause of the Hall effect, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Trimmer, Brush.</span><br> -A shears for cutting off evenly and squarely the ends of copper dynamo<br> -brushes. The brushes when uneven from wear are removed from the brush<br> -holders, and their ends are sheared off in the trimmer.<br> -<br> -<br> -<span style="font-weight: bold;">Trolley.</span><br> -A grooved metallic pulley or set of pulleys which runs along an active<br> -wire of a circuit, a lead from which trolley goes to earth or connects<br> -with another wire, so that the trolley takes current generally for<br> -operating a street car motor placed upon the circuit leading from it; a<br> -rolling contact with an electric lead.<br> -<br> -Trolleys are principally used on electric railroads, and are now<br> -universally of the sub-wire system, being at the end of a pole which is<br> -inclined backward and forced upward by springs, so as to press the<br> -trolley against the bottom of the wire. Thus the trolley does not<br> -increase the sagging of the wire, but tends to push it up a little in<br> -its passage.<br> -<br> -<br> -<span style="font-weight: bold;">Trolley, Double.</span><br> -A trolley with two rollers or grooved wheels, placed side by side, and<br> -running on two parallel leads of wire. It is adapted to systems<br> -employing through metallic trolley lines with the motors in multiple<br> -arc, connecting or across the two leads.<br> -<br> -<br> -<span style="font-weight: bold;">Trolley Section.</span><br> -An unbroken or continuous section of trolley wire.<br> -<br> -<br> -<span style="font-weight: bold;">Trouvé's Solution.</span><br> -An acid exciting and depolarizing solution for a zinc-carbon battery.<br> -Its formula is as follows: Water, 80 parts; pulverized potassium<br> -bichromate, 12 parts; concentrated sulphuric acid, 36 parts; all parts<br> -by weight. The pulverized potassium bichromate is added to the water,<br> -and the acid is added slowly with constant stirring. As much as 25 parts<br> -potassium bichromate may be added to 100 parts of water. The heating<br> -produced by the acid and water dissolves nearly all the potassium salt.<br> -Use cold.<br> -<br> -<br> -550 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">True Contact Force.</span><br> -A species of electro-motive force whose existence is supposed to be<br> -proved by the Peltier effect. The lowering in temperature of a contact<br> -of dissimilar metals is attributed to a force that helps the current on<br> -its way if in the direction of thermo-current proper to the junction and<br> -opposing it if in the reverse. The true contact force is taken to<br> -explain this phenomenon; thermo-electric force cannot, as there is no<br> -heat or cold applied to the junction.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Trumpet, Electric.</span><br> -An apparatus consisting of a vibrating tongue, kept in motion by<br> -electricity as in the buzzer, q. v., placed in the small end of a<br> -trumpet-shaped tube.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Trunking Switchboard.</span><br> -A telephone switchboard arranged in sections, which sections are<br> -connected by trunk lines, through which trunk lines the desired<br> -connections<br> -are made.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Trunk Lines.</span><br> -In telephone distribution systems, the lines connecting different<br> -stations, or different sections of a switch-board and used by anyone<br> -requiring such connections; one trunk line answers for a number of<br> -subscribers.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Tube, Electric.</span><br> -A tube of glass around which is pasted a series of tinfoil circles,<br> -diamonds, or little squares, or other form of interrupted conductor. The<br> -pieces generally are placed in the line of a spiral. When a static<br> -discharge of electricity takes place along the conductor a row of bright<br> -sparks is produced at the breaks in the conductor. These by reflection<br> -are multiplied apparently, and a beautiful effect of intersecting or<br> -crossing spirals of sparks is presented.<br> -<br> -The experiment is in line with the luminous pane and lightning jar, and<br> -is used merely as a demonstration, or lecture experiment.<br> -<br> -Synonym--Luminous Tube.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Tubular Braid.</span><br> -A braid woven of tissue or worsted, and tubular or hollow. Its object is<br> -to provide a covering which can be drawn over joints in covered wires.<br> -In making the joint the ends of the wires are necessarily bared, and a<br> -short piece of tubular braid is used for covering them. It is drawn by<br> -hand over the joint.<br> -<br> -<br> -<span style="font-weight: bold;">Turns.</span><br> -An expression applied to the convolutions of wire in a solenoid,<br> -electro-magnet, or other apparatus or construction of that kind. A turn<br> -indicates a complete encircling of the core or axis of the object. Thus<br> -a wire wound five times around a bar gives five turns.<br> -<br> -While this is its primary meaning the term if compounded may refer to<br> -virtual turns. Thus an ampere-turn means one ampere passing through one<br> -turn. But ten ampere-turns may mean ten amperes passing through ten<br> -turns, five amperes passing through two turns, and so on. This use is<br> -analogous to a dimension of length in a compound word, as foot-pound.<br> -<br> -[Transcriber's note: "But ten ampere-turns may mean ten amperes passing<br> -through ONE turn or one ampere through ten turns, and so on."]<br> -<br> -There may be a number of kinds of turns qualified by descriptive<br> -adjectives, as series-turns, the turns of wire in a series circuit of a<br> -compound dynamo. In the same way there are shunt-turns. If series<br> -ampere-turns or shunt ampere-turns are meant the word ampere should be<br> -included.<br> -<br> -<br> -551 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Turns, Dead, of a Dynamo.</span><br> -The rotations of a dynamo armature while it is building itself up or<br> -exciting itself. The expression is a bad one, as it is likely to be<br> -confounded with the dead turns of armature wire.<br> -<br> -<br> -<span style="font-weight: bold;">Turns, Primary Ampere-.</span><br> -The ampere-turns in a primary circuit of an induction coil or<br> -transformer. In an electric welding transformer, or in the transformer<br> -used in the alternating current system, where efficiency is an important<br> -element, the ampere-turns in primary and secondary for an efficiency of<br> -100 per cent. should be equal. In the case of an experimental induction<br> -coil other considerations outweigh that of mere efficiency. Insulation,<br> -including security from piercing, and the production of as long a spark<br> -as possible, are, in these cases, the controlling consideration.<br> -<br> -[Transcriber's note: A 100 per cent efficient transformer is impossible,<br> -but over 99 per cent is common. At room temperature there is always some<br> -lost flux, eddy currents and resistive losses.]<br> -<br> -<br> -<span style="font-weight: bold;">Turns, Secondary Ampere-.</span><br> -The ampere-turns on the secondary circuit of an induction coil or<br> -transformer. These depend on the path provided for the current. If of<br> -negligible inductance, such as a number of incandescent lamps would<br> -provide, the ampere-turns should be equal to those of the primary coil.<br> -(See Turns, Primary Ampere.)<br> -<br> -<br> -<span style="font-weight: bold;">Typewriter, Electric.</span><br> -A typewriter in which the work of printing or of pressing the type faces<br> -against the paper, or printing ribbon, is done by electro-magnetic<br> -attraction. The keys close electric circuits, throwing the<br> -electro-magnetic action into play. This involves the use of electricity<br> -for what is ordinarily only a mechanical process. The strength of the<br> -impression, however, is independent of the touch of the operator. It has<br> -not come into very extensive use.<br> -<br> -[Transcriber's note: IBM introduced widely used electric typewriters in<br> -1935.]</big></big><br> -<big><big><br> -</big></big><big><big><br> -551 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Ultra-gaseous Matter.</span><br> -Gas so rarefied that its molecules do not collide or very rarely do so.<br> -<br> -Experiments of very striking nature have been devised by Crookes and<br> -others to illustrate the peculiar phenomena that this matter presents.<br> -The general lines of this work are similar to the methods used in<br> -Geissler tube experiments, except that the vacua used are very much<br> -higher.<br> -<br> -When the vacuum is increased so that but one-millionth of the original<br> -gas is left the radiant state is reached. The molecules in their kinetic<br> -movements beat back and forth in straight lines without colliding, or<br> -with very rare collisions. Their motions can be guided and rendered<br> -visible by electrification. A tube or small glass bulb with platinum<br> -electrodes sealed in it, is exhausted to the requisite degree and is<br> -hermetically sealed by melting the glass. The electrodes are connected<br> -to the terminals of an induction coil or other source of high tension<br> -electrification. The molecules which come in contact with a negatively<br> -electrified pole are repelled from it in directions normal to its<br> -surface. They produce different phosphorescent or luminous effects in<br> -their mutual collisions.<br> -<br> -Thus if they are made to impinge upon glass, diamond or ruby, intense<br> -phosphorescence is produced. A piece of platinum subjected to molecular<br> -bombardment is brought to white heat. A movable body can be made to move<br> -under their effects. Two streams proceeding from one negative pole repel<br> -each other. The stream of molecules can be drawn out of their course by<br> -a magnet.<br> -<br> -The experiments are all done on a small scale in tubes and bulbs,<br> -resembling to a certain extent Geissler tubes.<br> -<br> -[Transcriber's note: These effects are caused by plasma--ionized gas and<br> -electrons.]<br> -<br> -<br> -552 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Unbuilding.</span><br> -The loss of its charge or excitation by a self-exciting dynamo. It is<br> -the reverse of building-up. The latter indicates the exciting of the<br> -field by the action of the machine itself; the former the spontaneous<br> -loss of charge on open circuit or from other cause.<br> -<br> -<br> -<span style="font-weight: bold;">Underground Conductor.</span><br> -An electric conductor insulated and placed under the surface of the<br> -earth, as distinguished from aerial conductors.<br> -<br> -<br> -<span style="font-weight: bold;">Underground Electric Subway.</span><br> -A subway for the enclosing of electric telegraph and other conductors<br> -under the surface, generally in the line of streets, to do away with<br> -telegraph poles and aerial lines of wire. Many systems have been<br> -devised. The general type includes tubes called ducts in sets, called<br> -conduits, bedded in concrete or otherwise protected. Every two or three<br> -hundred feet the sets lead into a cistern-like cavity called a manhole.<br> -The insulated wires or cables, generally sheathed with a lead alloy are<br> -introduced into the tubes through the man-holes. A rope is first fed<br> -through the tube. To do this short rods which screw together are<br> -generally employed. One by one they are introduced, and each end one is<br> -screwed to the series of rods already in the duct. When the end of the<br> -duct is reached the rope is fastened to the last rod, and the rods are<br> -then drawn through, unscrewed one by one and removed, the rope following<br> -them. By means of the rope a windlass or capstan may be applied to draw<br> -the cable into the duct. At least at every second man-hole the cables<br> -have to be spliced.<br> -<br> -Each cable may contain a large number of conductors of small size for<br> -telephoning, or a smaller number for electric light and power. The<br> -tendency is now to separate the different classes of wires in important<br> -lines, placing the heavier wires on one side of the street and the<br> -telephone and telegraph wires on the other. This of course necessitates<br> -two separate conduits.<br> -<br> -The advantage of underground distribution affects not only the<br> -appearance of streets in doing away with unsightly telegraph poles, but<br> -it also removes an element of danger at fires. Aerial wires interfere<br> -greatly with the handling of ladders at fires, and expose the firemen<br> -who attempt to cut them to danger to their lives from shock.<br> -<br> -<br> -533 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Unidirectional. adj.</span><br> -Having one direction as a "unidirectional current" or "unidirectional<br> -leak." The term is descriptive, and applicable to many cases.<br> -<br> -<br> -<span style="font-weight: bold;">Uniform. adj.</span><br> -Unvarying; as a uniform potential difference, uniform current or<br> -conductor of uniform resistance per unit of length. The term is<br> -descriptive, and its application and meaning are obvious.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Uniform Field of Force.</span><br> -A field of evenly distributed force; one in which the number of lines of<br> -force per unit of area of any equipotential surface is the same.<br> -<br> -<br> -<span style="font-weight: bold;">Unipolar. adj.</span><br> -Strictly speaking this term means having only one pole, and is applied<br> -to magnets, armatures and the like. In its use a solecism is involved,<br> -for there is no such condition possible as unipolar magnetism or<br> -distribution of magnetism. An example of its use is shown in unipolar<br> -magnets. (See Magnet, Unipolar.)<br> -<br> -<br> -<span style="font-weight: bold;">Unipolar Armature.</span><br> -An armature of a unipolar dynamo; an armature whose windings<br> -continuously cut the lines of force about the one pole, and hence whose<br> -polarity is unchanged in its rotation.<br> -<br> -<br> -<span style="font-weight: bold;">Unipolar Current Induction.</span><br> -Current induction produced by moving a conductor through a magnetic<br> -field of force so that it always cuts the lines in similar relation to<br> -itself. Thus it produces a constant current through its own circuit, if<br> -a closed one, and no commutator is required. As this case always in<br> -practice amounts to the cutting of lines of force in the neighborhood of<br> -a single pole the term unipolar is employed to designate the action.<br> -<br> -The simplest representation of unipolar induction is the rotating of a<br> -conductor around the end of a bar magnet, its axis of rotation<br> -corresponding with the axis of the magnet.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Unipolar Dynamo.</span><br> -A dynamo in which one part of the conductor slides on or around the<br> -magnet, so as always to cut lines of force near the same pole of the<br> -magnet.<br> -<br> -<br> -<span style="font-weight: bold;">Unit.</span><br> -A directly or indirectly conventional and arbitrary quantity, in terms<br> -of which measurements of things with dimensions expressible in the<br> -chosen units are executed.<br> -<br> -Thus for length the c. g. s. unit is the centimeter; the B. E. unit is<br> -the foot.<br> -<br> -<br> -554 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Unit, Absolute.</span><br> -A unit based on the three fundamental units of length, mass and time.<br> -These units are the centimeter, gram and second. Each one in itself may<br> -be termed a fundamental absolute unit. The system of such units is<br> -termed the centimeter-gram-second system.<br> -<br> -<br> -<span style="font-weight: bold;">Unit, Angle.</span><br> -A factor or datum in angular velocity, q. v. It is the angle subtended<br> -by a portion of the circumference equal in length to the radius of the<br> -circle. It is equal very nearly to 57.29578° or 57° 17' 44.8".<br> -<br> -<br> -<span style="font-weight: bold;">Unit, B. A.</span><br> -This term, while logically applicable to any of the British Association<br> -units, is often restricted to the ohm as formerly defined by the British<br> -Association, the B. A. Unit of Resistance, q. v.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Unit, Fundamental.</span><br> -The three units of length, mass and time, the centimeter, gram and<br> -second, are termed fundamental units. On them is based the absolute<br> -system of units, and on multiples of them the practical system of units.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Unit Jar.</span><br> -A Leyden jar which is used as a unit of measure of charge.<br> -<br> -It consists of a Leyden jar about 4 inches long and 3/4 inch diameter,<br> -with about 6 square inches of its outer and the same of its inner<br> -surface coated with tinfoil. It is placed between a source of<br> -electricity and a larger jar or battery of jars which is to be charged.<br> -The inner coating connects with the machine; the outer coating with the<br> -jars to be charged. Short conductors terminating in knobs connect with<br> -inner and outer coatings, and the knobs are adjusted at any desired<br> -distance apart.<br> -<br> -By the charging operation the large jar or battery of jars receives a<br> -charge by induction, and the charge of the small jar is at first equal<br> -to this quantity. After a while a spark passes from knob to knob,<br> -discharging the small jar. This indicates the reception by the large<br> -jars of the quantity of electricity represented by the charge of the<br> -small jar. The charging goes on, and for every spark approximately the<br> -same quantity of electricity is received by the larger jars.<br> -<br> -The sparking distance m is directly proportional to the quantity of<br> -electricity, and inversely proportional to the area of coated surface,<br> -or is proportional to the potential difference of the two coats. This is<br> -only true for short sparking distance, hence for accuracy the knobs<br> -should be adjusted not too far from each other.<br> -<br> -<br> -555 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Unit of Supply.</span><br> -A commercial unit for the sale of electric energy, as defined<br> -provisionally by the English Board of Trade; 1,000 amperes flowing for<br> -one hour under an E. M. F. of 1 volt; 3,600,000 volt-coulombs, or 1,000<br> -watt-hours, are its equivalent. It is equal to 1000/746 = 1.34 electric<br> -horse power.<br> -<br> -Synonym--Board of Trade Unit.<br> -<br> -[Transcriber's note: Now called a kilowatt-hour.]<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Units, Circular.</span><br> -A system of units of cross-sectional area, designed especially for use<br> -in describing wire conductors. The cross-sectional area of such is<br> -universally a circle, and the areas of two wires of different sizes vary<br> -with the square of their radii or diameters. Hence if the area of a<br> -circle of known diameter is determined it may be used as a unit for the<br> -dimensions of other circles. Any other circle will have an area<br> -proportioned to the area of the unit circle, as the squares of the<br> -diameters are to each other.<br> -<br> -In practise the commonest circular unit is the circular mil. This is the<br> -area of a circle one mil, 1/1000 inch, in diameter and is equal to<br> -.0000007854 square inch. A wire two mils in diameter has an area of four<br> -circular mils; one ten mils in diameter has an area of one hundred<br> -circular mils.<br> -<br> -Thus if the resistance of a given length of wire 1 mil in diameter is<br> -stated, the corresponding resistance of the same length of wire of the<br> -same material, but of other diameter, is given by dividing the first<br> -wire's resistance by the square of the diameter in mils of the wire in<br> -question.<br> -<br> -As it is a basic unit, most conveniently applied by multiplication, the<br> -smaller units are used; these are the circular mil, and circular<br> -millimeter.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Units, Derived.</span><br> -Units derived by compounding or other processes, from the three<br> -fundamental units. Such are the units of area, volume, energy and work,<br> -momentum and electric units generally. In some cases the dimensions of<br> -the derived unit may reduce to those of a simple unit as inductance<br> -reduces to length, but the unit, as deduced from the fundamental ones,<br> -is still a derived unit.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Units, Practical.</span><br> -A system of units employed in practical computation. The absolute units,<br> -especially in electricity, have been found too large or too small, and<br> -the attempt to make them more convenient has resulted in this system. It<br> -is based on exactly the same considerations as the absolute system of<br> -units, except that multiples of the original fundamental units of<br> -length, mass, and time have been taken as the base of the new system.<br> -These basic units are multiples of the fundamental units. They are the<br> -following: The unit of length is 1E9 centimeters; the unit of mass is<br> -1E-11 gram; the unit of time remains 1 second.<br> -<br> -While this has conduced to convenience in giving better sized units,<br> -micro- and mega-units and other multiples or fractions have to be used.<br> -The following are the principal practical electric units:<br> -<small><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -Electrostatic Electromagnetic</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -C. G. S Units. C. G. S. Units.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Intensity-Ampere -equal to -3E9 -1E-1</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Quantity-Coulomb -" -3E9 -1E-1</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Potential-Volt -" (1/3)* -E-2 1E8</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Resistance-Ohm -" (1/9)* -E-11 1E9</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;">Capacity-Farad -" -9E11 -1E-9</span></small><br> -<br> -<br> -556 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Universal Battery System.</span><br> -A term in telegraphy. If several equal and high resistance telegraphic<br> -circuits are connected in parallel with each other from terminal to<br> -terminal of a battery of comparatively low resistance each circuit will<br> -receive the same current, and of practically the same strength as if<br> -only one circuit was connected. This is termed the universal battery<br> -system. It is a practical corollary of Ohm's law. The battery being of<br> -very low resistance compared to the lines the joining of several lines<br> -in parallel practically diminishes the total resistance of the circuit<br> -in proportion to their own number. Thus suppose a battery of ten ohms<br> -resistance and ten volts E. M. F. is working a single line of one<br> -hundred ohms resistance. The total resistance of the circuit is then one<br> -hundred and ten ohms. The total current of the circuit, all of which is<br> -received by the one line is 10/110 = .09 ampere, or 90 milliamperes. Now<br> -suppose that a second line of identical resistance is connected to the<br> -battery in parallel with the first. This reduces the external resistance<br> -to fifty ohms, giving a total resistance of the circuit of sixty ohms.<br> -The total current of the circuit, all of which is received by the two<br> -lines in equal parts, is 10/60 = .166 amperes. But this is equally<br> -divided between two lines, so that each one receives .083 ampere or 83<br> -milliamperes; practically the same current as that given by the same<br> -battery to the single line. It will be seen that high line resistance<br> -and low battery resistance, relatively speaking, are required for the<br> -system. For this reason the storage battery is particularly available.<br> -The rule is that the resistance of the battery shall be less than the<br> -combined resistance of all the circuits worked by it.<br> -<br> -<br> -<span style="font-weight: bold;">Unmarked End.</span><br> -The south-seeking pole of a magnet, so called because the other end,<br> -called the marked end, is usually marked with a scratch or notch by the<br> -maker, while the south pole is unmarked.<br> -</big></big><big><big><span style="text-decoration: underline;"><br> -</span></big></big><big><big><br> -556 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">V.</span><br> -(a) Symbol for velocity.<br> -<br> -(b) Symbol or abbreviation for volume.<br> -<br> -(c) Symbol or abbreviation for volt.<br> -<br> -<br> -557 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">V. A.</span><br> -Symbol or abbreviation for voltaic alternatives, q. v.<br> -<br> -<br> -<span style="font-weight: bold;">Vacuum.</span><br> -A space destitute of any substance. The great pervading substance is in<br> -general sense the atmosphere. It is the gaseous mixture which surrounds<br> -and envelopes the earth and its inhabitants. It consists of a simple<br> -mixture of oxygen, 1 part, nitrogen, 4 parts, with 4 to 6 volumes of<br> -carbonic acid gas in 10,000 volumes of air, or about one cubic inch to<br> -one cubic foot. It presses with a force of about 14.7 lbs. per square<br> -inch under the influence of the force of gravity. The term vacuum in<br> -practise refers to any space from which air has been removed. It may be<br> -produced chemically. Air may be displaced by carbonic acid gas and the<br> -latter may be absorbed by caustic alkali or other chemical. The air may<br> -be expelled and the space may be filled with steam which is condensed to<br> -produce the vacuum. Of course in all cases the space must be included in<br> -an hermetically sealed vessel, such as the bulb of an incandescent lamp.<br> -But the universal method of producing a vacuum is by air pumps. An<br> -absolute vacuum means the entire absence of gas or air, something almost<br> -impossible to produce. A high vacuum is sometimes understood to mean one<br> -in which the path of the molecules is equal in length to the diameter of<br> -the containing vessels, as in Crookes' Radiometer and other apparatus<br> -for illustrating the radiant condition of matter. The air left after<br> -exhaustion is termed residual air or residual atmosphere.<br> -<br> -[Transcriber's note: Dry air is about .78 nitrogen, .21 oxygen, .01<br> -argon, .00038 carbon dioxide, and trace amounts of other gases. Argon<br> -was suspected by Henry Cavendish in 1785. It was discovered in 1894 by<br> -Lord Rayleigh and Sir William Ramsay.]<br> -<br> -<br> -<span style="font-weight: bold;">Vacuum, Absolute.</span><br> -A space free of all material substance. It is doubtful whether an<br> -absolute vacuum has ever been produced.<br> -<br> -<br> -<span style="font-weight: bold;">Vacuum, High.</span><br> -An approximate vacuum, so nearly perfect that the molecules of the<br> -residual gas in their kinetic motions rarely collide, and beat back and<br> -forth between the walls of the containing vessel, or between any solid<br> -object contained in the vessel and the walls of the vessel. The gas in<br> -such a vacuum is in the radiant or ultra-gaseous state. (See<br> -Ultra-gaseous Matter.)<br> -<br> -<br> -<span style="font-weight: bold;">Vacuum, Low.</span><br> -A vacuum inferior to a high vacuum; a vacuum in which the molecules<br> -collide with each other and do not move directly from side to side of<br> -the containing vessel.<br> -<br> -<br> -<span style="font-weight: bold;">Vacuum, Partial.</span><br> -A space partially exhausted of air so as to contain less than an equal<br> -volume of the surrounding atmosphere. It really should come below a low<br> -vacuum, but is often treated as synonymous therewith.<br> -<br> -<br> -<span style="font-weight: bold;">Vacuum, Torricellian.</span><br> -The vacuum existing above the mercurial column in a barometer tube. The<br> -principle of this vacuum is applied in the Geissler and other air pumps.<br> -(See Pump, Geissler--Pump, Sprengel--Pump, Swinburne.)<br> -<br> -<br> -558 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Valency.</span><br> -The relative power of replacing hydrogen or combining therewith<br> -possessed by different elements; the number of atomic bonds belonging to<br> -any element. Thus oxygen has a twofold valency, is bivalent or is a<br> -dyad, and combines with two atoms of hydrogen because the latter has a<br> -unitary atomicity, is monovalent or is a monad.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Valve, Electrically Controlled.</span><br> -A valve which is moved by or whose movements are regulated by<br> -electricity.<br> -<br> -In the block system of railroad signaling the semaphores are worked by<br> -weights and pneumatic cylinders and pistons. The valves for admitting or<br> -releasing the compressed air are operated by coil and plunger mechanism.<br> -There are many other instances of the control of valves by the electric<br> -current.<br> -<br> -<br> -<span style="font-weight: bold;">Vapor Globe.</span><br> -A protecting glass globe surrounding an incandescent lamp, when the lamp<br> -is to be used in an atmosphere of explosive vapor, as in mines or<br> -similar places; or when in a place where it is exposed to dripping water<br> -which would break the hot lamp bulb if it fell upon it.<br> -<br> -<br> -<span style="font-weight: bold;">Variable Period.</span><br> -The period of adjustment when a current is started through a conductor<br> -of some capacity. It is the period of duration of the variable state, q.<br> -v., in a conductor. As indicated in the next definition in a cable of<br> -high electrostatic capacity a variable period of nearly two minutes may<br> -exist. This indicates the retardation in signaling to be anticipated in<br> -cables and other lines of high capacity.<br> -<br> -<br> -<span style="font-weight: bold;">Variable State.</span><br> -When an electric circuit is closed the current starts through the<br> -conductor with its full strength from the point of closure, and advances<br> -with a species of wave front so that some time elapses before it attains<br> -its full strength in the most distant parts of the conductor, owing to<br> -its having to charge the conductor to its full capacity at the given<br> -potential. The state of the line while the current thus varies is called<br> -the variable state.<br> -<br> -A long telegraph line when a message is being transmitted may be always<br> -in the variable state. The current at the receiving end may never attain<br> -its full strength.<br> -<br> -In the case of such a conductor as the Atlantic cable, 108 seconds would<br> -be required for a current to attain 9/10 of its full strength at the<br> -distant end, and but 1/5 second to attain 1/100 of its final value.<br> -During the period of increase of current the variable state exists.<br> -<br> -<br> -<span style="font-weight: bold;">Variation of the Compass.</span><br> -The declination of the magnetic needle. (See Elements, Magnetic.) As the<br> -declination is subject to daily, annual and secular variations, it is<br> -unfortunate that this term is synonymous with declination. Thus the<br> -variation of the compass means its declination, while there is also the<br> -variation of the declination and of other elements. The term variation<br> -of the compass is more colloquial than the more definite expression<br> -"declination," or "magnetic declination."<br> -<br> -<br> -559 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Variometer.</span><br> -An apparatus used in determining the relative values of the horizontal<br> -component of the earth's magnetic field in different places.<br> -<br> -<br> -<span style="font-weight: bold;">Varley's Condenser.</span><br> -A static condenser whose conducting surfaces are platinum electrodes<br> -immersed in dilute sulphuric acid. When the potential difference is<br> -1/50th that of a Daniell's cell, two square inches of platinum have a<br> -capacity equal to that of an air condenser whose plates have an area of<br> -80,000,000 square inches, and separated 1/8th of an inch from each<br> -other. As the E. M. F. increases the capacity also increases.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Varley's Resistances.</span><br> -Variable resistances formed of discs of carbonized cloth, q. v., piled<br> -up, and pressed together more or less firmly to vary the resistance as<br> -desired.<br> -<br> -<br> -<span style="font-weight: bold;">Varnish.</span><br> -A glossy transparent coating of the nature of paint, applied as a<br> -protective, or ornamental coating to objects.<br> -<br> -<br> -<span style="font-weight: bold;">Varnish, Electric.</span><br> -Alcoholic or etherial varnishes are the best for electrical apparatus.<br> -They dry quickly and perfectly, and tend to form surfaces unfavorable to<br> -the hygroscopic collection of water. Sealing wax dissolved in alcohol,<br> -or shellac dissolved in the same solvent are used for electrical<br> -apparatus, although the first is rather a lacquer than a varnish.<br> -Etherial solution of gum-copal is used to agglomerate coils of wire. It<br> -is well to bake varnished objects to harden the coating.<br> -<br> -<br> -<span style="font-weight: bold;">Varnish, Red.</span><br> -A solution of sealing wax in 90 per cent. alcohol. It is best made thin<br> -and applied in several coats, each coat being allowed to dry perfectly<br> -before the next is applied. It is often seen on Leyden jars. It is a<br> -protector from surface leakage.<br> -<br> -<br> -<span style="font-weight: bold;">Vat.</span><br> -A vessel for chemical or other solutions. A depositing vat is one in<br> -which a plating solution is worked, for the deposition of electroplate<br> -upon articles immersed in the liquid, and electrolyzed by an electric<br> -current.<br> -<br> -<br> -<span style="font-weight: bold;">Velocity.</span><br> -The rate of motion of a body. It is usually expressed in distance<br> -traversed per second of time. The absolute unit is one centimeter per<br> -second or kine. The foot per second is very largely used also.<br> -<br> -The dimensions of velocity are length (L) divided by time (T) or L/T.<br> -<br> -<span style="font-weight: bold;">Velocity, Angular.</span><br> -Velocity in a circle defined by the unit angle, or the angle which<br> -subtends a circular arc equal in length to itself. The radius of the<br> -circle traversed by the moving body does not enter into this definition,<br> -as the real velocity of the object is not stated. If its angular<br> -velocity and the radius of the path it travels are given its actual<br> -velocity can be deduced.<br> -<br> -<br> -560 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Velocity of Signaling.</span><br> -The speed of transmission of electric signals is affected by the nature<br> -of the line, as regards its static capacity, and by the delicacy of the<br> -receiving instruments, which may need a more or less strong current to<br> -be affected. Thus of an original current one per cent. may suffice to<br> -operate a sensitive instrument. This might give almost the velocity of<br> -light, while if the instrument would only respond to the full current<br> -nearly two minutes (see Variable State) might be required for the<br> -production of a signal.<br> -<br> -<br> -<span style="font-weight: bold;">Velocity Ratio.</span><br> -A term applied to the ratios existing between the electrostatic and<br> -electro-magnetic units. If we take as numerators the dimensions of the<br> -different qualities in the electrostatic system, and their dimensions in<br> -the electro-magnetic system as denominators, the fractions thus obtained<br> -reduce to expressions containing only velocity or V in some form. Thus<br> -if we divide the dimensions of the electrostatic quantity by the<br> -dimensions of electro-magnetic quantity the quotient is simply V or<br> -velocity. A like division for potential, electrostatic and<br> -electro-magnetic gives (1/V), and so on.<br> -<br> -The value of the velocity ratio is very nearly 3E10 (sometimes given as<br> -2.98E10) centimeters per second. This is almost exactly that of light<br> -(2.9992E10 centimeters per second.) This is one of the proofs of Clerk<br> -Maxwell's magnetic theory of light. (See Maxwell's Theory of Light.)<br> -<br> -[Transcriber's note: The SI metre was defined in 1983 such that the<br> -speed of light in a vacuum is exactly 299,792,458 metres per second or<br> -about 186,282.397 miles per second.]<br> -<br> -<br> -<span style="font-weight: bold;">Ventilation of Armature.</span><br> -In a dynamo or motor ventilation of the armature is often provided for<br> -by apertures through it in order to prevent heating. This heating is<br> -caused by Foucault currents. By proper disposition of the interior of<br> -the armature with properly disposed vanes and orifices an action like<br> -that of a fan blower can be produced, which by creating a current of air<br> -cools the machine very efficiently.<br> -<br> -<br> -<span style="font-weight: bold;">Verticity, Poles of.</span><br> -Points upon the earth's surface where the horizontal component of<br> -magnetic force disappears, leaving only the vertical component active.<br> -The term is derived from the verticity of the dipping needle when over<br> -either of them.<br> -<br> -<br> -561 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Vibration Period.</span><br> -In electrical resonance the period of a vibration in an electrical<br> -resonator. The length of this period indicates the quality of the<br> -resonator in responding to electrical oscillations by sympathetic<br> -vibration. For conductors of small resistance the period is thus<br> -calculated. Let T be the period of one-half a full vibration; L the<br> -absolute coefficient of self-induction expressed in centimeters or in<br> -henries X 10-9; C the electrostatic capacity of the terminals, also<br> -expressed in the same unit; v the velocity of light in centimeters per<br> -second. Then we have the formula<br> -<br> - T = PI * SquareRoot( L * C ) / v<br> -<br> -[Transcriber's note: If the inductance is in henries and the capacitance<br> -in farads, frequency in hertz = 1/(2 * PI * squareRoot( L * C ) )]<br> -<br> -<br> -<span style="font-weight: bold;">Vibration, Sympathetic.</span><br> -A vibration in a cord or other body susceptible of elastic vibration<br> -produced by the vibrations of exactly the same period in a neighboring<br> -vibrating body. Thus if two tuning forks are tuned to precisely the same<br> -pitch, and are placed near each other, if one is sounded it will start<br> -the other into vibration by sympathy.<br> -<br> -In electricity its application is found in electric resonance<br> -experiments. The resonator has a definite period of electric resonance,<br> -and is made to give a spark by the exciter of identical period. This is<br> -by what may be called electric sympathetic vibration, and is exactly<br> -analogous to the action of the tuning forks upon each other.<br> -<br> -<br> -<span style="font-weight: bold;">Vibrator, Electro-magnetic.</span><br> -The make and break mechanism used on induction coils, or other similar<br> -apparatus in which by alternate attractions by and releases from an<br> -electro-magnet an arm or spring is kept in motion. In most cases the<br> -work is done by a single magnet, whose armature is attracted to the<br> -magnet, when the latter is excited, but against the action of a spring<br> -which tends to pull it away from the magnet. In its motions a make and<br> -break action is produced, to give the requisite alternations of<br> -attraction and release. Two electro-magnets may be connected so as<br> -alternately to be excited and keep an arm carrying a mutual armature in<br> -vibration, or the same result may be attained by a polarized relay. The<br> -make and break is illustrated under Bell, Electric--Coil, Induction--<br> -Anvil.<br> -<br> -<br> -<span style="font-weight: bold;">Villari's Critical Value.</span><br> -Magnetization induced or residual in a wire is diminished on stretching,<br> -provided that the magnetization corresponds to an inducing force above a<br> -certain critical value, known as above; this being (Sir Wm. Thomson)<br> -about 24 times the terrestrial intensity. Below that critical value<br> -tension increases the magnetization of a magnetized wire. The effects of<br> -transverse expansive stress are opposed to those of longitudinal<br> -stretching. (Daniell.)<br> -<br> -<br> -<span style="font-weight: bold;">Viole's Standard of Illuminating Power.</span><br> -A standard authorized by the International Congress of 1881. It is the<br> -light given by one square centimeter of platinum, melted, but just at<br> -the point of solidification. It is equal to 20 English standard candles<br> -almost exactly.<br> -<br> -It has not been very widely accepted, the tendency among photometrists<br> -being to adhere to the old standards, carcel or candle. It is obvious<br> -that actual use of the Viole would be very inconvenient and would<br> -involve expensive apparatus, difficult to work with.<br> -<br> -Synonym--Viole.<br> -<br> -<br> -562 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Vis Viva.</span><br> -The kinetic energy of a body in motion; "mechanical energy."<br> -<br> -<span style="font-weight: bold;">Vitreous Electricity.</span><br> -Positive electricity; the electricity produced on the surface of glass<br> -by rubbing it with silk and other substances. (See Electrostatic<br> -Series.)<br> -<br> -The term "positive electricity" should be allowed to supplant it. It is<br> -the analogue and opposite of resinous electricity.<br> -<br> -<br> -<span style="font-weight: bold;">Vitriol, Blue.</span><br> -A colloquial or trade name for copper sulphate (Cu SO4).<br> -<br> -<br> -<span style="font-weight: bold;">Vitriol, Green.</span><br> -A colloquial or trade name for ferrous sulphate (Fe SO4).<br> -<br> -<br> -<span style="font-weight: bold;">Vitriol, White.</span><br> -A colloquial or trade name for zinc sulphate (Zn SO4).<br> -<br> -<br> -<span style="font-weight: bold;">Volt.</span><br> -The practical unit of electro-motive force or potential difference. It<br> -may be referred to various data.<br> -<br> -An electro-motive force of one volt will cause a current of one ampere<br> -to flow through a resistance of one ohm.<br> -<br> -A condenser of one farad capacity charged with one coulomb will have a<br> -rise of potential of one volt.<br> -<br> -The cutting of 100,000,000 lines of force per second by a conductor<br> -induces one volt E. M. F.<br> -<br> -A Daniell's battery gives an E. M. F. of 1.07 volts; about the most<br> -familiar approximate standard that can be cited.<br> -<br> -It is equal to 1/300 absolute electrostatic unit.<br> -<br> -It is equal to 1E8 absolute electro-magnetic units.<br> -<br> -[Transcriber's note: The SI definition of a volt: The potential<br> -difference across a conductor when a current of one ampere dissipates<br> -one watt of power.]<br> -<br> -<br> -<span style="font-weight: bold;">Voltage.</span><br> -Potential difference or electro-motive force expressed in volts; as a<br> -voltage of 100 volts. Thus voltage may express the electro-motive force<br> -absorbed in a conductor, while electro-motive force is a term generally<br> -applied where it is produced, evolved or present in the object. The term<br> -voltage of a lamp expresses simply the volts required, but does not<br> -suggest the possession of electromotive force.<br> -<br> -<br> -563 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Voltage, Terminal.</span><br> -The voltage or potential difference at the terminals of an electric<br> -current generator, such as a dynamo, as distinguished from the total<br> -electro-motive force of the dynamo or generator.<br> -<br> -In batteries the distinction is not generally made in practice; the<br> -total electro-motive force of the battery is made the basis of<br> -calculations.<br> -<br> -<br> -<span style="font-weight: bold;">Voltaic. adj.</span><br> -This adjective is used to qualify a great many things appertaining to or<br> -connected with current electricity. It is derived from Volta, the<br> -inventor of the voltaic battery, and now tends to displace the term<br> -"galvanic," formerly in general use.<br> -<br> -<br> -<span style="font-weight: bold;">Voltaic Alternatives.</span><br> -A term used in electro-therapeutics or medical electricity to indicate<br> -an alternating battery current.<br> -<br> -Synonym--Alternative current.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Voltaic Effect.</span><br> -The potential difference developed by contact of different conductors.<br> -It is the basis of the contact theory, q. v., of electricity, although<br> -it may be accepted as the expression for a condition of things by those<br> -who reject the above theory. This potential difference is slight when<br> -the conductors are separated, but it is calculated that it would be<br> -enormous could the metals be so quickly separated as to hold each its<br> -own charge.<br> -<br> -Thus if a copper and a zinc plate are assumed to be in contact, really<br> -1/20000000 centimeter or 1/50000000 inch apart, they may be treated as a<br> -pair of condenser plates. Being so near, their density of charge, which<br> -is a strongly bound charge, is enormous. If it were possible to separate<br> -them without permitting any discharge, their potential would rise by the<br> -separation, on the principle of Epinus' condenser, q. v., to such an<br> -extent that they would spark through twenty feet of air. (See Volta's<br> -Fundamental Experiment.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Voltaic Electricity.</span><br> -Electricity of low potential difference and large current intensity;<br> -electricity such as produced by a voltaic battery; current or dynamic<br> -electricity as opposed to static electricity.<br> -<br> -<br> -<span style="font-weight: bold;">Voltameter.</span><br> -In general an apparatus for determining the quantity of electricity<br> -passing through a conductor by measuring the electrolytic action it can<br> -perform.<br> -<br> -<br> -<span style="font-weight: bold;">Voltameter, Copper.</span><br> -An apparatus which may be of similar construction with the silver<br> -voltameter (see Voltameter, Silver), but in which a copper anode and a<br> -solution of copper sulphate are substituted for the silver anode and<br> -silver nitrate solution. One coulomb corresponds to .329 milligram or<br> -.005084 grain of copper deposited. It is not accepted as of as high a<br> -standard as the silver voltameter.<br> -<br> -The electrodes should be placed half an inch from each other. Two square<br> -plate electrodes may conveniently be used, and not less than two square<br> -inches on each plate should be the area per ampere of current.<br> -<br> -<br> -564 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Voltameter, Differential, Siemens'.</span><br> -A volume or gas voltameter with duplicate eudiometers and pairs of<br> -electrodes. It is used for determining the resistance of the platinum<br> -conductor used in his pyrometer. A current divides between the two<br> -voltameters; in one branch of the circuit the platinum conductor is<br> -placed, in the other a known resistance. The current strength varying<br> -inversely with the resistance, the resistances of the two conductors are<br> -inversely proportional to the gas evolved.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Voltameter, Gas.</span><br> -A voltameter whose indications are based on the electrolysis of water,<br> -made an electrolyte by the addition of sulphuric acid. The gases evolved<br> -are measured. It may take several forms.<br> -<br> -In one form it is an apparatus consisting of a single eudiometer or<br> -graduated glass tube with upper end closed and its lower end or mouth<br> -open, collecting the mixture of hydrogen and oxygen.<br> -<br> -In the form shown in the cut three tubes are connected, the side tubes<br> -representing eudiometers. For each side tube there is a platinum<br> -electrode. In this apparatus the oxygen and hydrogen are connected in<br> -opposite tubes. A is an open tube filled with dilute sulphuric acid. By<br> -opening the cocks on B and C they can both be completely filled with<br> -acid. As shown in the cut, this operation is not yet completed. The<br> -hydrogen alone may in this case be measured.<br> -<br> -The mixed gas voltameter has only one eudiometer.<br> -<br> -The exact equivalents are only approximately known. The volume of mixed<br> -gases per coulomb is given as .1738 cubic centimeters (Ayrton); .172<br> -cubic centimeters (Hospitalier); and other values by other authorities.<br> -The hydrogen is equal to 1/3 of the mixed gases almost exactly.<br> -<br> -Synonyms--Volume Voltameter--Sulphuric Acid Voltameter.<br> -<br> -The gas is measured at 0º (32º F.) and 76 centimeters, or 30 -inches<br> -barometer.<br> -<br> -<br> -<img style="width: 234px; height: 522px;" alt="" - src="images/564F341.JPG"><br> -Fig. 341. GAS VOLTAMETER.<br> -<br> -<br> -565 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -If the gas is measured in cubic inches, the temperature in degrees F.,<br> -and the barometric height in inches, the following formula may be used<br> -for reduction to standard pressure and temperature. It is the volume<br> -corresponding to one coulomb.<br> - ( .01058 * 30 * (491 + Fº - 32) ) / (h* 491)<br> -<br> -For the metric measurements and degrees C.<br> - (.1738 * 76 * (273 + Cº)) / (h X 273)<br> -<br> -<br> -<span style="font-weight: bold;">Voltameter, Silver.</span><br> -An apparatus consisting of a platinum vessel containing a solution of<br> -silver nitrate into which solution a silver anode dips, whose end is<br> -wrapped in muslin to prevent the detachment of any particles. When a<br> -current is passed by connecting one terminal to the dish and the other<br> -to the rod, securing a proper direction of current, silver will be<br> -deposited on the dish and the same amount will be dissolved from the<br> -rod. The dish is weighed before and after the test. Its increase in<br> -weight gives the silver deposited.<br> -<br> -<br> -<img style="width: 627px; height: 568px;" alt="" - src="images/565F342.JPG"><br> -FIG. 342. SILVER VOLTAMETER.<br> -<br> -<br> -In the cut Ag is the silver anode, Pt is the platinum dish, r is the<br> -conducting rod, p is a wooden standard, Cu is a copper plate on which<br> -the dish rests and which also serves as a conductor and contact surface,<br> -b is a muslin cloth to place over the silver plate to prevent detached<br> -particles falling in the dish; s s' are the binding screws.<br> -<br> -The weight of silver corresponding to a coulomb is given variously by<br> -different authorities. Ayrton and Daniell take 1.11815 milligrams or<br> -.017253 grain of metallic silver. Other determinations are as follows:<br> - 1.1183 milligrams (Kohlrausch).<br> - 1.124 -" -(Merscart).<br> -<br> -The solution of silver nitrate should be from 15 to 30 per cent. of<br> -strength. The current should not exceed one ampere per six square<br> -inches; or in other words not more than about 3/1000 grain of silver<br> -should be deposited per second on a square inch area of the dish. The<br> -edge of the silver disc or anode should be about equidistant from the<br> -side and bottom of the dish. The latter notes are due to Lord Rayleigh.<br> -<br> -<br> -566 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Voltameter, Weight.</span><br> -A voltameter in which the amount of decomposition is determined by<br> -weighing the products, or one of the products of the electrolysis. The<br> -titles Voltameter, Copper, and Voltameter, Silver, may be cited.<br> -<br> -<br> -<img style="width: 623px; height: 465px;" alt="" - src="images/566F343.JPG"><br> -Fig. 343. WEIGHT VOLTAMETERS.<br> -<br> -<br> -In the cuts are shown examples of weight gas voltameters. These are<br> -tubes light enough to be weighed when charged. Each contains a<br> -decomposition cell T, with its platinum electrodes, and charged with<br> -dilute sulphuric acid, while t is calcium chloride or other drying agent<br> -to collect any water carried off as vapor or as spray by the escaping<br> -gases; c are corks placed in position when the weighing is being<br> -executed, so as to prevent the calcium chloride from absorbing moisture<br> -from the air.<br> -<br> -In use the tubes are weighed. They are then connected to the circuit,<br> -after removal of the corks, and the decomposition proceeds. After a<br> -sufficient time they are removed, the corks put in place, and they are<br> -weighed again. The loss gives the water decomposed.<br> -<br> -The water corresponding to one coulomb is<br> -<small><span style="font-family: monospace;"> .09326 -milligram .001430 grain, Ayrton,</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -.092 -" -Hospitalier,</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -.0935 -" -Daniell.</span></small><br> -<br> -<br> -567 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Voltametric Law.</span><br> -The law on which voltameters are based. The amount of chemical<br> -decomposition produced by an electric current in a given electrolyte is<br> -proportional to the quantity of electricity passed through the solution.<br> -<br> -<br> -<span style="font-family: monospace;"><img - style="width: 500px; height: 568px;" alt="" src="images/567F344.JPG"></span><br> -Fig. 344. VOLTA'S FUNDAMENTAL EXPERIMENT.<br> -<br> -<br> -<span style="font-weight: bold;">Volta's Fundamental Experiment.</span><br> -The moistened finger is placed on the upper plate of a condensing or<br> -electrophorous electroscope. The other hand holds a plate of zinc z,<br> -soldered to a plate of copper c. The lower plate is touched with the<br> -copper. On removing the cover the gold leaves l diverge and with<br> -negative electricity. Hence zinc is supposed to be positively<br> -electrified when in contact with copper. The experiment is used to<br> -demonstrate the contact theory of electricity.<br> -<br> -<br> -568 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Volta's Law of Galvanic Action.</span><br> -The electro-motive force between any two metals in an electro-chemical<br> -series (see Electro-Chemical Series) is equal to the sum of the<br> -electro-motive forces between all the intervening metals.<br> -<br style="font-weight: bold;"> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Volta's Law of Thermo-electricity.</span><br> -In a compound circuit, consisting of a number of different metals, all<br> -points of which are at the same temperature, there is no current.<br> -<br> -<br> -<span style="font-weight: bold;">Volt, B. A.</span><br> -The volt based on the B. A. ohm. It is equal to .9889 legal volt.<br> -<br> -<br> -<span style="font-weight: bold;">Volt, Congress.</span><br> -The volt based upon the congress or legal ohm; the legal volt.<br> -<br> -<br> -<span style="font-weight: bold;">Volt-coulomb.</span><br> -The unit of electric work; the watt-second; it is equivalent to<br> -<small><span style="font-family: monospace;"> -1.0E7 ergs.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> .24068 -gram degree C. (calorie)</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> .737337 foot -lbs.,</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> .00134 -horse power seconds.</span></small><br> -<br> -<br> -<span style="font-weight: bold;">Volt Indicator.</span><br> -A form of easily read voltameter for use in electric light stations and<br> -for similar work.<br> -<br> -<br> -<span style="font-weight: bold;">Volt, Legal.</span><br> -The legal volt based upon the legal ohm. It is equal to 1.00112 B. A.<br> -volt.<br> -<br> -<br> -<span style="font-weight: bold;">Voltmeter.</span><br> -An instrument for determining the potential difference of any two<br> -points.<br> -<br> -In many cases it is a calibrated galvanometer wound with a coil of high<br> -resistance. The object to be attained is that it shall receive only an<br> -insignificant portion of current and that such portion shall suffice to<br> -actuate it. If connected in parallel with any portion of a circuit, it<br> -should not noticeably diminish its resistance.<br> -<br> -The divisions into which ammeters range themselves answer for<br> -voltmeters. In practice the same construction is adopted for both. The<br> -different definitions of ammeters in disclosing the general lines of<br> -these instruments are in general applicable to voltmeters, except that<br> -the wire winding of the coils must be of thin wire of great length. The<br> -definitions of ammeters may be consulted with the above understanding<br> -for voltmeters.<br> -<br> -In the use made of voltmeters there is a distinction from ammeters. An<br> -ammeter is a current measurer and all the current measured must be<br> -passed through it. But while a voltmeter is in fact a current measurer,<br> -it is so graduated and so used that it gives in its readings the<br> -difference of potential existing between two places on a circuit, and<br> -while measuring the current passing through its own coils, it is by<br> -calibration made to give not the current intensity, but the<br> -electro-motive force producing such current.<br> -<br> -In use it may be connected to two terminals of an open circuit, when as<br> -it only permits an inconsiderable current to pass, it indicates the<br> -potential difference existing between such points on open circuit. Or it<br> -may be connected to any two parts of a closed circuit. Owing to its high<br> -resistance, although it is in parallel with the intervening portion of<br> -the circuit, as it is often connected in practice, it is without any<br> -appreciable effect upon the current. It will then indicate the potential<br> -difference existing between the two points.<br> -<br> -<br> -569 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Voltmeter, Battery.</span><br> -A voltmeter for use in running batteries. In one form (Wirt's) it is<br> -constructed for a low range of voltage, reading up to two and a half<br> -volts and having exactly one ohm resistance, thus giving the battery<br> -some work to do.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Voltmeter, Cardew.</span><br> -A voltmeter in which the current passing through its conductor heats<br> -such conductor, causing it to expand. Its expansion is caused to move an<br> -index needle. By calibration the movements of the needle are made to<br> -correspond to the potential differences producing the actuating currents<br> -through it. The magnetic action of the current plays no part in its<br> -operation. It is the invention of Capt. Cardew, R. E.<br> -<br> -The construction of the instrument in one of its most recent forms is<br> -shown in the cut. On each side of the drum-like case of the instrument<br> -are the binding screws. These connect with the blocks m and n. To these<br> -the fine wire conductor is connected and is carried down and up over the<br> -two pulleys seen at the lowest extremity, its centre being attached to<br> -c. From c a wire is carried to the drum p, shown on an enlarged scale on<br> -the left of the cut. A second wire from the same drum or pulley connects<br> -to the spring S. The winding of the two wires is shown in the separate<br> -figure of c, where it is seen that they are screwed fast to the<br> -periphery of the little drum, and are virtually continuations of each<br> -other. By the screw A the tension of the spring S is adjusted.<br> -<br> -On the shaft of the little drum p is a pinion, which works into the<br> -teeth of the cog-wheel r. The shaft of r is extended through the dial<br> -of the instrument, and carries an index. The dial is marked off for<br> -volts; g g and h h are standards for carrying the pulleys.<br> -<br> -<br> -570 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The action of the instrument is as follows. The current passing through<br> -the wire heats it. This current by Ohm's law is proportional to the<br> -electro-motive force between the terminals. As it is heated it expands<br> -and as it cools contracts, definite expanding and contracting<br> -corresponding to definite potential differences. As the wire expands and<br> -contracts the block or pin c moves back and forth, thus turning the drum<br> -p and cogwheel r one way or permitting it to turn the other way under<br> -the pull of the spring S.<br> -<br> -<br> -<img style="width: 376px; height: 649px;" alt="" - src="images/570F345.JPG"><br> -Fig. 345. CARDEW VOLTMETER.<br> -<br> -<br> -In this construction for a given expansion of the wire the piece c only<br> -moves one half as much. The advantage of using a wire twice as long as<br> -would be required for the same degree of movement were the full<br> -expansion utilized is that a very thin wire can be employed. Such a wire<br> -heats and cools more readily, and hence the instrument reaches its<br> -reading more quickly or is more deadbeat, if we borrow a phraseology<br> -properly applicable only to instruments with oscillating indexes.<br> -<br> -In the most recent instruments about thirteen feet of wire .0025 inch in<br> -diameter, and made of platinum-silver alloy is used.<br> -<br> -<br> -571 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -If the potential difference to be measured lies between 30 and 120 volts<br> -the wire as described suffices. But to extend the range of the<br> -instrument a resistance in series is required. If such resistance is<br> -double that of the instrument wire, and remains double whether the<br> -latter is hot or cold the readings on the scale will correspond to<br> -exactly twice the number of volts. This is brought about in some<br> -instruments by the introduction in series of a duplicate wire, precisely<br> -similar to the other wire, and like it, carried around pulleys and kept<br> -stretched by a spring.<br> -<br> -[Transcriber's note: If the series resistance is twice that of the<br> -voltmeter, the indicated voltage will be ONE THIRD of the total<br> -voltage.]<br> -<br> -Thus whatever ratio of resistance exists between the two wires cold, it<br> -is always the same at any temperature, as they both increase in<br> -temperature at exactly the same rate. Tubes are provided to enclose the<br> -stretched wires and pulleys, which tubes are blackened.<br> -<br> -The voltmeter is unaffected by magnetic fields, and, as its<br> -self-induction is very slight, it is much used for alternating currents.<br> -The tubes containing the wire may be three feet long.<br> -<br> -Its disadvantages are thus summarized by Ayrton. It absorbs a good deal<br> -of energy; it cannot be constructed for small potential differences, as<br> -the wire cannot be made thicker, as it would make it more sluggish;<br> -there is vagueness in the readings near the zero point and sometimes<br> -inaccuracy in the upper part of the scale.<br> -<br> -<br> -<span style="font-weight: bold;">Volts, Lost.</span><br> -The volts at the terminals of a dynamo at full load fall short of their<br> -value on open circuit. The difference of the two values are termed lost<br> -volts.<br> -<br> -<br> -<span style="font-weight: bold;">Voltmeter, Electrostatic.</span><br> -A voltmeter based on the lines of the quadrant electrometer. It includes<br> -two sets of quadrants, each oppositely excited by one of the two parts,<br> -whose potential difference is to be determined. They attract each other<br> -against a controlling force as of gravity.<br> -<br> -One form has the two sets poised on horizontal axes, bringing the parts<br> -so that the flat quadrants move in vertical planes.<br> -<br> -In another form a number of quadrants are used in each set, the members<br> -of the two sets alternating with each other. One set is fixed, the<br> -others move and carry the index.<br> -<br> -<br> -<span style="font-weight: bold;">Vulcanite.</span><br> -Vulcanized india rubber which by high proportion of sulphur and proper<br> -vulcanization has been made hard. It is sometimes distinguished from<br> -ebonite as being comparatively light in color, often a dull red, while<br> -ebonite is black. For its electrical properties see Ebonite.<br> -<br> -Both substances have their defects, in producing surface leakage.<br> -Washing with weak ammonia, or with dilute soda solution, followed by<br> -distilled water, is recommended for the surface, if there is any trouble<br> -with surface leakage. It may also be rubbed over with melted paraffine<br> -wax.<br> -<br> -</big></big><big><big><br> -572 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">W.</span><br> -(a) A symbol or abbreviation for watt.<br> -<br> -(b) A symbol or abbreviation for work.<br> -<br> -(c) A symbol or abbreviation for weight.<br> -<br> -<br> -<span style="font-weight: bold;">Wall Bracket.</span><br> -A telegraph bracket to be attached to the external walls of buildings to<br> -which wires are attached as they come from the poles to reach<br> -converters, or for direct introduction into a building.<br> -<br> -<br> -<span style="font-weight: bold;">Wall Sockets.</span><br> -Sockets for incandescent lamps constructed to be attached to a wall.<br> -<br> -<br> -<span style="font-weight: bold;">Ward.</span><br> -Direction in a straight line; a term proposed by Prof. James Thompson.<br> -The words "backward" and "forward" indicate its scope.<br> -<br> -<br> -<span style="font-weight: bold;">Water.</span><br> -A compound whose molecule consists of two atoms of hydrogen and one atom<br> -of oxygen; formula, H2 O.<br> -<br> -Its specific gravity is 1, it being the base of the system of specific<br> -gravities of solids and liquids.<br> -<br> -If pure, it is almost a non-conductor of electricity. If any impurity is<br> -present it still presents an exceedingly high, almost immeasurable true<br> -resistance, but becomes by the presence of any impurity an electrolyte.<br> -<br> -<br> -<span style="font-weight: bold;">Water Equivalent.</span><br> -In a calorimeter of any kind the weight of water which would be raised<br> -as much as is the calorimeter with its contents by the addition of any<br> -given amount of heat received by the calorimeter.<br> -<br> -<br> -<span style="font-weight: bold;">Waterproof Lamp Globe.</span><br> -An outer globe for incandescent lamps, to protect them from water.<br> -<br> -<br> -<span style="font-weight: bold;">Watt.</span><br> -(a) The practical unit of electric activity, rate of work, or rate of<br> -energy. It is the rate of energy or of work represented by a current of<br> -one ampere urged by one volt electro-motive force; the volt-ampere.<br> -<br> -It is the analogue in electricity of the horse power in mechanics;<br> -approximately, 746 watts represent one electric horse power.<br> -<br> -Ohm's law, taken as C = E/R, gives as values for current, C and E/R, and<br> -for electro- motive force C R. In these formulas, C represents current<br> -strength, R represents resistance and E represents electro-motive force.<br> -Then a watt being the product of electro-motive force by current<br> -strength, we get the following values for rate of electric energy, of<br> -which the watt is the practical unit: (1) E2/R -- (2) C*E -- (3) C2 * R.<br> -<br> -<br> -The equivalents of the watt vary a little according to different<br> -authorities. Ayrton gives the following equivalents: 44.25 foot pounds<br> -per minute--.7375 foot pounds per second--1/746 horse power. These<br> -values are practically accurate. Hospitalier gives .7377 foot pounds per<br> -second. Hering gives .737324 foot pounds per second, and 1000/745941<br> -horse power.<br> -<br> -<br> -573 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -It is equal to 1E7 ergs per second.<br> -<br> -Synonym--Volt-ampere.<br> -<br> -(c) It has been proposed to use the term as the unit of energy, instead<br> -of activity or rate of energy (Sir C. W. Siemens, British Association,<br> -1882); this use has not been adopted and may be regarded as abandoned.<br> -<br> -[Transcriber's note; Watt is a unit of POWER--energy per unit of time.]<br> -<br> -<br> -<span style="font-weight: bold;">Watt-hour.</span><br> -A unit of electric energy or work; one watt exerted or expended for one<br> -hour.<br> -<br> -It is equivalent to :<br> -<small><span style="font-family: monospace;"> 866.448 -gram-degrees C. (calories)</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> 2654.4 -foot lbs.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -3600 watt-seconds or volt-coulombs.</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -60 watt-minutes.</span></small><br> -<br> -<br> -<span style="font-weight: bold;">Watt-minute.</span><br> -A unit of electric energy or work; one watt exerted or expended for one<br> -minute.<br> -<br> -It is equivalent to<br> -<small><span style="font-family: monospace;"> 14.4408 -gram-degrees C. (calories),</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> 44.240 foot -pounds,</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -60 watt seconds or volt-coulombs,</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> -1/60 watt hour.</span></small><br> -<br> -<br> -<span style="font-weight: bold;">Watts, Apparent.</span><br> -The product in an alternating current dynamo of the virtual amperes by<br> -the virtual volts. To give the true watts this product must be<br> -multiplied by the cosine of the angle of lead or lag. (See Current,<br> -Wattless.)<br> -<br> -[Transcriber's note: This is now called a volt-amp. The usual usage is<br> -KVA, or kilovolt-ampere.]<br> -<br> -<br> -<span style="font-weight: bold;">Watt-second.</span><br> -A unit of electric energy or work. One watt exerted or expended for one<br> -second.<br> -<br> -It is equivalent to<br> -<small><span style="font-family: monospace;"> -.24068 gram degree C. (calorie),</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> .000955 -lb. degree F.,</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> .737337 -foot lbs.,</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> .0013406 horse -power second (English),</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> .0013592 horse -power second (metric).</span></small><br> -<br> -Synonym--Volt-coulomb.<br> -<br> -<br> -<span style="font-weight: bold;">Waves, Electro-magnetic.</span><br> -Ether waves caused by electromagnetic disturbances affecting the<br> -luminiferous ether. (See Discharge, Oscillatory--Maxwell's Theory of<br> -Light--Resonance. Electric.)<br> -<br> -[Transcriber's note: The Michaelson-Morley experiment (1887) had already<br> -called ether into question, but quantum theory and photons are decades<br> -in the future.]<br> -<br> -<br> -574 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Weber.</span><br> -(a.) A name suggested by Clausius and Siemens to denote a magnet pole of<br> -unit strength. This use is abandoned.<br> -<br> -(b.) It has been used to designate the unit of quantity--the coulomb.<br> -This use is abandoned.<br> -<br> -(c.) It has been used to designate the unit of current strength the<br> -ampere. This use is abandoned.<br> -<br> -[Transcriber's note: Definition (a) is now used. One weber of magnetic<br> -flux linked to a circuit of one turn produces an electromotive force of<br> -1 volt if it is reduced to zero at a uniform rate in 1 second.]<br> -<br> -<br> -<span style="font-weight: bold;">Weber-meter.</span><br> -An ampere-meter or ammeter. The term is not used since the term "weber,"<br> -indicating the ampere or coulomb, has been abandoned.<br> -<br> -<br> -<span style="font-weight: bold;">Welding, Electric.</span><br> -Welding metals by heat produced by electricity. The heat may be produced<br> -by a current passing through the point of junction (Elihu Thomson) or by<br> -the voltaic arc. (Benardos & Olzewski.)<br> -<br> -<br> -<img style="width: 448px; height: 489px;" alt="" - src="images/574F346.JPG"><br> -Fig. 346. ELECTRIC WELDING INDUCTION COIL.<br> -<br> -<br> -The current process is carried out by pressing together the objects to<br> -be united, while holding them in conducting clamps. A heavy current is<br> -turned on by way of the clamps and rapidly heats the metals at the<br> -junction, which is of course the point of highest resistance. As the<br> -metal softens, it is pressed together, one of the clamps being mounted<br> -with feed motion, flux is dropped on if necessary, and the metal pieces<br> -unite.<br> -<br> -The most remarkable results are thus attained; almost all common metals<br> -can be welded, and different metals can be welded together. Tubes and<br> -other shapes can also be united. In many cases the weld is the strongest<br> -part.<br> -<br> -<br> -575 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The alternating current is employed. A special dynamo is sometimes used<br> -to produce it. This dynamo has two windings on the armature. One is of<br> -fine wire and is in series with the field magnets and excites them. The<br> -other is of copper bars, and connects with the welding apparatus, giving<br> -a current of high intensity but actuated by low potential.<br> -<br> -Where the special dynamo is not used, an induction coil or transformer<br> -is used. The primary includes a large number of convolutions of<br> -relatively fine wire; the secondary may only be one turn of a large<br> -copper bar.<br> -<br> -The cut shows in diagram an electric welding coil. P is the primary coil<br> -of a number of turns of wire; S S is the secondary, a single copper bar<br> -bent into an almost complete circle. It terminates in clamps D D for<br> -holding the bars to be welded. B C, B' C are the bars to be welded. They<br> -are pressed together by the screw J. The large coil I of iron wire<br> -surrounding the coils represents the iron core.<br> -<br> -The real apparatus as at present constructed involves many<br> -modifications. The diagram only illustrates the principle of the<br> -apparatus.<br> -<br> -In welding by the voltaic arc the place to be heated is made an<br> -electrode of an arc by connection with one terminal of an electric<br> -circuit. A carbon is connected to the other terminal. An arc is started<br> -by touching and withdrawal of the carbon. The heat may be used for<br> -welding, soldering, brazing, or even for perforating or dividing metal<br> -sheets.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Welding Transformer.</span><br> -The induction coil or transformer used in electric welding. For its<br> -general principles of construction, see Welding, Electric.<br> -<br> -<br> -<span style="font-weight: bold;">Wheatstone's Bridge.</span><br> -A system of connections applied to parallel circuits, including<br> -resistance coils for the purpose of measuring an unknown resistance. A<br> -single current is made to pass from A through two parallel connected<br> -branches, joining together again at C. A cross connection B D has a<br> -galvanometer or other current indicator in circuit. In any conductor<br> -through which a current is passing, the fall of potential at given<br> -points is proportional to the resistance between such points. Referring<br> -to the diagram a given fall of potential exists between A and C. The<br> -fall between A and B is to the fall between A and C as the resistance r<br> -between A and B is to the resistance r + r' between A and C. The same<br> -applies to the other branch, with the substitution of the resistances s<br> -and S' and the point D for r r' and B. Therefore, if this proportion<br> -holds, r : r' : : s : S'. No current will go through B D , and the<br> -galvanometer will be unaffected. Assume s' to be of unknown resistance,<br> -the above proportion will give it, if r, r' and s are known, or if the<br> -ratio of r to r' and the absolute value of s is known.<br> -<br> -<br> -576 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -In use the resistances r, r', and s are made to vary as desired. To<br> -measure an unknown resistance it is introduced at S', and one of the<br> -other resistances is varied until the galvanometer is unaffected. Then<br> -the resistance of S' is determined by calculation as just explained. The<br> -artificial resistances may be resistance coils, q. v., or it is enough<br> -to have one unknown resistance at s. Then if the length of wire ABC is<br> -accurately known, the point B can be shifted along it until the balance<br> -is attained. The relative lengths A B, and B C, will then give the ratio<br> -r : r' needed for the calculation. This assumes the wire ABC to be of<br> -absolutely uniform resistance. This is the principle of the meter-bridge<br> -described below. The use of coils is the more common method and is<br> -carried out by special resistance boxes, with the connections arranged<br> -to carry out the exact principle as explained. The principle of<br> -construction and use of a resistance box of the Wheatstone bridge type,<br> -as shown in the cut, is described under Box Bridge, q. v.<br> -<br> -<br> -<img style="width: 414px; height: 610px;" alt="" - src="images/576F347.JPG"><br> -FIG. 347. WHEATSTONE BRIDGE CONNECTIONS.<br> -<br> -<br> -<img style="width: 582px; height: 430px;" alt="" - src="images/576F348.JPG"><br> -FIG. 348. TOP OF BOX BRIDGE.<br> -<br> -<br> -577 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -The next cut shows the sliding form of bridge called the meter bridge,<br> -if the slide wire is a meter long or a half- or a quarter-meter bridge,<br> -etc., according to the length of this wire. It is described under Meter<br> -Bridge, q. v. Many refinements in construction and in proper proportion<br> -of resistances for given work apply to these constructions.<br> -<br> -Synonyms--Electric Balance--Resistance Bridge--Wheatstone's Balance.<br> -<br> -<br> -<img style="width: 614px; height: 396px;" alt="" - src="images/577F349.JPG"><br> -Fig. 349. METER BRIDGE.<br> -<br> -<br> -<span style="font-weight: bold;">Whirl, Electric.</span><br> -(a) A conductor carrying an electric current is surrounded by circular<br> -lines of force, which are sometimes termed an electric whirl.<br> -<br> -(b) The Electric Flyer. (See Flyer, Electric.)<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Wimshurst Electric Machine.</span><br> -An influence machine for producing high potential or static electricity.<br> -<br> -Two circular discs of thin glass are mounted on perforated hubs or<br> -bosses of wood or ebonite. Each hub has a groove turned upon it to<br> -receive a cord. Each disc is shellacked. They are mounted on a<br> -horizontal steel spindle so as to face and to be within one-eighth of an<br> -inch of each other. On the outside of each disc sixteen or eighteen<br> -sectors of tinfoil or thin metal are cemented.<br> -<br> -<br> -578 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -Two curved brass rods terminating in wire brushes curved into a<br> -semi-ellipse just graze the outer surfaces of the plates with their<br> -brushes. They lie in imaginary planes, passing through the axis of the<br> -spindle and at right angles from each other.<br> -<br> -Four collecting combs are arranged horizontally on insulating supports<br> -to collect electricity from the horizontal diameters of the discs. These<br> -lie at an angle of about 45° with the other equalizing rods. -Discharging<br> -rods connect with the collecting combs.<br> -<br> -The principle of the machine is that one set of sector plates act as<br> -inductors for the other set. Its action is not perfectly understood.<br> -<br> -It works well in damp weather, far surpassing other influence machines<br> -in this respect. On turning the handle a constant succession or stream<br> -of sparks is produced between the terminals of the discharging rods.<br> -<br> -<br> -<span style="font-weight: bold;">Windage.</span><br> -In a dynamo the real air gap between the armature windings and pole<br> -pieces is sometimes thus termed.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Wind, Electric.</span><br> -The rush of air particles from a point connected to a statically charged<br> -condenser.<br> -<br> -<br> -<span style="font-weight: bold;">Winding, Compound.</span><br> -A method of winding a generator or motor in which a shunt winding is<br> -used for the field magnets and in which also a second winding of the<br> -magnet is placed in series with the outer circuit. (See Winding,<br> -Series--Winding, Shunt.)<br> -<br> -<br> -<img style="width: 607px; height: 372px;" alt="" - src="images/578F350.JPG"><br> -Fig. 350. CHARACTERISTIC CURVES OF SHUNT AND SERIES WINDING.<br> -<br> -<br> -The object of compound winding is to make a self-regulating dynamo and<br> -this object is partly attained for a constant speed.<br> -<br> -The characteristic curves of shunt and series winding are of opposite<br> -natures. The first increases in electro-motive force for resistance in<br> -the outer circuit, the latter decreases under the same conditions. If<br> -the windings are so proportioned that these conditions for each one of<br> -the two windings are equal and opposite, it is evident that the<br> -characteristic may be a straight line. This, however, it will only be at<br> -a single speed of rotation.<br> -<br> -<br> -579 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Winding, Disc.</span><br> -A winding which (S. P. Thompson) may be treated as a drum winding<br> -extended radially, the periphery corresponding to the back end of the<br> -drum. The magnet poles are generally placed so as to face the side or<br> -sides of the disc.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Winding, Lap.</span><br> -A method of winding disc and drum armatures. It consists in lapping back<br> -each lead of wire towards the preceding lead upon the commutator end of<br> -the armature. Thus taking the letter U as the diagrammatical<br> -representation of a turn of wire in connecting its ends to the<br> -commutator bars they are brought towards each other so as to connect<br> -with contiguous commutator bars. This carries out the principle of<br> -keeping the two members of the U moving in regions of opposite polarity<br> -of field, so that the currents induced in them shall have opposite<br> -directions, thus producing a total current in one sense through the bent<br> -wire.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Winding, Long Shunt.</span><br> -A system of compound winding for dynamos and motors. The field is wound<br> -in series and, in addition thereto, there is a shunt winding connected<br> -across from terminal to terminal of the machine, and which may be<br> -regarded either as a shunt to the outer circuit, or as a shunt to the<br> -series-field and armature winding. (See Winding, Short Shunt.)<br> -<br> -Synonyms--Series and Long Shunt Winding.<br> -<br> -<br> -<span style="font-weight: bold;">Winding, Multiple.</span><br> -A winding of an electro-magnet, in which separate coils are wound on the<br> -core, so that one or any number may be used as desired in parallel or in<br> -series. For each coil a separate binding post should be provided.<br> -<br> -<br> -<span style="font-weight: bold;">Winding, Multipolar.</span><br> -Winding adapted for armatures of multi-polar dynamos or motors.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Winding, Series.</span><br> -A method of winding a generator or motor, in which one of the<br> -commutator-brush connections is connected to the field-magnet winding;<br> -the other end of the magnet winding connects with the outer circuit. The<br> -other armature-brush connects with the other terminal of the outer<br> -circuit.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Winding, Series and Separate Coil.</span><br> -A method of automatic regulation applied to alternating current dynamos.<br> -<br> -<br> -<span style="font-weight: bold;">Winding, Short Shunt.</span><br> -A method of compound winding for dynamos and motors. The field is wound<br> -in series, and in addition thereto there is a shunt winding connected<br> -from brush to brush only, thus paralleling the armature. (See Winding,<br> -Long Shunt.)<br> -<br> -Synonyms--Series and Short Shunt Winding.<br> -<br> -<br> -580 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Winding, Shunt.</span><br> -A method of winding a generator or motor. Each commutator-brush has two<br> -connections. One set are the terminals of the outer circuit, the other<br> -set are the terminals of the field-magnet windings. In other words, the<br> -field-magnet windings are in shunt or in parallel with the outer<br> -circuit.<br> -<br> -<br> -<span style="font-weight: bold;">Winding, Shuttle.</span><br> -A method of dynamo or motor-armature winding. A single groove passes<br> -longitudinally around the core and in this the wire is continuously<br> -wound. The system is not now used. The old Siemens' H armature<br> -illustrates the principle.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Winding, Wave.</span><br> -A method of winding disc and drum armatures. It consists in advancing<br> -the commutator ends of the U shaped turns progressively, so that as many<br> -commutator bars intervene between any two consecutive commutator<br> -connections of the wire as there are leads of wire on the drum between<br> -consecutive leads of the wire. This is carried out with due regard to<br> -the principle that taking the letter U as the diagrammatical<br> -representation of a turn of wire, its two members must move through<br> -regions of the field of opposite polarity.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Wire Finder.</span><br> -A galvanometer or other instrument used for identifying the ends of a<br> -given wire in a cable containing several.<br> -<br> -<br> -<span style="font-weight: bold;">Work.</span><br> -When a force acts upon a body and the body moves in the direction of the<br> -force, the force does work. Hence, work is the action of a force through<br> -space against resistance.<br> -<br> -It is generally expressed in compound units of length and weight, as<br> -foot-pounds, meaning a pound raised one foot.<br> -<br> -<br> -<span style="font-weight: bold;">Work, Electric, Unit of.</span><br> -The volt-coulomb, q. v., or watt-second, as it is often termed.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Working, Diode.</span><br> -In multiplex telegraphy the transmission of two messages,<br> -simultaneously, over one wire. (See Telegraphy, Multiple.)<br> -<br> -<br> -<span style="font-weight: bold;">Working, Contraplex.</span><br> -A variety of duplex telegraphy in which the messages are sent from<br> -opposite ends of the line, simultaneously, so as to be transmitted in<br> -opposite directions. (See Working, Diplex.)<br> -<br> -<br> -<span style="font-weight: bold;">Working, Diplex.</span><br> -In duplex telegraphy the sending of two independent messages from the<br> -same end of the line in the same direction.<br> -<br> -<br> -581 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Working, Double Curb.</span><br> -A method of working telegraph lines. When a signal is sent the line is<br> -charged. This has to be got rid of, and is an element of retardation. In<br> -double curb working it is disposed of by sending a momentary current<br> -first in the reverse, and then in the same, and finally in the reverse<br> -direction. This is found to reduce the charge to a very low point.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Working, Hexode.</span><br> -In multiplex telegraphy the transmission of six messages simultaneously<br> -over one wire. (See Telegraphy, Multiplex.)<br> -<br> -<br> -<span style="font-weight: bold;">Working, Pentode.</span><br> -In multiplex telegraphy the transmission of five messages simultaneously<br> -over one wire. (See Telegraphy, Multiplex.)<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Working, Reverse Current.</span><br> -A method of telegraphy, in which the currents are reversed or alternated<br> -in direction.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Working, Single Curb.</span><br> -A simpler form of telegraph signaling than double curb working. It<br> -consists in sending a reverse current through the line for each signal<br> -by reversing the battery connection.<br> -<br> -<br> -<span style="font-weight: bold;">Working, Tetrode.</span><br> -In multiplex telegraphy the transmission of four messages simultaneously<br> -over the same line. (See Telegraphy, Multiplex.)<br> -<br> -<br> -<span style="font-weight: bold;">Working, Triode.</span><br> -In multiplex telegraphy the transmission of three messages<br> -simultaneously over the same wire. (See Telegraphy, Multiplex.)<br> -<br> -<br> -<span style="font-weight: bold;">Work, Unit of.</span><br> -The erg, q. v. It is the same as the unit of energy, of which work is<br> -the corelative, being equal and opposite to the energy expended in doing<br> -it. There are many other engineering units of work, as the foot-pound<br> -and foot-ton.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Yoke.</span><br> -In an electro-magnet, the piece of iron which connects the ends furthest<br> -from the poles of the two portions of the core on which the wire is<br> -wound.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Zamboni's Dry Pile.</span><br> -A voltaic pile or battery. It is made of discs of paper, silvered or<br> -tinned on one side and sprinkled on the other with binoxide of<br> -manganese. Sometimes as many as 2,000 of such couples are piled up in a<br> -glass tube and pressed together with two rods which form the terminals.<br> -They maintain a high potential difference, but having very high<br> -resistance and slight polarization capacity, give exceedingly small<br> -quantities.<br> -<br> -<span style="font-weight: bold;">Zero.</span><br> -(a) The origin of any scale of measurement.<br> -<br> -(b) An infinitely small quantity or measurement.<br> -<br> -<br> -582 STANDARD ELECTRICAL DICTIONARY.<br> -<br> -<br> -<span style="font-weight: bold;">Zero, Absolute.</span><br> -From several considerations it is believed that at a certain temperature<br> -the molecules of all bodies would touch each other, their kinetic motion<br> -would cease, and there would be no heat. This temperature is the<br> -absolute zero. It is put at -273° C. (-459° F.)<br> -<br> -[Transcriber's note; The modern value is 0</big></big><big><big>°</big></big><big><big> -Kelvin, -273.15</big></big><big><big>°</big></big><big><big> -C, or<br> --459.67</big></big><big><big>°</big></big><big><big> F. The lowest -reported temperature observed is 1E-10</big></big><big><big>°</big></big><big><big> -K.]<br> -<br> -<br> -<span style="font-weight: bold;">Zero, Potential.</span><br> -Conventionally, the potential of the earth. True zero potential could<br> -only exist in the surface of a body infinitely distant from other<br> -electrified bodies.<br> -<br> -<br> -<span style="font-weight: bold;">Zero, Thermometric.</span><br> -There are three thermometric zeros. In the Réaumur and centigrade<br> -scales, it is at the temperature of melting ice; in the Fahrenheit<br> -scale, it is 32° F. below that temperature, or corresponds to --17.78° C.<br> -<br> -The third is the absolute zero. (See Zero, Absolute.)<br> -<br> -<br> -<span style="font-weight: bold;">Zinc.</span><br> -A metal; one of the elements; atomic weight, 65.1;<br> -specific gravity, 6.8 to 7.2.<br> -<small><br style="font-family: monospace;"> -<span style="font-family: monospace;"> -microhms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Resistance at 0° C. (32° -F.), per centimeter cube, -5.626</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Resistance at 0° C. (32° -F.), per inch -cube, 2.215</span><br - style="font-family: monospace;"> -<br style="font-family: monospace;"> -<span style="font-family: monospace;">Relative resistance (silver = -1), -3.741</span><br style="font-family: monospace;"> -<br style="font-family: monospace;"> -<span style="font-family: monospace;"> -ohms.</span><br style="font-family: monospace;"> -<span style="font-family: monospace;">Resistance of a wire, 1 foot -long, weighing 1 grain, .5766</span><br - style="font-family: monospace;"> -<span style="font-family: monospace;"> (a) 1 foot long, 1 -millimeter -diameter, -33.85</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> (b) 1 meter long, weighing -1 -gram, -.4023</span><br style="font-family: monospace;"> -<span style="font-family: monospace;"> (c) 1 meter long, 1 -millimeter -diameter, -.07163</span></small> -<br> -<br> -Zinc is principally used in electrical work as the positive plate in<br> -voltaic batteries.<br> -<br> -<br> -<span style="font-weight: bold;">Zincode.</span><br> -The terminal connecting with the zinc plate, or its equivalent in an<br> -electric circuit; the negative electrode; the kathode. A term now little<br> -used.<br> -<br> -<br> -<span style="font-weight: bold;">Zinc Sender.</span><br> -An apparatus used in telegraphy for sending a momentary reverse current<br> -into the line after each signal, thus counteracting retardation.<br> -<br> -<br> -<span style="font-weight: bold;">Zone, Peripolar.</span><br> -In medical electricity, the region surrounding the polar zone, q. v.<br> -<br> -<br style="font-weight: bold;"> -<span style="font-weight: bold;">Zone, Polar.</span><br> -In medical electricity, the region surrounding the electrode applied to<br> -the human body.<br> -<br> -<br> -</big></big><big><big><br> -583-624 INDEX.<br> -<br> - Page<br> -A 7<br> -Absolute 7<br> -Absolute Calibration 97<br> -Absolute Electric Potential 429<br> -Absolute Electrometer 222<br> -Absolute Galvanometer 266<br> -Absolute Measurement 8<br> -Absolute Potential 428<br> -Absolute Temperature 8<br> -Absolute Unit 554<br> -Absolute Unit Resistance, Weber's 468<br> -Absolute Vacuum 557<br> -Absolute Zero 581<br> -Abscissa 7<br> -Abscissas, Axis of 54<br> -Absorption, Electric 8<br> -A. C. C. 8<br> -Acceleration 8<br> -Accumulator 8<br> -Accumulator, Electrostatic 8<br> -Accumulator, Water Dropping 9<br> -Acetic Acid Battery 58<br> -Acheson Effect 208<br> -Acid, Carbonic 108<br> -Acid, Chromic, Battery 61<br> -Acid, Hydrochloric, Battery 66<br> -Acid, Spent 491<br> -Acid, Sulphuric 497<br> -Acidometer 10<br> -Acierage 494<br> -Aclinic Line 10<br> -Acoustic Telegraphy 10<br> -Acoutemeter 10, 53<br> -Action, Electrophoric 230<br> -Action, Local 331<br> -Action, Magne-crystallic 335<br> -Action, Refreshing 454<br> -Action, Secondary 477<br> -Actinic Photometer 411<br> -Actinic Rays. 11<br> -Actinism 11<br> -Actinometer, Electric 11<br> -Active Electric Circuit, 123<br> -Activity 11<br> -Actual Horse Power 290<br> -Adapter 11<br> -A. D. C., 11<br> -Adherence, Electro-magnetic 11<br> -Adherence, Magnetic 338<br> -Adjuster, Cord 152<br> -Adjustment of Brushes 90<br> -Admiralty Rules of Heating 12<br> -AEolotropic 34<br> -Aerial Cable 95<br> -Aerial Conductor 12<br> -Affinity 12<br> -Affinity, Molecular 380<br> -After Current,. 159<br> -Agglomerate Leclanché Battery 66<br> -Agir Motor 13<br> -Agone 13<br> -Agonic Line, 13<br> -Air 13<br> -Air Blast 13<br> -Air Condenser 14<br> -Air Field 252<br> -Air Gaps 15<br> -Air Line Wire 15<br> -Air Pump, Heated 15<br> -Air Pump, Mercurial 16<br> -Air Pumps, Short Fall 16<br> -Alarm, Burglar 16<br> -Alarm, Electric 17<br> -Alarm, Fire, Electric Automatic 257<br> -Alarm, Fire and Heat 17<br> -Alarm, Overflow 18<br> -Alarm, Water Level 18<br> -Alcohol, Electric Rectification of 18<br> -Alignment, 18<br> -Allotropy 18<br> -Alloy 18<br> -Alloy, Platinum 419<br> -Alloy, Platinum-Silver 419<br> -Alloys, Paillard 400<br> -Alphabet, Telegraphic 19<br> -Alternating 23<br> -Alternating Current 159<br> -Alternating Current Arc 23<br> -Alternating Current Dynamo 193<br> -Alternating Current Generator or Dynamo 24<br> -Alternating Current Meter 373<br> -Alternating Current System 23<br> -Alternating Field 252<br> -Alternative Current 563<br> -Alternative Path 24<br> -Alternatives, Voltaic 563<br> -Alternator 24<br> -Alternator, Constant Current 24<br> -Alternator, Dead Point of an 177<br> -Alternation 23<br> -Alternation, Complete 23<br> -Alternation, Cycle of 175<br> -Alum Battery 58<br> -Aluminum 24<br> -Aluminum Battery 58<br> -Amalgam 24<br> -Amalgamation 25<br> -Amber 25<br> -American Twist Joint 309<br> -Ammeter 26<br> -Ammeter, Ayrton 26<br> -Ammeter, Commutator 26<br> -Ammeter, Cunynghame's 26<br> -Ammeter, Eccentric Iron Disc 27<br> -Ammeter, Electro-magnetic 27<br> -Ammeter, Gravity 27<br> -Ammeter, Magnetic Vane 27<br> -Ammeter, Magnifying Spring 28<br> -Ammeter, Permanent Magnet 28<br> -Ammeter, Reducteur for 453<br> -Ammeter, Solenoid 28<br> -Ammeter, Spring 28<br> -Ammeter, Steel Yard 28<br> -Ammunition Hoist, Electric 29<br> -Amperage 29<br> -Ampere 29<br> -Ampere- and Volt-meter Galvanometer 274<br> -Ampere Arc 30<br> -Ampere Balance 56<br> -Ampere Currents 30<br> -Ampere Feet 30<br> -Ampere-hour 30<br> -Amperes, Lost 30<br> -Ampêre's Memoria Technica 30<br> -Ampere Meters 26, 30<br> -Ampere Meter, Balance 391<br> -Ampere Meter, Neutral Wire 391<br> -Ampere-minute 30<br> -Ampere Ring 30<br> -Ampere-second 30<br> -Ampere's Theory of Magnetism 354<br> -Ampere-turns 31<br> -Ampere-turns, Primary 31<br> -Ampere-turns, Secondary 31, 551<br> -Ampere Windings 31<br> -Ampérian Currents 165<br> -Amplitude of Waves 31<br> -Analogous Pole 31, 425<br> -Analysis 31<br> -Analysis, Electric 32<br> -Analysis, Electrolytic 214<br> -Analyzer, Electric 32<br> -Anelectrics 32<br> -Anelectrotonus 32<br> -Angle of Declination 32, 177<br> -Angle of the Polar Span 32<br> -Angle of Inclination or Dip 33<br> -Angle of Lag 33-318<br> -Angle of Lead 33<br> -Angle of Maximum Sensitiveness 479<br> -Angle of Polar Span 423<br> -Angle, Polar 423<br> -Angle, Unit 554<br> -Angular Currents 165<br> -Angular Currents, Laws of 165<br> -Angular Force 544<br> -Angular Velocity 32, 559<br> -Animal Electricity 33<br> -Animal System, Electric Excitability of 247<br> -Anion 33<br> -Anisotropic 34<br> -Annealing, Electric 34<br> -Annular Electro-magnet 216<br> -Annunciator 34<br> -Annunciator Clock 35<br> -Annunciator Clock, Electric 127<br> -Annunciator Drop 35<br> -Annunciator, Gravity Drop 35<br> -Annunciator, Needle 35<br> -Annunciator, Swinging or Pendulum 35<br> -Anodal Diffusion 35<br> -Anode 36<br> -Anodic Closure Contraction 36<br> -Anodic Duration Contraction 36<br> -Anodic Opening Contraction 36<br> -Anodic Reactions 36<br> -Anomalous Magnet 335<br> -Anti-induction Conductor 36, 145<br> -Anti-magnetic Shield 37<br> -Antilogous Pole, 425<br> -Antimony 37<br> -Anvil 37<br> -A. O. C. 38<br> -Aperiodic 38<br> -Aperiodic Galvanometer 266<br> -Apparent Coefficient of Magnetic Induction 346<br> -Apparent Resistance 297, 462<br> -Apparent Watts 573<br> -Arago's Disc 88<br> -Arc 39<br> -Arc, Ampere 30<br> -Arc, Compound. 39<br> -Arc, Electric Blow-pipe 84<br> -Arc, Metallic 39<br> -Arc, Micrometer 39, 376<br> -Arc, Multiple 387<br> -Arc, Simple 39<br> -Arc, Voltaic 39<br> -Arc Box, Multiple 387<br> -Arc Lamp 319<br> -Arc Lamp, Differential 320<br> -Arc Lamp, Double Carbon 191<br> -Areometer 41<br> -Areometer, Bead 41<br> -Argyrometry 41<br> -Arm 41<br> -Armature 41<br> -Armature, Bar 42<br> -Armature, Bipolar 42<br> -Armature Bore 42<br> -Armature Chamber 42<br> -Armature, Closed Coil 43<br> -Armature Coil, or Coils 43<br> -Armature Conductors, Lamination of 319<br> -Armature Core 43<br> -Armature, Cylinder 43<br> -Armature, Cylindrical 45<br> -Armature, Disc 43<br> -Armature, Drum 45<br> -Armature Factor 45<br> -Armature, Flat Ring 45<br> -Armature, Girder 49<br> -Armature, H 49<br> -Armature, Hinged 45<br> -Armature, Hole 45<br> -Armature, Intensity 45<br> -Armature Interference 45<br> -Armature, Load of 46<br> -Armature, Multipolar 46<br> -Armature, Neutral 46<br> -Armature, Neutral Relay 46, 390<br> -Armature, Non-polarized 46<br> -Armature of Influence Machine 46<br> -Armature of Leyden Jar or Static Condenser 46<br> -Armature, Open Coil 46<br> -Armature, Perforated 45<br> -Armature, Pivoted 47<br> -Armature Pockets 47<br> -Armature, Polarized 47<br> -Armature, Pole 47<br> -Armature, Quantity 47<br> -Armature, Radial 47<br> -Armature Reactions 41<br> -Armature, Revolving, Page's 47<br> -Armature, Ring 48<br> -Armature, Rolling 49<br> -Armatures, Gyrostatic Action of 288<br> -Armature, Shuttle 49<br> -Armature, Siemens' Old 49<br> -Armature, Spherical 49<br> -Armature, Stranded Conductor 49<br> -Armature, Unipolar 50, 553<br> -Armature, Ventilation of 560<br> -Armor of Cable 50<br> -Arm, Rheostat 472<br> -Arms, Proportionate 436<br> -Arms, Ratio 437<br> -Arms, Rocker 50-474<br> -Arrester, Lightning 328<br> -Arrester, Lightning, Counter-electro-motive Force 329<br> -Arrester, Lightning, Plates 329<br> -Arrester, Lightning, Vacuum. 329<br> -Arrester Plate 417<br> -Arrester, Spark 489<br> -Arrival Curve 168<br> -Articulate Speech 50<br> -Artificial Carbon 106<br> -Artificial Magnet 335<br> -Ascending Lightning 330<br> -Assymmetrical Resistance 462<br> -Astatic 50<br> -Astatic Circuit 12<br> -Astatic Couple 157<br> -Astatic Galvanometer 266<br> -Astatic Needle 50<br> -Astronomical Meridian, 372<br> -Asymptote 51<br> -Atmosphere 51<br> -Atmosphere, Residual 51, 460<br> -Atmospheric Electricity 51<br> -Atom 52<br> -Atomic Attraction 52<br> -Atomic Current 160<br> -Atomic Energy 238<br> -Atomic Heat 52-285<br> -Atomic Weight 53<br> -Atomicity 52<br> -Attracted Disc Electrometer 223<br> -Attraction 53<br> -Attraction, Atomic 52<br> -Attraction, Magnetic 338<br> -Attraction, Molar 380<br> -Attraction, Molecular 380<br> -Attraction and Repulsion, Electro-dynamic 211<br> -Attraction and Repulsion, Electro-magnetic 217<br> -Attraction and Repulsion, Electro-static 234<br> -Attraction and Repulsion, Electro-static, Coulomb's Law of -155<br> -Audiometer 53<br> -Aura, Electrical 53<br> -Aurora 53<br> -Austral Pole 54<br> -Autographic Telegraph 510<br> -Automatic Circuit Breaker 121<br> -Automatic Cut Out 175, 475<br> -Automatic Drop 192<br> -Automatic Electric Bell 78<br> -Automatic Electric Fire Alarm 257<br> -Automatic Switch 500<br> -Automatic Telegraph 504<br> -A. W. G., 54<br> -Axial Couple 514<br> -Axial Force 544<br> -Axial Magnet 336<br> -Axis, Electric 54<br> -Axis, Magnetic 338<br> -Axis of Abscissas 54<br> -Axis of Ordinates 54, 397<br> -Axis of X 54<br> -Axis of Y 54, 397<br> -Ayrton's Ammeter 26<br> -Azimuth 54<br> -Azimuth Circle 54<br> -Azimuth Compass 141<br> -Azimuth, Magnetic 338<br> -<br> -B 55<br> -B. A. 55<br> -Back Electro-motive Force of Polarization 156<br> -Back Induction 55<br> -Back Shock or Stroke of Lightning 55<br> -Back Stroke 55<br> -Bagration Battery 59<br> -Balance 55<br> -Balance, Ampere 56<br> -Balance Ampere Meter 391<br> -Balance, Electric 577<br> -Balance, Inductance 293<br> -Balance, Plating 417<br> -Balance, Slide 374<br> -Balance, Thermic 85<br> -Balance, Torsion, Coulomb's 544<br> -Balance, Wheatstone's 577<br> -Balata 56<br> -Ballistic Galvanometer 567<br> -Balloon Battery 59<br> -B. and S. W. G. 56<br> -Banked Battery 59<br> -Bank of Lamps 323<br> -B. A. Ohm 394<br> -Barad 56<br> -Bar, Armature 42<br> -Bar, Bus 94<br> -Bar Electro-magnet 217<br> -Bar Magnet 336<br> -Barometer 56<br> -Bar, Omnibus 94<br> -Bar Photometer 411<br> -Bars, Commutator 56, 140<br> -Bath 57<br> -Bath, Bipolar Electric 57<br> -Bath, Copper 152<br> -Bath, Copper Stripping 152<br> -Bath, Electric Head 284<br> -Bath, Electric Shower 57<br> -Bath, Gold 279<br> -Bath, Gold Stripping 279<br> -Bath, Multipolar Electric 57<br> -Bath, Nickel 391<br> -Bath, Plating 418<br> -Baths, Electro-medical 222<br> -Bath, Silver 484<br> -Bath, Silver Stripping 484<br> -Bath, Stripping 57<br> -Bath, Unipolar Electric 57<br> -Batten 57-58<br> -Battery, Acetic Acid 58<br> -Battery, Alum 58<br> -Battery, Aluminum 58<br> -Battery, Bagration 59<br> -Battery, Balloon 59<br> -Battery, Banked 59<br> -Battery, Bichromate 59<br> -Battery, Bunsen 59<br> -Battery, Cadmium 60<br> -Battery, Callan 60<br> -Battery, Camacho's 60<br> -Battery, Carré's 60<br> -Battery, Cautery 61<br> -Battery Cell, Element of a 237<br> -Battery, Chloric Acid 61<br> -Battery, Chloride of Lime 61<br> -Battery, Chromic Acid 61<br> -Battery, Closed Circuit 61<br> -Battery, Column 61<br> -Battery, d'Arsonval's 62<br> -Battery, de la Rue .62<br> -Battery, de la Rive's Floating 179<br> -Battery, Dry 63<br> -Battery, Elements of 63<br> -Battery, Faradic 63<br> -Battery, Ferric Chloride 63<br> -Battery, Fuller's 63<br> -Battery, Gas 63<br> -Battery, Gas, Grove's 281<br> -Battery Gauge 64<br> -Battery, Gravity 64<br> -Battery, Grenet 65<br> -Battery, Grove's 65<br> -Battery, Hydrochloric Acid 66<br> -Battery, Lalande & Chaperon 69<br> -Battery, Lalande-Edison 69<br> -Battery, Lead Chloride 66<br> -Battery, Lead Sulphate 66<br> -Battery, Leclanché 66<br> -Battery, Leclanché Agglomerate 66<br> -Battery, Local 66, 831<br> -Battery, Magnetic 338<br> -Battery, Main 66<br> -Battery, Marié Davy's 67<br> -Battery, Maynooth's 67<br> -Battery, Medical 67<br> -Battery, Meidinger's 68<br> -Battery, Mercury Bichromate 63<br> -Battery Mud 68<br> -Battery, Multiple Connected 68<br> -Battery, Niaudet's 61<br> -Battery, Nitric Acid 68<br> -Battery of Dynamos 6S<br> -Battery of Leyden Jars, 68<br> -Battery, Open Circuit 68<br> -Battery or Pile, Thermo-electric 530<br> -Battery, Oxide of Copper 68<br> -Battery, Peroxide of Lead 69<br> -Battery, Platinized Carbon 69<br> -Battery, Plunge 69<br> -Battery, Pneumatic 69<br> -Battery, Primary 69, 434<br> -Battery, Pulvermacher's Electro-medical 69<br> -Battery, Sal Ammoniac 69<br> -Battery, Salt, or Sea Salt 69<br> -Battery, Sand 70<br> -Battery, Secondary 70<br> -Battery, Secondary, Planté's 72<br> -Battery, Secondary, Real Efficiency of 205<br> -Battery, Sir William Thomson's 72<br> -Battery, Siemens and Halske's 72<br> -Battery, Skrivanow 72<br> -Battery, Smee's 73<br> -Battery Solutions, Chromic Acid 73<br> - 119, 178, 192, 232, 318, 421, 542, 549<br> -Battery, Spiral 73<br> -Battery, Split 73<br> -Battery, Sulphate of Mercury 67<br> -Battery System, Universal 556<br> -Battery, Thermo-chemical 530<br> -Battery, Trough 73<br> -Battery, Trouvé's Blotting Paper 73<br> -Battery, Tyer's 74<br> -Battery, Upward's 75<br> -Battery, Varley's 76<br> -Battery, Volta's 76<br> -Battery, Voltaic or Galvanic 76<br> -Battery Voltmeter 569<br> -Battery, Water 77<br> -Battery, Wollaston 78<br> -B. A. Unit, 554<br> -B. A. Unit of Resistance 78, 462<br> -B. A. Volt 568<br> -B. E. 78<br> -Bead Areometer 41<br> -Becquerel's Laws of Thermo-electricity 78<br> -Beaumé Hydrometer 78<br> -Bed-piece 78<br> -Bell, Automatic Electric 78<br> -Bell, Call 78, 98<br> -Bell Call 79<br> -Bell Call, Extension 248<br> -Bell, Circular 79<br> -Bell, Differentially Wound 79<br> -Bell, Electric 79<br> -Bell, Electro-mechanical 80<br> -Bell, Indicating 80, 297<br> -Bell, Magneto 80<br> -Bell, Magneto Call 361<br> -Bell, Night 392<br> -Bell-shaped Magnet, 336<br> -Bells, Relay 80, 457<br> -Bell, Trembling 78<br> -Bell, Vibrating. 78<br> -Belts, Joints in 311<br> -Bennett's Electroscope 233<br> -Bias 80<br> -Bias of Tongue of Polarized Relay 542<br> -Bichromate Battery 59<br> -Bichromate Mercury Battery 63<br> -Bifilar Suspension 498<br> -Bifilar Winding 81<br> -Binary Compound 81<br> -Binding 81<br> -Binding Posts or Screws 81<br> -Binnacle 81<br> -Biology, Electro- 208<br> -Bioscopy, Electric 82<br> -Bipolar Armature 42<br> -Bipolar Electric Bath 57<br> -Bisected Coils 132<br> -Bismuth 82<br> -Bi-telephone 82, 524<br> -Black, Platinum 419<br> -Blasting, Electric 83<br> -Bleaching, Electric 83<br> -Block, Branch 87<br> -Block, Cross-over 158<br> -Block System 83<br> -Block Wire 83<br> -Blotting Paper Battery, Trouvé's 73<br> -Blow-pipe 83<br> -Blow-pipe, Electric Arc 84<br> -Blue Magnetism 355<br> -Bluestone 84<br> -Blue Vitriol 562<br> -Board, Cross-connecting 157<br> -Board, Fuse 263<br> -Board, Hanger 284<br> -Board, Key 313<br> -Board, Multiple Switch 387<br> -Board of Trade Ohm 394<br> -Board of Trade Unit 555<br> -Board, Switch 500<br> -Boat, Electric 84<br> -Bobbins 84<br> -Body Protector 84<br> -Bohenberger's Electroscope 233<br> -Boiler Feed, Electric 84<br> -Boiling 84<br> -Boll 85<br> -Bolometer 85<br> -Bombardment, Molecular 380<br> -Bore, Armature 42<br> -Boreal Pole 85<br> -Bot 85<br> -Bound Charge 115<br> -Box Bridge 85<br> -Box, Cable 95<br> -Box, Cooling 151<br> -Box, Distributing 190<br> -Boxes, Flush 258<br> -Box, Fishing 311<br> -Box, Fuse 263<br> -Boxing the Compass 86<br> -Box, Junction 311<br> -Box, Multiple Arc 387<br> -Box, Resistance 462<br> -Box, Resistance, Sliding 463<br> -Box Sounding Relay 457<br> -Box, Splice 492<br> -Bracket, Saddle 475<br> -Bracket, Wall 572<br> -Braid, Tubular 550<br> -Brake, Electro-magnetic 86<br> -Brake, Magneto-electric 362<br> -Brake, Prony 435<br> -Branch 87<br> -Branch Block 87<br> -Branch Circuit 121<br> -Branch Conductor 87<br> -Branding, Electric 87<br> -Brassing 87<br> -Brazing, Electric 87<br> -Break 88<br> -Break, Circuit Loop 125<br> -Break-down Switch 88<br> -Breaker, Automatic Circuit 121<br> -Breaker, Circuit 121<br> -Breaker, Circuit, File 121<br> -Breaker, Contact 121, 146<br> -Break Induced Current 162<br> -Breaking Weight 89<br> -Break, Loop 332<br> -Break Shock 482<br> -Breath Figures, Electric 89<br> -Breeze, Electric 89<br> -Breeze, Static 493<br> -Breguet Unit of Resistance 463<br> -Bridge 89<br> -Bridge, Box 89<br> -Bridge, Inductance 293<br> -Bridge, Induction 293<br> -Bridge Key 313<br> -Bridge, Magnetic 338<br> -Bridge, Meter 373<br> -Bridge, Resistance 577<br> -Bridge, Reversible 472<br> -Bridge, Slide 374<br> -Bridge, Wheatstone . 575<br> -Bridge, Wheatstone, Commercial 36<br> -British Association Bridge 89<br> -Britannia Joint 309<br> -Broadside Method 89<br> -Broken Circuit 125<br> -Bronzing 89<br> -Brush 90<br> -Brush, Carbon 90<br> -Brush, Collecting 90<br> -Brush, Discharge 187<br> -Brushes, Adjustment of 90<br> -Brushes, Lead of 90<br> -Brushes, Negative Lead of 324<br> -Brushes, Scratch 476<br> -Brush, Faradic 251<br> -Brush Holders 91<br> -Brush, Pilot 91<br> -Brush, Rotating 91<br> -Brush, Third 91<br> -Brush Trimmer 549<br> -Brush, Wire Gauge 92<br> -Buckling 92<br> -Bug 92<br> -Bug Trap 92<br> -Bunched Cable 95<br> -Bunsen Battery 59<br> -Bunsen Disc 92<br> -Bunsen's Photometer 412<br> -Buoy, Electric 93<br> -Burglar Alarm 16<br> -Burner, Electric Gas 93<br> -Burning 94<br> -Bus Bar 94<br> -Bus Rod 94<br> -Bus Wire 94<br> -Butt Joint 310<br> -Button, Call 98<br> -Button, Press 94<br> -Button, Push 93, 98<br> -Buzzer 94<br> -B. W. G. 94<br> -<br> -C 95<br> -C. C. 109<br> -Cable 95<br> -Cable, Aerial 95<br> -Cable, Armature of 50<br> -Cable, Armor of 50<br> -Cable Box 95<br> -Cable, Bunched 95<br> -Cable, Capacity of 95<br> -Cable Clip 97<br> -Cable Core 96<br> -Cable, Duplex 96<br> -Cable, Flat 96<br> -Cablegram 96<br> -Cable Grip 96<br> -Cable Hanger 96<br> -Cable Hanger Tongs 97<br> -Cable, Suspension Wire of 97<br> -Cable Tank 97<br> -Cadmium Battery 60<br> -Calamine 97<br> -Cal Electricity 208<br> -Calibration 97<br> -Calibration, Absolute 97<br> -Calibration, Invariable 97<br> -Calibration, Relative 98<br> -Call Bell 78, 79, 98<br> -Call Bell, Extension 248<br> -Call Bell, Magneto 361<br> -Call Button 98<br> -Call, Thermo 530<br> -Call, Thermo-electric 531<br> -Callan Battery 60<br> -Calling Drop 98<br> -Calorie or Calory 98<br> -Calorimeter 98<br> -Calorimetric Photometer 412<br> -Calory or Calorie 98<br> -Cam, Listening 330<br> -Camacho's Battery 60<br> -Candle 99<br> -Candle, Concentric 99<br> -Candle, Debrun 99<br> -Candle, Decimal 99<br> -Candle, Electric 99<br> -Candle-foot 259<br> -Candle, German Standard 99<br> -Candle Holder 99<br> -Candle, Jablochkoff 100<br> -Candle, Jamin 100<br> -Candle, Meter 374<br> -Candle Power 100<br> -Candle Power, Nominal 101<br> -Candle Power, Rated 101<br> -Candle Power, Spherical 101<br> -Candle, Standard 101<br> -Candle, Wilde 101<br> -Caoutchouc 101<br> -Cap, Insulator 306<br> -Capacity, Carrying 108<br> -Capacity, Dielectric 102<br> -Capacity, Electric or Electrostatic 102<br> -Capacity, Instantaneous 102<br> -Capacity, Magnetic Inductive 346, 349<br> -Capillarity, Electro- 209<br> -Capillary Electrometer 224<br> -Capacity of a Telegraph Conductor 103<br> -Capacity of Cable 95<br> -Capacity of Polarization of a Voltaic Cell 103<br> -Capacity, Polarization 424<br> -Capacity, Residual 103<br> -Capacity, Specific Inductive 103<br> -Capacity, Storage 105, 495<br> -Capacity, Unit of 105<br> -Capillarity 105<br> -Capillary Telephone 525<br> -Carbon 106<br> -Carbon, Artificial 106<br> -Carbon Brush 90<br> -Carbon, Concentric 107<br> -Carbon, Cored 107<br> -Carbon Dioxide 107<br> -Carbon Holders 107<br> -Carbonic Acid, 108<br> -Carbonic Acid Gas 108<br> -Carbonization 107<br> -Carbonized Cloth 107<br> -Carbon, Platinized, Battery 69<br> -Carbon Resistance 463<br> -Carbon, Retort 471<br> -Carbons, Lamp, Flashing of Incandescent 257<br> -Carbon, Telephone 525<br> -Carbon Transmitter 549<br> -Carbon, Volatilization of 108<br> -Carburetted Hydrogen, Heavy 397<br> -Carcel 108<br> -Carcel Gas Jet 108<br> -Carcel Lamp 108<br> -Card, Compass 142<br> -Cardew Voltmeter 569<br> -Carré's Battery 60<br> -Carrying Capacity 108<br> -Cascade 108<br> -Cascade, Charging and Discharging Leyden Jars in 108<br> -Cascade, Gassiot's 275<br> -Case-hardening, Electric 109<br> -Cataphoresis 109<br> -Catch, Safety 175<br> -Cathode, etc. See Kathode 312<br> -Caustry, Galvano 109<br> -Cautery Battery 61<br> -Cautery, Electric 109<br> -Cautery, Galvano 109<br> -Cautery, Galvano-electric 109<br> -Cautery, Galvano-thermal 109<br> -Cell, Battery, Element of a 237<br> -Cell, Constant 109<br> -Cell, Electrolytic 109<br> -Cell, Porous 427<br> -Cell, Selenium 478<br> -Cell, Standard Voltaic 109<br> -Cell, Standard Voltaic, Daniells' 109<br> -Cell, Standard Voltaic, Latimer Clark's 110<br> -Central Station 493<br> -Central Station Distribution or Supply 112<br> -Centre of Gravity 112<br> -Centre of Gyration 112<br> -Centre of Oscillation 112<br> -Centre of Percussion 112<br> -Centrifugal Force 112<br> -Centrifugal Governor 113<br> -C. G. S. 113<br> -Chain, Molecular 380<br> -Chamber, Armature 42<br> -Chamber of Incandescent Lamp 113<br> -Change, Chemical 116<br> -Changer, Pole 425<br> -Changing Over Switch 500<br> -Changing Switch 500<br> -Chaperon, Lalande &, Battery 69<br> -Characteristic 169<br> -Characteristic Curve 113, 168<br> -Characteristic Curve, External 171<br> -Characteristic Curve of Converter 169<br> -Characteristic, Drooping 114<br> -Characteristic, External 114<br> -Characteristic, Internal 114<br> -Characteristics of Sound 114<br> -Charge 114<br> -Charge and Discharge Key 313<br> -Charge, Bound 115<br> -Charge Current 160<br> -Charge, Density of 115, 180<br> -Charge, Dissipation of 115<br> -Charge, Distribution of 115<br> -Charge, Free 115<br> -Charge, Negative 389<br> -Charge, Residual 116<br> -Charging Curve 170<br> -Chatterton's Compound 116<br> -Chemical Change 116<br> -Chemical Electric Meter 375<br> -Chemical, Electro-, Equivalents 244<br> -Chemical Element 236<br> -Chemical Energy 239<br> -Chemical Equivalent 244<br> -Chemical, Cautery Galvano 265<br> -Chemical Recorder 117<br> -Chemical Telephone 526<br> -Chemical Equivalent, Thermo- 245<br> -Chemistry 118<br> -Chemistry, Electro- 209<br> -Cheval, Force de 260<br> -Chicle 56<br> -Chimes, Electric 118<br> -Chloric Acid Battery 61<br> -Chloride, Ferric, Battery 63<br> -Chloride, Lead, Battery 66<br> -Chloride of Lime Battery 61<br> -Chlorimeter 73<br> -Choking Coil 132<br> -Chronograph, Electric 118<br> -Chromic Acid Battery 61<br> -Chromic Acid Battery Solutions 73<br> -Chromoscope 119<br> -Chutaux's Solution 119<br> -Cipher Code 130<br> -Circle, Azimuth 54<br> -Circle, Delezenne's 133<br> -Circle, Galvanic or Voltaic 119<br> -Circle, Magic 119<br> -Circuit 120<br> -Circuit, Astatic 120<br> -Circuit, Branch 121<br> -Circuit Breaker 121<br> -Circuit Breaker, Automatic 121<br> -Circuit Breaker, File 121<br> -Circuit Breaker, Mercury 121<br> -Circuit Breaker, Pendulum 121<br> -Circuit Breaker, Tuning-fork 121<br> -Circuit, Broken 125<br> -Circuit Changing Switch 500<br> -Circuit, Closed, Battery 61<br> -Circuit, Derivative 123<br> -Circuit, Derived 123<br> -Circuit, Electrostatic 123<br> -Circuit, Electric, Active 123<br> -Circuit, External 123<br> -Circuit, Grounded 123<br> -Circuit, Incomplete 125<br> -Circuit Indicator 298<br> -Circuit Induction, Open 303<br> -Circuit, Leg of 325<br> -Circuit, Local 331<br> -Circuit, Loop 125<br> -Circuit, Loop Break 125<br> -Circuit, Magnetic 340<br> -Circuit, Magnetic Double 340<br> -Circuit, Main 125<br> -Circuit, Main Battery 125<br> -Circuit, Metallic 125<br> -Circuit, Negative Side of 125<br> -Circuit, Open 125<br> -Circuit, Positive Side of 125<br> -Circuit, Recoil 125<br> -Circuit, Return 125<br> -Circuits, Forked 126<br> -Circuit, Short 482<br> -Circuit, Shunt 123, 126<br> -Circuit, Simple 126<br> -Circuits, Parallel 123, 126<br> -Circuit, Voltaic 126<br> -Circuit Working, Short 482<br> -Circular Bell, 79<br> -Circular Current, 160<br> -Circular, Mil 379<br> -Circular Units 126, 555<br> -Circumflux 126<br> -Clamp 126<br> -Clark's Compound 126<br> -Cleansing, Fire 257<br> -Clearance Space, 489<br> -Cleat, Crossing 127<br> -Cleats 127<br> -Cleavage, Electrification by 127<br> -Clip, Cable 97<br> -Clock, Annunciator 35<br> -Clock, Controlled 127<br> -Clock, Controlling 127<br> -Clock, Electric Annunciator 127<br> -Clock, Electrolytic 128<br> -Clock, Master 127<br> -Clock, Secondary 127<br> -Clock, Self-winding, Electric 128<br> -Clockwork Feed 128<br> -Cloisons 128<br> -Closed Circuit Battery 61<br> -Closed Coil Armature 43<br> -Closure 128<br> -Closure Contraction, Kathodic 312<br> -Cloth, Carbonized 107<br> -Club-foot Electro-magnet 217<br> -Clutch 128<br> -Clutch, Electro-magnetic 128<br> -Coatings of a Condenser, or Prime Conductor 129<br> -Cockburn Fuse 263<br> -Code, Cipher 130<br> -Code, S. N. 486<br> -Code, Telegraphic 130, 511<br> -Coefficient 130<br> -Coefficient, Apparent, of Magnetic Induction 346<br> -Coefficient, Economic 130, 204, 205<br> -Coefficient of Electrical Energy 205<br> -Coefficient of Expansion 247<br> -Coefficient of Induced Magnetization 359, 354<br> -Coefficient of Magnetic Induction 346, 349<br> -Coefficient of Mutual Induction 301<br> -Coefficient of Self-induction 298<br> -Coercitive Force 471<br> -Coercive Force 471<br> -Coercive or Coercitive Force 131<br> -Coil and Plunger 131<br> -Coil and Coil Plunger 131<br> -Coil and Plunger, Differential 132<br> -Coil, Armature 43<br> -Coil, Choking 132<br> -Coil, Earth 133<br> -Coil, Electric 133<br> -Coil, Exploring 350<br> -Coil, Flat 133<br> -Coil, Induction 133<br> -Coil, Induction, Inverted 136<br> -Coil, Induction, Telephone 137<br> -Coil. Kicking 132<br> -Coil, Magnet 336<br> -Coil, Magnetizing 137<br> -Coil, Reaction 132<br> -Coil, Resistance 137<br> -Coil, Resistance, Standard 464<br> -Coil, Rhumkorff 138<br> -Coil, Ribbon 138<br> -Coils, Bisected 132<br> -Coils, Compensating 138<br> -Coils, Sectioned 138<br> -Coils, Henry's 138<br> -Coils, Idle 295<br> -Coil, Single, Dynamo 202<br> -Coil, Spark 489<br> -Coil, Sucking 132<br> -Collecting Brush 90<br> -Collecting Ring 139<br> -Collector 139<br> -Colombin, 139<br> -Colophony 460<br> -Colors of Secondary Plates 478<br> -Column Battery 61<br> -Column, Electric 139<br> -Comb 140<br> -Combined Resistance 464<br> -Comb Protector 437<br> -Commercial Efficiency 204<br> -Commercial Efficiency of Dynamo 195<br> -Commercial Wheatstone Bridge 86<br> -Common Reservoir 460<br> -Communicator 140<br> -Commutation, Diameter of 182<br> -Commutator 140<br> -Commutator Ammeter 26<br> -Commutator Bars 140, 56<br> -Commutator, Flats in 140<br> -Commutator, High Bars of 289<br> -Commutator, Neutral Line of 390<br> -Commutator, Neutral Point of 390<br> -Commutator of Current Generators and Motors 140<br> -Commutators, Bars of 56<br> -Commutator Segments 56<br> -Commutator, Split Ring 141<br> -Commuted Current 160<br> -Commuter 140<br> -Commuting Transformer 547<br> -Compass 141<br> -Compass, Azimuth 141<br> -Compass, Boxing the 86<br> -Compass Card, 142<br> -Compass, Declination 142<br> -Compass, Inclination 142<br> -Compass, Mariners' 142<br> -Compass, Points of the 143<br> -Compass, Spirit 143<br> -Compass, Surveyors 143<br> -Compass, Variation of the 32, 558<br> -Compensating Coils 138<br> -Compensating Magnet 336<br> -Compensating Poles 426<br> -Compensating Resistance 144<br> -Complementary Distribution 144<br> -Complete Alternation 23<br> -Component 144<br> -Components of Earth's Magnetism 356<br> -Composition of Forces 260<br> -Compound Arc 39<br> -Compound, Binary 81<br> -Compound, Chatterton's 116<br> -Compound, Clark's 126<br> -Compound Dynamo 195<br> -Compounding, Over- 399<br> -Compound Magnet 336<br> -Compound or Compound Wound Motor 382<br> -Compound Winding 578<br> -Concentration of Ores, Magnetic 340<br> -Concentrator, Magnetic 340<br> -Concentric Candle 99<br> -Concentric Carbon 107<br> -Condenser 144<br> -Condenser, Coatings of a, or Prime Conductor 129<br> -Condenser, Epinus' 242<br> -Condenser, Plate 417<br> -Condenser, Sliding 144<br> -Condenser, Varley's 559<br> -Condensing Electroscope 233<br> -Conductance 144<br> -Conductance, Magnetic 340<br> -Conduction 144<br> -Conduction, Electrolytic 215<br> -Conductive Discharge 187<br> -Conductivity 144<br> -Conductivity, Magnetic 340<br> -Conductivity, Specific 145<br> -Conductivity, Unit of 145<br> -Conductivity, Variable 145<br> -Conductor 145<br> -Conductor, Anti-induction 145<br> -Conductor, Branch 87<br> -Conductor, Capacity of a Telegraph 103<br> -Conductor, Conical 145<br> -Conductor, Imbricated 146<br> -Conductor, Interpolar 307<br> -Conductor, Leakage 325<br> -Conductor, Prime 146, 434<br> -Conductors, Equivalent 146<br> -Conductors, Lamination of Armature 319<br> -Conductors, Service 481<br> -Conductor, Underground 552<br> -Congress Ohm 395<br> -Congress Volt 568<br> -Conical Conductor 145<br> -Conjugate 146<br> -Connect 146<br> -Connection, Cross 158<br> -Connection, Relay 457<br> -Connector 146<br> -Consequent Points 422<br> -Consequent Poles 146, 478<br> -Conservation of Electricity 146<br> -Conservation of Energy 239<br> -Constant Current 160<br> -Constant Current Alternator 24<br> -Constant Current Regulation 454<br> -Constant, Dielectric 183<br> -Constant, Galvanometer 268<br> -Constant Potential 429<br> -Constant Potential Regulation 455<br> -Constant, Time 54l<br> -Contact Breaker 121, 146<br> -Contact, Electric 147<br> -Contact Electricity 147<br> -Contact Faults 147<br> -Contact Key, Double 314<br> -Contact Key, Sliding 316<br> -Contact Lamp 320<br> -Contact, Line of 330<br> -Contact Point 147<br> -Contact Potential Difference 147<br> -Contact Ring 473<br> -Contact Spring 148<br> -Contact Series 147<br> -Contact Theory 148<br> -Continuity, Magnetic 340<br> -Continuous Alternating Transformer 547<br> -Continuous Current 161<br> -Continuous Current Transformer 384, 547<br> -Contraction, Anodic Closure 36<br> -Contraction, Anodic Duration 36<br> -Contraction, Anodic Opening 36<br> -Contraction, Kathodic Closure 312<br> -Contraction, Kathodic Duration 312<br> -Contractures 148<br> -Contraplex Working 580<br> -Control, Electro-magnetic 218<br> -Control, Gravity 281<br> -Controlled Clock, 127<br> -Controlling Clock 127<br> -Controlling Field 148<br> -Controlling Force 148<br> -Controlling Magnet 185, 336<br> -Control, Magnetic 341<br> -Control, Spring 492<br> -Convection, Electric 149<br> -Convection, Electrolytic 149, 214<br> -Convection of Heat, Electric 149<br> -Convective Discharge 187<br> -Conversion, Efficiency of 205<br> -Converter 149<br> -Cooling Box 151<br> -Co-ordinates, Origin of 391<br> -Co-ordinates, System of 150<br> -Copper 151<br> -Copper Bath 152<br> -Copper Stripping Bath 152<br> -Copper Voltameter 563<br> -Cord Adjuster 152<br> -Cord, Flexible 152<br> -Cord, Pendant 405<br> -Core 152<br> -Core, Armature 43<br> -Core, Cable 96<br> -Cored Carbon 107<br> -Core-discs 152<br> -Core-discs, Perforated 154<br> -Core-discs, Pierced 152<br> -Core-discs, Toothed 154<br> -Core, Laminated 154<br> -Core, Magnet 336<br> -Core Ratio 154<br> -Core, Ribbon 154<br> -Core, Ring 155<br> -Cores, Krizik's 318<br> -Core, Stranded 155<br> -Core, Tangentially Laminated 155<br> -Core Transformer 155<br> -Core, Tubular 155<br> -Corpusants 155<br> -Corresponding Points 422<br> -Coulomb 155<br> -Coulomb's Law of Electrostatic Attraction and Repulsion 155<br> -Coulomb's Law of Magnetic Attraction and Repulsion 338<br> -Coulomb's Torsion Balance 544<br> -Coulomb, Volt- 568<br> -Counter, Electric 156<br> -Counter Electro-motive Force 156, 228<br> -Counter-electro-motive Force Lightning Arrester 329<br> -Counter Inductive Effect 204<br> -Couple 156<br> -Couple, Astatic 157<br> -Couple, Axial 544<br> -Couple, Magnetic 341<br> -Couple, Moment of 544<br> -Couple, Thermo-electric 532<br> -Couple, Voltaic or Galvanic 156<br> -Coupling 259<br> -Coupling of Dynamo 201<br> -C. P. 157<br> -Crater 157<br> -Creep, Diffusion 184<br> -Creeping 157<br> -Creeping, Magnetic 341<br> -Creeping of Magnetism 356<br> -Crith 157<br> -Critical Current 161<br> -Critical Distance of Alternative Path 190<br> -Critical Resistance 464<br> -Critical Speed 157<br> -Critical Value, Villari's 561<br> -Crookes' Dark Space 489<br> -Cross 157<br> -Cross-connecting Board 157<br> -Cross Connection 158<br> -Cross Induction 298<br> -Crossing Cleat 127<br> -Crossing Wires 158<br> -Cross-magnetizing Effect 158, 298<br> -Cross-over Block 158<br> -Cross, Peltier's 405<br> -Cross Talk 158<br> -Crucible, Electric 158<br> -Crystallization, Electric 158<br> -Cube, Faraday's 249<br> -Culture. Electro- 209<br> -Cunynghame's Ammeter 26<br> -Cup, Mercury 371<br> -Cup, Porous 159, 426<br> -Current 159<br> -Current, After 159<br> -Current, Alternating 159<br> -Current, Alternating System 23<br> -Current, Alternative 563<br> -Current Arc, Alternating 23<br> -Current, Atomic 160<br> -Current, Break Induced 162<br> -Current, Charge 160<br> -Current, Circular 160<br> -Current, Commuted 160<br> -Current, Constant 160<br> -Current, Continuous 161<br> -Current, Continuous, Transformer 384<br> -Current, Critical 161<br> -Current, Daniel 161<br> -Current, U. S. or Siemens' Unit 161<br> -Current, Demarcation 161<br> -Current Density 161<br> -Current, Derived 164<br> -Current, Diacritical 161<br> -Current, Diaphragm 161<br> -Current, Direct 162<br> -Current, Direct Induced 162<br> -Current, Direction of 162<br> -Current, Displacement 162<br> -Current, Extra 162<br> -Current, Faradic 162<br> -Current, Field of Force of a 255<br> -Current, Foucault 163<br> -Current, Franklinic 163<br> -Current Generator 277<br> -Current, Induced 163<br> -Current Induction 163<br> -Current Induction, Unipolar 553<br> -Current Intensity 163<br> -Current, Inverse Induced 163<br> -Current, Jacobi's Unit of 163<br> -Current, Joint 163<br> -Current, Linear 164<br> -Current, Make and Break 164, 367<br> -Current, Make Induced 163<br> -Current Meter 164, 375<br> -Current Meter, Alternating 373<br> -Current, Negative 164<br> -Current, Nerve and Muscle 164<br> -Current, Opposed 164<br> -Current, Partial 164<br> -Current, Polarizing 164<br> -Current, Positive 164<br> -Current, Power of Periodic 433<br> -Current, Pulsatory 164<br> -Current, Rectified 164<br> -Current, Rectilinear 165<br> -Current, Redressed 165<br> -Current Regulation, Constant 454<br> -Current, Reverse Induced 163<br> -Current Reverser 165<br> -Currents, Ampere 30<br> -Currents, Ampérian 165<br> -Currents, Angular. 165<br> -Currents, Angular, Laws of 165<br> -Currents, Earth 166<br> -Current, Secondary 166<br> -Current, Secretion 166<br> -Currents, Eddy 163<br> -Currents, Eddy Displacement 162<br> -Currents in Parallel Circuits, Independence of 297<br> -Current, Sinuous 166<br> -Current, Sheet 166<br> -Current, Shuttle 483<br> -Currents, Local 163<br> -Currents, Local 331<br> -Currents, Multiphase 166<br> -Currents, Natural 166, 389<br> -Currents, Nerve 390<br> -Currents of Motion 167<br> -Currents of Rest 167<br> -Currents, Orders of 167<br> -Currents, Parasitical 163<br> -Currents, Polyphase 167<br> -Currents, Rotatory 167<br> -Currents, Thermo-electric 167<br> -Current Streamlets 495<br> -Current, Swelling 167<br> -Current, Tailing 501<br> -Current, Undulatory 167<br> -Current, Unit 167<br> -Current, Wattless 168<br> -Curve, Arrival 168<br> -Curve, Characteristic 113, 168<br> -Curve, Characteristic, of Converter 169<br> -Curve, Charging 170<br> -Curve, Discharging 170<br> -Curve, Elastic 206<br> -Curve, Electro-motive Force 170<br> -Curve, External Characteristic . 171<br> -Curve, Harmonic 174, 485<br> -Curve, Horse Power 171<br> -Curve, Isochasmen 171<br> -Curve, Life 171<br> -Curve, Load 172<br> -Curve, Magnetization 172<br> -Curve of Distribution of Potential in Armature 172<br> -Curve of Dynamo 173<br> -Curve of Saturation of Magnetic Circuit 174<br> -Curve of Sines 173, 485<br> -Curve of Torque 174<br> -Curve, Permeability Temperature 174<br> -Curve, Sine 174, 485<br> -Curve, Sinusoidal 174, 485<br> -Curves, Magnetic 341<br> -Cut In 174<br> -Cut Out 174<br> -Cut Out, Automatic 175, 475<br> -Cut Out, Magnetic 175<br> -Cut Out, Plug 175<br> -Cut Out, Safety 175<br> -Cut Out, Spring Jack 493<br> -Cut Outs, Time 541<br> -Cut Out, Wedge 175<br> -Cutting of Lines of Force 175<br> -Cycle of Alternation 175<br> -Cycle of Magnetization 360<br> -Cylinder, Armature 43<br> -Cylinder, Electric Machine 333<br> -Cylindrical Armature 45<br> -Cystoscopy 175<br> -<br> -Damper 176<br> -Damping 176<br> -Damping Magnet 336<br> -Daniell's Standard Voltaic Cell 109<br> -Dark Space, Faraday's 249<br> -D'Arsonval's Battery 62<br> -Dash-pot 176<br> -Dead Beat 38, 176<br> -Dead Beat Discharge 187<br> -Dead Earth 176, 203<br> -Dead Point of an Alternator 177<br> -Dead Turns 177<br> -Dead Turns of a Dynamo 551<br> -Dead Wire 177<br> -Death, Electrical 177<br> -Debrun Candle 99<br> -Decalescence 177<br> -Decay of Magnetism 356<br> -Deci 177<br> -Decimal Candle 99<br> -Declination, Angle of 32-177<br> -Declination Compass 142<br> -Declination, Magnetic 342<br> -Declination Map 309<br> -Declination of the Magnetic Needle 178<br> -Decomposition 178<br> -Decomposition, Electrolytic 178<br> -Decrement 178<br> -De-energize 178<br> -Deflagration 178<br> -Deflagrator, Hare's 73<br> -Deflecting Field 178<br> -Deflection 178<br> -Deflection Method 178<br> -Deflection of Magnet 337<br> -Degeneration, Reaction of 179<br> -Degradation of Energy 239<br> -Deka 179<br> -De la Rive's Floating Battery 179<br> -De la Rue Battery 62<br> -Delaurier's Solution 179<br> -Delezenne's Circle 133<br> -Demarcation Current 161<br> -Demagnetization 179<br> -Density, Current 161<br> -Density, Electrical 115<br> -Density, Electric Superficial 180<br> -Density, Field 252<br> -Density, Magnetic 342<br> -Density of Charge 115, 180<br> -Dental Mallet, Electric 180<br> -Deposit, Electrolytic 180<br> -Deposit, Nodular 392<br> -Depolarization 180<br> -Depolarizing Fluid 258<br> -Derivation, Points of 180, 423<br> -Derivative Circuit 123<br> -Derived Circuit 123<br> -Derived Current 164<br> -Derived Units 555<br> -Desk Push 180<br> -Detector 180<br> -Detector, Lineman's 180<br> -Deviation of Discharge 188<br> -Deviation, Quadrantal 180<br> -Deviation, Semi-circular 181<br> -Device, Safety 475<br> -Dextrotorsal 181<br> -Diacritical 181<br> -Diacritical Current 161<br> -Diagometer 181<br> -Diagnosis, Electro- 181, 210<br> -Diagram, Thermo-electric 532<br> -Dial Telegraph 505<br> -Diamagnetic 181<br> -Diamagnetic Polarity 181, 423<br> -Diamagnetism 182<br> -Diameter of Commutation 182<br> -Diapason, Electric 182<br> -Diaphragm 182<br> -Diaphragm Current 161<br> -Dielectric, 182<br> -Dielectric Capacity 102<br> -Dielectric Constant 183<br> -Dielectric, Energy of 183<br> -Dielectric Polarization 183<br> -Dielectric Resistance 183, 464<br> -Dielectric Strain 183<br> -Dielectric Strength 183<br> -Dielectric Stress 496<br> -Differential Arc Lamp 320<br> -Differential Coil and Plunger 132<br> -Differential Galvanometer 268<br> -Differentially Wound Bell, 79<br> -Differential Magnetometer 365<br> -Differential Motor 382<br> -Differential Relay 457<br> -Differential Thermo-electric Pile 533<br> -Differential Winding Working 183<br> -Diffusion 184<br> -Diffusion, Anodal . 35<br> -Diffusion Creep 184<br> -Digney Unit of Resistance 464<br> -Dimensions and Theory of Dimensions 184<br> -Dimmer 185<br> -Diode Working 580<br> -Dioxide, Carbon 107<br> -Dioxide, Sulphur 497<br> -Dip, Magnetic 342, 346<br> -Dip of Magnetic Needle 185<br> -Dipping 185<br> -Dipping Needle 185<br> -Direct Current 162<br> -Direct Current Dynamo 197<br> -Direct Induced Current, . 162<br> -Direct Reading Galvanometer 269<br> -Directing Magnet 185<br> -Direction 185<br> -Direction of Current 162<br> -Direction, Positive 428<br> -Directive Power 187<br> -Disc, Arago's 38<br> -Disc, Armature 43<br> -Disc, Bunsen 92<br> -Disc, Dynamo 197<br> -Disc, Faraday's 249<br> -Discharge and Charge Key 313<br> -Discharge, Brush 187<br> -Discharge, Conductive 187<br> -Discharge, Convective 187<br> -Discharge, Dead Beat 187<br> -Discharge, Disruptive 187<br> -Discharge, Duration of 188<br> -Discharge, Glow 187<br> -Discharge, Impulsive 188<br> -Discharge Key, Kempe's 315<br> -Discharge, Lateral 188<br> -Discharge of Magnetism 356<br> -Discharge, Oscillatory 188<br> -Discharger 188<br> -Discharger, Henley's Universal 189<br> -Discharger, Universal 189<br> -Discharger, Universal, Henley's 189<br> -Discharge, Silent 187, 189, 206<br> -Discharge, Spark 189<br> -Discharge, Surging 188<br> -Discharging Curve 170<br> -Discharging Rod 189<br> -Discharging Tongs 189<br> -Disconnection 189<br> -Discontinuity, Magnetic 342<br> -Discovery, Oerstedt's 394<br> -Disc Winding 579<br> -Dispersion Photometer 412<br> -Displacement Current 162<br> -Displacement, Electric 188<br> -Displacement, Oscillatory 398<br> -Disruptive Discharge 187<br> -Disruptive Tension 189<br> -Dissimulated Electricity 189<br> -Dissipation of Charge 115<br> -Dissociation 189, 535<br> -Distance, Critical, of Alternative Path 190<br> -Distance, Explosive 190<br> -Distance, Sparking 190<br> -Distance, Striking 496<br> -Distant Station 493<br> -Distillation 190<br> -Distortion of Field 252<br> -Distributing Box 190<br> -Distributing Switches 190<br> -Distribution, Complementary 144<br> -Distribution, Isolated 309<br> -Distribution of Charge 115<br> -Distribution of Electric Energy, Systems of 190<br> -Distribution of Magnetism, Lamellar, 357<br> -Distribution of Magnetism, Solenoidal 358<br> -Distribution of Supply, Central Station 112<br> -Door Opener, Electric 190<br> -Dosage, Galvanic 190<br> -Double Break Switch 500<br> -Double Carbon Arc Lamp 191<br> -Double Contact Key 314<br> -Double Curb Working 581<br> -Double Fluid Theory 191<br> -Double Fluid Voltaic Cell 191<br> -Double Magnetic Circuit 340<br> -Double Needle Telegraph 506<br> -Double Plug 191<br> -Double Pole Switch 500<br> -Double Tapper Key 314<br> -Double Touch, Magnetization by 358<br> -Double Trolley 549<br> -Double Wedge 191<br> -Doubler 191<br> -D. P. 191<br> -Drag 191<br> -Drag of Field 254<br> -Dreh-Strom 191<br> -Drill, Electric 191<br> -Drip Loop 192<br> -Driving Horns 192<br> -Dronier's Salt 192<br> -Drooping Characteristic 114<br> -Drop, Annunciator 35<br> -Drop, Automatic 192<br> -Drop, Calling 98<br> -Drum Armature 45<br> -Drum, Electric 193<br> -Dry Battery 63<br> -Dry Pile, Zamboni's 581<br> -Dub's Laws 193<br> -Duct 193<br> -Duplex Bridge Telegraph 506<br> -Duplex Cable 96<br> -Duplex Differential Telegraph 507<br> -Duplex Telegraph, 506<br> -Duration Contraction, Kathodic 312<br> -Duration of Electric Spark 490<br> -Dyad 193<br> -Dyeing, Electric 193<br> -Dynamic Electricity 193<br> -Dynamic, Electro- 211<br> -Dynamic Induction, Magnetic 347<br> -Dynamo, Alternating Current 193<br> -Dynamo, Alternating Current Regulation of 195<br> -Dynamos, Battery of 68<br> -Dynamo, Commercial Efficiency of 195<br> -Dynamo, Compound 195<br> -Dynamo, Coupling of 201<br> -Dynamo, Curve of 173<br> -Dynamo, Dead Turns of a 551<br> -Dynamo, Direct Current 197<br> -Dynamo, Disc 197<br> -Dynamo-electric Machine 197<br> -Dynamo, Electroplating 198<br> -Dynamo, Equalizing 198<br> -Dynamo, Field and Armature Reaction of 450<br> -Dynamo, Far Leading 198<br> -Dynamo or Magneto-electric Generator, Flashing in a 257<br> -Dynamo, Inductor 199<br> -Dynamo, Interior Pole 199<br> -Dynamo, Iron Clad 200<br> -Dynamo, Ironwork Fault of a 308<br> -Dynamo, Motor 200<br> -Dynamo, Multipolar 200<br> -Dynamo, Non-polar 200<br> -Dynamo, Open Coil 200<br> -Dynamo, Overtype 399<br> -Dynamos, Regulation of 455<br> -Dynamo, Ring 200<br> -Dynamo, Self Exciting 201<br> -Dynamo, Separate Circuit 201<br> -Dynamo, Separately Excited 201, 479<br> -Dynamo, Series 201<br> -Dynamo, Shunt 202<br> -Dynamo, Single Coil 202<br> -Dynamo, Tuning Fork 202<br> -Dynamo, Unipolar 202, 553<br> -Dynamograph 199<br> -Dynamometer 200<br> -Dyne 203<br> -<br> -Earth 203<br> -Earth Coil 133<br> -Earth Currents 166<br> -Earth, Dead 176, 203<br> -Earth, Magnetization by 359<br> -Earth, Partial 203, 404<br> -Earth Plate 203<br> -Earth Return 203<br> -Earth's Magnetism, Components of 356<br> -Earth, Solid 203<br> -Earth, Swinging 203<br> -Earth, Total 203<br> -Ebonite 203<br> -Eccentric Iron Disc Ammeter 27<br> -Economic Coefficient 130, 204, 205<br> -Eddy Currents 163<br> -Eddy Displacement Currents 162<br> -Ediswan 204<br> -Edison Effect 204<br> -Edison-Lalande Battery 69<br> -Eel, Electric 204<br> -Effect, Acheson 208<br> -Effect, Counter-inductive 204<br> -Effect, Cross-magnetizing 158, 298<br> -Effect, Edison 204<br> -Effect, Faraday 249<br> -Effect, Ferranti 251<br> -Effect, Hall 284<br> -Effect, Joule 311<br> -Effect, Kerr 235, 312<br> -Effect, Mordey 381<br> -Effect, Page 401<br> -Effect, Peltier 404<br> -Effect, Photo-voltaic 415<br> -Effect, Seebeck 478<br> -Effect, Skin 486<br> -Effect, Thomson 538<br> -Effect, Voltaic 563<br> -Efficiency 204<br> -Efficiency, Commercial 204<br> -Efficiency, Electrical 205<br> -Efficiency, Gross 205<br> -Efficiency, Intrinsic 205<br> -Efficiency, Net 205<br> -Efficiency of Conversion 205<br> -Efficiency of Secondary Battery Quantity 205<br> -Efficiency of Secondary Battery, Real 205<br> -Efflorescence 206<br> -Effluvium, Electric 206<br> -Egg, Philosopher's 409<br> -Elastic Curve 206<br> -Elasticity, Electric 206<br> -Electrepeter 206<br> -Electric, Absolute, Potential 429<br> -Electric Absorption 8<br> -Electric Actinometer 11<br> -Electric Alarm 17<br> -Electrical Classification of Elements 237<br> -Electrically Controlled Valve 558<br> -Electric Ammunition Hoist 29<br> -Electric Analysis 32<br> -Electric Analyzer 32<br> -Electric Annealing 34<br> -Electric Annunciator Clock 127<br> -Electric Arc Blow-pipe 84<br> -Electric Aura 53<br> -Electric Automatic Fire Extinguisher 257<br> -Electric Axis 54<br> -Electric Balance 577<br> -Electric Bath, Bipolar 57<br> -Electric Bath, Multipolar 57<br> -Electric Bath, Unipolar 57<br> -Electric Bell 79<br> -Electric Bell, Automatic 78<br> -Electric Bioscopy 82<br> -Electric Blasting 83<br> -Electric Bleaching 83<br> -Electric Boat 84<br> -Electric Boiler Feed 84<br> -Electric Branding 87<br> -Electric Brazing 87<br> -Electric Breath Figures 89<br> -Electric Breeze 89<br> -Electric Buoy 93<br> -Electric Candle 99<br> -Electric Case Hardening 109<br> -Electric Cautery 109<br> -Electric Chimes 118<br> -Electric Chronograph 118<br> -Electric Circuit, Active 123<br> -Electric Clock, Self-winding 128<br> -Electric Coil 133<br> -Electric Column 139<br> -Electric Contact 147<br> -Electric Convection 149<br> -Electric Convection of Heat 149, 286<br> -Electric Counter 156<br> -Electric Crucible 158<br> -Electric Crystallization 158<br> -Electric Death 177<br> -Electric Density 115<br> -Electric Dental Mallet 180<br> -Electric Diapason 182<br> -Electric Displacement 189<br> -Electric Door Opener 190<br> -Electric Double Refraction 454<br> -Electric Drill 191<br> -Electric Drum 193<br> -Electric Dyeing 193<br> -Electric Eel 204<br> -Electric Efficiency 205<br> -Electric Effluvium 206<br> -Electric Elasticity 206<br> -Electric Endosmose 238<br> -Electric Energy 239<br> -Electric Energy, Coefficient of 205<br> -Electric Energy, Systems of Distribution of 190<br> -Electric Engraving 245<br> -Electric Entropy 242<br> -Electric Etching 245<br> -Electric Evaporation 246<br> -Electric Excitability of Animal Systems 247<br> -Electric Exosmose 247<br> -Electric Expansion 247<br> -Electric Fire Alarm, Automatic 257<br> -Electric Floor Matting 369<br> -Electric Fluid 258<br> -Electric Fly or Flyer 259<br> -Electric Fog 259<br> -Electric Furnace 263<br> -Electric Fuse 264<br> -Electric Gas Burners 93<br> -Electric Headlight 285<br> -Electric Head Bath 284<br> -Electric Heat 285<br> -Electric Heater 286<br> -Electric Horse Power 290<br> -Electric Image 296<br> -Electric Incandescence 297<br> -Electric Influence 305<br> -Electric Insulation 305<br> -Electricities, Separation of 479<br> -Electricity 206<br> -Electricity, Animal 33<br> -Electricity, Atmospheric 51<br> -Electricity, Cal 208<br> -Electricity, Conservation of 146<br> -Electricity, Contact 147<br> -Electricity, Dissimulated 189<br> -Electricity, Dynamic 193<br> -Electricity, Frictional 262<br> -Electricity, Latent 323<br> -Electricity, Negative 389<br> -Electricity, Plant 317<br> -Electricity, Positive 428<br> -Electricity, Specific Heat of 491<br> -Electricity, Static 493<br> -Electricity, Storage of 495<br> -Electricity, Voltaic 563<br> -Electricity, Vitreous 562<br> -Electric Machine, Plate 417<br> -Electric Machine, Wimshurst 577<br> -Electric Mains 367<br> -Electric Mass 368<br> -Electric Matter 368<br> -Electric Meter, Chemical 375<br> -Electric Meter, Thermal 375<br> -Electric Meter, Time 375<br> -Electric Mortar 382<br> -Electric Motor 382<br> -Electric or Electrostatic Capacity 102<br> -Electric Organ 397<br> -Electric Oscillations 398<br> -Electric Osmose 398<br> -Electric Pen 405<br> -Electric Pendulum 405<br> -Electric Piano 415<br> -Electric Picture 415<br> -Electric Pistol 416<br> -Electric Popgun 282<br> -Electric Portrait 415<br> -Electric Potential Difference 429<br> -Electric Potential, Unit of 432<br> -Electric Power 433<br> -Electric Pressure 434<br> -Electric Probe 435<br> -Electric Prostration 437<br> -Electric Protector 437<br> -Electric Radiometer 447<br> -Electric Ray 450<br> -Electric Rectification of Alcohol 18<br> -Electric Reduction of Ores 453<br> -Electric Reduction of Phosphorous 410<br> -Electric Register 454<br> -Electric Residue 116, 460<br> -Electricity, Resinous 461<br> -Electric Resonance 468<br> -Electric Resonator 470<br> -Electric Rings 392<br> -Electrics 208<br> -Electric Saw 476<br> -Electric Screen, 476<br> -Electric Shadow 480<br> -Electric Shock 482<br> -Electric Shower Bath 57<br> -Electric Soldering 487<br> -Electric Spark, Duration of 490<br> -Electric Sphygmophone 491<br> -Electric Storms 495<br> -Electric Striae 496<br> -Electric Subway 496<br> -Electric Subway, Underground 552<br> -Electric Sunstroke 497<br> -Electric Superficial Density 180<br> -Electric Swaging 499<br> -Electric Tele-barometer 504<br> -Electric Telemanometer 521<br> -Electric Telemeter 521<br> -Electric Tempering 527<br> -Electric Tension 529<br> -Electric Thermometer 535<br> -Electric Thermostat 537<br> -Electric Torpedo 543<br> -Electric Tower 545<br> -Electric Transmission of Energy 240<br> -Electric Trumpet 550<br> -Electric Tube 550<br> -Electric Typewriter 551<br> -Electric Unit of Work 580<br> -Electric Varnish 559<br> -Electric Welding 574<br> -Electric Whirl 577<br> -Electric Wind 578<br> -Electrification 208<br> -Electrification by Cleavage 127<br> -Electrification by Pressure 434<br> -Electrified Body, Energy of an . 241<br> -Electrization 208<br> -Electro-biology 208<br> -Electro-capillarity 209<br> -Electro-chemical Equivalents 209, 244<br> -Electro-chemical Series 209<br> -Electro-chemistry 209<br> -Electro-culture 209<br> -Electrode 210<br> -Electrode, Indifferent 210<br> -Electrodes, Erb's Standard of 210<br> -Electrodes, Non-polarizable 210<br> -Electrodes, Shovel 483<br> -Electrode, Therapeutic 210<br> -Electro-diagnosis 181, 210<br> -Electro-dynamic 211<br> -Electro-dynamic Attraction and Repulsion, 211<br> -Electro-dynamic Rotation of Liquids 474<br> -Electro-dynamometer, Siemens' 212<br> -Electro-gilding 277<br> -Electro-kinetic 211<br> -Electrolier 212<br> -Electrolysis 212<br> -Electrolysis, Laws of 213<br> -Electrolyte 214<br> -Electrolytic Analysis 214<br> -Electrolytic Cell 109<br> -Electrolytic Clock 128<br> -Electrolytic Conduction 215<br> -Electrolytic Convection 149, 214<br> -Electrolytic Deposit 180<br> -Electrolytic Iron 308<br> -Electrolytic Resistance 464<br> -Electro-magnet 215, 337<br> -Electro-magnet, Annular 216<br> -Electro-magnet, Bar 217<br> -Electro-magnet, Club-foot 217<br> -Electro-magnet, Hinged 217<br> -Electro-magnet, Hughes' 291<br> -Electro-magnetic Ammeter 27<br> -Electro-magnetic and Magnetic Equipotential Surface 244<br> -Electro-magnetic Attraction and Repulsion 217<br> -Electro-magnetic Brake 86<br> -Electro-magnetic Clutch 128<br> -Electro-magnetic Control 218<br> -Electro-magnetic Eye 248<br> -Electro-magnetic Field of Force 218<br> -Electro-magnetic Force 260<br> -Electro-magnetic Gun 282<br> -Electro-magnetic Induction 218, 299<br> -Electro-magnetic Inertia 305<br> -Electro-magnetic Induction, Mutual 302<br> -Electro-magnetic Interrupter for Tuning Fork 307<br> -Electro-magnetic Leakage 219<br> -Electro-magnetic Lines of Force 219<br> -Electro-magnetic Liquids, Rotation of 475<br> -Electro-magnetic Meter 375<br> -Electro-magnetic Quantity 445<br> -Electro-magnetic Quantity, Practical Unit of 445<br> -Electro-magnetic Shunt .483<br> -Electro-magnetic Stress 219, 496<br> -Electro-magnetic Theory of Light 219<br> -Electro-magnetic Unit of Energy 220<br> -Electro-magnetic Vibrator 561<br> -Electro-magnetic Waves, 573<br> -Electro-magnet, Ironclad 219<br> -Electro-magnetism 220<br> -Electro-magnet, Joule's 337<br> -Electro-magnet, Long Range 220<br> -Electro-magnet, One Coil 219<br> -Electro-magnet, Plunger 220<br> -Electro-magnet, Polarized 220<br> -Electro-magnets, Interlocking 221<br> -Electro-magnets, Multiple Wire Method of Working 388<br> -Electro-magnet, Stopped Coil 221<br> -Electro-magnets, Surgical 222<br> -Electro-mechanical Bell 80<br> -Electro-mechanical Equivalent 244<br> -Electro-medical Baths 222<br> -Electro-medical Battery, Pulvermacher's 69<br> -Electro-metallurgy 222<br> -Electrometer 222<br> -Electrometer, Absolute 222<br> -Electrometer. Attracted Disc 223<br> -Electrometer, Capillary 224<br> -Electrometer Gauge 226<br> -Electrometer, Lane's 226<br> -Electrometer, Quadrant 226<br> -Electrometer, Thermo- 536<br> -Electrometer, Weight 223<br> -Electro-motive Force 227<br> -Electro-motive Force, Counter- 228<br> -Electro-motive Force Curve 170<br> -Electro-motive Force, Impressed 297<br> -Electro-motive Force, Motor 384<br> -Electro-motive Force. Oscillatory 398<br> -Electro-motive Force, Transverse 549<br> -Electro-motive Force, Unit 228<br> -Electro-motive Intensity 228<br> -Electro-motive Potential Difference 429<br> -Electro-motive Series 228<br> -Electro-motograph 229<br> -Electro-motor 229<br> -Electro-muscular Excitation 229<br> -Electro-negative 229<br> -Electro-optics 229<br> -Electrophoric Action 230<br> -Electrophorus 230<br> -Electro-physiology 231<br> -Electroplating 231, 418<br> -Electroplating Dynamo 198<br> -Electro-pneumatic Signals 231<br> -Electropoion Fluid 232<br> -Electro-positive 232<br> -Electro-puncture 232<br> -Electro-receptive 232<br> -Electroscope 232<br> -Electroscope, Bennett's 233<br> -Electroscope, Bohenberger's 233<br> -Electroscope, Condensing 233<br> -Electroscope, Gold Leaf 233<br> -Electroscope, Pith Ball 234<br> -Electrostatic Attraction and Repulsion 234<br> -Electrostatic Attraction and Repulsion. Coulomb's Law of 155<br> -Electrostatic Circuit 123<br> -Electrostatic Equipotential Surface 244<br> -Electrostatic Field of Force 254<br> -Electrostatic Force 260<br> -Electrostatic Induction 302<br> -Electrostatic Induction, Coefficient of 234<br> -Electrostatic Induction, Mutual 303<br> -Electrostatic Lines of Force 234<br> -Electrostatic Quantity 445<br> -Electrostatic Refraction 235<br> -Electrostatics 235<br> -Electrostatic Series 235<br> -Electrostatic Stress 236, 496<br> -Electrostatic Telephone 526<br> -Electrostatic Voltmeter 571<br> -Electro-thermal Equivalent 245<br> -Electro-therapeutics or Therapy 236<br> -Electrotonic State 493<br> -Electrotonus 236<br> -Electrotype 236<br> -Element, Chemical 236<br> -Element, Galvanic 264<br> -Element, Mathematical 237<br> -Element, Negative 390<br> -Element of a Battery Cell 237<br> -Element, Positive 277<br> -Elements, Electrical Classification of 237<br> -Elements, Magnetic 342<br> -Elements of Battery 63<br> -Elements, Thermo-electric 237<br> -Element, Voltaic 237<br> -Elias' Method of Magnetization 360<br> -Elongation 237, 540<br> -Elongation, Magnetic 344<br> -Embosser, Telegraph 237<br> -E. M. D. P. 238<br> -E. M. F. 238<br> -Energy 238<br> -Energy, Atomic 238<br> -Energy, Chemical 239<br> -Energy, Conservation of 239<br> -Energy, Degradation of 239<br> -Energy, Electric 239<br> -Energy, Electrical, Coefficient of 205<br> -Energy, Electric Transmission of 240<br> -Energy, Electro-magnetic, Unit of 220<br> -Energy, Kinetic 241<br> -Energy, Mechanical 241<br> -Energy Meter 375<br> -Energy, Molar 241<br> -Energy, Molecular 241<br> -Energy of an Electrified Body 241<br> -Energy of Dielectric 183<br> -Energy of Position 211<br> -Energy of Stress 241<br> -Energy, Physical 241<br> -Energy, Potential, or Static 241<br> -Energy, Radiant 446<br> -Energy, Thermal 242<br> -End-on Method 238<br> -End or Pole, Marked 368<br> -Endosmose, Electric 238<br> -End Play 238<br> -End, Unmarked 556<br> -English Absolute or Foot Second Unit of Resistance 465<br> -Engraving, Electric 245<br> -Entropy 242<br> -Entropy, Electric 242<br> -Epinus Condenser 242<br> -E. P. S. 243<br> -Equator, Magnetic 344<br> -Equator of Magnet 337<br> -Equipotential 244<br> -Equipotential Surface 498<br> -Equipotential Surface, Electrostatic 244<br> -Equipotential Surface, Magnetic and Electro-magnetic 244<br> -Equalizer 243<br> -Equalizer, Feeder 251<br> -Equalizing Dynamo 198<br> -Equivalent, Chemical 116, 244<br> -Equivalent Conductors 146<br> -Equivalent, Electro-thermal 245<br> -Equivalent, Joule's 311<br> -Equivalent Resistance 465<br> -Equivalents, Electro-chemical 209, 244<br> -Equivalent, Thermo-chemical 245<br> -Equivalent, Water 572<br> -Equivolt 245<br> -Erb's Standard of Electrodes 210<br> -Erg 245<br> -Erg-ten 245<br> -Error, Heating 286<br> -Escape 245<br> -Essential Resistance 465, 466<br> -Etching, Electric 245<br> -Ethene 397<br> -Ether 246<br> -Eudiometer 246<br> -Evaporation, Electric 246<br> -Ewing's Theory of Magnetism 356<br> -Exchange, Telephone 246<br> -Excitation, Electro-muscular 229<br> -Excitability, Faradic 246<br> -Excitability, Galvanic 247<br> -Excitability of Animal System, Electric 247<br> -Exciter 247<br> -Exosmose, Electric 247<br> -Expansion, Coefficient of 247<br> -Expansion, Electric 247<br> -Experiment, Franklin's 261<br> -Experiment, Hall's 284<br> -Experiment, Kerr's 312<br> -Experiment, Matteueci's 369<br> -Experiments, Hertz's 470<br> -Experiment, Volta's Fundamental 567<br> -Experiment with Frog, Galvani's 262<br> -Exploder 247<br> -Explorer 247<br> -Exploring Coil 350<br> -Explosive Distance 190<br> -Extension Bell Call 248<br> -Extension, Polar 423<br> -External Characteristic 114<br> -External Characteristic Curve 171<br> -External Circuit 123<br> -External Resistance 465, 467<br> -Extinguisher, Automatic Electric Fire 257<br> -Extra Current 162<br> -Extra-polar Region 454<br> -Eye, Electro-magnetic 248<br> -Eye, Selenium 478<br> -<br> -Facsimile Telegraph 510<br> -Factor, Armature 45<br> -Fahrenheit Scale 248<br> -Fall of Potential 430<br> -False Poles, Magnetic 350<br> -Farad 248<br> -Faraday, Effect 249<br> -Faraday's Cube 249<br> -Faraday's Dark Space 249, 489<br> -Faraday's Disc 249<br> -Faraday's Net 250<br> -Faraday's Ring 473<br> -Faraday's Transformer 250<br> -Faraday's Voltameter 250<br> -Faradic 250<br> -Faradic Battery 63<br> -Faradic Brush 251<br> -Faradic Current 162<br> -Faradic Excitability 246<br> -Faradization 251<br> -Faradization, Galvano- 265<br> -Far Leading Dynamo 198<br> -Fault of a Dynamo, Ironwork 308<br> -Faults 251<br> -Faults, Contact 147<br> -Feed Clockwork 128<br> -Feeder 251<br> -Feeder, Equalizer 251<br> -Feeder, Main or Standard 251<br> -Feeder, Negative 251<br> -Feeder, Neutral 251<br> -Feeder, Positive 251<br> -Feeder, Switch 500<br> -Feet, Ampere 30<br> -Ferranti Effect 251<br> -Ferric Chloride Battery 63<br> -Ferro-magnetic 252<br> -Fibre and Spring Suspension 252<br> -Fibre Suspension 252<br> -Field, Air 252<br> -Field, Alternating 252<br> -Field and Armature Reaction of Dynamo, 450<br> -Field, Controlling 148<br> -Field, Deflecting 178<br> -Field Density 252<br> -Field, Distortion of 252<br> -Field, Drag of 254<br> -Field, Intensity of a Magnetic 306<br> -Field Magnet 337<br> -Field of Force . 254<br> -Field of Force, Electro-magnetic 218<br> -Field of Force, Electrostatic 254<br> -Field of Force, Magnetic 344<br> -Field of Force of a Current 255<br> -Field of Force, Uniform 553<br> -Field, Pulsatory 256<br> -Field, Rotating 256<br> -Field, Stray 256, 495<br> -Field, Uniform 256<br> -Field, Uniform Magnetic 345<br> -Field, Waste 256<br> -Figure of Merit 256<br> -Figures, Haldat's 284<br> -Figures, Lichtenberg's 327<br> -Figures, Magnetic 345<br> -Filament 256<br> -Filament, Magnetic 345<br> -Filaments, Paper 402<br> -File, Circuit Breaker 121<br> -Finder, Position 427<br> -Finder, Range 447<br> -Finder, Wire 580<br> -Fire Alarm, Electric Automatic 257<br> -Fire and Heat Alarm 17<br> -Fire Extinguisher, Electric Automatic 257<br> -Fire Cleansing 257<br> -Fire, St. Elmo's 494<br> -Fishing Box 311<br> -Flashing in a Dynamo or Magneto-Electric Generator 257<br> -Flashing of Incandescent Lamp Carbons 257<br> -Flashing Over 258<br> -Flash, Side 484<br> -Flat Cable 96<br> -Flat Coil 133<br> -Flat Ring Armature 45<br> -Flats 258<br> -Flats in Commutator 140<br> -Flexible Cord 152<br> -Floating Battery, De la Rive's 179<br> -Floating Magnets, Meyer's 370<br> -Floor Matting, Electric 369<br> -Floor Push 258<br> -Fluid, Depolarizing 258<br> -Fluid, Electric 258<br> -Fluid, Electropoion 232<br> -Fluid, Insulator. 306<br> -Fluid, North Magnetic 357<br> -Fluids, Magnetic 345<br> -Fluid, South Magnetic 356<br> -Fluid Theory, Single 486<br> -Fluorescence 258<br> -Flush Boxes 258<br> -Fluviograph 259<br> -Flux, Magnetic 345<br> -Fly or Flyer, Electric 259<br> -Foci Magnetic 259<br> -Fog, Electric 259<br> -Following Horns 259<br> -Foot-candle 259<br> -Foot, Mil- 379<br> -Foot-pound 259<br> -Foot-step 259<br> -Force 259<br> -Force, Annular 544<br> -Force, Axial 544<br> -Force, Centrifugal 112<br> -Force, Coercive or Coercitive 131-471<br> -Force, Controlling 148<br> -Force, Counter-electro-motive 156<br> -Force de Cheval 260<br> -Force, Electro-magnetic 260<br> -Force, Electro-motive 227<br> -Force, Electro-motive, Transverse 549<br> -Force, Electrostatic 260<br> -Force, Field of 254<br> -Force, Field of, of a Current 255<br> -Force, Field of, Electrostatic 254<br> -Force, Kapp Line of 312<br> -Force, Lines of 330<br> -Force, Magnetic 346<br> -Force, Magnetic Field of 344<br> -Force, Magnetic Lines of 348<br> -Force, Magneto-motive 365<br> -Force, Motor Electro-motive 384<br> -Force of Polarization, Back Electro-motive 156<br> -Force, Oscillatory, Electro-motive 398<br> -Force, Photo-electro-motive 410<br> -Forces, Composition of 260<br> -Forces, Parallelogram of 260<br> -Forces, Resolution of 261<br> -Force, True Contact 549<br> -Force, Tubes of 261<br> -Force, Unit of 261<br> -Forked Circuits 126<br> -Fork, Tuning, Dynamo 202<br> -Forming 261<br> -Formula of Merit 256<br> -Foucault Current 163<br> -Foundation Ring 261<br> -Fourth State of Matter 261<br> -Frame 261<br> -Frame, Resistance 465<br> -Franklinic Current 163<br> -Franklin's Experiment 261<br> -Franklin's Plate 262<br> -Franklin's Theory 262-486<br> -Free Charge 115<br> -Free Magnetism 356<br> -Frequency 262<br> -Frequency, High 289<br> -Frictional Electricity 262<br> -Frictional Electric Machine 333<br> -Frictional Heating 262<br> -Friction Gear, Magnetic 276<br> -Friction, Magnetic 295-346<br> -Fringe 262<br> -Frog, Galvani's Experiment with 262<br> -Frog, Rheoscopic 262<br> -Frying 263<br> -Fulgurite 263<br> -Fuller's Battery 63<br> -Fulminating Pane 262<br> -Fundamental Unit 554<br> -Furnace, Electric 263<br> -Fuse Block 175<br> -Fuse Board 263<br> -Fuse Box 263<br> -Fuse, Cockburn 263<br> -Fuse, Electric 264<br> -Fuse Links 330<br> -Fuse, Safety 175-475<br> -<br> -Galvanic 264<br> -Galvanic Action, Volta's Law of 568<br> -Galvanic Dosage 190<br> -Galvanic Element 264<br> -Galvanic Excitability 247<br> -Galvanic or Voltaic Battery 76<br> -Galvanic or Voltaic Circle 119<br> -Galvanic or Voltaic Couple 156<br> -Galvanic Polarization 265<br> -Galvani's Experiment with Frog 262<br> -Galvanism 265<br> -Galvanization 265<br> -Galvanization, Labile 265<br> -Galvanized Iron 265<br> -Galvano-cautery 109<br> -Galvano-cautery, Chemical 265<br> -Galvano-electric Cautery 109<br> -Galvano-faradization 265<br> -Galvanometer 265<br> -Galvanometer, Absolute 266<br> -Galvanometer, Aperiodic 266<br> -Galvanometer, Astatic 266<br> -Galvanometer, Ballistic 267<br> -Galvanometer Constant 268<br> -Galvanometer, Differential 268<br> -Galvanometer, Direct Reading 269<br> -Galvanometer, Marine 269<br> -Galvanometer, Mirror 271<br> -Galvanometer, Potential 269<br> -Galvanometer, Proportional 269<br> -Galvanometer, Quantity 269<br> -Galvanometer, Reflecting 270<br> -Galvanometer, Shunt 271-483<br> -Galvanometer, Sine 271<br> -Galvanometer, Tangent 272<br> -Galvanometer, Torsion 273-544<br> -Galvanometer, Upright 274<br> -Galvanometer, Vertical 274<br> -Galvanometer, Volt and Ampere Meter 274<br> -Galvano-plastics 275<br> -Galvano-puncture 232-275<br> -Galvanoscope 275<br> -Galvano-thermal Cautery 100<br> -Gap, Spark 490<br> -Gas Battery 63<br> -Gas Battery, Grove's 281<br> -Gas Burner, Electric 93<br> -Gas, Carbonic Acid 108<br> -Gas, Electrolytic 275<br> -Gases, Magnetism of 357<br> -Gases, Mixed 275<br> -Gas Jet, Carcel 108<br> -Gas, Olefiant 397<br> -Gassing 275<br> -Gassiot s Cascade 275<br> -Gastroscope 275<br> -Gas Voltameter 564<br> -Gauge, Battery 64<br> -Gauge, Electrometer 226<br> -Gauss 275<br> -Gauss' Principle 276<br> -Gauss, Tangent Positions of 276<br> -Gauze Brush, Wire 92<br> -Gear, Magnetic 346<br> -Gear, Magnetic Friction 276<br> -Geissler Pump 437<br> -Geissler Tubes 276<br> -Generating Plate 277<br> -Generator, Current 277<br> -Generator Inductor 199<br> -Generator, Magneto-electric 362<br> -Generator, Magneto-electric, Flashing in a Dynamo or 257<br> -Generator, Motor 384<br> -Generator, Pyromagnetic. 442<br> -Generators and Motors, Commutator of Current 140<br> -Generator, Secondary 277-477<br> -Geographic Meridian 372<br> -German Mile Unit of Resistance 466<br> -German Silver 277<br> -German Standard Candle 99<br> -Gilding, Electro- 277<br> -Gilding Metal 277<br> -Gimbals 278<br> -Girder Armature 49<br> -Glass 278<br> -Globe or Globular Lightning 330<br> -Glow Discharge 187<br> -Gold 278<br> -Gold Bath 279<br> -Gold Leaf Electroscope 233<br> -Gold Stripping Bath 279<br> -Governor, Centrifugal 113<br> -Governor, Rate 449<br> -Graduator 279<br> -Gram 280<br> -Gram-atom 280<br> -Gram-molecule 280<br> -Graphite 280<br> -Gravitation 280<br> -Gravity, Acceleration of 280<br> -Gravity Ammeter 27<br> -Gravity Battery 64<br> -Gravity, Centre of 112<br> -Gravity Control 281<br> -Gravity Drop Annunciator 35<br> -Grease Spot 92<br> -Green Vitriol 562<br> -Grenet Battery 65<br> -Grid 281<br> -Grid Plug 420<br> -Grip, Cable 96<br> -Gross Efficiency 205<br> -Ground 281<br> -Grounded Circuit 123<br> -Ground Plate 417<br> -Ground Wire 281<br> -Grove's Battery 65<br> -Grove's Gas Battery 281<br> -Guard Ring 282<br> -Guard Tube 282<br> -Gun, Electro-magnetic 282<br> -Gutta Percha 282<br> -Gyration, Centre of 112<br> -Gyrostatic Action of Armatures 283<br> -<br> -H 283<br> -H Armature 49<br> -Haarlem Magnet 337<br> -Hair, Removal of, by Electrolysis 283<br> -Haldat's Figures 284<br> -Hall Effect 284<br> -Hall Effect, Real 284<br> -Hall Effect, Spurious 284<br> -Halleyan Lines 308<br> -Hall's Experiment 284<br> -Halske's and Siemens' Battery 72<br> -Hand Hole 190<br> -Hanger Board 284<br> -Hanger, Cable 96<br> -Hanger, Cable, Tongs 97<br> -Harcourt's Pentane Standard 406<br> -Hare's Deflagrator 73<br> -Harmonic 23<br> -Harmonic Curve 174, 485<br> -Harmonic Motion, Simple 486<br> -Harmonic Receiver 284, 451<br> -Head Bath, Electric 284<br> -Head-light, Electric 285<br> -Head, Torsion 544<br> -Heat 285<br> -Heat and Fire Alarm 17<br> -Heat, Atomic 52, 285<br> -Heat, Electric 285<br> -Heat, Electric, Convection of 149, 286<br> -Heat, Irreversible. 286<br> -Heat, Mechanical Equivalent of 286<br> -Heat, Molecular 286<br> -Heat, Specific 286<br> -Heat, Specific, of Electricity 288<br> -Heat Units 288<br> -Heater, Electric 286<br> -Heating, Admiralty Rules of 12<br> -Heating Error 286<br> -Heating, Frictional 262<br> -Heating Magnet 286<br> -Heavy Carburetted Hydrogen, 397<br> -Hecto 288<br> -Hedgehog Transformer 548<br> -Heliograph 288<br> -Helix 288<br> -Henley's Universal Discharger 189<br> -Henry 288<br> -Henry's Coils 138<br> -Hermetically Sealed 289<br> -Hertz's Experiments 470<br> -Heterostatic Method 280<br> -Hexode Working 581<br> -High Bars of Commutator 289<br> -High Frequency 289<br> -High Vacuum 557<br> -Hinged Armature 45<br> -Hinged Electro-magnet 217<br> -Hissing 289<br> -Hittorf's Resistance 466<br> -Hittorf's Solution 289<br> -Hoffer's Method of Magnetization 360<br> -Hole Armature 45<br> -Hole, Hand 190<br> -Holders 289<br> -Holder, Brush 91<br> -Holder, Candle 99<br> -Holders, Carbon 107<br> -Holophote Lamp 321<br> -Holtz's Influence Machine 334<br> -Home Station 493<br> -Hood 290<br> -Horizontal Induction 302<br> -Horns 290<br> -Horns, Driving 132<br> -Horns, Following 259<br> -Horns, Leading 324<br> -Horns, Trailing 259<br> -Horse Power 290<br> -Horse Power, Actual 290<br> -Horse Power Curve 171<br> -Horse Power, Electric 290<br> -Horse Power Hour 290<br> -Horse Power, Indicated 290<br> -Horseshoe Magnet 337<br> -Hour, Ampere- 30<br> -Hour, Horse Power 290<br> -H. P. 290<br> -Hughes' Electro-magnet 291<br> -Hughes' Induction Balance 291<br> -Hughes' Sonometer 488<br> -Hughes' Telegraph 511<br> -Hughes' Theory of Magnetism 357<br> -Hughes' Type Printer 511<br> -Human Body, Resistance of 467<br> -Hydrochloric Acid Battery 66<br> -Hydro-electric 293<br> -Hydro-electric Machine 293<br> -Hydrogen 294<br> -Hydrogen, Carburetted, Heavy 397<br> -Hydrometer, Beaumé 78<br> -Hygrometer 294<br> -Hyperbolic Logarithms 389<br> -Hysteresis 295<br> -Hysteresis, Magnetic 294<br> -Hysteresis, Static 295<br> -Hysteresis, Viscous 295, 356<br> -<br> -Idioelectrics 295<br> -Idiostatic Method 295<br> -Idle Coils 295<br> -Idle Poles 296<br> -Idle Wire 291<br> -Igniter 296<br> -I. H P. 296<br> -Illuminating Power 296<br> -Illuminating Power, Spherical 296<br> -Illuminating Power, Standard of, Viole's 561<br> -Illumination, Unit of 296<br> -Image, Electric 296<br> -Imbricated Conductor 146<br> -Immersion, Simple 185<br> -Impedance 297, 462<br> -Impedance, Impulsive 297<br> -Impedance, Oscillatory 297<br> -Impressed Electro-motive Force 297<br> -Impulse 297<br> -Impulsive Discharge 188<br> -Impulsive Impedance 297<br> -In-and-out, Soaking 486<br> -Incandescence, Electric 297<br> -Incandescent Lamp 321<br> -Incandescent Lamp Carbons, Flashing of 257<br> -Incandescent Lamp, Chamber of 113<br> -Incandescent Lamp, Life of 327<br> -Incandescent Lamp, Three Filament 322<br> -Inclination Compass 142<br> -Inclination, Magnetic 346<br> -Inclination Map 297<br> -Inclination or Dip, Angle of 33<br> -Incomplete Circuit 125<br> -Increment Key 314<br> -Independence of Currents in Parallel Circuits 297<br> -India Rubber 102<br> -Indicated Horse Power 290<br> -Indicating Bell 80, 297<br> -Indicator 298<br> -Indicator, Circuit 298<br> -Indicator, Throw-back 540<br> -Indicator, Volt 568<br> -Indifferent Electrode 210<br> -Indifferent Point 421<br> -Induced Current 163<br> -Induced Magnetization, Coefficient of 354, 359<br> -Inductance 298<br> -Inductance Balance 293<br> -Inductance Bridge 293<br> -Induction, Anti-, Conductor 36<br> -Induction, Back 55<br> -Induction Balance, Hughes 291<br> -Induction, Coefficient of Magnetic 349<br> -Induction, Coefficient of Mutual 301<br> -Induction, Coefficient of Self- 298<br> -Induction Coil 133<br> -Induction Coil, Inverted 136<br> -Induction Coil, Telephone 137, 526<br> -Induction, Cross 298<br> -Induction Current 163<br> -Induction, Electro-magnetic 218, 299<br> -Induction, Electrostatic 302<br> -Induction, Electrostatic, Coefficient of 234<br> -Induction, Horizontal 302<br> -Induction, Lateral 302<br> -Induction, Lines of 330<br> -Induction, Magnetic 302, 346<br> -Induction, Magnetic, Apparent Coefficient of 346<br> -Induction, Magnetic, Coefficient of 346<br> -Induction, Magnetic Dynamic 347<br> -Induction, Magnetic, Self- 352<br> -Induction, Magnetic Static 347<br> -Induction, Magnetic, Tube of 347<br> -Induction, Mutual, Electro-magnetic 302<br> -Induction, Mutual, Electrostatic 303<br> -Induction, Open Circuit 303<br> -Induction, Oscillatory 398<br> -Induction Protector, Mutual 481<br> -Induction, Self- 303<br> -Induction Sheath 303<br> -Induction. Unipolar 304<br> -Induction, Unit of Self- 304<br> -Induction, Vertical 304<br> -Inductive Capacity, Magnetic 346, 349<br> -Inductive Effect, Counter- 204<br> -Inductive Resistance 466<br> -Inductophone 304<br> -Inductor 305<br> -Inductor Dynamo 199<br> -Inductor Generator 199<br> -Inductor, Magneto- 363<br> -Inductor, Pacinotti's 400<br> -Inductorium 138<br> -Inertia 305<br> -Inertia, Electro-magnetic 305<br> -Inertia, Magnetic 347<br> -Infinity Plug 305, 420<br> -Influence, Electric 305<br> -Influence Machine 334<br> -Influence Machine, Armature of 46<br> -Influence Machine, Holtz 334<br> -Influence, Magnetic 346<br> -Installation 305<br> -Instantaneous Capacity 102<br> -Insulating Stool 305<br> -Insulating Tape 305<br> -Insulating Varnish 306<br> -Insulation, Electric 305<br> -Insulation, Magnetic 347<br> -Insulation, Oil 396<br> -Insulation Resistance 466<br> -Insulator 306<br> -Insulator Caps 306<br> -Insulator, Fluid 306<br> -Insulator, Line or Telegraph 306<br> -Intensity 306<br> -Intensity Armature 45<br> -Intensity Current 163<br> -Intensity, Electro-motive 228<br> -Intensity, Magnetic 348<br> -Intensity of a Magnetic Field 306<br> -Intensity of Magnetization 360<br> -Intensity, Poles of 426<br> -Inter-air Space 489<br> -Intercrossing 307<br> -Interference, Armature 45<br> -Interferric Space 489<br> -Interior Pole Dynamo 191<br> -Interlocking- Electro-magnets. 229<br> -Intermediate Metals, Law of 323<br> -Intermittent, 307<br> -Internal Characteristic 114<br> -Internal Resistance 466<br> -lnterpolar Conductor 307<br> -Interpolar Region 307<br> -Interpolation 307<br> -Interrupter, Electro-magnetic, for Tuning Fork 307<br> -Intrinsic Efficiency 205<br> -Invariable Calibration 97<br> -Inverse Induced Current 163<br> -Inverse Squares, Law of 323<br> -Inversion, Thermo-electric 533<br> -Ions 307<br> -Iron 308<br> -Ironclad Dynamo 200<br> -Ironclad Electro-magnet, 219<br> -Ironclad Magnet 356<br> -Iron Disc Ammeter, Eccentric 27<br> -Iron, Electrolytic 308<br> -Iron, Galvanized 265<br> -Ironwork Fault of a Dynamo 308<br> -Irreversible Heat 286<br> -Isochasmen Curve 171<br> -Isochronism 308<br> -Isoclinic Lines 308<br> -Isoclinic Map 308<br> -Isodynamic Lines 308<br> -Isodynamic Map 308<br> -Isoelectric Points 422<br> -Isogonal Lines 308<br> -Isogonic Map 309<br> -Isolated Distribution 309<br> -Isolated Plant 309<br> -Isolated Supply 309<br> -Isotropic 309<br> -Isthmus Method of Magnetization 360<br> -I. W. G., 309<br> -<br> -J 309<br> -Jablochkoff Candle 160<br> -Jack. Spring- 492<br> -Jacketed Magnet 356<br> -Jacobi's Law 309<br> -Jacobi's Method of Magnetization 360<br> -Jacobi's Unit of Current 163<br> -Jacobi's Unit of Resistance 466<br> -Jamin Candle 100<br> -Jar, Leyden 325<br> -Jar, Lightning 330<br> -Jar, Luminous 332<br> -Jars, Leyden, Charging and Discharging 108<br> -Jar, Unit 554<br> -Jewelry 309<br> -Joulad 311<br> -Joule 311<br> -Joule Effect 311<br> -Joule's Electro-magnet 337<br> -Joule's Equivalent, 311<br> -Joint, American Twist 309<br> -Joint, Britannia 309<br> -Joint, Butt 310<br> -Joint Current 160<br> -Joint, Lap 310<br> -Joint, Marriage 310<br> -Joint, Resistance 464<br> -Joints in Belts 311<br> -Joint, Sleeve 310<br> -Joint, Splayed 311<br> -Junction Box 311<br> -Junction, Thermo-electric 533<br> -<br> -K. 311<br> -Kaolin 311<br> -Kapp. Line of Force 312<br> -Kathelectrotonus 312<br> -Kathode 312<br> -Kathodic Closure Contraction 312<br> -Kathodic Duration Contraction 312<br> -K. C. C. 312<br> -K. D. C. 312<br> -Kempe's Discharge Key 315<br> -Keeper 312<br> -Kerr Effect 235, 312<br> -Kerr's Experiment 312<br> -Key 313<br> -Key Board 313<br> -Key, Bridge 313<br> -Key, Double Contact 314<br> -Key, Double Tapper 314<br> -Key, Charge and Discharge 313<br> -Key, Increment 314<br> -Key, Kempe's Discharge 315<br> -Key, Magneto-electric 315<br> -Key, Make and Break 316<br> -Key, Plug 316<br> -Key, Reversing 316<br> -Key, Sliding-contact 316<br> -Key, Telegraph 316<br> -Kicking Coil 132<br> -Kilo 316<br> -Kilodyne 316<br> -Kilogram 317<br> -Kilojoule 317<br> -Kilometer 317<br> -Kilowatt 317<br> -Kine 317<br> -Kinnersley's Thermometer 536<br> -Kinetics, Electro- 211<br> -Kinetic Energy 241<br> -Kirchoff's Laws 317<br> -Knife Break Switch 501<br> -Knife Edge Suspension 317<br> -Knife Edge Switch 501<br> -Knife Switch 501<br> -Knot 317<br> -Kohlrausch's Law 317<br> -Kookogey's Solution 318<br> -Krizik's Cores 318<br> -<br> -L 318<br> -Lag, Angle of 33, 318<br> -Lag, Electric 332<br> -Lag, Magnetic 348<br> -Lalande & Chaperon Battery 69<br> -Lalande-Edison Battery 69<br> -Lamellar Distribution of Magnetism 357<br> -Laminated 318<br> -Laminated Core 154<br> -Laminated Core, Tangentially 155<br> -Lamination 318<br> -Lamination of Armature Conductors 319<br> -Lamination of Magnet 361<br> -Lamp, Arc 319<br> -Lamp, Arc, Double Carbon 191<br> -Lamp Carbons, Flashing of Incandescent 257<br> -Lamp, Carcel 108<br> -Lamp, Contact 320<br> -Lamp, Differential Arc 320<br> -Lamp Globe, Waterproof 572<br> -Lamp, Holophote 321<br> -Lamp-hour 321<br> -Lamp, Incandescent 321<br> -Lamp, Incandescent, Chamber of 113<br> -Lamp, Incandescent, Three Filament 322<br> -Lamp, Life of Incandescent 327<br> -Lamp, Lighthouse 322<br> -Lamp, Monophote 321<br> -Lamp, Pilot 323<br> -Lamp, Polyphote 323<br> -Lamp, Semi-Incandescent 323<br> -Lamp-socket 323<br> -Lamps, Bank of 323<br> -Lane's Electrometer 226<br> -Langdon Davies' Rate Governor or Phonophone 450<br> -Lenz's Law 325<br> -Lap Joint 310<br> -Lap Winding 570<br> -Latent Electricity 323<br> -Lateral Discharge 188<br> -Lateral Induction 302<br> -Latitude, Magnetic 348<br> -Law, Jacobi's 309<br> -Law, Kohlrausch's 317<br> -Law, Lenz's 325<br> -Law of Angular Currents 165<br> -Law of Electrolysis 213<br> -Law of Intermediate Metals 323<br> -Law of Inverse Squares 323<br> -Law of Magnetic Attraction and Repulsion. Coulomb's 338<br> -Law of Successive Temperatures 324<br> -Law, Magnus' 367<br> -Law, Ohm's 396<br> -Law, Pflüger's. 409<br> -Law, Right Handed Screw 324<br> -Law, Sine 486<br> -Laws, Kirchoff's 317<br> -Laws of Thermo-electricity, Becquerel's 78<br> -Law, Tangent 502<br> -Law, Voltametric 567<br> -Lead 324<br> -Lead, Angle of 33<br> -Lead Chloride Battery 66<br> -Lead of Brushes 90<br> -Lead of Brushes, Negative 324<br> -Lead, Peroxide of, Battery 69<br> -Lead Sulphate Battery 66<br> -Lead Tee 504<br> -Leading Horns 324<br> -Leading-in Wires 324<br> -Leak 324<br> -Leakage 324<br> -Leakage Conductor 325<br> -Leakage, Electro-magnetic 219<br> -Leakage, Magnetic. 348<br> -Leakage, Surface 498<br> -Leclanché Agglomerate Battery 66<br> -Leclanché Battery 66<br> -Leg of Circuit 325<br> -Legal Ohm 395<br> -Legal Quadrant 444<br> -Legal Volt 568<br> -Length of Spark 490<br> -Letter Boxes, Electric 325<br> -Leyden Jar 325<br> -Leyden Jar, Armature of 46<br> -Leyden Jars, Battery of 68<br> -Leyden Jars, Charging and Discharging 108<br> -Leyden Jars, Sir William Thomson's 326<br> -Lichtenberg's Figures 327<br> -Life Curve 171<br> -Life of Incandescent Lamp 327<br> -Light, Electro-magnetic, Theory of 219<br> -Light, Maxwell's Theory of 369<br> -Lighthouse Lamp 322<br> -Lightning 327<br> -Lightning Arrester 328<br> -Lightning Arrester, Counter-electro-motive Force 329<br> -Lightning Arrester Plates 329<br> -Lightning Arrester, Vacuum 329<br> -Lightning, Ascending 330<br> -Lightning, Globe or Globular 330<br> -Lightning Jar 330<br> -Lightning, Back Stroke or Shock of 55<br> -Lime, Chloride of, Battery 61<br> -Limit, Magnetic 348<br> -Limit of Magnetization 361<br> -Linear Current 164<br> -Lineman's Detector 180<br> -Line of Commutator, Neutral 300<br> -Line of Contact 330<br> -Line of Force, Kapp 312<br> -Line of Magnet, Neutral 361<br> -Line or Telegraph Insulator 306<br> -Lines, Halleyan 308<br> -Lines, Isoclinic 308<br> -Lines, Isodynamic 308<br> -Lines, Isogonal 308<br> -Lines, Isogonic 308<br> -Lines of Force 330<br> -Lines of Force, Cutting of 175<br> -Lines of Force, Electro-magnetic 219<br> -Lines of Force, Electrostatic 234<br> -Lines of Force, Magnetic 348<br> -Lines of Induction 330<br> -Lines of Slope 330<br> -Lines or Points of Least Sparking 490<br> -Lines, Trunk 550<br> -Links, Fuse 330<br> -Liquids, Electro-dynamic Rotation of 474<br> -Liquids, Electro-magnetic Rotation of 475<br> -Liquor, Spent 491<br> -Listening Cam 330<br> -Lithanode 331<br> -Load 331<br> -Load Curve 172<br> -Load of Armature 46<br> -Local Action 331<br> -Local Battery 331<br> -Local Circuit 331<br> -Local Currents 163, 331<br> -Localization 331<br> -Locus 331<br> -Lodestone 332<br> -Logarithm 332<br> -Logarithms, Hyperbolic 389<br> -Logarithms, Napierian 389<br> -Local Battery 66<br> -Long Coil Magnet 361<br> -Long Range Electro-magnet 220<br> -Long Shunt and Series Winding 579<br> -Long Shunt Winding 579<br> -Loop 332<br> -Loop Break 332<br> -Loop, Circuit 125<br> -Loop, Drip 192<br> -Lost Amperes 30<br> -Lost Volts 571<br> -Low Vacuum 557<br> -Luces 332<br> -Luminous Jar 332<br> -Luminous Pane 401<br> -Luminous Tube 550<br> -Lux 332<br> -<br> -M 332<br> -Machine, Cylinder Electric 333<br> -Machine, Electric, Wimshurst 577<br> -Machine, Frictional Electric 333<br> -Machine, Holtz Influence 334<br> -Machine, Hydro-electric 293<br> -Machine, Influence 334<br> -Machine, Nairne's Electrical 389<br> -Machine, Plate Electrical 417<br> -Machine, Rheostatic 472<br> -Machine, Toeppler-Holtz 334<br> -Machine, Wimshurst 335<br> -Mack 335<br> -Magic Circle 119<br> -Magne-crystallic Action 335<br> -Magnet 335<br> -Magnet, Anomalous 335<br> -Magnet, Artificial 335<br> -Magnet, Axial 336<br> -Magnet, Bar 336<br> -Magnet, Bell Shaped 336<br> -Magnet Coils, Sheath for 481<br> -Magnet, Compensating 336<br> -Magnet, Compound 336<br> -Magnet, Controlling 185, 336<br> -Magnet, Damping 336<br> -Magnet, Deflection of 337<br> -Magnet, Directing 185<br> -Magnet, Electro- 215, 337<br> -Magnet, Equator of 337<br> -Magnet, Field 337<br> -Magnet, Haarlem 337<br> -Magnet, Heating 286<br> -Magnet, Horseshoe 337<br> -Magnet, Ironclad 356<br> -Magnet, Joule's Electro- 337<br> -Magnet-keeper 361<br> -Magnet, Lamination of 361<br> -Magnet, Long Coil 361<br> -Magnet, Natural 361<br> -Magnet, Neutral Line of 361<br> -Magnet, Normal 361<br> -Magnet Operation 365<br> -Magnet, Permanent 365<br> -Magnet Pole 365<br> -Magnet, Portative Power of 366<br> -Magnet, Projecting Power of a 435<br> -Magnet, Relay 457<br> -Magnet, Simple 366<br> -Magnet, Solenoidal 366<br> -Magnet, Sucking 366<br> -Magnet, Unipolar 366<br> -Magnet Coil 336<br> -Magnet Core 336<br> -Magnet Poles, Secondary 366<br> -Magnet Pole, Unit 366<br> -Magnetic Adherence 338<br> -Magnetic and Electro-magnetic Equipotential Surface 244<br> -Magnetic Attraction 338<br> -Magnetic Attraction and Repulsion, Coulomb's Law of 338<br> -Magnetic Axis 338<br> -Magnetic Azimuth 338<br> -Magnetic Battery 338<br> -Magnetic Bridge 338<br> -Magnetic Circuit 340<br> -Magnetic Circuit, Curve of Saturation of 174<br> -Magnetic Concentration of Ores 340<br> -Magnetic Concentrator 340<br> -Magnetic Continuity 340<br> -Magnetic Conductance and Conductivity 340<br> -Magnetic Control 341<br> -Magnetic Couple 341<br> -Magnetic Creeping 341<br> -Magnetic Curves 341<br> -Magnetic Cut Out 175<br> -Magnetic Declination 342<br> -Magnetic Density 342<br> -Magnetic Dip 342, 346<br> -Magnetic Discontinuity 342<br> -Magnetic Double Circuit 340<br> -Magnetic Eye, Electro- 248<br> -Magnetic Elements 342<br> -Magnetic Elongation 344<br> -Magnetic Equator 344<br> -Magnetic False Poles 350<br> -Magnetic, Ferro- 252<br> -Magnetic Field, Intensity of a 306<br> -Magnetic Field of Force 344<br> -Magnetic Field, Uniform 345<br> -Magnetic Figures 345<br> -Magnetic Filament 345<br> -Magnetic Fluid, North 357<br> -Magnetic Fluids 345<br> -Magnetic Flux 345<br> -Magnetic Force 346<br> -Magnetic Friction 295, 346<br> -Magnetic Friction Gear 276<br> -Magnetic Fluid, South 356<br> -Magnetic Foci 259<br> -Magnetic Gear 346<br> -Magnetic Hysteresis 294<br> -Magnetic Inclination 346<br> -Magnetic Induction 302<br> -Magnetic Induction, Apparent Coefficient of 346<br> -Magnetic Induction, Coefficient of 346-349<br> -Magnetic Induction, Dynamic 347<br> -Magnetic Induction, Static 347<br> -Magnetic Induction, Tube of 347<br> -Magnetic Inductive Capacity 349<br> -Magnetic Inertia 347<br> -Magnetic Influence 346<br> -Magnetic Insulation 347<br> -Magnetic Intensity 348<br> -Magnetic Lag 348<br> -Magnetic Latitude 348<br> -Magnetic Leakage 348<br> -'Magnetic Limit 348<br> -Magnetic Lines of Force 348<br> -Magnetic Mass 349<br> -Magnetic Matter 349<br> -Magnetic Memory 349<br> -Magnetic Meridian 349<br> -Magnetic Moment 349<br> -Magnetic Needle 349<br> -Magnetic Needle, Declination of the 178<br> -Magnetic Needle, Dip of 185<br> -Magnetic Needle, Oscillation of a 397<br> -Magnetic Output 399<br> -Magnetic Parallels 349<br> -Magnetic Permeability 349<br> -Magnetic Perturbations 350<br> -Magnetic Poles 350<br> -Magnetic Potential 350, 431<br> -Magnetic Proof Piece 350<br> -Magnetic Proof Plane 350<br> -Magnetic Quantity 350<br> -Magnetic Reluctance 351, 458<br> -Magnetic Reluctivity 351<br> -Magnetic Remanence 358<br> -Magnetic Repulsion 338<br> -Magnetic Resistance 458<br> -Magnetic Retentivity 351<br> -Magnetic Rotatory Polarization 351<br> -Magnetic Saturation 251<br> -Magnetic Screen 351<br> -Magnetic Self-induction 352<br> -Magnetic Separator 352<br> -Magnetic Shell 352<br> -Magnetic Shell, Strength of 352<br> -Magnetic Shield 353<br> -Magnetic Shunt 353<br> -Magnetic Storms 353<br> -Magnetic Strain 354<br> -Magnetic Stress 354<br> -Magnetic Susceptibility 254, 359<br> -Magnetic Tick 354<br> -Magnetic Top 542<br> -Magnetic Twist 354<br> -Magnetic Vane Ammeter 27<br> -Magnetic Variations 354<br> -Magnetism, Ampere's Theory of 354<br> -Magnetism, Blue 355<br> -Magnetism, Components of Earth's 356<br> -Magnetism, Creeping of 356<br> -Magnetism, Decay of 356<br> -Magnetism, Discharge of 356<br> -Magnetism, Electro 220<br> -Magnetism, Ewing's Theory of 356<br> -Magnetism, Free 356<br> -Magnetism, Hughes' Theory of 357<br> -Magnetism, Lamellar Distribution of 357<br> -Magnetism of Gases 357<br> -Magnetism, Red 357<br> -Magnetism, Residual 358<br> -Magnetism, Solenoidal Distribution of 358<br> -Magnetism, Sub-permanent 358<br> -Magnetism, Terrestrial 358<br> -Magnetism, Weber's Theory of 358<br> -Magnetization by the Earth 359<br> -Magnetization by Double Touch 358<br> -Magnetization by Separate Touch 359<br> -Magnetization by Single Touch 359<br> -Magnetization, Coefficient of Induced 359<br> -Magnetization Curve 172<br> -Magnetization, Cycle of 360<br> -Magnetization, Elias' Method of 360<br> -Magnetization, Hoffer's Method of 360<br> -Magnetization, Intensity of 360<br> -Magnetization, Isthmus Method of 360<br> -Magnetization, Jacobi's Method 360<br> -Magnetization, Limit of 361<br> -Magnetization, Maximum 361<br> -Magnetization, Specific 361<br> -Magnetization, Surface 356<br> -Magnetizing Coil 127<br> -Magneto 361<br> -Magneto Bell 80<br> -Magneto Call Bell 361<br> -Magneto-electric 361<br> -Magneto-electric Brake 362<br> -Magneto-electric Generator 362<br> -Magneto-electric Generator, or Dynamo, Flashing in a 257<br> -Magneto-electric Key 315<br> -Magneto-electric Telegraph 512<br> -Magnetograph 363<br> -Magneto-inductor 363<br> -Magnetometer 363<br> -Magnetometer, Differential 365<br> -Magnetometry 364<br> -Magneto-motive Force 365<br> -Magnetophone 367<br> -Magnetoscope 365<br> -Magnifying Spring Ammeter 28<br> -Magnus' Law 367<br> -Main Battery 66<br> -Main Battery Circuit 125<br> -Main Circuit 125<br> -Main or Standard Feeder 251<br> -Mains, Electric 367<br> -Make 367<br> -Make and Break Current 164, 367<br> -Make and Break Key 316<br> -Make-induced Current 163<br> -Malapterurus 367<br> -Map, Declination 309<br> -Map, Inclination 297<br> -Map, Isoclinic 308<br> -Map, Isodynamic 308<br> -Map, Isogonic 309<br> -Marié Davy's Battery 67<br> -Marine Galvanometer 269<br> -Mariner's Compass 142<br> -Marked End or Pole 368<br> -Marriage Joint 310<br> -Mass, Electric 368<br> -Mass, Magnetic 349<br> -Master Clock 127<br> -Mathematical Element 237<br> -Matteueci's Experiment 369<br> -Matter, Electric 368<br> -Matter, Fourth State of 261<br> -Matter, Magnetic 349<br> -Matter, Radiant 368<br> -Matter, Ultra Gaseous 551<br> -Matthiessen's Meter-gram Standard Resistance,. 466<br> -Matthiessen's Unit of Resistance 466<br> -Matting, Electric Floor 369<br> -Maximum Magnetization 361<br> -Maxwell's Theory of Light 369<br> -Mayer's Floating Magnet 370<br> -Maynooth's Battery 67<br> -Measurement, Absolute 8<br> -Measurements 370<br> -Mechanical Equivalent of Heat 286<br> -Mechanical Energy 241<br> -Mechanical Equivalent, Electro- 244<br> -Medical Battery 67<br> -Medium, Polarization of the 424<br> -Meg or Mega 370<br> -Meidinger's Battery 68<br> -Memoria Technica, Ampére's 30<br> -Memory, Magnetic 349<br> -Mercury 371<br> -Mercury Bichromate, Battery 63<br> -Mercury Circuit Breaker 121<br> -Mercury Cups 371<br> -Mercury, Sulphate of, Battery 67<br> -Mercurial Air Pump 16<br> -Meridian, Astronomical 372<br> -Meridian, Geographic 372<br> -Meridian, Magnetic. 349<br> -Merit, Figure of 256<br> -Merit, Formula of 256<br> -Metal, Gilding 277<br> -Metallic Arc 39<br> -Metallic Circuit 125<br> -Metallochromes 392<br> -Metallurgy, Electro- 222<br> -Metals, Law of Intermediate 323<br> -Meter. Alternating Current 373<br> -Meter, Ampere and Volt, Galvanometer . 274<br> -Meter, Balance Ampere 391<br> -Meter Bridge 373<br> -Meter Bridge, Slide 486<br> -Meter Candle 374<br> -Meter, Chemical Electric 375<br> -Meter, Current 375<br> -Meter, Electro-magnetic 375<br> -Meter, Energy 375<br> -Meter Gram Standard Resistance, Matthiesen's 466<br> -Meter-millimeter 375<br> -Meter-millimeter Unit of Resistance 466<br> -Meter, Neutral Wire Ampere. 391<br> -Meter, Quantity 445<br> -Meters. Ampere 39<br> -Meter, Thermal-Electric 375<br> -Meter, Time Electric 375<br> -Meter, Watt 375<br> -Method, Broadside 89<br> -Method, Deflection 178<br> -Method, End on 238<br> -Method, Idiostatic 295<br> -Method, Multiple Wire 388<br> -Method, Null 393<br> -Method of Magnetization, Elias' 360<br> -Method of Magnetization, Isthmus 360<br> -Method of Magnetization, Jacobi's 360<br> -Methven Standard or Screen 376<br> -Mho, 376<br> -Mica 376<br> -Mica, Moulded 376<br> -Micro 376<br> -Micrometer 376<br> -Micrometer, Arc 39, 376<br> -Micrometer, Spark 470<br> -Micron 376<br> -Microphone 376<br> -Microphone Relay 377, 457<br> -Microscope. Photo-electric 410<br> -Microtasimeter 377<br> -Mil 379<br> -Mil, Circular 379<br> -Mil-foot 379<br> -Mil-foot Unit of Resistance 467<br> -Milli 379<br> -Milligram 379<br> -Millimeter 379<br> -Milli-oerstedt 380<br> -Mil, Square 379<br> -Minute, Ampere- 30<br> -Mirror Galvanometer. 271<br> -Mixed Gases 275<br> -mm. 380<br> -Molar 380<br> -Molar Energy 241<br> -Molecular Affinity 380<br> -Molecular Attraction 380<br> -Molecular Bombardment 380<br> -Molecular Chain 380<br> -Molecular Energy 241<br> -Molecular Heat 286<br> -Molecular Rigidity 380, 473<br> -Molecular Shadow 480<br> -Molecule 380<br> -Moment 381<br> -Moment, Magnetic 349<br> -Moment of Couple 544<br> -Moment, Turning 544<br> -Monophote Lamp 321<br> -Mordey Effect 381<br> -Morse Receiver 381<br> -Morse Recorder 451<br> -Morse Telegraph 512<br> -Mortar, Electric 382<br> -Motion, Currents of 167<br> -Motograph, Electro- 229<br> -Motor. Compound or Compound Wound,. 382<br> -Motor, Differential 382<br> -Motor, Dynamo 200<br> -Motor, Electric 382<br> -Motor, Electro- 229<br> -Motor, Electro-motive Force 384<br> -Motor-generator 384<br> -Motor, Multiphase 384<br> -Motor, Overtype 399<br> -Motor, Prime 385<br> -Motor, Pulsating 386<br> -Motor, Pyromagnetic 442<br> -Motor, Reciprocating 385<br> -Motor, Series 386<br> -Motor, Shunt 386<br> -Moulded Mica 376<br> -Moulding 58<br> -Movable Secondary 477<br> -Mud, Battery 68<br> -Multiphase Currents 166<br> -Multiphase Motor 384<br> -Multiple 386<br> -Multiple Arc 387<br> -Multiple Arc Box 387<br> -Multiple Connected Battery 68<br> -Multiple-series 387, 480<br> -Multiple Switch 501<br> -Multiple Switch Board 387<br> -Multiple Transformer 548<br> -Multiple Winding 579<br> -Multiple Wire Method 388<br> -Multiplex Harmonic Telegraph 510<br> -Multiplex Telegraph 514<br> -Multiplex Telegraphy 388<br> -Multiplier, Schweigger's 476<br> -Multiplying Power 347, 349<br> -Multiplying Power of a Shunt 388<br> -Multipolar Armature 46<br> -Multipolar Dynamo 200<br> -Multipolar Electric Bath 57<br> -Multipolar Winding 579<br> -Muscular Pile 388<br> -Mutual Electro-magnetic Induction 302<br> -Mutual Electrostatic Induction 303<br> -Mutual Induction, Coefficient of 301<br> -Mutual Induction Protector 481<br> -Myria 388<br> -<br> -Nairne's Electrical Machine 389<br> -Napierian Logarithms 389<br> -Nascent State 389<br> -Natural Currents 166, 389<br> -Natural Magnet 361<br> -Needle 389<br> -Needle Annunciator 35<br> -Needle, Astatic 50<br> -Needle, Dipping 185<br> -Needle, Magnetic 349<br> -Needle, Orientation of a Magnetic 397<br> -Needle of Oscillation 389<br> -Needle Telegraph, Single 519<br> -Needle, Telegraphic 389<br> -Negative Charge 389<br> -Negative Current 164<br> -Negative Electricity 389<br> -Negative, Electro- 229<br> -Negative Element 390<br> -Negative Feeder 251<br> -Negative Lead of Brushes 324<br> -Negative Plate 417<br> -Negative Pole 425<br> -Negative Potential 432<br> -Negative Side of Circuit 125<br> -Nerve and Muscle Current 164<br> -Nerve Currents 390<br> -Net Efficiency 205<br> -Net, Faraday's 250<br> -Network 390<br> -Neutral Armature 46<br> -Neutral Feeder 251<br> -Neutral Line of Commutator 390<br> -Neutral Line of Magnet 361<br> -Neutral Point 421<br> -Neutral Point of Commutator 390<br> -Neutral Point, Thermo-electric 390<br> -Neutral Relay Armature 46, 390<br> -Neutral Temperature 390<br> -Neutral Wire 390<br> -Neutral Wire Ampere Meter 391<br> -N. H. P. 391<br> -Niaudet's Battery 61<br> -Nickel 391<br> -Nickel Bath 391<br> -Night Bell 392<br> -Nitric Acid Battery 68<br> -Nobili's Rings 392<br> -Nodal Point 422<br> -Nodular Deposit 392<br> -Nominal Candle Power 101<br> -Non-conductor 392<br> -Non-essential Resistance 465-467<br> -Non-inductive Resistance 467<br> -Non-polar Dynamo 200<br> -Non-polarizable Electrodes 210<br> -Non-Polarized Armature 46<br> -Normal Magnet 361<br> -North Magnetic Fluid 357<br> -North Pole 392<br> -North Seeking Pole 393<br> -Null Method 393<br> -Null Point 422<br> -<br> -Occlusion 393<br> -Oerstedt 394<br> -Oerstedt's Discovery 394<br> -Oerstedt, Milli- 380<br> -Ohm 394<br> -Ohmage 394<br> -Ohm, B. A. 394<br> -Ohm, Board of Trade 394<br> -Ohm, Congress 395<br> -Ohmic Resistance 394, 467<br> -Ohm, Legal 395<br> -Ohmmeter 395<br> -Ohm, Rayleigh 396<br> -Ohm's Law 396<br> -Ohm, True 396<br> -Oil Insulation 396<br> -Oil Transformer 548<br> -Old Armature, Siemens' 49<br> -Olefiant Gas 397<br> -Omnibus Bar 94<br> -Omnibus Rod 94<br> -Omnibus Wire 94<br> -One Coil Electro-magnet 219<br> -Open 397<br> -Open Circuit 125<br> -Open Circuit Battery 68<br> -Open Circuit Induction 303<br> -Open Circuit Oscillation 397<br> -Open Coil Armature 46<br> -Open Coil Dynamo 200<br> -Opening Shock 482<br> -Operation, Magnet 365<br> -Opposed Current 164<br> -Optics, Electro- 229<br> -Orders of Currents 167<br> -Ordinate 397<br> -Ordinates, Axis of 54, 397<br> -Ores, Electric Reduction of 453<br> -Ores, Magnetic Concentration of 340<br> -Organ, Electric 397<br> -Orientation of a Magnetic Needle 397<br> -Origin of Co-ordinates 397<br> -Oscillation, Centre of 112<br> -Oscillation, Electric 398<br> -Oscillation, Needle of 389<br> -Oscillation, Open Circuit 397<br> -Oscillatory 23<br> -Oscillatory Discharge 188<br> -Oscillatory Displacement 398<br> -Oscillatory Electro-motive Force 398<br> -Oscillatory Impedance 297<br> -Oscillatory Induction 398<br> -Osmose, Electric 398<br> -Outlet 399<br> -Output 399<br> -Output, Magnetic 399<br> -Output, Unit of 399<br> -Over-compounding 399<br> -Over, Flashing 258<br> -Overflow Alarm 18<br> -Over-house Telegraph 515<br> -Overload 399<br> -Overtype Dynamo or Motor 399<br> -Oxide of Copper Battery 68<br> -Ozone 399<br> -<br> -Pacinotti's Inductor 400<br> -Pacinotti's Ring 400<br> -Pacinotti Teeth 400<br> -Page Effect 401<br> -Page's Revolving Armature 47<br> -Paillard Alloys 400<br> -Palladium 401<br> -Pane, Fulminating 262<br> -Pane, Luminous 401<br> -Pantelegraphy 402, 510<br> -Paper Filaments 402<br> -Parabola 402<br> -Parabolic Reflector 402<br> -Paraffine 402<br> -Paraffine Wax 402<br> -Paragrêles 403<br> -Parallax 403<br> -Parallel 403<br> -Parallel Circuits 123-126<br> -Parallelogram of Forces 260<br> -Parallels, Magnetic 349<br> -Paramagnetic 403<br> -Paramagnetism 404<br> -Parasitical Currents 163<br> -Parchmentizing 404<br> -Partial Current 164<br> -Partial Earth 203, 404<br> -Partial Vacuum 557<br> -Passive State 404<br> -Path, Alternative 24<br> -P. D. 404<br> -Peltier's Cross 405<br> -Peltier Effect 404<br> -Pen, Electric 405<br> -Pendant Cord 405<br> -Pendulum Circuit Breaker 121<br> -Pendulum, Electric 405<br> -Pendulum or Swinging Annunciator 35<br> -Pentane Standard, Harcourt's 406<br> -Pentode Working 581<br> -Percussion, Centre of 112<br> -Perforated Armature 45<br> -Perforated Core Discs 154<br> -Perforator 407<br> -Period 407<br> -Period, Vibration 560<br> -Periodic 23<br> -Periodic Current, Power of 433<br> -Periodicity 262, 408<br> -Peripolar Zone 582<br> -Permanency 408<br> -Permanent Magnet 365<br> -Permanent Magnet Ammeter 28<br> -Permanent State 408<br> -Permeability 346-349<br> -Permeability-temperature Curve, 174<br> -Permeameter 408<br> -Permeance 408<br> -Peroxide of Lead Battery 69<br> -Perturbations, Magnetic 350<br> -Pflüger's Law 409<br> -Phantom Wires 409<br> -Phase 409<br> -Phase, Retardation of 471<br> -Phenomenon, Porret's 427<br> -Pherope 409, 527<br> -Philosopher's Egg 409<br> -Phonautograph, 409<br> -Phone 409<br> -Phonic Wheel 409<br> -Phonograph 410<br> -Phonophone or Rate Governor, Langdon Davies' 450<br> -Phonozenograph 410<br> -Phosphorescence 410<br> -Phosphorous, Electrical Reduction of 410<br> -Photo-electric Microscope 410<br> -Photo-electricity 410<br> -Photo-electro-motive Force 410<br> -Photometer 411<br> -Photometer, Actinic 411<br> -Photometer, Bar 411<br> -Photometer, Bunsen's 412<br> -Photometer, Calorimetric 412<br> -Photometer, Dispersion 412<br> -Photometer, Shadow 414<br> -Photometer, Translucent Disc 412<br> -Photophore 415<br> -Photo-voltaic Effect 415<br> -Physical Energy 241<br> -Physiology, Electro- 231<br> -Piano, Electric 415<br> -Pickle 415<br> -Picture, Electric 415<br> -Piece, Bed 78<br> -Piece, Magnetic Proof 350<br> -Piece, Pole 423<br> -Pierced Core-discs, 152<br> -Pile 415<br> -Pile, Differential Thermo-electric 533<br> -Pile, Muscular 388<br> -Pile or Battery, Thermo-electric 530<br> -Pilot Brush 91<br> -Pilot Lamp 323<br> -Pilot Transformer 415<br> -Pilot Wires 415<br> -Pistol, Electric 416<br> -Pith 416<br> -Pith Ball Electroscope 234<br> -Pith-balls 416<br> -Pivoted Armature 47<br> -Pivot Suspension 416<br> -Plane, Magnetic Proof 350<br> -Plant 417<br> -Plant Electricity 417<br> -Plant, Isolated 309<br> -Planté's Secondary Battery, 72<br> -Plate, Arrester 417<br> -Plate Condenser 417<br> -Plate, Earth 203<br> -Plate Electrical Machine 417<br> -Plate, Franklin's 262<br> -Plate, Generating 277<br> -Plate, Ground 417<br> -Plate, Negative 417<br> -Plate, Positive 277, 417<br> -Plating Balance 417<br> -Plating Bath 418<br> -Plating, Electro- 418<br> -Platinized Carbon Battery 69<br> -Platinoid 418<br> -Platinum 419<br> -Platinum Alloy 419<br> -Platinum Black 419<br> -Platinum Silver Alloy 419<br> -Platinum Sponge 419<br> -Play, End 238<br> -Plow 420<br> -Plücker Tubes 420<br> -Plug 420<br> -Plug Cut Out 175<br> -Plug, Double 191<br> -Plug, Grid 420<br> -Plug, Infinity 305, 420<br> -Plug Key 316<br> -Plug Switch 420<br> -Plumbago 421<br> -Plunge Battery 69<br> -Plunge 421<br> -Plunger and Coil 131<br> -Plunger and Coil, Differential 132<br> -Plunger, Coil and 131<br> -Plunger Electro-magnet 220<br> -Pneumatic Battery 69<br> -Pneumatic Signals, Electro- 231<br> -P.O. 421<br> -Pockets, Armature 47<br> -Poggendorf's Solution 421<br> -Point, Contact 147<br> -Point, Indifferent 421<br> -Point, Neutral 421<br> -Point. Nodal 422<br> -Point, Null 422<br> -Point of Commutator, Neutral 390<br> -Point Poles 422<br> -Points, Consequent 422<br> -Points, Corresponding 422<br> -Points, Iso-electric 422<br> -Points of Derivation 180, 423<br> -Point, Thermo-electric Neutral 390<br> -Polar Angle 423<br> -Polar Extension 423<br> -Polarity, Diamagnetic 181, 423<br> -Polarity, Resultant 470<br> -Polarization 423<br> -Polarization, Back Electro-motive force of 156<br> -Polarization Capacity 424<br> -Polarization, Dielectric 183<br> -Polarization, Galvanic 265<br> -Polarization, Magnetic Rotary 351<br> -Polarization of the Medium 424<br> -Polarized Armature 47<br> -Polarized Electro-magnet 220<br> -Polarized Relay 458<br> -Polarized Relay, Tongue of 542<br> -Polarizing Current 164<br> -Polar Region 424<br> -Polar Span 424<br> -Polar Span, Angle of 32, 423<br> -Polar Tips 423<br> -Polar Zone 582<br> -Pole, Analogous 31, 425<br> -Pole, Antilogous 425<br> -Pole, Armature 47<br> -Pole, Austral 54<br> -Pole, Boreal 85<br> -Pole Brackets, Telegraph 515<br> -Pole Changer 425<br> -Pole Changing Switch, 501<br> -Pole Dynamo, Interior 199<br> -Pole, Magnet 366<br> -Pole, Negative 425<br> -Pole, North 392<br> -Pole, North-seeking 393<br> -Pole or End, Marked 368<br> -Pole Piece 423<br> -Pole Pieces 425<br> -Pole, Positive 425<br> -Pole, Salient 426<br> -Pole, Terminal 529<br> -Pole Tips 290, 426<br> -Pole, Traveling 426<br> -Pole, Unit Magnet 366<br> -Poles 425<br> -Poles, Compensating 426<br> -Poles, Consequent 146<br> -Poles, Idle 296<br> -Poles, Magnetic 350<br> -Poles, Magnetic, False 350<br> -Poles of Intensity 426<br> -Poles of Verticity 426, 560<br> -Poles, Point 422<br> -Poles, Secondary 478<br> -Poles, Secondary Magnet 366<br> -Polyphase Currents 167<br> -Polyphote Lamp 323<br> -Popgun, Electric 282<br> -Porous Cell 427<br> -Porous Cup 159, 426<br> -Porret's Phenomenon 427<br> -Portative Power of Magnet 366<br> -Portelectric Railroad 427<br> -Portrait, Electric 415<br> -Position, Energy of 241<br> -Position Finder 427<br> -Position, Sighted 484<br> -Positive Current 164<br> -Positive Direction 428<br> -Positive Electricity 428<br> -Positive Element 277<br> -Positive Feeder 251<br> -Positive Plate 277, 417<br> -Positive Pole 425<br> -Positive Potential 432<br> -Positive Side of Circuit 125<br> -Post Office 428<br> -Posts, Binding, or Screws 81<br> -Potential 428<br> -Potential, Absolute 428<br> -Potential, Constant 429<br> -Potential Difference, Contact 147<br> -Potential Difference, Electric 429<br> -Potential Difference, Electro-motive 429<br> -Potential, Electric Absolute 429<br> -Potential, Fall of 430<br> -Potential Galvanometer 269<br> -Potential in Armature, Curve of Distribution of 172<br> -Potential, Magnetic 350, 431<br> -Potential, Negative 432<br> -Potential or Static Energy 241<br> -Potential, Positive 432<br> -Potential Regulation, Constant 455<br> -Potential, Unit of Electric 432<br> -Potential, Zero 432, 582<br> -Potentiometer 432<br> -Poundal 433<br> -Pound-foot 259<br> -Power 438<br> -Power, Candle 100<br> -Power, Directive 187<br> -Power, Electric 433<br> -Power, Horse 290<br> -Power, Illuminating 296<br> -Power, Multiplying 349<br> -Power of Magnet, Portative 366<br> -Power of Periodic Current 433<br> -Powers of Ten 527<br> -Power, Stray 495<br> -Power, Thermo-electric 533<br> -Press Button 94<br> -Pressel 434<br> -Pressure 434<br> -Pressure, Electric 434<br> -Pressure, Electrification by 434<br> -Primary 434<br> -Primary Ampere-turns 31, 551<br> -Primary Battery 69, 434<br> -Prime 434<br> -Prime Conductor 146, 434<br> -Prime Conductor, Coatings of a 129<br> -Prime Motor 385<br> -Principle, Gauss' 276<br> -Printing Telegraph 515<br> -Probe, Electric 435<br> -Projecting Power of a Magnet 435<br> -Prony Brake 435<br> -Proof Piece, Magnetic 350<br> -Proof-plane 436<br> -Proof Plane, Magnetic 350<br> -Proof-sphere 436<br> -Proportional Galvanometer 269<br> -Proportionate Arms 436<br> -Prostration, Electric 437<br> -Protector, Body 84<br> -Protector, Comb 437<br> -Protector, Electric 437<br> -Pull 437<br> -Pulsatory Current 164<br> -Pulsatory Field 256<br> -Pulsating Motor 386<br> -Pulvermacher's Electro-medical Battery 69<br> -Pump, Geissler 437<br> -Pump, Sprengel 439<br> -Pump, Swinburne 440<br> -Pumping 439<br> -Puncture-electro 232<br> -Puncture-galvano 232<br> -Push Button 93. 98, 440<br> -Push, Desk 180<br> -Push, Floor 258<br> -Pyro-electricity 441<br> -Pyromagnetic Generator 442<br> -Pyromagnetic Motor 441<br> -Pyromagnetism 443<br> -Pyrometer, Siemens' Electric 443<br> -<br> -Q 443<br> -Quad 288, 443<br> -Quadrant 288, 443<br> -Quadrantal Deviation 180<br> -Quadrant, Legal 444<br> -Quadrant, Standard 444<br> -Quadrature 444<br> -Quadruplex Telegraph 515<br> -Qualitative 444<br> -Quality of Sound 444<br> -Quantitative 444<br> -Quantity 444<br> -Quantity Armature 47<br> -Quantity, Electric 444<br> -Quantity, Electro-magnetic 445<br> -Quantity, Electro-magnetic, Practical Unit of 445<br> -Quantity, Electrostatic 445<br> -Quantity Galvanometer 269<br> -Quantity, Magnetic 350<br> -Quantity Meter 445<br> -Quartz 445<br> -Quicking 446<br> -<br> -R 446<br> -Racing of Motors 446<br> -Radial Armature 47<br> -Radian 446<br> -Radiant Energy 446<br> -Radiant Matter 368<br> -Radiation 446<br> -Radicals 446<br> -Radiometer 447<br> -Radiometer, Electric 447<br> -Radio-micrometer 447<br> -Radiophony 447<br> -Railroad, Portelectric 427<br> -Range Finder 447<br> -Rate Governor 449<br> -Rate Governor or Phonophone, Langdon Davies' 450<br> -Rated Candle Power 101<br> -Ratio Arms 437<br> -Ratio, Core 154<br> -Ratio, Shunt 483<br> -Ratio, Velocity 560<br> -Ray, Electric 450<br> -Rayleigh Ohm 396<br> -Reaction Coil 132<br> -Reaction of a Dynamo Field and Armature 450<br> -Reaction of Degeneration 179<br> -Reactions, Anodic 36<br> -Reactions, Armature 47<br> -Reaction Telephone 527<br> -Reaction Wheel 259<br> -Reading Galvanometer, Direct 269<br> -Reading, Sound 489<br> -Reading Telescope 450<br> -Real Efficiency of Secondary Battery 205<br> -Real Hall Effect 284<br> -Réaumur Scale 450<br> -Recalescence 451<br> -Receiver 451<br> -Receiver, Harmonic 284, 451<br> -Receiver, Morse 381<br> -Receptive, Electro- 232<br> -Recharge 115<br> -Reciprocal 451<br> -Reciprocating Motor 385<br> -Recoil Circuit 125<br> -Recorder, Chemical 117<br> -Recorder, Morse 451<br> -Recorder, Siphon 452<br> -Record, Telephone 451<br> -Rectification of Alcohol, Electric 18<br> -Rectified Current 164<br> -Rectilinear Current 165<br> -Red Varnish 559<br> -Red Magnetism 357<br> -Redressed Current 165<br> -Reduced Resistance 467<br> -Reducteur for Ammeter 453<br> -Reducteur for Voltmeter 453<br> -Reduction of Ores, Electric 453<br> -Reduction of Phosphorous, Electrical 410<br> -Reflecting Galvanometer 270<br> -Reflector, Parabolic 402<br> -Refraction, Electric Double 454<br> -Refraction, Electrostatic 235<br> -Refreshing Action 454<br> -Region, Extra-polar 454<br> -Region, Intrapolar 307<br> -Region, Polar 424<br> -Register, Electric 454<br> -Register, Telegraphic 454<br> -Regulation, Constant Current 454<br> -Regulation, Constant Potential 455<br> -Regulation of Alternating Current Dynamo 195<br> -Regulation of Dynamos 455<br> -Reguline 456<br> -Relative 456<br> -Relative Calibration 98<br> -Relay 456<br> -Relay Bell 80<br> -Relay Bells 457<br> -Relay, Box Sounding 457<br> -Relay Connection 457<br> -Relay, Differential 457<br> -Relay Magnet 457<br> -Relay, Microphone 377, 457<br> -Relay, Neutral, Armature 390<br> -Relay, Polarized 457<br> -Reluctance 458<br> -Reluctance, Magnetic 351, 458<br> -Reluctance, Unit of 438<br> -Reluctivity 459<br> -Reluctivity, Magnetic 351<br> -Remanence 459<br> -Remanence, Magnetic 358<br> -Removal of Hair by Electrolysis 283<br> -Renovate 115<br> -Repeater 459<br> -Repeater, Telegraph 518<br> -Replenisher, Sir Wm. Thomson's 459<br> -Repulsion, Magnetic 338<br> -Repulsion and Attraction, Electrostatic 234<br> -Repulsion and Attraction, Electro-magnetic 217<br> -Reservoir, Common 460<br> -Residual Atmosphere 460<br> -Residual Capacity 103<br> -Residual Charge 116<br> -Residual Magnetism 358<br> -Residue, Electric 116, 460<br> -Resin 460<br> -Resinous Electricity 461<br> -Resistance 461<br> -Resistance, Apparent 297, 462<br> -Resistance, Assymmetrical 462<br> -Resistance Box 462<br> -Resistance, B. A. Unit of 462<br> -Resistance Box, Sliding 463<br> -Resistance, Breguet Unit of 463<br> -Resistance Bridge 577<br> -Resistance Coil 137<br> -Resistance Coil, Standard 464<br> -Resistance, Carbon 463<br> -Resistance, Combined 464<br> -Resistance, Compensating 144<br> -Resistance, Critical 464<br> -Resistance, Dielectric 183, 464<br> -Resistance, Digney Unit of 464<br> -Resistance, Electrolytic 464<br> -Resistance, English Absolute or Foot-second Unit of 465<br> -Resistance, Equivalent 465<br> -Resistance, Essential 465<br> -Resistance, External 465<br> -Resistance Frame 465<br> -Resistance, German Mile Unit of 466<br> -Resistance, Hittorf's 466<br> -Resistance, Inductive 466<br> -Resistance, Insulation 466<br> -Resistance, Internal 466<br> -Resistance, Jacobi's Unit of 466<br> -Resistance, Joint 464<br> -Resistance, Magnetic 351, 458<br> -Resistance, Matthiessen's Meter-gram Standard of 466<br> -Resistance, Matthiessen's Unit of 466<br> -Resistance, Meter-millimeter Unit of 466<br> -Resistance, Mil-foot Unit of 467<br> -Resistance, Non-essential 465, 467<br> -Resistance, Non-inductive 467<br> -Resistance of Human Body 467<br> -Resistance, Ohmic 394, 467<br> -Resistance, Reduced 467<br> -Resistance, Siemens' Unit of 467<br> -Resistance, Specific 467<br> -Resistance. Specific Conduction 467<br> -Resistance, Spurious 467<br> -Resistance, Steadying 468<br> -Resistance, Swiss Unit of 468<br> -Resistance, Thomson's Unit of 468<br> -Resistance to Sparking 490<br> -Resistance, True 467<br> -Resistance, Unit 468<br> -Resistance, Unit of, B. A. 78<br> -Resistance, Varley's 559<br> -Resistance, Varley's Unit of 468<br> -Resistance, Virtual 297<br> -Resistance, Weber's Absolute Unit 468<br> -Resolution of Forces 261<br> -Resonator, Electric 468-470<br> -Rest, Currents of 167<br> -Resultant 470<br> -Resultant Polarity 470<br> -Retardation 470<br> -Retardation of Phase 471<br> -Retentivity 471<br> -Retentivity, Magnetic 351<br> -Retort Carbon 471<br> -Return 471<br> -Return Circuit 125<br> -Return, Earth 203<br> -Return Stroke 55<br> -Reversal, Thermo-Electric 533<br> -Reverse Current Working 581<br> -Reverse-induced Current 163<br> -Reverser, Current 165<br> -Reversibility 471<br> -Reversible Bridge 472<br> -Reversing Key 316<br> -Reversing Switch 501<br> -Revivify 115<br> -Revolving Armature, Page's 47<br> -Rheochord 472<br> -Rheometer 472<br> -Rheomotor 472<br> -Rheophore 472<br> -Rheoscope 472<br> -Rheoscopic Frog 262<br> -Rheostat 472<br> -Rheostat Arm 472<br> -Rheostatic Machine 472<br> -Rheostat, Wheatstone's 472<br> -Rheotome 473<br> -Rheotrope 473<br> -Rhigolene 473<br> -Rhumbs 473<br> -Rhumkorff Coil 138, 473<br> -Ribbon Coil 138<br> -Ribbon Core 154<br> -Right-handed Screw Law 324<br> -Rigidity, Molecular 380, 473<br> -Ring, Ampere 30<br> -Ring Armature 48<br> -Ring. Collecting 139<br> -Ring Contact 473<br> -Ring Core 155<br> -Ring, Dynamo 200<br> -Ring, Faraday's 473<br> -Ring, Foundation 261<br> -Ring, Guard 282<br> -Ring, Pacinotti's 400<br> -Rings, Electric 392<br> -Rings, Nobili's 392<br> -Ring, Split, Commutator 141<br> -Roaring 474<br> -Rocker 474<br> -Rocker Arms 50, 474<br> -Rod, Bus 94<br> -Rod, Discharging 189<br> -Rod, Omnibus 94<br> -Roget's Spiral 474<br> -Rolling Armature 49<br> -Rosin 460<br> -Rotary Polarization, Magnetic 351<br> -Rotating Brush 91<br> -Rotating Field 256<br> -Rotation of Liquids, Electro-dynamic 474<br> -Rotation of Liquids, Electro-magnetic 475<br> -Rotatory Currents 167<br> -Rubber 102, 475<br> -Rubber, India 102<br> -<br> -Saddle Bracket 475<br> -Safety Catch 175<br> -Safety Cut Out 175<br> -Safety Device 475<br> -Safety Fuse 175, 475<br> -Safety Fuse, Plug, or Strip 475<br> -Sal Ammoniac Battery 69<br> -Salient Pole 426<br> -Salt 475<br> -Salt, Dronier's 192<br> -Salt or Sea-salt Battery 69<br> -Sand Battery 90<br> -Saturated 476<br> -Saturation, Magnetic 351<br> -Saw, Electric 476<br> -Scale, Fahrenheit 248<br> -Scale, Réaumur 450<br> -Scale, Tangent 502<br> -Schweigger's Multiplier 476<br> -Scratch Brushes 476<br> -Screen, Electric 476<br> -Screen, Magnetic 351<br> -Screen, Methven 376<br> -Screws or Posts, Binding 81<br> -Sealed, Hermetically 289<br> -Sea Salt or Salt Battery 69<br> -Secohm 288<br> -Second, Ampere- 30<br> -Secondary Actions 477<br> -Secondary Ampere-turns 31, 551<br> -Secondary Battery 70<br> -Secondary Battery, Efficiency of, Quantity 205<br> -Secondary Battery, Planté's 72<br> -Secondary Clock 127<br> -Secondary Current 166<br> -Secondary Generator 277, 477<br> -Secondary Magnet Poles 366<br> -Secondary, Movable 477<br> -Secondary Plates, Colors of 478<br> -Secondary Poles 478<br> -Secretion Current 166<br> -Section Trolley 549<br> -Sectioned Coils 138<br> -Seebeck Effect 478<br> -Segments 56<br> -Segments, Commutator 56<br> -Selenium 478<br> -Selenium Cell 478<br> -Selenium Eye 478<br> -Self-exciting Dynamo 201<br> -Self-induction 303<br> -Self-induction, Magnetic 352<br> -Self-induction, Unit of 304<br> -Self-repulsion 478<br> -Self-winding Electric Clock 128<br> -Semi-circular Deviation 181<br> -Semi-conductors 478<br> -Semi-incandescent Lamp 323<br> -Sender, Zinc 582<br> -Sensibility 479<br> -Sensitiveness, Angle of Maximum 479<br> -Separate Circuit Dynamo 201<br> -Separate Touch 359, 479<br> -Separate Touch, Magnetization by 359<br> -Separately Excited Dynamo 201, 479<br> -Separation of Electricities 479<br> -Separator 479<br> -Separator, Magnetic 352<br> -Series 479<br> -Series and Long Shunt Winding 579<br> -Series and Separate Coil Winding 579<br> -Series and Short Shunt Winding 580<br> -Series, Contact 147<br> -Series Dynamo 201<br> -Series, Electro-chemical 209<br> -Series, Electro motive 228<br> -Series, Electrostatic 235<br> -Series Motor 386<br> -Series, Multiple- 387<br> -Series-multiple 480<br> -Series, Thermo-electric 534<br> -Series Transformer 548<br> -Series Winding 579<br> -Service Conductors 480<br> -Serving 480<br> -Shackle 480<br> -Shadow, Electric 480<br> -Shadow, Molecular 480<br> -Shadow Photometer 414<br> -Sheath for Magnet Coils 481<br> -Sheath for Transformers 481<br> -Sheath, Induction 303<br> -Sheet Current 166<br> -Shell, Magnetic 352<br> -Shell, Strength of Magnetic 352<br> -Shellac 481<br> -Shellac Varnish 481<br> -Shield, Anti-magnetic 37<br> -Shield, Magnetic 351, 353<br> -Shielded 481<br> -S. H. M. 482<br> -Shock, Back, or Stroke of Lightning 55<br> -Shock, Break 482<br> -Shock, Electric 482<br> -Shock, Opening 482<br> -Shock, Static 482<br> -Short Circuit 482<br> -Short Circuit Working 482<br> -Short Fall Air Pumps 16<br> -Short Shunt Winding 579<br> -Shovel Electrodes 483<br> -Shower Bath, Electric 57<br> -Shunt 483<br> -Shunt Box 483<br> -Shunt Circuit 123, 126<br> -Shunt Dynamo 202<br> -Shunt, Electro-magnetic 483<br> -Shunt, Galvanometer 271, 483<br> -Shunt, Magnetic 353<br> -Shunt Motor 386<br> -Shunt. Multiplying Power of a 388<br> -Shunt Ratio 483<br> -Shunt Winding 580<br> -Shuttle Armature 49<br> -Shuttle Current 483<br> -Shuttle Winding 483, 580<br> -Side Flash 484<br> -Siemens and Halske's Battery 72<br> -Siemens' Differential Voltameter 564<br> -Siemens' Electro-dynamometer 212<br> -Siemens' Old Armature 49<br> -Siemens' Unit of Resistance 467<br> -Sighted Position 484<br> -Signaling, Velocity of 560<br> -Signals, Electro-pneumatic 231<br> -Signal, Telegraph 519<br> -Silent Discharge 187, 189, 206<br> -Silver 484<br> -Silver Bath 484<br> -Silver, German 277<br> -Silver Stripping Bath 484<br> -Silver Voltameter 565<br> -Simple Arc 39<br> -Simple Circuit 126<br> -Simple Harmonic Motion 486<br> -Simple Immersion 185<br> -Simple Magnet 366<br> -Simple Substitution 485<br> -Sims-Edison Torpedo 543<br> -Sine Curve 174, 485<br> -Sine Galvanometer 271<br> -Sine Law 486<br> -Sines, Curve of 173, 485<br> -Single Coil Dynamo 202<br> -Single Curb Working 581<br> -Single Fluid Theory 486<br> -Single Fluid Voltaic Cell 486<br> -Single Needle Telegraph 519<br> -Single Touch, Magnetization by 359<br> -Sinistrotorsal 486<br> -Sinuous Current 166<br> -Sinusoidal Curve 174, 485<br> -Siphon Recorder 452<br> -Sir William Thomson's Battery 72<br> -Skin Effect 486<br> -Skrivanow Battery 72<br> -Sled 486<br> -Sleeve, Joint 310<br> -Slide, Balance 374<br> -Slide Bridge 374<br> -Slide Meter Bridge 486<br> -Sliding Condenser 144<br> -Sliding-contact Key 316<br> -Sliding Resistance Box 463<br> -Slope, Lines of 330<br> -Smee's Battery 73<br> -S. N. Code 486<br> -Snap Switch 501<br> -Soaking-in-and-out 486<br> -Socket, Lamp 323<br> -Socket, Wall 572<br> -Soldering, Electric 487<br> -Solenoid 487<br> -Solenoid Ammeter 28<br> -Solenoidal Distribution of Magnetism 358<br> -Solenoidal Magnet 366<br> -Solid Earth 203<br> -Solutions, Battery, Chromic Acid 73<br> -Solution, Chutaux's 119<br> -Solution, Delaurier's 179<br> -Solution, Hittorf's 289<br> -Solution, Kookogey's 318<br> -Solution, Poggendorf's 421<br> -Solution, Striking 496<br> -Solution, Tissandier's 542<br> -Solution, Trouvé's 549<br> -Sonometer, Hughes' 488<br> -Sonorescence 488<br> -Sound, Characteristics of 114<br> -Sounder 488<br> -Sounders, Tin 542<br> -Sound, Quality of 444<br> -Sound Reading 489<br> -South Magnetic Fluid 356<br> -Space, Clearance 489<br> -Space, Crookes' Dark 489<br> -Space, Dark, Faraday's 249, 489<br> -Space, Faraday's Dark 249, 489<br> -Space, Inter-air 489<br> -Space, Interferric 489<br> -Span, Polar 424<br> -Span, Polar, Angle of the 32<br> -Spark Arrester 489<br> -Spark Coil 489<br> -Spark Discharge 189<br> -Spark, Duration of Electric 490<br> -Spark Gap 490<br> -Spark, Length of 490<br> -Spark Micrometer 470<br> -Spark Tube 491<br> -Sparking 490<br> -Sparking Distance 190<br> -Sparking, Lines or Points of Least 490<br> -Sparking, Resistance to 490<br> -Specific Conduction Resistance 467<br> -Specific Conductivity 145<br> -Specific Heat 286<br> -Specific Heat of Electricity 491<br> -Specific Inductive Capacity 103<br> -Specific Magnetization 361<br> -Specific Resistance 467<br> -Speech, Articulate 50<br> -Speed, Critical 157<br> -Spent Acid 491<br> -Spent Liquor 491<br> -Spherical Armature 49<br> -Spherical Candle Power 101<br> -Spherical Illuminating Power 296<br> -Sphygmophone 491<br> -Sphygmophone, Electric 491<br> -Spiders 491<br> -Spiral 492<br> -Spiral Battery 73<br> -Spiral, Roget's 474<br> -Spiral Winding 492<br> -Spirit Compass 143<br> -Splayed Joint 311<br> -Splice Box 492<br> -Split Battery 73<br> -Split Ring Commutator 141<br> -Spluttering 492<br> -Sponge, Platinum 419<br> -Spot, Grease 92<br> -Sprengel Pump 439<br> -Spring Ammeter 28<br> -Spring and Fibre Suspension 252<br> -Spring-contact 148<br> -Spring Control 492<br> -Spring Jack Cut-out 493<br> -Spurious Hall Effect 284<br> -Spurious Resistance 467<br> -Spurious Voltage 493<br> -Square Mil 379<br> -Square Wire 493<br> -Squares, Law of Inverse 323<br> -St. Elmo's Fire 494<br> -Staggering 493<br> -Standard Candle 101<br> -Standard Candle, German 99<br> -Standard, Harcourt's Pentane 406<br> -Standard, Methven 376<br> -Standard of Illuminating Power, Viole's 561<br> -Standard or Main Feeder 251<br> -Standard Quadrant 444<br> -Standard Resistance Coil 464<br> -Standard Voltaic Cell 109<br> -Standard Voltaic Cell, Daniell's 109<br> -Standard Voltaic Cell, Latimer Clark's. 110<br> -State, Electrotonic 493<br> -State, Nascent 389<br> -State of Matter, Fourth 261<br> -State, Passive 404<br> -State, Permanent 408<br> -Static Breeze 493<br> -Static Condenser, Armature of 46<br> -Static Electricity 493<br> -Static Hysteresis 295<br> -Static Induction, Magnetic 347<br> -Static Shock 482<br> -Station, Central 493<br> -Station, Distant 493<br> -Station, Home 493<br> -Station, Transforming 494<br> -Steadying Resistance 468<br> -Steel 494<br> -Steeling 494<br> -Steel Yard Ammeter 28<br> -Step-by-step Telegraph 506<br> -Step-by-step Telegraphy 494<br> -Step-down 494<br> -Step, Foot- 259<br> -Sticking 494<br> -Stool, Insulating 305<br> -Stopped Coil Electro-magnets 221<br> -Stopping Off 495<br> -Storage Battery 70<br> -Storage Battery Changing Switch 501<br> -Storage Battery, Planté's 72<br> -Storage Capacity 105, 495<br> -Storage of Electricity 495<br> -Storms, Electric 495<br> -Storms. Magnetic 353<br> -Strain 495<br> -Strain, Dielectric 183<br> -Strain, Magnetic 354<br> -Stranded Conductor Armature 49<br> -Stranded Core 155<br> -Stray Field 256, 495<br> -Stray Power 495<br> -Streamlets. Current 495<br> -Strength, Dielectric 183<br> -Strength of Magnetic Shell 352<br> -Stress 495<br> -Stress, Dielectric 496<br> -Stress, Electro-magnetic 219, 496<br> -Stress, Electrostatic 236, 496<br> -Stress, Energy of 241<br> -Stress, Magnetic 354<br> -Striae, Electric 496<br> -Striking Distance 496<br> -Striking Solution 496<br> -Stripping 496<br> -Stripping Bath 57<br> -Stripping Bath, Gold 279<br> -Stripping Bath, Silver 484<br> -Stroke, Back 55<br> -Stroke or Shock of Lightning, Back 55<br> -Stroke, Return 55<br> -Sub-branch 496<br> -Sub-main 496<br> -Sub-permanent Magnetism 358<br> -Substitution, Simple 485<br> -Subway, Electric 496<br> -Successive Temperatures, Law of 324<br> -Sucking Coil 182<br> -Sucking Magnet 366<br> -Sulphate of Lead Battery 66<br> -Sulphate of Mercury Battery 67<br> -Sulphating 497<br> -Sulphur Dioxide 497<br> -Sulphuric Acid 497<br> -Sulphuric Acid Voltameter 564<br> -Sulphurous Acid Gas 497<br> -Sunstroke, Electric 497<br> -Superficial Density, Electric 180<br> -Supersaturated, 497<br> -Supply, Isolated 309<br> -Surface 497<br> -Surface Density 498<br> -Surface, Equipotential 498<br> -Surface Leakage 498<br> -Surface Magnetization 356<br> -Surgical Electro-magnet 222<br> -Surging Discharge 188<br> -Surveyors' Compass 143<br> -Susceptibility, Magnetic 354, 359<br> -Suspension 498<br> -Suspension, Bifilar 498<br> -Suspension, Fibre 252<br> -Suspension, Knife Edge 317<br> -Suspension, Pivot 416<br> -Suspension, Spring and Fibre 252<br> -Suspension, Torsion 545<br> -Suspension Wire of Cable 97<br> -Swaging. Electric 499<br> -Swelling Current 167<br> -S. W. G. 499<br> -Swinburne Pump 440<br> -Swinging Earth 203<br> -Swinging or Pendulum Annunciator 35<br> -Swiss Unit of Resistance 468<br> -Switch 499<br> -Switch, Automatic 500<br> -Switch Board 500<br> -Switch Board, Multiple 387<br> -Switch Board, Trunking 550<br> -Switch, Break-down 88<br> -Switch, Changing 500<br> -Switch, Changing Over 500<br> -Switch, Circuit Changing 500<br> -Switch, Double Break 500<br> -Switch, Double Pole 500<br> -Switch Feeder 500<br> -Switch, Knife 501<br> -Switch, Knife Break 501<br> -Switch, Knife Edge 501<br> -Switch, Multiple 501<br> -Switch, Plug 420<br> -Switch, Pole Changing 501<br> -Switch, Reversing 501<br> -Switch, Snap 501<br> -Switch, Storage Battery Changing 501<br> -Switch, Three Way 501<br> -Switches, Distributing 190<br> -Symmer's Theory 191<br> -Sympathetic Vibration 501, 561<br> -System, Block 83<br> -System of Co-ordinates 150<br> -System, Tower 545<br> -<br> -T 501<br> -Tailing Current 501<br> -Tailings 501<br> -Talk, Cross 158<br> -Tamidine 502<br> -Tangent Galvanometer 272<br> -Tangent Law 502<br> -Tangent Positions of, Gauss 276<br> -Tangent Scale 502<br> -Tangentially Laminated Core 155<br> -Tank, Cable 97<br> -Tape, Insulating 305<br> -Tapper Key, Double 314<br> -Teazer 504<br> -Technica, Memoria, Ampére's 30<br> -Tee, Lead 504<br> -Teeth, Pacinotti 400<br> -Tel-autograph 504<br> -Tele-barometer, Electric 504<br> -Telegraph, A. B. C. 504<br> -Telegraph, Autographic 510<br> -Telegraph, Automatic 504<br> -Telegraph, Dial 505<br> -Telegraph, Double Needle 506<br> -Telegraph, Duplex 506<br> -Telegraph, Duplex, Bridge 506<br> -Telegraph, Duplex, Differential 507<br> -Telegraph Embosser 237<br> -Telegraph, Facsimile 510<br> -Telegraph, Harmonic Multiplex 510<br> -Telegraph. Hughes' 511<br> -Telegraph Insulator 306<br> -Telegraph Key 316<br> -Telegraph, Magneto-electric 512<br> -Telegraph, Morse 512<br> -Telegraph, Multiplex 514<br> -Telegraph, Single Needle 519<br> -Telegraph, Overhouse 515<br> -Telegraph Pole Brackets 515<br> -Telegraph, Printing 515<br> -Telegraph, Quadruplex 515<br> -Telegraph Repeater 518<br> -Telegraph Signal 519<br> -Telegraph, Step-by-step 506<br> -Telegraph, Wheatstone's, A. B. C. 521<br> -Telegraph. Writing 521<br> -Telegraphic Alphabet 19<br> -Telegraphic Code 130, 511<br> -Telegraphic Needle 389<br> -Telegraphic Register 454<br> -Telegraphy, Multiplex 388<br> -Telegraphy, Step-by-step 494<br> -Telemanometer, Electric 521<br> -Telemeter, Electric 521<br> -Telepherage 522<br> -Telephone 522<br> -Telephone, Bi- 524<br> -Telephone, Capillary 525<br> -Telephone, Carbon 525<br> -Telephone, Chemical 526<br> -Telephone, Electrostatic 526<br> -Telephone Exchange 246<br> -Telephone Induction Coil 137, 526<br> -Telephone, Reaction 527<br> -Telephone Record 451<br> -Telephone, Thermo-electric 527<br> -Telephone Tinnitus 542<br> -Telephotography 521<br> -Telephote 527<br> -Telescope, Reading 450<br> -Teleseme 527<br> -Tele-thermometer 527<br> -Terminal 529<br> -Terminal Pole 529<br> -Terminal Voltage 562<br> -Temperature, Absolute 8<br> -Temperature, Neutral 390<br> -Temperatures, Laws of Successive 324<br> -Tempering, Electric 527<br> -Temporary Magnetism or Magnetization 357<br> -Ten, Powers of 527<br> -Tension 529<br> -Tension, Disruptive 189<br> -Tension, Electric 529<br> -Terrestrial Magnetism 358<br> -Tetanus, Acoustic 529<br> -Tetrode Working 581<br> -Theatrophone 529<br> -Theory, Contact 148<br> -Theory, Double Fluid 191<br> -Theory, Franklin's 262<br> -Theory of Dimensions 184<br> -Theory of Light, Electro-magnetic 219<br> -Theory of Light, Maxwell's 369<br> -Theory of Magnetism, Ampére's 354<br> -Theory of Magnetism, Ewing's 356<br> -Theory of Magnetism, Hughes' 357<br> -Theory of Magnetism, Weber's 358<br> -Theory, Symmer's 191<br> -Therapeutic Electrode 210<br> -Therapeutics, Electro- 236<br> -Therm 529<br> -Thermaesthesiometer 530<br> -Thermal Electric Meter 375<br> -Thermal Equivalent, Electro- 245<br> -Thermal Energy 242<br> -Thermic Balance 85<br> -Thermo Call 530<br> -Thermo-chemical Battery 530<br> -Thermo-chemical Equivalent 245<br> -Thermo-electric Battery or Pile 530<br> -Thermo-electric Call 531<br> -Thermo-electric Couple 532<br> -Thermo-electric Current 167<br> -Thermo-electric Diagram 532<br> -Thermo-electric Element 237<br> -Thermo-electric Inversion 533<br> -Thermo-electric Junction 533<br> -Thermo-electric Neutral Point 390<br> -Thermo-electric Pile, Differential 533<br> -Thermo-electric Power 533<br> -Thermo-electric Reversal 533<br> -Thermo-electric Series 534<br> -Thermo-electric Telephone 527<br> -Thermo-electric Thermometer 535<br> -Thermo-electricity 533<br> -Thermo-electricity, Laws of, Becquerel's 78<br> -Thermo-electricity, Volta's Law of 568<br> -Thermo-electrometer 536<br> -Thermolysis 535<br> -Thermo-multiplier 536<br> -Thermometer 535<br> -Thermometer, Electric 535<br> -Thermometer, Kinnersley's 536<br> -Thermometer, Tele- 527<br> -Thermometer, Thermo-electric 535<br> -Thermophone 537<br> -Thermostat, Electric 537<br> -Third Brush 91<br> -Thomson Effect 538<br> -Thomson's Replenisher, Sir William 459<br> -Thomson's Battery, Sir William 72<br> -Thomson's Unit of Resistance 468<br> -Three Filament Incandescent Lamp 322<br> -Three Way Switch 501<br> -Three Wire System 539<br> -Throw 237, 540<br> -Throw-back Indicator 540<br> -Thrust Bearings 540<br> -Thunder 540<br> -Ticker 540<br> -Tick, Magnetic 354<br> -Timbre 444<br> -Time Constant 541<br> -Time Cut-outs 541<br> -Time Electric Meter 375<br> -Time-fall 541<br> -Time-reaction 541<br> -Time-rise 541<br> -Tin 541<br> -Tin Sounders 542<br> -Tinnitus, Telephone 542<br> -Tips, Polar 423<br> -Tips, Pole 290, 426<br> -Tissandier's Solution 542<br> -Toeppler-Holtz Machine 334<br> -Tongs, Cable Hanger 97<br> -Tongs, Discharging 189<br> -Tongue of Polarized Relay 542<br> -Tongue of Polarized Relay, Bias of 542<br> -Toothed Core-discs 154<br> -Top, Magnetic 542<br> -Torpedo, Electric 543<br> -Torpedo, Sims-Edison 543<br> -Torque 543<br> -Torque, Curve of 174<br> -Torricellian Vacuum 557<br> -Torsion Balance, Coulomb's 544<br> -Torsion Galvanometer 273, 544<br> -Torsion Head 544<br> -Torsion Suspension 545<br> -Total Earth 203<br> -Touch 545<br> -Touch, Separate 479<br> -Tourmaline 545<br> -Tower, Electric 545<br> -Tower System 545<br> -Trailing Horns 259<br> -Transformer 545<br> -Transformer, Commuting 547<br> -Transformer, Continuous Alternating 547<br> -Transformer, Continuous Current 384, 547<br> -Transformer, Core 547<br> -Transformer, Faraday's 250<br> -Transformer, Hedgehog 548<br> -Transformer, Multiple 548<br> -Transformer, Oil 548<br> -Transformer, Pilot 415<br> -Transformer, Series 548<br> -Transformer. Sheath for 481<br> -Transforming Station 494<br> -Transformer, Welding 548, 575<br> -Translator 519<br> -Translucent Disc Photometer 412<br> -Transmitter 548<br> -Transmitter, Carbon 549<br> -Transmission of Energy, Electric 240<br> -Transposing 549<br> -Transverse Electro-motive Force 549<br> -Trap, Bug 92<br> -Traveling Pole 426<br> -Trembling Bell 78<br> -Trolley 549<br> -Trolley, Double 549<br> -Trolley Section 549<br> -Trough Battery 73<br> -Trouvé's Blotting Paper Battery 73<br> -Trouvé's Solution 549<br> -True Contact Force 549<br> -True Ohm 396<br> -True Resistance 467<br> -Trimmer, Brush 549<br> -Trumpet, Electric 550<br> -Trunk Lines 550<br> -Trunking Switch Board 550<br> -Tube, Electric 550<br> -Tube, Guard 282<br> -Tube, Luminous 550<br> -Tube of Magnetic Induction 347<br> -Tube, Spark 491<br> -Tube, Stratification 495<br> -Tubes, Geissler 276<br> -Tubes of Force 261<br> -Tubes, Plücker 420<br> -Tubular Braid 550<br> -Tubular Core 155<br> -Tubular Magnet 356<br> -Tuning Fork Circuit Breaker 121<br> -Tuning Fork Dynamo 202<br> -Tuning Fork, Interrupter for 307<br> -Turning Moment 544<br> -Turns 550<br> -Turns, Ampere- 31<br> -Turns, Dead, of a Dynamo 551<br> -Turns, Primary Ampere- 551<br> -Turns, Secondary Ampere- 551<br> -Twist Joint, American 309<br> -Twist, Magnetic 354<br> -Tyer's Battery 74<br> -Typewriter, Electric 551<br> -Type Printer, Hughes' 511<br> -<br> -Ultra-gaseous Matter 551<br> -Unbuilding 552<br> -Underground Conductor 552<br> -Underground Electric Subway 552<br> -Undulatory 23<br> -Undulatory Current 167<br> -Unidirectional 553<br> -Uniform Field 256<br> -Uniform Field of Force 553<br> -Uniform Magnetic Field 345<br> -Unipolar 553<br> -Unipolar Armature 50, 553<br> -Unipolar Current Induction 553<br> -Unipolar Dynamo 202-553<br> -Unipolar Electric Bath 57<br> -Unipolar Induction 304<br> -Unipolar Magnet 366<br> -Unit 553<br> -Unit, Absolute 554<br> -Unit Angle 554<br> -Unit. B. A. 554<br> -Unit, B. A., of Resistance 462<br> -Unit Current 167<br> -Unit Electro-motive Force 228<br> -Unit, Fundamental 554<br> -Unit Jar 554<br> -Unit Magnet Pole 366<br> -Unit of Capacity 105<br> -Unit of Conductivity 145<br> -Unit of Electric Potential 432<br> -Unit of Energy, Electro-magnetic 220<br> -Unit of Force 261<br> -Unit of Illumination 296<br> -Unit of Output 399<br> -Unit of Reluctance 458<br> -Unit of Resistance, B. A. 78<br> -Unit of Resistance, Breguet 463<br> -Unit of Resistance, Digney 464<br> -U nit of Resistance, English Absolute or Foot-second 465<br> -Unit of Resistance, German Mile 466<br> -Unit of Resistance, Jacobi's 466<br> -Unit of Resistance, Meter-millimeter. 466<br> -Unit of Resistance, Mil-foot 467<br> -Unit of Resistance, Siemens' 467<br> -Unit of Resistance, Swiss 468<br> -Unit of Resistance, Thomson's 468<br> -Unit of Resistance, Varley's 468<br> -Unit of Self-induction 304<br> -Unit of Supply 554<br> -Unit of Work 581<br> -Unit Resistance 468<br> -Units, Circular 126, 555<br> -Units, Derived 555<br> -Units, Heat 288<br> -Units, Practical 555<br> -Universal Battery System 556<br> -Universal Discharger 189<br> -Unmarked End 556<br> -Upright Galvanometer 274<br> -Upward's Battery 75<br> -<br> -V 556<br> -V. A. 557<br> -Vacuum 557<br> -Vacuum, Absolute 557<br> -Vacuum, High 557<br> -Vacuum Lightning Arrester 329<br> -Vacuum, Low 557<br> -Vacuum, Partial 557<br> -Vacuum, Torricellian 557<br> -Valency 557<br> -Valve, Electrically Controlled 558<br> -Vapor Globe 558<br> -Variable Conductivity 145<br> -Variable Period 558<br> -Variable State 558<br> -Variation of the Compass 32, 558<br> -Variations, Magnetic 354<br> -Variometer 559<br> -Varley's Battery 76<br> -Varley's Condenser 559<br> -Varley's Resistance 559<br> -Varley's Unit of Resistance 468<br> -Varnish 559<br> -Varnish, Electric 559<br> -Varnish, Insulating 306<br> -Varnish, Red 559<br> -Varnish, Shellac 481<br> -Vat 559<br> -Velocity 559<br> -Velocity, Angular 32, 559<br> -Velocity of Signaling 560<br> -Velocity Ratio 560<br> -Ventilation of Armature 560<br> -Vertical Galvanometer 274<br> -Vertical Induction 304<br> -Verticity, Poles of 426, 560<br> -Vibrating Bell 78<br> -Vibration Period 560<br> -Vibration, Sympathetic 501, 561<br> -Vibrator, Electro-magnetic 561<br> -Villari's Critical Value 561<br> -Viole 562<br> -Viole's Standard of Illuminating Power 561<br> -Virtual Resistance 297<br> -Viscous Hysteresis 295, 356<br> -Vis Viva 562<br> -Vitreous Electricity 562<br> -Vitriol, Blue 562<br> -Vitriol, Green 562<br> -Vitriol, White 562<br> -Volatilization of Carbon 108<br> -Volt 562<br> -Volt-ampere 573<br> -Volt and Ampere Meter Galvanometer 274<br> -Volt, B. A. 568<br> -Volt, Congress 568<br> -Volt, Coulomb 568, 573<br> -Volt Indicator 568<br> -Volt. Legal 568<br> -Voltage 562<br> -Voltage, Spurious 493<br> -Voltage, Terminal 562<br> -Voltaic 563<br> -Voltaic Alternatives 563<br> -Voltaic Arc 39<br> -Voltaic Cell, Daniell's Standard 109<br> -Voltaic Cell, Double Fluid 191<br> -Voltaic Cell, Capacity of Polarization of a 103<br> -Voltaic Cell, Single Fluid 486<br> -Voltaic Cell, Standard 109<br> -Voltaic Cell, Standard, Latimer Clark's 110<br> -Voltaic Circuit 126<br> -Voltaic Effect 563<br> -Voltaic Electricity 563<br> -Voltaic Element 237<br> -Voltaic or Galvanic Battery 76<br> -Voltaic or Galvanic Circle 119<br> -Voltaic or Galvanic Couple 156<br> -Voltameter 563<br> -Voltameter, Copper 563<br> -Voltameter, Differential, Siemens' 564<br> -Voltameter, Faraday's 250<br> -Voltameter, Gas 564<br> -Voltameter, Silver 565<br> -Voltameter, Sulphuric Acid 564<br> -Voltameter, Volume 564<br> -Voltameter, Weight 566<br> -Voltametric Law 567<br> -Volta's Battery 76<br> -Volta's Fundamental Experiments 567<br> -Volta's Law of Galvanic Action 568<br> -Volta's Law of Thermo-electricity 568<br> -Voltmeter 568<br> -Voltmeter, Battery 569<br> -Voltmeter, Cardew 569<br> -Voltmeter, Electrostatic 571<br> -Voltmeter, Reducteur for 453<br> -Volts, Lost 571<br> -Volume Voltameter 564<br> -Vulcanite 571<br> -<br> -W 572<br> -Wall Bracket 572<br> -Wall Socket 572<br> -Ward 572<br> -Waste Field 256<br> -Water 572<br> -Water Battery 77<br> -Water Equivalent 572<br> -Water Level Alarm 18<br> -Waterproof Lamp Globe 572<br> -Wattless Current 168<br> -Watt 572<br> -Watt-hour 573<br> -Watt Meter 375<br> -Watt-minute 573<br> -Watt-second 573<br> -Watts, Apparent 573<br> -Wave Winding 580<br> -Waves, Amplitude of 31<br> -Waves. Electro-magnetic 573<br> -Wax, Paraffine 402<br> -Weber 574<br> -Weber s Absolute Unit Resistance 468<br> -Weber-meter 574<br> -Weber's Theory of Magnetism 358<br> -Wedge Cut-out 175<br> -Wedge. Double 191<br> -Weight, Atomic 53<br> -Weight, Breaking 89<br> -Weight Electrometer 223<br> -Weight Voltameter 566<br> -Welding, Electric 574<br> -Welding Transformer 548, 575<br> -Wheatstone's A. B. C. Telegraph 521<br> -Wheatstone's Balance 577<br> -Wheatstone's Bridge 575<br> -Wheatstone's Bridge, Commercial 86<br> -Wheatstone's Rheostat 472<br> -Wheel, Phonic 409<br> -Wheel, Reaction 259<br> -Whirl, Electric 577<br> -White Vitriol 562<br> -Wilde Candle 101<br> -Wimshurst Electric Machine 335, 577<br> -Wimshurst Machine 335, 577<br> -Wind, Electric 578<br> -Windage 578<br> -Windings, Ampere 31<br> -Winding, Bifilar 81<br> -Winding, Compound 578<br> -Winding, Disc 579<br> -Winding, Lap 579<br> -Winding, Long Shunt 579<br> -Winding, Long Shunt and Series 579<br> -Winding, Multiple 579<br> -Winding, Multipolar 579<br> -Winding, Series 579<br> -Winding, Series and Separate Coil 579<br> -Winding, Series and Short Shunt 580<br> -Winding, Short Shunt 579<br> -Winding, Shunt 483, 580<br> -Winding Shuttle 580<br> -Winding, Wave 580<br> -Winding Working, Differential 183<br> -Wire, Block 83<br> -Wire, Bus 94<br> -Wire, Dead 177<br> -Wire Finder 580<br> -Wire Gauze Brush 92<br> -Wire, Idle 296<br> -Wire, Neutral 390<br> -Wire, Omnibus 94<br> -Wire, Square 493<br> -Wire System, Three 539<br> -Wires, Crossing 158<br> -Wires, Leading-in 324<br> -Wires, Phantom 409<br> -Wires, Pilot 415<br> -Wollaston Battery 78<br> -Work 580<br> -Work, Electric, Unit of 580<br> -Work, Unit of 581<br> -Working, Contraplex 580<br> -Working, Diode 580<br> -Working, Diplex 580<br> -Working, Double Curb 581<br> -Working, Hexode 581<br> -Working, Pentode 581<br> -Working, Reverse Current 581<br> -Working, Single Curb 581<br> -Working Tetrode 581<br> -Writing Telegraph 521<br> -<br> -X, Axis of 54<br> -<br> -Y, Axis of 54, 397<br> -Yoke 581<br> -<br> -Zamboni's Dry Pile 581<br> -Zero 581<br> -Zero, Absolute 581<br> -Zero Potential 432, 582<br> -Zero, Thermometric 582<br> -Zinc 582<br> -Zinc Sender 582<br> -Zincode 582<br> -Zone, Peripolar 582<br> -Zone, Polar 582</big></big><br> -<br> -<br> - - -<pre> - - - - - -End of the Project Gutenberg EBook of The Standard Electrical Dictionary, by -T. 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