,,warning3 ,this book of one hundred years ago describes experiments which are too dangerous to attempt by either adults or children4 ,it is published for historical interest only4 ,,the ,,how-,,to-,,do-,,it ,,books ,,electricity ,,for ,,boys ,illustration3 ,fig4 #a4 ,,work ,,bench ,,the ,,how-,,to-,,do-,,it ,,books ,,electricity ,,for ,,boys ,a working guide1 in the successive steps of electricity1 described in simple terms ,,with ,,many ,,original ,,illustrations ,by ,j4 ,s4 ,,zerbe1 ,m4,e4 ,,author ,,of ,,carpentry ,,for ,,boys ,,practical ,,mechanics ,,for ,,boys ,illustration3 ,printer's ,mark ,,the ,,new ,,york ,,book ,,company ,,new ,,york ,,copyright1 #aiad1 ,,by ,,the ,,new ,,york ,,book ,,company ,,contents ,,introductory ,page #a ,i4 ,,electricity ,,considered4 ,,brief ,,historical ,,events ,page #e ,the ,study of ,electricity4 ,first ,historical ,accounts4 ,bottling ,electricity4 ,discovery of ,galvanic ,electricity4 ,electro-motive ,force4 ,measuring ,instruments4 ,rapidity of ,modern ,progress4 ,how to ,acquire the ,vast ,knowledge4 ,the ,means ,employed4 ,,ii4 ,,what ,,tools ,,and ,,apparatus ,,are ,,needed ,page #aa ,preparing the ,workshop4 ,uses of ,our ,workshop4 ,what to ,build4 ,what to ,learn4 ,uses of the ,electrical ,devices4 ,tools4 ,magnet-winding ,reel4 ,,iii4 ,,magnets1 ,,coils1 ,,armatures1 ,,etc4 ,page #ah ,the ,two ,kinds of ,magnets4 ,permanent ,magnets4 ,electro-,magnets4 ,magnetism4 ,materials for ,magnets4 ,non-magnetic ,material4 ,action of a ,second ,magnet4 ,what ,north and ,south ,pole ,mean4 ,repulsion and ,attraction4 ,positives and ,negatives4 ,magnetic ,lines of ,force4 ,the ,earth as a ,magnet4 ,why the ,compass ,points ,north and ,south4 ,peculiarity of a ,magnet4 ,action of the ,electro-,magnet4 ,exterior ,magnetic ,influence ,around a ,wires ,carrying a ,current4 ,parallel ,wires4 ,,iv4 ,,frictional1 ,,voltaic ,,or ,,galvanic ,,and ,,electro-,,magnetic ,,electricity ,page #bi ,three ,electrical ,sources4 ,frictional ,electricity4 ,leyden ,jar4 ,voltaic or ,galvanic ,electricity4 ,voltaic ,pile2 ,how ,made4 ,plus and ,minus ,signs4 ,the ,common ,primary ,cell4 ,battery ,resistance4 ,electrolyte and ,current4 ,electro-magnetic ,electricity4 ,magnetic ,radiation4 ,different ,kinds of ,dynamos4 ,direct ,current ,dynamos4 ,simple ,magnet ,construction4 ,how to ,wind4 ,the ,dynamo ,fields4 ,the ,armature4 ,armature ,windings4 ,mounting the ,armature4 ,the ,commutator4 ,commutator ,brushes4 ,dynamo ,windings4 ,the ,field4 ,series-wound ,field4 ,shunt-wound4 ,compound-wound4 ,v4 ,,how ,,to ,,detect ,,and ,,measure ,,electricity ,page #di ,measuring ,instruments4 ,the ,detector4 ,direction of ,current4 ,simple ,current ,detector4 ,how to ,place the ,detector4 ,different ,ways to ,measure a ,current4 ,the ,sulphuric ,acid ,voltameter4 ,the ,copper ,voltameter4 ,the ,galvanoscope ,electro-magnetic ,method4 ,the ,calorimeter4 ,the ,light ,method4 ,the ,preferred ,method4 ,how to ,make a ,sulphuric ,acid ,voltameter4 ,how to ,make a ,copper ,voltameter4 ,objections to the ,calorimeter4 ,,vi4 ,,volts1 ,,amperes1 ,,ohms ,,and ,,watts ,page #fj ,understanding ,terms4 ,intensity and ,quantity4 ,voltage4 ,amperage ,meaning of ,watts and ,kilowatt4 ,a ,standard of ,measurement4 ,the ,ampere ,standard4 ,the ,voltage ,standard4 ,the ,ohm4 ,calculating the ,voltage4 ,,vii4 ,,push ,,buttons1 ,,switches1 ,,annunciators1 ,,bells ,,and ,,like ,,apparatus ,page #fe ,simple ,switches4 ,a ,two-,pole ,switch4 ,double-,pole ,switch4 ,sliding ,switch4 ,reversing ,switch4 ,push ,buttons4 ,electric ,bells4 ,how ,made4 ,how ,operated4 ,annunciators4 ,burglar ,alarm4 ,wire ,circuiting4 ,circuiting ,system with ,two ,bells and ,push ,buttons4 ,the ,push ,buttons1 ,annunciators and ,bells4 ,wiring ,up a ,house4 ,,viii4 ,,accumulators1 ,,storage ,,or ,,secondary ,,batteries ,page #hb ,storing ,up ,electricity4 ,the ,accumulator4 ,accumulator ,plates4 ,the ,grid4 ,the ,negative ,pole4 ,connecting ,up the ,plates4 ,charging the ,cells4 ,the ,initial ,charge4 ,the ,charging ,current4 ,,ix4 ,,the ,,telegraph ,page #ij ,mechanism in ,telegraph ,circuit4 ,the ,sending ,key4 ,the ,sounder4 ,connecting ,up the ,key and ,sounder4 ,two ,stations in ,circuit4 ,the ,double ,click4 ,illustrating the ,dot and the ,dash4 ,the ,morse ,telegraph ,code4 ,example in ,use4 ,x4 ,,high-,,tension ,,apparatus1 ,,condensers1 ,,etc4 ,page #ih ,induction4 ,low and ,high ,tension4 ,elastic ,property of ,electricity4 ,the ,condenser4 ,connecting up a ,condenser4 ,the ,interrupter4 ,uses of ,high-tension ,coils4 ,,xi4 ,,wireless ,,telegraphy ,page #ajd ,telegraphing ,without ,wires4 ,surging ,character of ,high-tension ,currents4 ,the ,coherer4 ,how ,made4 ,the ,decoherer4 ,the ,sending ,apparatus4 ,the ,receiving ,apparatus4 ,how the ,circuits are ,formed4 ,,xii4 ,,the ,,telephone ,page #aaj ,vibrations4 ,the ,acoustic ,telephone4 ,sound ,waves4 ,hearing ,electricity4 ,the ,diaphragm in a ,magnetic ,field4 ,a ,simple ,telephone ,circuit4 ,how to ,make a ,telephone4 ,telephone ,connections4 ,complete ,installation4 ,the ,microphone4 ,light ,contact ,points4 ,how to ,make a ,microphone4 ,microphone1 the ,father of the ,transmitter4 ,automatic ,cut-outs for ,telephones4 ,complete ,circuiting with ,transmitters4 ,,xiii4 ,,electrolysis1 ,,water ,,purification1 ,,electroplating ,page #abc ,decomposing ,liquids4 ,making ,hydrogen and ,oxygen4 ,purifying ,water4 ,rust4 ,oxygen as a ,purifier4 ,composition of ,water4 ,common ,air ,not a ,good ,purifier4 ,pure ,oxygen a ,water ,purifier4 ,the ,use of ,hydrogen in ,purification4 ,aluminum ,electrodes4 ,electric ,hand ,purifier4 ,purification and ,separation of ,metals4 ,electroplating4 ,plating ,iron with ,copper4 ,direction of ,current4 ,,xiv4 ,,electric ,,heating4 ,,thermo-,,electricity ,page #ace ,generating ,heat in a ,wire4 ,resistance of ,substances4 ,signs of ,connectors4 ,comparison of ,metals4 ,a ,simple ,electric ,heater4 ,how to ,arrange for ,quantity of ,current ,used4 ,an ,electric ,iron4 ,thermo-,electricity ,converting ,heat ,directly into ,electricity ,metals4 ,electric1 ,positive1 ,negative4 ,thermo-electric ,coupler4 ,,xv4 ,,alternating ,,currents1 ,,choking ,,coil1 ,,transformer ,page #ade ,direct ,current4 ,alternating ,current4 ,the ,magnetic ,field4 ,action of a ,magnetized ,wire4 ,the ,movement of a ,current in a ,charged ,wire4 ,current ,reversing ,itself4 ,self-,induction4 ,brushes in a ,direct ,current ,dynamo3 ,alternating1 ,positive and ,negative ,poles4 ,how an ,alternating ,current ,dynamo is ,made4 ,the ,windings4 ,the ,armature ,wires4 ,choking ,coils4 ,the ,transformer4 ,how the ,voltage is ,determined4 ,voltage and ,amperage in ,transformers4 ,,xvi4 ,,electric ,,lighting ,page #afa ,early conditions4 ,fuels4 ,reversibility of ,dynamo4 ,electric arc4 ,mechanism to maintain the arc4 ,resistance coil4 ,parallel carbons for making arc4 ,series current4 ,incandescent system4 ,multiple circuit4 ,subdivision of electric light4 ,the filament4 ,the glass bulb4 ,metallic filaments4 ,vapor lamps4 ,directions for improvements4 ,heat in electric lighting4 ,curious superstitions concerning electricity4 ,magnetism4 ,amber4 ,discovery of the properties of a magnet4 ,electricity in mountain regions4 ,early beliefs as to magnetism and electricity4 ,the lightning rod4 ,protests against using it4 ,pliny's explanation of electricity4 ,,xvii4 ,,power1 ,,and ,,various ,,other ,,electrical ,,manifestations ,page #age ,early beliefs concerning the dynamo4 ,experiments with magnets4 ,physical action of dynamo and motor4 ,electrical influence in windings4 ,comparing motor and dynamo4 ,how the current acts in a dynamo4 ,its force in a motor4 ,loss in power transmission4 ,the four ways in which power is dissipated4 ,disadvantages of electric power4 ,its advantages4 ,transmission of energy4 ,high voltages4 ,the transformer4 ,step-down transformers4 ,electric furnaces4 ,welding by electricity4 ,merging the particles of the joined ends4 ,,xviii4 ,x-,,ray1 ,,radium ,,and ,,the ,,like ,page #ahd ,the camera and the eye4 ,actinic rays4 ,hertzian waves4 ,high-tension apparatus4 ,vacuum tubes4 ,character of the ultra-violet rays4 ,how distinguished4 ,the infra-red rays4 ,their uses4 ,x-rays not capable of reflection4 ,not subject to refraction4 ,transmission through opaque substances4 ,reducing rates of vibration4 ,radium4 ,radio-activity4 ,radio-active materials4 ,pitchblende4 ,a new form of energy4 ,electrical source4 ,healing power4 ,problems for scientists4 ,,list ,,of ,,illustrations ,,fig4 #a4 ,work bench ,frontispiece ,,page #b4 ,top of magnet-winding reel #ad #c4 ,side of magnet-winding reel #ad #d4 ,journal block #ae #e4 ,plain magnet bar #ai #f4 ,severed magnet #bj #g4 ,reversed magnets #ba #h4 ,horseshoe magnet #bb #i4 ,earth's magnetic lines #bc #aj4 ,two permanent magnets #bd #aa4 ,magnets in earth's magnetic field #bd #ab4 ,armatures for magnets #be #ac4 ,magnetized field #bf #ad4 ,magnetized bar #bf #ae4 ,direction of current #bg #af4 ,direction of induction current #bh #ag4 ,frictional-electricity machine #cj #ah4 ,leyden jar #cb #ai4 ,galvanic electricity4 ,crown of cups #cc #bj4 ,voltaic electricity #cd #ba4 ,primary battery #cf #bb4 ,dynamo field and pole piece #ci #bc4 ,base and fields assembled #da #bd4 ,details of the armature1 core #db #be4 ,details of the armature1 body #db #bf4 ,armature ,journals #dc #bg4 ,commutator #dc #bh4 ,end view of armature1 mounted #dd #bi4 ,top view of armature on base #de #cj4 ,field winding #dg #ca4 ,series-wound #dg #cb4 ,shunt-wound #dh #cc4 ,compound-wound #dh #cd4 ,compass magnet1 swing to the right #ej #ce4 ,magnetic compass #ej #cf4 ,magnet1 swing to the left #ej #cg4 ,indicating direction of current #ea #ch4 ,the bridge of the detector #eb #ci4 ,details of detector #ec #dj4 ,cross-section of detector #ed #da4 ,acid voltameter #ef #db4 ,copper voltameter #ef #dc4 ,two-pole switch #ff #dd4 ,double-pole switch #ff #de4 ,sliding switch #fg #df4 ,rheostat form of switch #fh #dg4 ,reversing switch #fi #dh4 ,push button #gj #di4 ,electric bell #ga #ej4 ,armature of electric bell #gb #ea4 ,vertical section of annunciator #gb #eb4 ,front view of annunciator #gb #ec4 ,horizontal section of annunciator #gb #ed4 ,front plate of annunciator #gb #ee4 ,alarm switch on window #gf #ef4 ,burglar alarm on window #gf #eg4 ,burglar alarm contact #gg #eh4 ,neutral position of contact #gh #ei4 ,circuiting for electric bell #gi #fj4 ,annunciators in circuit #hj #fa4 ,wiring system for a house #hj #fb4 ,accumulator grids #hc #fc4 ,assemblage of accumulator grids #he #fd4 ,connecting up storage battery in series #hg #fe4 ,parallel series #hh #ff4 ,charging circuit #hh #fg4 ,telegraph sending key #ia #fh4 ,telegraph sounder #ib #fi4 ,a telegraph circuit #id #gj4 ,induction coil and circuit #ii #ga4 ,illustrating elasticity #ajj #gb4 ,condenser #aja #gc4 ,high-tension circuit #ajb #gd4 ,current interrupter #ajc #ge4 ,wireless-telegraphy coherer #aje #gf4 ,wireless sending-apparatus #ajg #gg4 ,wireless receiving-apparatus #ajh #gh4 ,acoustic telephone #aaa #gi4 ,illustrating vibrations #aaa #hj4 ,the magnetic field #aab #ha4 ,section of telephone receiver #aad #hb4 ,the magnet and receiver head #aae #hc4 ,simple telephone connection #aaf #hd4 ,telephone stations in circuit #aag #he4 ,illustrating light contact points #aah #hf4 ,the microphone #aai #hg4 ,the transmitter #aai #hh4 ,complete telephone circuit #aba #hi4 ,device for making hydrogen and oxygen #abd #ij4 ,electric-water purifier #abg #ia4 ,portable electric purifier #abi #ib4 ,section of positive plate #acj #ic4 ,section of negative plate #acj #id4 ,positive and negative in position #acj #ie4 ,form of the insulator #acj #if4 ,simple electric heater #acg #ig4 ,side view of resistance device #aci #ih4 ,top view of resistance device #aci #ii4 ,plan view of electric iron #adj #ajj4 ,section of electric iron #ada #aja4 ,thermo-electric couple #adc #ajb4 ,cutting a magnetic field #adf #ajc4 ,alternations1 first position #adh #ajd4 ,alternations1 second position #adh #aje4 ,alternations1 third position #adh #ajf4 ,alternations1 fourth position #adh #ajg4 ,increasing alternations1 first view #adi #ajh4 ,increasing alternations1 second view #adi #aji4 ,connection of alternating dynamo armature #aej #aaj4 ,direct current dynamo #aea #aaa4 ,circuit wires in direct current dynamo #aeb #aab4 ,alternating polarity lines #aed #aac4 ,alternating current dynamo #aee #aad4 ,choking coil #aeg #aae4 ,a transformer #aeh #aaf4 ,parallel carbons #afd #aag4 ,arc-lighting circuit #afe #aah4 ,interrupted conductor #aff #aai4 ,incandescent circuit #afg #abj4 ,magnetic action in dynamo1 #ast #agg #aba4 ,magnetic action in dynamo1 #b;d #agg #abb4 ,magnetic action in dynamo1 #c;d #agh #abc4 ,magnetic action in dynamo1 #dth #agh #abd4 ,magnetic action in motor1 #ast #agi #abe4 ,magnetic action in motor1 #b;d #agi #abf4 ,magnetic action in motor1 #c;d #ahj #abg4 ,magnetic action in motor1 #dth #ahj ,,introductory ,electricity1 like every science1 presents two phases to the student1 one belonging to a theoretical knowledge1 and the other which pertains to the practical application of that knowledge4 ,the boy is directly interested in the practical use which he can make of this wonderful phenomenon in nature4 ,it is1 in reality1 the most successful avenue by which he may obtain the theory1 for he learns the abstract more readily from concrete examples4 ,it is an art in which shop practice is a greater educator than can be possible with books4 ,boys are not1 generally1 inclined to speculate or theorize on phenomena apart from the work itself2 but once put them into contact with the mechanism itself1 let them become a living part of it1 and they will commence to reason and think for themselves4 ,it would be a dry1 dull and uninteresting thing to tell a boy that electricity can be generated by riveting together two pieces of dissimilar metals1 and applying heat to the juncture4 ,but put into his hands the metals1 and set him to perform the actual work of riveting the metals together1 then wiring up the ends of the metals1 heating them1 and1 with a galvanometer1 watching for results1 it will at once make him see something in the experiment which never occurred when the abstract theory was propounded4 ,he will inquire first what metals should be used to get the best results1 and finally1 he will speculate as to the reasons for the phenomena4 ,when he learns that all metals are positive-negative or negative-positive to each other1 he has grasped a new idea in the realm of knowledge1 which he unconsciously traces back still further1 only to learn that he has entered a field which relates to the constitution of matter itself4 ,as he follows the subject through its various channels he will learn that there is a common source of all things2 a manifestation common to all matter1 and that all substances in nature are linked together in a most wonderful way4 ,an impulse must be given to a boy's training4 ,the time is past for the rule-and-rote method4 ,the rule can be learned better by a manual application than by committing a sentence to memory4 ,in the preparation of this book1 therefore1 ,i have made practice and work the predominating factors4 ,it has been my aim to suggest the best form in which to do the things in a practical way1 and from that work1 as the boy carries it out1 to deduce certain laws and develop the principles which underlie them4 ,wherever it is deemed possible to do so1 it is planned to have the boy make these discoveries for himself1 so as to encourage him to become a thinker and a reasoner instead of a mere machine4 ,a boy does not develop into a philosopher or a scientist through being told he must learn the principles of this teaching1 or the fundamentals of that school of reasoning4 ,he will unconsciously imbibe the spirit and the willingness if we but place before him the tools by which he may build even the simple machinery that displays the various electrical manifestations4 ,,chapter ,i ,,the ,,study ,,of ,,electricity4 ,,historical ,there is no study so profound as electricity4 ,it is a marvel to the scientist as well as to the novice4 ,it is simple in its manifestations1 but most complex in its organization and in its ramifications4 ,it has been shown that light1 heat1 magnetism and electricity are the same1 but that they differ merely in their modes of motion4 ,,first ,,historical ,,account4--,the first historical account of electricity dates back to #fjj years ,b4 ,c4 ,thales of ,miletus was the first to describe the properties of amber1 which1 when rubbed1 attracted and repelled light bodies4 ,the ancients also described what was probably tourmaline1 a mineral which has the same qualities4 ,the torpedo1 a fish which has the power of emitting electric impulses1 was known in very early times4 ,from that period down to about the year #afjj no accounts of any historical value have been given4 ,dr4 ,gilbert1 of ,england1 made a number of researches at that time1 principally with amber and other materials1 and ,boyle1 in #afej1 made numerous experiments with frictional electricity4 ,sir ,isaac ,newton also took up the subject at about the same period4 ,in #agje ,hawksbee made numerous experiments2 also ,gray1 in #agbj1 and a ,welshman1 ,dufay1 at about the same time4 ,the ,germans1 from #agdj to #aghj1 made many experiments4 ,in #agdj1 at ,leyden1 was discovered the jar which bears that name4 ,before that time1 all experiments began and ended with frictional electricity4 ,the first attempt to bottle electricity was attempted by ,muschenbroeck1 at ,leyden1 who conceived the idea that electricity in materials might be retained by surrounding them with bodies which did not conduct the current4 ,he electrified some water in a jar1 and communication having been established between the water and the prime conductor1 his assistant1 who was holding the bottle1 on trying to disengage the communicating wire1 received a sudden shock4 ,in #agdg ,sir ,william ,watson fired gunpowder by an electric spark1 and1 later on1 a party from the ,royal ,society1 in conjunction with ,watson1 conducted a series of experiments to determine the velocity of the electric fluid1 as it was then termed4 ,benjamin ,franklin1 in #agej1 showed that lightning was electricity1 and later on made his interesting experiments with the kite and the key4 ,,discovering ,,galvanic ,,electricity4--,the great discovery of ,galvani1 in #agij1 led to the recognition of a new element in electricity1 called galvanic or voltaic 7named after the experimenter1 ,volta71 and now known to be identical with frictional electricity4 ,in #ahje ,poisson was the first to analyze electricity2 and when ,,oersted of ,copenhagen1 in #ahbj1 discovered the magnetic action of electricity1 it offered a great stimulus to the science1 and paved the way for investigation in a new direction4 ,ampere was the first to develop the idea that a motor or a dynamo could be made operative by means of the electro-magnetic current2 and ,faraday1 about #ahcj1 discovered electro-magnetic rotation4 ,,electro-,,magnetic ,,force4--,from this time on the knowledge of electricity grew with amazing rapidity4 ,ohm's definition of electro-motive force1 current strength and resistance eventuated into ,ohm's law4 ,thomson greatly simplified the galvanometer1 and ,wheatstone invented the rheostat1 a means of measuring resistance1 about #ahej4 ,then primary batteries were brought forward by ,daniels1 ,grove1 ,bunsen and ,thomson1 and electrolysis by ,faraday4 ,then came the instruments of precision--the electrometer1 the resistance bridge1 the ammeter1 the voltmeter--all of the utmost value in the science4 ,,measuring ,,instruments4--,the perfection of measuring instruments did more to advance electricity than almost any other field of endeavor2 so that after #ahge the inventors took up the subject1 and by their energy developed and put into practical operation a most wonderful array of mechanism1 which has become valuable in the service of man in almost every field of human activity4 ,,rapidity ,,of ,,modern ,,progress4--,this brief history is given merely to show what wonders have been accomplished in a few years4 ,the art is really less than fifty years old1 and yet so rapidly has it gone forward that it is not at all surprising to hear the remark1 that the end of the wonders has been reached4 ,less than twenty-five years ago a high official of the ,united ,states ,patent ,office stated that it was probable the end of electrical research had been reached4 ,the most wonderful developments have been made since that time2 and now1 as in the past1 one discovery is but the prelude to another still more remarkable4 ,we are beginning to learn that we are only on the threshold of that storehouse in which nature has locked her secrets1 and that there is no limit to human ingenuity4 ,,how ,,to ,,acquire ,,the ,,vast ,,knowledge4--,as the boy1 with his limited vision1 surveys this vast accumulation of tools1 instruments and machinery1 and sees what has been and is now being accomplished1 it is not to be wondered at that he should enter the field with timidity4 ,in his mind the great question is1 how to acquire the knowledge4 ,there is so much to learn4 ,how can it be accomplished8 ,the answer to this is1 that the student of to-day has the advantage of the knowledge of all who have gone before2 and now the pertinent thing is to acquire that knowledge4 ,,the ,,means ,,employed4--,this brings us definitely down to an examination of the means that we shall employ to instil this knowledge1 so that it may become a permanent asset to the student's store of information4 ,the most significant thing in the history of electrical development is the knowledge that of all the great scientists not one of them ever added any knowledge to the science on purely speculative reasoning4 ,all of them were experimenters4 ,they practically applied and developed their theories in the laboratory or the workshop4 ,the natural inference is1 therefore1 that the boy who starts out to acquire a knowledge of electricity1 must not only theorize1 but that he shall1 primarily1 conduct the experiments1 and thereby acquire the information in a practical way1 one example of which will make a more lasting impression than pages of dry text4 ,throughout these pages1 therefore1 ,i shall1 as briefly as possible1 point out the theories involved1 as a foundation for the work1 and then illustrate the structural types or samples2 and the work is so arranged that what is done to-day is merely a prelude or stepping-stone to the next phase of the art4 ,in reality1 we shall travel1 to a considerable extent1 the course which the great investigators followed when they were groping for the facts and discovering the great manifestations in nature4 ,,chapter ,,ii ,,what ,,tools ,,and ,,apparatus ,,are ,,needed ,,preparing ,,the ,,workshop4--,before commencing actual experiments we should prepare the workshop and tools4 ,since we are going into this work as pioneers1 we shall have to be dependent upon our own efforts for the production of the electrical apparatus1 so as to be able1 with our home-made factory1 to provide the power1 the heat and the electricity4 ,then1 finding we are successful in these enterprises1 we may look forward for more worlds to conquer4 ,by this time our neighbors will become interested in and solicit work from us4 ,,uses ,,of ,,our ,,workshops4--,they may want us to test batteries1 and it then becomes necessary to construct mechanism to detect and measure electricity2 to install new and improved apparatus2 and to put in and connect up electric bells in their houses1 as well as burglar alarms4 ,to meet the requirements1 we put in a telegraph line1 having learned1 as well as we are able1 how they are made and operated4 ,but we find the telegraph too slow and altogether unsuited for our purposes1 as well as for the uses of the neighborhood1 so we conclude to put in a telephone system4 ,,what ,,to ,,build4--,it is necessary1 therefore1 to commence right at the bottom to build a telephone1 a transmitter1 a receiver and a switch-board for our system4 ,from the telephone we soon see the desirability of getting into touch with the great outside world1 and wireless telegraphy absorbs our time and energies4 ,but as we learn more and more of the wonderful things electricity will do1 we are brought into contact with problems which directly interest the home4 ,sanitation attracts our attention4 ,why cannot electricity act as an agent to purify our drinking water1 to sterilize sewage and to arrest offensive odors8 ,we must1 therefore1 learn something about the subject of electrolysis4 ,,what ,,to ,,learn4--,the decomposition of water is not the only thing that we shall describe pertaining to this subject4 ,we go a step further1 and find that we can decompose metals as well as liquids1 and that we can make a pure metal out of an impure one1 as well as make the foulest water pure4 ,but we shall also1 in the course of our experiments1 find that a cheap metal can be coated with a costly one by means of electricity--that we can electroplate by electrolysis4 ,,uses ,,of ,,the ,,electrical ,,devices4--,while all this is progressing and our factory is turning out an amazing variety of useful articles1 we are led to inquire into the uses to which we may devote our surplus electricity4 ,the current may be diverted for boiling water2 for welding metals2 for heating sad-irons1 as well as for other purposes which are daily required4 ,,tools4--,to do these things tools are necessary1 and for the present they should not be expensive4 ,a small1 rigidly built bench is the first requirement4 ,this may be made1 as shown in ,fig4 #a1 of three #b-;inch planks1 each #aj inches wide and #f feet long1 mounted on legs #cf inches in height4 ,in the front part are three drawers for your material1 or the small odds and ends1 as well as for such little tools as you may accumulate4 ,then you will need a small vise1 say1 with a #b-;inch jaw1 and you will also require a hand reel for winding magnets4 ,this will be fully described hereafter4 ,you can also1 probably1 get a small1 cheap anvil1 which will be of the greatest service in your work4 ,it should be mounted close up to the work bench4 ,two small hammers1 one with an ,a-shaped peon1 and the other with a round peon1 should be selected1 and also a plane and a small wood saw with fine teeth4 ,a bit stock1 or a ratchet drill1 if you can afford it1 with a variety of small drills2 two wood chisels1 say of #c_/h-;inch and #c_/d-;inch widths2 small cold chisels2 hack saw1 #aj-;inch blade2 small iron square2 pair of dividers2 tin shears2 wire cutters2 #b pairs of pliers1 one flat and the other round-nosed2 #b awls1 centering punch1 wire cutters1 and1 finally1 soldering tools4 ,illustration3 ,fig4 #b4 ,top ,view ,,magnet-,,winding ,,reel ,illustration3 ,fig4 #c4 ,side ,view ,,magnet-,,winding ,,reel ,if a gas stove is not available1 a brazing torch is an essential tool4 ,numerous small torches are being made1 which are cheap and easily operated4 ,a small soldering iron1 with pointed end1 should be provided2 also metal shears and a small square2 an awl and several sizes of gimlets2 a screwdriver2 pair of pliers and wire cutters4 ,from the foregoing it will be seen that the cost of tools is not a very expensive item4 ,this entire outfit1 not including the anvil and vise1 may be purchased new for about #bj4jj1 so we have not been extravagant4 ,,magnet-,,winding ,,reel4--,some little preparation must be made1 so we may be enabled to handle our work by the construction of mechanical aids4 ,illustration3 ,fig4 #d4 ,journal ,block4 ,first of these is the magnet-winding reel1 a plan view of which is shown in ,fig4 #b4 ,this1 for our present work1 will be made wholly of wood4 ,select a plank #a-a_/b inches thick and #h inches wide1 and from this cut off two pieces 7,a71 each #g inches long1 and then trim off the corners 7,b1 ,b71 as shown in ,fig4 #d4 ,to serve as the mandrel 7,c1 ,fig4 #b71 select a piece of broomstick #i inches long4 ,bore a hole 7,d7 in each block 7,a7 a half inch below the upper margin of the block1 this hole being of such diameter that the broomstick mandrel will fit and easily turn therein4 ,place a crank 7,e71 #e inches long1 on the outer end of the mandrel1 as in ,fig4 #c4 ,then mount one block on the end of the bench and the other block #c inches away4 ,affix them to the bench by nails or screws1 preferably the latter4 ,on the inner end of the mandrel put a block 7,f7 of hard wood4 ,this is done by boring a hole #a inch deep in the center of the block1 into which the mandrel is driven4 ,on the outer face of the block is a square hole large enough to receive the head of a #c_/h-;inch bolt1 and into the depression thus formed a screw 7,g7 is driven through the block and into the end of the mandrel1 so as to hold the block 7,f7 and mandrel firmly together4 ,when these parts are properly put together1 the inner side of the block will rest and turn against the inner journal block 7,a74 ,the tailpiece is made of a #b #d scantling 7,h71 #aj inches long1 one end of it being nailed to a transverse block 7,i7 #b #b #d4 ,the inner face of this block has a depression in which is placed a ,v-shaped cup 7,j71 to receive the end of the magnet core 7,k7 or bolt1 which is to be used for this purpose4 ,the tailpiece 7,h7 has a longitudinal slot 7,l7 #e inches long adapted to receive a #a_/b-;inch bolt 7,m71 which passes down through the bench1 and is1 therefore1 adjustable1 so it may be moved to and from the journal bearing 7,a71 thereby providing a place for the bolts to be put in4 ,these bolts are the magnet cores 7,k71 #f inches long1 but they may be even longer1 if you bore several holes 7,n7 through the bench so you may set over the tailpiece4 ,with a single tool made substantially like this1 over a thousand of the finest magnets have been wound4 ,its value will be appreciated after you have had the experience of winding a few magnets4 ,,order ,,in ,,the ,,workshop4--,select a place for each tool on the rear upright of the bench1 and make it a rule to put each tool back into its place after using4 ,this1 if persisted in1 will soon become a habit1 and will save you hours of time4 ,hunting for tools is the unprofitable part of any work4 ,,chapter ,,iii ,,magnets1 ,,coils1 ,,armatures1 ,,etc4 ,,the ,,two ,,kinds ,,of ,,magnet4--,generally speaking1 magnets are of two kinds1 namely1 permanent and electro-magnetic4 ,,permanent ,,magnets4--,a permanent magnet is a piece of steel in which an electric force is exerted at all times4 ,an electro-magnet is a piece of iron which is magnetized by a winding of wire1 and the magnet is energized only while a current of electricity is passing through the wire4 ,,electro-,,magnet4--,the electro-magnet1 therefore1 is the more useful1 because the pull of the magnet can be controlled by the current which actuates it4 ,the electro-magnet is the most essential of all contrivances in the operation and use of electricity4 ,it is the piece of mechanism which does the physical work of almost every electrical apparatus or machine4 ,it is the device which has the power to convert the unseen electric current into motion which may be observed by the human eye4 ,without it electricity would be a useless agent to man4 ,while the electro-magnet is1 therefore1 the form of device which is almost wholly used1 it is necessary1 first1 to understand the principles of the permanent magnet4 ,,magnetism4--,the curious force exerted by a magnet is called magnetism1 but its origin has never been explained4 ,we know its manifestations only1 and laws have been formulated to explain its various phases2 how to make it more or less intense2 how to make its pull more effective2 the shape and form of the magnet and the material most useful in its construction4 ,illustration3 ,fig #e4 ,,plain ,,magnet ,,bar ,,materials ,,for ,,magnets4--,iron and steel are the best materials for magnets4 ,some metals are non-magnetic1 this applying to iron if combined with manganese4 ,others1 like sulphur1 zinc1 bismuth1 antimony1 gold1 silver and copper1 not only are non-magnetic1 but they are actually repelled by magnetism4 ,they are called the diamagnetics4 ,,non-,,magnetic ,,materials4--,any non-magnetic body in the path of a magnetic force does not screen or diminish its action1 whereas a magnetic substance will4 ,in ,fig4 #e we show the simplest form of magnet1 merely a bar of steel 7,a7 with the magnetic lines of force passing from end to end4 ,it will be understood that these lines extend out on all sides1 and not only along two sides1 as shown in the drawing4 ,the object is to explain clearly how the lines run4 ,illustration3 ,fig4 #f4 ,,severed ,,magnet ,,action ,,of ,a ,,severed ,,magnet4--,now1 let us suppose that we sever this bar in the middle1 as in ,fig4 #f1 or at any other point between the ends4 ,in this case each part becomes a perfect magnet1 and a new north pole 7,n7 and a new south pole 7,s7 are made1 so that the movement of the magnetic lines of force are still in the same direction in each--that is1 the current flows from the north pole to the south pole4 ,,what ,,north ,,and ,,south ,,poles ,,mean4--,if these two parts are placed close together they will attract each other4 ,but if1 on the other hand1 one of the pieces is reversed1 as in ,fig4 #g1 they will repel each other4 ,from this comes the statement that likes repel and unlikes attract each other4 ,,repulsion ,,and ,,attraction4--,this physical act of repulsion and attraction is made use of in motors1 as we shall see hereinafter4 ,it will be well to bear in mind that in treating of electricity the north pole is always associated with the plus sign 77 and the south pole with the minus sign 7-74 ,or the ,n sign is positive and the ,s sign negative electricity4 ,illustration3 ,fig4 #g4 ,,reversed ,,magnets ,,positives ,,and ,,negatives4--,there is really no difference between positive and negative electricity1 so called1 but the foregoing method merely serves as a means of identifying or classifying the opposite ends of a magnet or of a wire4 ,,magnetic ,,lines ,,of ,,force4--,it will be noticed that the magnetic lines of force pass through the bar and then go from end to end through the atmosphere4 ,air is a poor conductor of electricity1 so that if we can find a shorter way to conduct the current from the north pole to the south pole1 the efficiency of the magnet is increased4 ,this is accomplished by means of the well-known horseshoe magnet1 where the two ends 7,n1 ,s7 are brought close together1 as in ,fig4 #h4 ,,the ,,earth ,,as ,a ,,magnet4--,the earth is a huge magnet and the magnetic lines run from the north pole to the south pole around all sides of the globe4 ,illustration3 ,fig4 #h4 ,,horseshoe ,,magnet ,the north magnetic pole does not coincide with the true north pole or the pivotal point of the earth's rotation1 but it is sufficiently near for all practical purposes4 ,fig4 #i shows the magnetic lines running from the north to the south pole4 ,,why ,,the ,,compass ,,points ,,north ,,and ,,south4--,now1 let us try to ascertain why the compass points north and south4 ,let us assume that we have a large magnet 7,a1 ,fig4 #aj71 and suspend a small magnet 7,b7 above it1 so that it is within the magnetic field of the large magnet4 ,this may be done by means of a short pin 7,c71 which is located in the middle of the magnet 7,b71 the upper end of this pin having thereon a loop to which a thread 7,d7 is attached4 ,the pin also carries thereon a pointer 7,e71 which is directed toward the north pole of the bar 7,b74 ,illustration3 ,fig4 #i4 ,,earth',s ,,magnetic ,,lines ,you will now take note of the interior magnetic lines 7,x71 and the exterior magnetic lines 7,z7 of the large magnet 7,a71 and compare the direction of their flow with the similar lines in the small magnet 7,b74 ,the small magnet has both its exterior and its interior lines within the exterior lines 7,z7 of the large magnet 7,a71 so that as the small magnet 7,b7 is capable of swinging around1 the ,n pole of the bar 7,b7 will point toward the ,s pole of the larger bar 7,a74 ,the small bar1 therefore1 is influenced by the exterior magnetic field 7,z74 ,illustration3 ,fig4 #aj4 ,,two ,,permanent ,,magnets ,illustration3 ,fig4 #aa4 ,,magnets ,,in ,,the ,,earth',s ,,magnetic ,,field ,let us now take the outline represented by the earth's surface 7,fig4 #aa71 and suspend a magnet 7,a7 at any point1 like the needle of a compass1 and it will be seen that the needle will arrange itself north and south1 within the magnetic field which flows from the north to the south pole4 ,,peculiarity ,,of ,a ,,magnet4--,one characteristic of a magnet is that1 while apparently the magnetic field flows out at one end of the magnet1 and moves inwardly at the other end1 the power of attraction is just the same at both ends4 ,in ,fig4 #ab are shown a bar 7,a7 and a horseshoe magnet 7,b74 ,the bar 7,a7 has metal blocks 7,c7 at each end1 and each of these blocks is attracted to and held in contact with the ends by magnetic influence1 just the same as the bar 7,d7 is attracted by and held against the two ends of the horseshoe magnet4 ,these blocks 7,c7 or the bar 7,d7 are called armatures4 ,through them is represented the visible motion produced by the magnetic field4 ,illustration3 ,fig4 #ab4 ,,armatures ,,for ,,magnets ,,action ,,of ,,the ,,electro-,,magnet4--,the electro-magnet exerts its force in the same manner as a permanent magnet1 so far as attraction and repulsion are concerned1 and it has a north and a south pole1 as in the case with the permanent magnet4 ,an electro-magnet is simply a bar of iron with a coil or coils of wire around it2 when a current of electricity flows through the wire1 the bar is magnetized4 ,the moment the current is cut off1 the bar is demagnetized4 ,the question that now arises is1 why an electric current flowing through a wire1 under those conditions1 magnetizes the bar1 or core1 as it is called4 ,illustration3 ,fig4 #ac4 ,,magnetized ,,field ,illustration3 ,fig4 #ad4 ,,magnetized ,,bar ,in ,fig4 #ac is shown a piece of wire 7,a74 ,let us assume that a current of electricity is flowing through this wire in the direction of the darts4 ,what actually takes place is that the electricity extends out beyond the surface of the wire in the form of the closed rings 7,b74 ,if1 now1 this wire 7,a7 is wound around an iron core 7,c1 ,fig4 #ad71 you will observe that this electric field1 as it is called1 entirely surrounds the core1 or rather1 that the core is within the magnetic field or influence of the current flowing through the wire1 and the core 7,c7 thereby becomes magnetized1 but it is magnetized only when the current passes through the wire coil 7,a74 ,illustration3 ,fig4 #ae4 ,,direction ,,of ,,current ,from the foregoing1 it will be understood that a wire carrying a current of electricity not only is affected within its body1 but that it also has a sphere of influence exteriorly to the body of the wire1 at all points2 and advantage is taken of this phenomenon in constructing motors1 dynamos1 electrical measuring devices and almost every kind of electrical mechanism in existence4 ,,exterior ,,magnetic ,,influence ,,around ,a ,,wire ,,carrying ,a ,,current4--,bear in mind that the wire coil 7,a1 ,fig4 #ad7 does not come into contact with the core 7,c74 ,it is insulated from the core1 either by air or by rubber or other insulating substance1 and a current passing from ,a to ,c under those conditions is a current of induction4 ,on the other hand1 the current flowing through the wire 7,a7 from end to end is called a conduction current4 ,remember these terms4 ,in this connection there is also another thing which you will do well to bear in mind4 ,in ,fig4 #ae you will notice a core 7,c7 and an insulated wire coil 7,b7 wound around it4 ,the current1 through the wire 7,b71 as shown by the darts 7,d71 moves in one direction1 and the induced current in the core 7,c7 travels in the opposite direction1 as shown by the darts 7,d74 ,illustration3 ,fig4 #af4 ,,direction ,,of ,,induction ,,current ,,parallel ,,wires4--,in like manner1 if two wires 7,a1 ,b1 ,fig4 #af7 are parallel with each other1 and a current of electricity passes along the wire 7,a7 in one direction1 the induced current in the wire 7,b7 will move in the opposite direction4 ,these fundamental principles should be thoroughly understood and mastered4 ,,chapter ,,iv ,,frictional1 ,,voltaic ,,or ,,galvanic1 ,,and ,,electro-,,magnetic ,,electricity ,,three ,,electrical ,,sources4--,it has been found that there are three kinds of electricity1 or1 to be more accurate1 there are three ways to generate it4 ,these will now be described4 ,when man first began experimenting1 he produced a current by frictional means1 and collected the electricity in a bottle or jar4 ,electricity1 so stored1 could be drawn from the jar1 by attaching thereto suitable connection4 ,this could be effected only in one way1 and that was by discharging the entire accumulation instantaneously4 ,at that time they knew of no means whereby the current could be made to flow from the jar as from a battery or cell4 ,,frictional ,,electricity4--,with a view of explaining the principles involved1 we show in ,fig4 #ag a machine for producing electricity by friction4 ,illustration3 ,fig4 #ag4 ,,friction-,,electricity ,,machine ,this is made up as follows3 ,a represents the base1 having thereon a flat member 7,b71 on which is mounted a pair of parallel posts or standards 7,c1 ,c71 which are connected at the top by a cross piece 7,d74 ,between these two posts is a glass disc 7,e71 mounted upon a shaft 7,f71 which passes through the posts1 this shaft having at one end a crank 7,g74 ,two leather collecting surfaces 7,h1 ,h71 which are in contact with the glass disc 7,e71 are held in position by arms 7,i1 ,j71 the arm 7,i7 being supported by the cross piece 7,d71 and the arm 7,j7 held by the base piece 7,b74 ,a rod 7,k71 ,u-shaped in form1 passes over the structure here thus described1 its ends being secured to the base 7,b74 ,the arms 7,i1 ,j7 are both electrically connected with this rod1 or conductor 7,k71 joined to a main conductor 7,l71 which has a terminating knob 7,m74 ,on each side and close to the terminal end of each leather collector 7,h7 is a fork-shaped collector 7,n74 ,these two collectors are also connected electrically with the conductor 7,k74 ,when the disc is turned electricity is generated by the leather flaps and accumulated by the collectors 7,n71 after which it is ready to be discharged at the knob 7,m74 ,in order to collect the electricity thus generated a vessel called a ,leyden jar is used4 ,,leyden ,,jar4--,this is shown in ,fig4 #ah4 ,the jar 7,a7 is of glass coated exteriorly at its lower end with tinfoil 7,b71 which extends up a little more than halfway from the bottom4 ,this jar has a wooden cover or top 7,c71 provided centrally with a hole 7,d74 ,the jar is designed to receive within it a tripod and standard 7,e7 of lead4 ,within this lead standard is fitted a metal rod 7,f71 which projects upwardly through the hole 7,d71 its upper end having thereon a terminal knob 7,g74 ,a sliding cork 7,h7 on the rod 7,f7 serves as a means to close the jar when not in use4 ,when in use this cork is raised so the rod may not come into contact1 electrically1 with the cover 7,c74 ,the jar is half filled with sulphuric acid 7,i71 after which1 in order to charge the jar1 the knob 7,g7 is brought into contact with the knob 7,m7 of the friction generator 7,fig4 #ag74 ,,voltaic ,,or ,,galvanic ,,electricity4--,the second method of generating electricity is by chemical means1 so called1 because a liquid is used as one of the agents4 ,illustration3 ,fig4 #ah4 ,,leyden ,,jar ,galvani1 in #agij1 made the experiments which led to the generation of electricity by means of liquids and metals4 ,the first battery was called the crown of cups1 shown in ,fig4 #ai1 and consisting of a row of glass cups 7,a71 containing salt water4 ,these cups were electrically connected by means of bent metal strips 7,b71 each strip having at one end a copper plate 7,c71 and at the other end a zinc plate 7,d74 ,the first plate in the cup at one end is connected with the last plate in the cup at the other end by a conductor 7,e7 to make a complete circuit4 ,illustration3 ,fig4 #ai4 ,,galvanic ,,electricity4 ,,crown ,,of ,,cups ,,the ,,cell ,,and ,,battery4--,from the foregoing it will be seen that within each cup the current flows from the zinc to the copper plates1 and exteriorly from the copper to the zinc plates through the conductors 7,b and ,e74 ,a few years afterwards ,volta devised what is known as the voltaic pile 7,fig4 #bj74 ,,voltaic ,,pile--,,how ,,made4--,this is made of alternate discs of copper and zinc with a piece of cardboard of corresponding size between each zinc and copper plate4 ,the cardboard discs are moistened with acidulated water4 ,the bottom disc of copper has a strip which connects with a cup of acid1 and one wire terminal 7,a7 runs therefrom4 ,the upper disc1 which is of zinc1 is also connected1 by a strip1 with a cup of acid from which extends the other terminal wire 7,b74 ,illustration3 ,fig4 #bj4 ,,voltaic ,,electricity ,plus and ,minus ,signs4--,it will be noted that the positive or copper disc has the plus sign 77 while the zinc disc has the minus 7-7 sign4 ,these signs denote the positive and the negative sides of the current4 ,the liquid in the cells1 or in the moistened paper1 is called the electrolyte and the plates or discs are called electrodes4 ,to define them more clearly1 the positive plate is the anode1 and the negative plate the cathode4 ,the current1 upon entering the zinc plate1 decomposes the water in the electrolyte1 thereby forming oxygen4 ,the hydrogen in the water1 which has also been formed by the decomposition1 is carried to the copper plate1 so that the plate finally is so coated with hydrogen that it is difficult for the current to pass through4 ,this condition is called polarization1 and to prevent it has been the aim of all inventors4 ,to it also we may attribute the great variety of primary batteries1 each having some distinctive claim of merit4 ,,the ,,common ,,primary ,,cell4--,the most common form of primary cell contains sulphuric acid1 or a sulphuric acid solution1 as the electrolyte1 with zinc for the anode1 and carbon1 instead of copper1 for the cathode4 ,the ends of the zinc and copper plates are called terminals1 and while the zinc is the anode or positive element1 its terminal is designated as the positive pole4 ,in like manner1 the carbon is the negative element or cathode1 and its terminal is designated as negative pole4 ,fig4 #ba will show the relative arrangement of the parts4 ,it is customary to term that end or element from which the current flows as positive4 ,a cell is regarded as a whole1 and as the current passes out of the cell from the copper element1 the copper terminal becomes positive4 ,illustration3 ,fig4 #ba4 ,,primary ,,battery ,,battery ,,resistance1 ,,electrolyte ,,and ,,current4--,the following should be carefully memorized3 ,a cell has reference to a single vessel4 ,when two or more cells are coupled together they form a battery4 ,resistance is opposition to the movement of the current4 ,if it is offered by the electrolyte1 it is designated ,internal ,resistance4 ,if1 on the other hand1 the opposition takes place1 for instance1 through the wire1 it is then called ,external ,resistance4 ,the electrolyte must be either acid1 or alkaline1 or saline1 and the electrodes must be of dissimilar metals1 so the electrolyte will attack one of them4 ,the current is measured in amperes1 and the force with which it is caused to flow is measured in volts4 ,in practice the word current is used to designate ampere flow2 and electromotive force1 or ,e4 ,m4 ,f41 is used instead of voltage4 ,,electro-,,magnetic ,,electricity4--,the third method of generating electricity is by electro-magnets4 ,the value and use of induction will now be seen1 and you will be enabled to utilize the lesson concerning magnetic action referred to in the previous chapter4 ,,magnetic ,,radiation4--,you will remember that every piece of metal which is within the path of an electric current has a space all about its surface from end to end which is electrified4 ,this electrified field extends out a certain distance from the metal1 and is supposed to maintain a movement around it4 ,if1 now1 another piece of metal is brought within range of this electric or magnetic zone and moved across it1 so as to cut through this field1 a current will be generated thereby1 or rather added to the current already exerted1 so that if we start with a feeble current1 it can be increased by rapidly cutting the lines of force1 as it is called4 ,,different ,,kinds ,,of ,,dynamo4--,while there are many kinds of dynamo1 they all1 without exception1 are constructed in accordance with this principle4 ,there are also many varieties of current4 ,for instance1 a dynamo may be made to produce a high voltage and a low amperage2 another with high amperage and low voltage2 another which gives a direct current for lighting1 heating1 power1 and electroplating2 still another which generates an alternating current for high tension power1 or transmission1 arc-lighting1 etc41 all of which will be explained hereafter4 ,in this place1 however1 a full description of a direct-current dynamo will explain the principle involved in all dynamos--that to generate a current of electricity makes it necessary for us to move a field of force1 like an armature1 rapidly and continuously through another field of force1 like a magnetic field4 ,,direct-,,current ,,dynamo4--,we shall now make the simplest form of dynamo1 using for this purpose a pair of permanent magnets4 ,illustration3 ,fig4 #bb4 ,,dynamo ,,field ,,and ,,pole ,,piece ,,simple ,,magnet ,,construction4--,a simple way to make a pair of magnets for this purpose is shown in ,fig4 #bb4 ,a piece of round #c_/d-;inch steel core 7,a71 #e-a_/b inches long1 is threaded at both ends to receive at one end a nut 7,b71 which is screwed on a sufficient distance so that the end of the core 7,a7 projects a half inch beyond the nut4 ,the other end of the steel core has a pole piece of iron 7,c7 #b #b #d1 with a hole midway between the ends1 threaded entirely through1 and provided along one side with a concave channel1 within which the armature is to turn4 ,now1 before the pole piece 7,c7 is put on1 we will slip on a disc 7,e71 made of hard rubber1 then a thin rubber tube 7,f71 and finally a rubber disc 7,g71 so as to provide a positive insulation for the wire coil which is wound on the bobbin thus made4 ,,how ,,to ,,wind4--,in practice1 and as you go further along in this work1 you will learn the value1 first1 of winding one layer of insulated wire on the spool1 coating it with shellac1 and then putting on the next layer1 and so on2 when completely wound1 the two wire terminals may be brought out at one end2 but for our present purpose1 and to render the explanation clearer1 the wire terminals are at the opposite ends of the spool 7,h1 ,h'74 ,,the ,,dynamo ,,fields4--,two of these spools are so made and they are called the fields of the dynamo4 ,we will next prepare an iron bar 7,i71 #e inches long and #a_/b inch thick and #a-a_/b inches wide1 then bore two holes through it so the distance measures #c inches from center to center4 ,these holes are to be threaded for the #c_/d-;inch cores 7,a74 ,this bar holds together the upper ends of the cores1 as shown in ,fig4 #bc4 ,illustration3 ,fig4 #bc4 ,,base ,,and ,,fields ,,assembled ,we then prepare a base 7,j7 of any hard wood1 #b inches thick1 #h inches long and #h inches wide1 and bore two #c_/d-;inch holes #c inches apart on a middle line1 to receive a pair of #c_/d-;inch cap screws 7,k71 which pass upwardly through the holes in the base and screw into the pole pieces 7,c74 ,a wooden bar 7,l71 #a-a_/b #a-a_/b1 #h inches long1 is placed under each pole piece1 which is also provided with holes for the cap screws 7,k74 ,the lower side of the base 7,j7 should be countersunk1 as at ,m1 so the head of the nut will not project4 ,the fields of the dynamo are now secured in position to the base4 ,illustration3 ,fig4 #bd4 ,,details ,,of ,,the ,,armature1 ,,core ,fig4 #be4 ,,details ,,of ,,the ,,armature1 ,,body ,,the ,,armature4--,a bar of iron 7,fig4 #bd71 #a #a and #b-a_/d inches long1 is next provided4 ,through this bar 7#a7 are then bored two #e_/af-;inch holes #a-c_/d inches apart1 and on the opposite sides of this bar are two half-rounded plates of iron 7#c7 7,fig4 #be74 ,,armature ,,winding4--,each plate is #a_/b inch thick1 #a-c_/d inches wide and #d inches long1 each plate having holes 7#d7 to coincide with the holes 7#b7 of the bar 7#a71 so that when the two plates are applied to opposite sides of the bar1 and riveted together1 a cylindrical member is formed1 with two channels running longitudinally1 and transversely at the ends2 and in these channels the insulated wires are wound from end to end around the central block 7#a74 ,,mounting ,,the ,,armature4--,it is now necessary to provide a means for revolving this armature4 ,to this end a brass disc 7#e1 ,fig4 #bf7 is made1 #b inches in diameter1 #a_/h inch thick4 ,centrally1 at one side1 is a projecting stem 7#f7 of round brass1 which projects out #b inches1 and the outer end is turned down1 as at #g1 to form a small bearing surface4 ,illustration3 ,fig4 #bf4 ,,journals ,fig4 #bg4 ,,commutator1 ,,armature ,,mountings ,the other end of the armature has a similar disc 7#h71 with a central stem 7#i71 #a-a_/b inches long1 turned down to #a_/d-;inch diameter up to within #a_/d inch of the disc 7#g71 so as to form a shoulder4 ,,the ,,commutator4--,in ,fig4 #bg is shown1 at #aj1 a wooden cylinder1 #a inch long and #a-a_/d inches in diameter1 with a hole 7#aa7 bored through axially1 so that it will fit tightly on the stem 7#f7 of the disc 7#e74 ,on this wooden cylinder is driven a brass or copper tube 7#ab71 which has holes 7#ac7 opposite each other4 ,screws are used to hold the tube to the wooden cylinder1 and after they are properly secured together1 the tube 7#ab7 is cut by a saw1 as at #ad1 so as to form two independent tubular surfaces4 ,illustration3 ,fig4 #bh4 ,,end ,,view ,,armature1 ,,mounted ,these tubular sections are called the commutator plates4 ,illustration3 ,fig4 #bi4 ,,top ,,view ,,of ,,armature ,,on ,,base ,in order to mount this armature1 two bearings are provided1 each comprising a bar of brass 7#ae1 ,fig4 #bh71 each #a_/d inch thick1 #a_/b inch wide and #d-a_/b inches long4 ,two holes1 #c inches apart1 are formed through this bar1 to receive round-headed wood screws 7#af71 these screws being #c inches long1 so they will pass through the wooden pieces 7,i7 and enter the base 7,j74 ,midway between the ends1 each bar 7#ae7 has an iron bearing block 7#ag71 #c_/d #a_/b and #a-a_/b inches high1 the #a_/d-;inch hole for the journal 7#g7 being midway between its ends4 ,,commutator ,,brushes4--,fig4 #bh shows the base1 armature and commutator assembled in position1 and to these parts have been added the commutator brushes4 ,the brush holder 7#ah7 is a horizontal bar made of hard rubber loosely mounted upon the journal pin 7#g71 which is #b-a_/b inches long4 ,at each end is a right-angled metal arm 7#ai7 secured to the bar 7#ah7 by screws 7#bj74 ,to these arms the brushes 7#ba7 are attached1 so that their spring ends engage with the commutator 7#ab74 ,an adjusting screw 7#bb7 in the bearing post 7#ag71 with the head thereof bearing against the brush-holder 7#ah71 serves as a means for revolubly adjusting the brushes with relation to the commutator4 ,,dynamo ,,windings4--,there are several ways to wind the dynamos4 ,these can be shown better by the following diagrams 7,figs4 #cj1 #ca1 #cb1 #cc73 ,,the ,,field4--,if the field 7,a1 ,fig4 #cj7 is not a permanent magnet1 it must be excited by a cell or battery1 and the wires 7,b1 ,b'7 are connected up with a battery1 while the wires 7,c1 ,c'7 may be connected up to run a motor4 ,this would1 therefore1 be what is called a separately excited dynamo4 ,in this case the battery excites the field and the armature 7,d71 cutting the lines of force at the pole pieces 7,e71 so that the armature gathers the current for the wires 7,c1 ,c'74 ,illustration3 ,fig4 #cj4 ,,field ,,winding ,illustration3 ,fig4 #ca4 ,,series-,,wound ,,series-,,wound ,,field4--,fig4 #ca shows a series-wound dynamo4 ,the wires of the fields 7,a7 are connected up in series with the brushes of the armature 7,d71 and the wires 7,g1 ,g'7 are led out and connected up with a lamp1 motor or other mechanism4 ,in this case1 as well as in ,figs4 #cb and #cc1 both the field and the armature are made of soft gray iron4 ,with this winding and means of connecting the wires1 the field is constantly excited by the current passing through the wires4 ,,shunt-,,wound ,,field4--,fig4 #cb represents what is known as a shunt-wound dynamo4 ,here the field wires 7,h1 ,h7 connect with the opposite brushes of the armature1 and the wires 7,i1 ,i'7 are also connected with the brushes1 these two wires being provided to perform the work required4 ,this is a more useful form of winding for electroplating purposes4 ,illustration3 ,fig4 #cb4 ,,shunt-,,wound ,fig4 #cb4 ,,compound-,,wound ,,compound-,,wound ,,field4--,fig4 #cc is a diagram of a compound-wound dynamo4 ,the regular field winding 7,j7 has its opposite ends connected directly with the armature brushes4 ,there is also a winding1 of a comparatively few turns1 of a thicker wire1 one terminal 7,k7 of which is connected with one of the brushes and the other terminal 7,k'7 forms one side of the lighting circuit4 ,a wire 7,l7 connects with the other armature brush to form a complete lighting circuit4 ,,chapter ,v ,,how ,,to ,,detect ,,and ,,measure ,,electricity ,,measuring ,,instruments4--,the production of an electric current would not be of much value unless we had some way by which we might detect and measure it4 ,the pound weight1 the foot rule and the quart measure are very simple devices1 but without them very little business could be done4 ,there must be a standard of measurement in electricity as well as in dealing with iron or vegetables or fabrics4 ,as electricity cannot be seen by the human eye1 some mechanism must be made which will reveal its movements4 ,,the ,,detector4--,it has been shown in the preceding chapter that a current of electricity passing through a wire will cause a current to pass through a parallel wire1 if the two wires are placed close together1 but not actually in contact with each other4 ,an instrument which reveals this condition is called a galvanometer4 ,it not only detects the presence of a current1 but it shows the direction of its flow4 ,we shall now see how this is done4 ,for example1 the wire 7,a1 ,fig4 #ce7 is connected up in an electric circuit with a permanent magnet 7,b7 suspended by a fine wire 7,c71 so that the magnet 7,b7 may freely revolve4 ,illustration3 ,fig4 #cd4 ,fig4 #ce4 ,fig4 #cf4 ,,to ,,the ,,right1 ,,compass ,,magnet1 ,,to ,,the ,,left ,for convenience1 the magnetic field is shown flowing in the direction of the darts1 in which the dart 7,d7 represents the current within the magnet 7,b7 flowing toward the north pole1 and the darts 7,e7 showing the exterior current flowing toward the south pole4 ,now1 if the wire 7,a7 is brought up close to the magnet 7,b71 and a current passed through ,a1 the magnet 7,b7 will be affected4 ,fig4 #ce shows the normal condition of the magnetized bar 7,b7 parallel with the wire 7,a7 when a current is not passing through the latter4 ,,direction ,,of ,,current4--,if the current should go through the wire 7,a7 from right to left1 as shown in ,fig4 #cd1 the magnet 7,b7 would swing in the direction taken by the hands of a clock and assume the position shown in ,fig4 #cd4 ,if1 on the other hand1 the current in the wire 7,a7 should be reversed or flow from left to right1 the magnet 7,b7 would swing counter-clock-wise1 and assume the position shown in ,fig4 #cf4 ,the little pointer 7,g7 would1 in either case1 point in the direction of the flow of the current through the wire 7,a74 ,illustration3 ,fig4 #cg4 ,,indicating ,,direction ,,of ,,current ,,simple ,,current ,,detector4--,a simple current detector may be made as follows3 ,prepare a base #c' #d' in size and #a inch thick4 ,at each corner of one end fix a binding post1 as at ,a1 ,a'1 ,fig4 #cg4 ,then select #bj feet of ,no4 #bh cotton-insulated wire1 and make a coil 7,b7 #b inches in diameter1 leaving the ends free1 so they may be affixed to the binding posts 7,a1 ,a'74 ,now glue or nail six blocks 7,c7 to the base1 each block being #a #a #b1 and lay the coil on these blocks4 ,then drive an ,l-shaped nail 7,d7 down into each block1 on the inside of the coil1 as shown1 so as to hold the latter in place4 ,illustration3 ,fig4 #ch4 ,,the ,,bridge ,now make a bridge 7,e1 ,fig4 #ch7 of a strip of brass #a_/b inch wide1 #a_/af inch thick and long enough to span the coil1 and bend the ends down1 as at ,f1 so as to form legs4 ,a screw hole 7,g7 is formed in each foot1 so it may be screwed to the base4 ,midway between the ends this bridge has a transverse slot 7,h7 in one edge1 to receive therein the pivot pin of the swinging magnet4 ,in order to hold the pivot pin in place1 cut out an ,h-shaped piece of sheet brass 7,i71 which1 when laid on the bridge1 has its ends bent around the latter1 as shown at ,j1 and the crossbar of the ,h-shaped piece then will prevent the pivot pin from coming out of the slot 7,h74 ,illustration3 ,fig4 #ci4 ,,details ,,of ,,detector ,the magnet is made of a bar of steel 7,k1 ,fig4 #ci7 #a-a_/b inches long1 #c_/h inch wide and #a_/af inch thick1 a piece of a clock spring being very serviceable for this purpose4 ,the pivot pin is made of an ordinary pin 7,l71 and as it is difficult to solder the steel magnet 7,k7 to the pin1 solder only a small disc 7,m7 to the pin 7,l74 ,then bore a hole 7,n7 through the middle of the magnet 7,k71 larger in diameter than the pin 7,l71 and1 after putting the pin in the hole1 pour sealing wax into the hole1 and thereby secure the two parts together4 ,near the upper end of the pin 7,l7 solder the end of a pointer 7,o71 this pointer being at right angles to the armature 7,k74 ,it is better to have a metal socket for the lower end of the pin4 ,when these parts are put together1 as shown in ,fig4 #cg1 a removable glass top1 or cover1 should be provided4 ,this is shown in ,fig4 #dj1 in which a square1 wooden frame 7,p7 is used1 and a glass 7,q7 fitted into the frame1 the glass being so arranged that when the cover is in position it will be in close proximity to the upper projecting end of the pivot pin 7,l71 and thus prevent the magnet from becoming misplaced4 ,illustration3 ,fig4 #dj4 ,,cross ,,section ,,of ,,detector ,,how ,,to ,,place ,,the ,,detector4--,if the detector is placed north and south1 as shown by the two markings1 ,n and ,s 7,fig4 #cg71 the magnet bar will point north and south1 being affected by the earth's magnetism2 but when a current of electricity flows through the coil 7,b71 the magnet will be deflected to the right or to the left1 so that the pointer 7,o7 will then show the direction in which the current is flowing through the wire 7,r7 which you are testing4 ,the next step of importance is to measure the current1 that is1 to determine its strength or intensity1 as well as the flow or quantity4 ,,different ,,ways ,,of ,,measuring ,a ,,current4--,there are several ways to measure the properties of a current1 which may be defined as follows3 #a4 ,,the ,,sulphuric ,,acid ,,voltameter4--,by means of an electrolytic action1 whereby the current decomposes an acidulated solution--that is1 water which has in it a small amount of sulphuric acid--and then measuring the gas generated by the current4 #b4 ,,the ,,copper ,,voltameter4--,by electro-chemical means1 in which the current passes through plates immersed in a solution of copper sulphate4 #c4 ,,the ,,galvanoscope4--,by having a coil of insulated wire1 with a magnet suspended so as to turn freely within the coil1 forming what is called a galvanoscope4 #d4 ,,electro-,,magnetic ,,method4--,by using a pair of magnets and sending a current through the coils1 and then measuring the pull on the armature4 #e4 ,,the ,,power ,,or ,,speed ,,method4--,by using an electric fan1 and noting the revolutions produced by the current4 #f4 ,,the ,,calorimeter4--,by using a coil of bare wire1 immersed in paraffine oil1 and then measuring the temperature by means of a thermometer4 ,illustration3 ,fig4 #da4 ,,acid ,,voltameter ,illustration3 ,fig4 #db4 ,,copper ,,voltameter #g4 ,,the ,,light ,,method4--,lastly1 by means of an electric light1 which shows1 by its brightness1 a greater or less current4 ,,the ,,preferred ,,methods4--,it has been found that the first and second methods are the only ones which will accurately register current strength1 and these methods have this advantage--that the chemical effect produced is not dependent upon the size or shape of the apparatus or the plates used4 ,,how ,,to ,,make ,a ,,sulphuric ,,acid ,,voltameter4--,in ,fig4 #da is shown a simple form of sulphuric acid voltameter1 to illustrate the first method4 ,a is a jar1 tightly closed by a cover 7,b74 ,within is a pair of platinum plates 7,c1 ,c71 each having a wire 7,d7 through the cover4 ,the cover has a vertical glass tube 7,e7 through it1 which extends down to the bottom of the jar1 the electrolyte therein being a weak solution of sulphuric acid4 ,when a current passes through the wires 7,d71 the solution is partially decomposed--that is1 converted into gas1 which passes up into the vacant space 7,f7 above the liquid1 and1 as it cannot escape1 it presses the liquid downwardly1 and causes the latter to flow upwardly into the tube 7,e74 ,it is then an easy matter1 after the current is on for a certain time1 to determine its strength by the height of the liquid in the tube4 ,,how ,,to ,,make ,a ,,copper ,,voltameter4--,the second1 or copper voltameter1 is shown in ,fig4 #db4 ,the glass jar 7,a7 contains a solution of copper sulphate1 known in commerce as blue vitriol4 ,a pair of copper plates 7,b1 ,b'7 are placed in this solution1 each being provided with a connecting wire 7,c74 ,when a current passes through the wires 7,c71 one copper plate 7,b7 is eaten away and deposited on the other plate 7,b'74 ,it is then an easy matter to take out the plates and find out how much in weight ,b' has gained1 or how much ,b has lost4 ,in this way1 in comparing the strength of1 say1 two separate currents1 one should have each current pass through the voltameter the same length of time as the other1 so as to obtain comparative results4 ,it is not necessary1 in the first and second methods1 to consider the shapes1 the sizes of the plates or the distances between them4 ,in the first method the gas produced1 within a given time1 will be the same1 and in the second method the amount deposited or eaten away will be the same under all conditions4 ,,disadvantages ,,of ,,the ,,galvanoscope4--,with the third method 7using the galvanoscope7 it is necessary1 in order to get a positively correct reading instrument1 to follow an absolutely accurate plan in constructing each part1 in every detail1 and great care must be exercised1 particularly in winding4 ,it is necessary also to be very careful in selecting the sizes of wire used and in the number of turns made in the coils4 ,this is equally true of the fourth method1 using the electro-magnet1 because the magnetic pull is dependent upon the size of wire from which the coils are made and the number of turns of wire4 ,,objections ,,to ,,the ,,calorimeter4--,the calorimeter1 or sixth method1 has the same objection4 ,the galvanoscope and electro-magnet do not respond equally to all currents1 and this is also true1 even to a greater extent1 with the calorimeter4 ,,chapter ,,vi ,,volts1 ,,amperes1 ,,ohms ,,and ,,watts ,,understanding ,,terms4--,we must now try to ascertain the meaning of some of the terms so frequently used in connection with electricity4 ,if you intended to sell or measure produce or goods of any kind1 it would be essential to know how many pints or quarts are contained in a gallon1 or in a bushel1 or how many inches there are in a yard1 and you also ought to know just what the quantity term bushel or the measurement yard means4 ,,intensity ,,and ,,quantity4--,electricity1 while it has no weight1 is capable of being measured by means of its intensity1 or by its quantity4 ,light may be measured or tested by its brilliancy4 ,if one light is of less intensity than another and both of them receive their impulses from the same source1 there must be something which interferes with that light which shows the least brilliancy4 ,electricity can also be interfered with1 and this interference is called resistance4 ,,voltage4--,water may be made to flow with greater or less force1 or velocity1 through a pipe1 the degree of same depending upon the height of the water which supplies the pipe4 ,so with electricity4 ,it may pass over a wire with greater or less force under one condition than another4 ,this force is called voltage4 ,if we have a large pipe1 a much greater quantity of water will flow through it than will pass through a small pipe1 providing the pressure in each case is alike4 ,this quantity in electricity is called amperage4 ,in the case of water1 a column #a #a1 #bh inches in height1 weighs #a pound2 so that if a pipe #a inch square draws water from the bottom it flows with a pressure of #a pound4 ,if the pipe has a measurement of #b square inches1 double the quantity of water will flow therefrom1 at the same pressure4 ,,amperage4--,if1 on the other hand1 we have a pipe #a inch square1 and there is a depth of #ef inches of water in the reservoir1 we shall get as much water from the reservoir as though we had a pipe of #b square inches drawing water from a reservoir which is #bh inches deep4 ,,meaning ,,of ,,watts4--,it is obvious1 therefore1 that if we multiply the height of the water in inches with the area of the pipe1 we shall obtain a factor which will show how much water is flowing4 ,here are two examples3 #a4 #bh inches height of the water in the reservoir4 #b square inches size of the pipe4 ,multiply #bh #b #ef4 #b4 #ef height of the water in the reservoir4 #a square inch size of the pipe4 ,multiply #ef #a #ef4 ,thus the two problems are equal4 ,a ,,kilowatt4--,now1 in electricity1 remembering that the height of the water corresponds with voltage in electricity1 and the size of the pipe with amperage1 if we multiply volts by amperes1 or amperes by volts1 we get a result which is indicated by the term watts4 ,one thousand of these watts make a kilowatt1 and the latter is the standard of measurement by which a dynamo or motor is judged or rated4 ,thus1 if we have #e amperes and #aaj volts1 the result of multiplying them would be #eej watts1 or #e volts and #aaj amperes would produce #eej watts4 ,a ,,standard ,,of ,,measurement4--,but with all this we must have some standard4 ,a bushel measure is of a certain size1 and a foot has a definite length1 so in electricity there is a recognized force and quantity which are determined as follows3 ,,the ,,ampere ,,standard4--,it is necessary1 first1 to determine what an ampere is4 ,for this purpose a standard solution of nitrate of silver is used1 and a current of electricity is passed through this solution4 ,in doing so the current deposits silver at the rate of #j4jjaaah grains per second for each ampere4 ,,the ,,voltage ,,standard4--,in order to determine the voltage we must know something of resistance4 ,different metals do not transmit a current with equal ease4 ,the size of a conductor1 also1 is an important factor in the passage of a current4 ,a large conductor will transmit a current much better than a small conductor4 ,we must therefore have a standard for the ohm1 which is the measure of resistance4 ,,the ,,ohm4--,it is calculated in this way3 ,there are several standards1 but the one most generally employed is the ,international ,ohm4 ,to determine it1 by this system1 a column of pure mercury1 #ajf4c millimeters long and weighing #ad4deba grams1 is used4 ,this would make a square tube about #id inches long1 and a little over #a_/be of an inch in diameter4 ,the resistance to a current flow in such a column would be equal to #a ohm4 ,,calculating ,,the ,,voltage4--,in order to arrive at the voltage we must use a conductor1 which1 with a resistance of #a ohm1 will produce #a ampere4 ,it must be remembered that the volt is the practical unit of electro-motive force4 ,while it would be difficult for the boy to conduct these experiments in the absence of suitable apparatus1 still1 it is well to understand thoroughly how and why these standards are made and used4 ,,chapter ,,vii ,,push ,,buttons1 ,,switches1 ,,annunciators1 ,,bells ,,and ,,like ,,apparatus ,,simple ,,switches4--,we have now gone over the simpler or elementary outlines of electrical phenomena1 and we may commence to do some of the practical work in the art4 ,we need certain apparatus to make connections1 which will be constructed first4 ,a ,,two-,,pole ,,switch4--,a simple two-pole switch for a single line is made as follows3 ,a base block 7,a1 ,fig4 #dc7 #c inches long1 #b inches wide and #c_/d inch thick1 has on it1 at one end1 a binding screw 7,b71 which holds a pair of fingers 7,c7 of brass or copper1 these fingers being bent upwardly and so arranged as to serve as fingers to hold a switch bar 7,d7 between them4 ,this bar is also of copper or brass and is pivoted to the fingers4 ,near the other end of the base is a similar binding screw 7,e7 and fingers 7,f7 to receive the blade of the switch bar4 ,the bar has a handle 7,g7 of wood4 ,the wires are attached to the respective binding screws 7,b1 ,e74 ,,double-,,pole ,,switch4--,a double-pole switch or a switch for a double line is shown in ,fig4 #dd4 ,this is made similar in all respects to the one shown in ,fig4 #dc1 excepting that there are two switch blades 7,a1 ,a7 connected by a cross bar 7,b7 of insulating material1 and this bar carries the handle 7,c74 ,illustration3 ,fig4 #dc4 ,,two-,,pole ,,switch ,illustration3 ,fig4 #dd4 ,,double-,,pole ,,switch ,other types of switch will be found very useful4 ,in ,fig4 #de is a simple sliding switch in which the base block has1 at one end1 a pair of copper plates 7,a1 ,b71 each held at one end to the base by a binding screw 7,c71 and having a bearing or contact surface 7,d7 at its other end4 ,at the other end of the base is a copper plate 7,e7 held by a binding screw 7,f71 to the inner end of which plate is hinged a swinging switch blade 7,g71 the free end of which is adapted to engage with the plates 7,a1 ,b74 ,illustration3 ,fig4 #de4 ,,sliding ,,switch ,,sliding ,,switch4--,this sliding switch form may have the contact plates 7,a1 ,b and ,c1 ,fig4 #df7 circularly arranged and any number may be located on the base1 so they may be engaged by a single switching lever 7,h74 ,it is the form usually adopted for rheostats4 ,,reversing ,,switch4--,a reversing switch is shown in ,fig4 #dg4 ,the base has two plates 7,a1 ,b7 at one end1 to which the parallel switch bars 7,c1 ,d7 are hinged4 ,the other end of the base has three contact plates 7,e1 ,f1 ,g7 to engage the swinging switch bars1 these latter being at such distance apart that they will engage with the middle and one of the outer plates4 ,the inlet wires1 positive and negative1 are attached to the plates 7,a1 ,b1 respectively71 and one of the outlet wires 7,h7 is attached to the middle contact plate 7,f71 while the other wire is connected up with both of the outside plates4 ,when the switch bars 7,c1 ,d7 are thrown to the left so as to be in contact with ,e1 ,f1 the outside plate 7,e7 and the middle plate 7,f7 will be positive and negative1 respectively2 but when the switch is thrown to the right1 as shown in the figure1 plate ,f becomes positive and plate ,e negative1 as shown4 ,illustration3 ,fig4 #df4 ,,rheostat ,,form ,,of ,,switch ,,push ,,buttons4--,a push button is but a modified structure of a switch1 and they are serviceable because they are operating1 or the circuit is formed only while the finger is on the button4 ,illustration3 ,fig4 #dg4 ,,reversing ,,switch ,in its simplest form 7,fig4 #dh7 the push button has merely a circular base 7,a7 of insulating material1 and near one margin1 on the flat side1 is a rectangular plate 7,b71 intended to serve as a contact plate as well as a means for attaching one of the wires thereto4 ,in line with this plate is a spring finger 7,c71 bent upwardly so that it is normally out of contact with the plate 7,b71 its end being held by a binding screw 7,d74 ,to effect contact1 the spring end of the finger 7,c7 is pressed against the bar 7,b71 as at ,e4 ,this is enclosed in a suitable casing1 such as will readily suggest itself to the novice4 ,,electric ,,bell4--,one of the first things the boy wants to make1 and one which is also an interesting piece of work1 is an electric bell4 ,to make this he will be brought1 experimentally1 in touch with several important features in electrical work4 ,he must make a battery for the production of current1 a pair of electro-magnets to be acted upon by the current1 a switch to control it1 and1 finally1 he must learn how to connect it up so that it may be operated not only from one1 but from two or more push buttons4 ,illustration3 ,fig4 #dh4 ,,push ,,button ,,how ,,made4--,in ,fig4 #di is shown an electric bell1 as usually constructed1 so modified as to show the structure at a glance1 with its connections4 ,a is the base1 ,b1 ,b' the binding posts for the wires1 ,c1 ,c the electro-magnets1 ,c' the bracket for holding the magnets1 ,d the armature1 ,e the thin spring which connects the armature with the post ,f1 ,g the clapper arm1 ,h the bell1 ,i the adjusting screw on the post ,j1 ,k the wire lead from the binding post ,b to the first magnet1 ,l the wire which connects the two magnets1 ,m the wire which runs from the second magnet to the post ,j1 and ,n a wire leading from the armature post to the binding post ,b'4 ,illustration3 ,fig4 #di4 ,,electric ,,bell ,the principle of the electric bell is this3 ,in looking at ,fig4 #di1 you will note that the armature bar ,d is held against the end of the adjusting screw by the small spring ,e4 ,when a current is turned on1 it passes through the connections and conduits as follows3 ,wire ,k to the magnets1 wire ,m to the binding post ,j1 and set screw ,i1 then through the armature to the post ,f1 and from post ,f to the binding post ,b'4 ,illustration3 ,fig4 #ej4 ,,armature ,,of ,,electric ,,bell ,,electric ,,bell--,,how ,,operated4--,the moment a current passes through the magnets 7,c1 ,c71 the core is magnetized1 and the result is that the armature 7,d7 is attracted to the magnets1 as shown by the dotted lines 7,o71 when the clapper strikes the bell4 ,but when the armature moves over to the magnet1 the connection is broken between the screw 7,i7 and armature 7,d71 so that the cores of the magnets are demagnetized and lose their pull1 and the spring 7,e7 succeeds in drawing back the armature4 ,this operation of vibrating the armature is repeated with great rapidity1 alternately breaking and re-establishing the circuit1 by the action of the current4 ,in making the bell1 you must observe one thing1 the binding posts 7,b1 ,b'7 must be insulated from each other1 and the post ,j1 or the post ,f1 should also be insulated from the base4 ,for convenience we show the post ,f insulated1 so as to necessitate the use of wire 7,n7 from post 7,f7 to binding post 7,b'74 ,the foregoing assumes that you have used a cast metal base1 as most bells are now made2 but if you use a wooden base1 the binding posts 7,b1 ,b'7 and the posts 7,f1 ,j7 are insulated from each other1 and the construction is much simplified4 ,it is better1 in practice1 to have a small spring 7,p1 ,fig4 #ej7 between the armature 7,d7 and the end of the adjusting screw 7,i71 so as to give a return impetus to the clapper4 ,the object of the adjusting screw is to push and hold the armature close up to the ends of the magnets1 if it seems necessary4 ,if two bells are placed on the base with the clapper mounted between them1 both bells will be struck by the swinging motion of the armature4 ,an easily removable cap or cover is usually placed over the coils and armature1 to keep out dust4 ,a very simple annunciator may be attached to the bell1 as shown in the following figures3 ,illustration3 ,figs4 #ea-ed4 ,,annunciator ,,annunciators4--,make a box of wood1 with a base 7,a7 #d #e and #a_/b inch thick4 ,on this you can permanently mount the two side pieces 7,b7 and two top and bottom pieces 7,c71 respectively1 so they project outwardly #d-a_/b inches from the base4 ,on the open front place a wood or metal plate 7,d71 provided with a square opening 7,d71 as in ,fig4 #ed1 near its lower end4 ,this plate is held to the box by screws 7,e74 ,within is a magnet 7,f71 screwed into the base 7,a71 as shown in ,fig4 #ea2 and pivoted to the bottom of the box is a vertical armature 7,g71 which extends upwardly and contacts with the core of the magnet4 ,the upper end of the armature has a shoulder 7,h71 which is in such position that it serves as a rest for a ,v-shaped stirrup 7,i71 which is hinged at ,j to the base 7,c74 ,this stirrup carries the number plate 7,k71 and when it is raised to its highest point it is held on the shoulder 7,h71 unless the electro-magnet draws the armature out of range of the stirrup4 ,a spring 7,l7 bearing against the inner side of the armature keeps its upper end normally away from the magnet core4 ,when the magnet draws the armature inwardly1 the number plate drops and exposes the numeral through the opening in the front of the box4 ,in order to return the number plate to its original position1 as shown in ,fig4 #ea1 a vertical trigger 7,m7 passes up through the bottom1 its upper end being within range of one of the limbs of the stirrup4 ,this is easily made by the ingenious boy1 and will be quite an acquisition to his stock of instruments4 ,in practice1 the annunciator may be located in any convenient place and wires run to that point4 ,illustration3 ,fig4 #ee4 ,,alarm ,,switch ,,on ,,window ,illustration3 ,fig4 #ef4 ,,burglar ,,alarm ,,attachment ,,to ,,window ,,burglar ,,alarm4--,in order to make a burglar alarm connection with a bell1 push buttons or switches may be put in circuit to connect with the windows and doors1 and by means of the annunciators you may locate the door or window which has been opened4 ,the simplest form of switch for a window is shown in the following figures3 ,the base piece 7,a71 which may be of hard rubber or fiber1 is #a_/d inch thick and #a #a-a_/b in size4 ,illustration3 ,fig4 #eg4 ,,burglar ,,alarm ,,contact ,at one end is a brass plate 7,b71 with a hole for a wood screw 7,c71 this screw being designed to pass through the plate and also into the window-frame1 so as to serve as a means of attaching one of the wires thereto4 ,the inner end of the plate has a hole for a round-headed screw 7,c'7 that also goes through the base and into the window-frame4 ,it also passes through the lower end of the heart-shaped metal switch-piece 7,d74 ,the upper end of the base has a brass plate 7,e71 also secured to the base and window by a screw 7,f7 at its upper end4 ,the heart-shaped switch is of such length and width at its upper end that when it is swung to the right with one of the lobes projecting past the edge of the window-frame1 the other lobe will be out of contact with the plate 7,e74 ,illustration3 ,fig4 #eh4 ,,neutral ,,position ,,of ,,contact ,the window sash 7,g7 has a removable pin 7,h71 which1 when the sash moves upwardly1 is in the path of the lobe of the heart-shaped switch1 as shown in ,fig4 #ef1 and in this manner the pin 7,h7 moves the upper end of the switch 7,d7 inwardly1 so that the other lobe contacts with the plate 7,e71 and establishes an electric circuit1 as shown in ,fig4 #eg4 ,during the daytime the pin 7,h7 may be removed1 and in order to protect the switch the heart-shaped piece 7,d7 is swung inwardly1 as shown in ,fig4 #eh1 so that neither of the lobes is in contact with the plate 7,e74 ,,wire ,,circuiting4--,for the purpose of understanding fully the circuiting1 diagrams will be shown of the simple electric bell with two push buttons2 next in order1 the circuiting with an annunciator and then the circuiting necessary for a series of windows and doors1 with annunciator attachments4 ,illustration3 ,fig4 #ei4 ,,circuiting ,,for ,,electric ,,bell ,,circuiting ,,system ,,with ,a ,,bell ,,and ,,two ,,push ,,buttons4--,fig4 #ei shows a simple circuiting system which has two push buttons1 although any number may be used1 so that the bell will ring when the circuit is closed by either button4 ,,the ,,push ,,buttons ,,and ,,the ,,annunciator ,,bells4--,fig4 #fj shows three push buttons and an annunciator for each button4 ,these three circuits are indicated by ,a1 ,b and ,c1 so that when either button makes contact1 a complete circuit is formed through the corresponding annunciator4 ,illustration3 ,fig4 #fj4 ,annunciators ,illustration3 ,fig4 #fa4 ,,wiring ,,system ,,for ,a ,,house ,,wiring ,,up ,a ,,house4--,the system of wiring up a house so that all doors and windows will be connected to form a burglar alarm outfit1 is shown in ,fig4 #fa4 ,it will be understood that1 in practice1 the bell is mounted on or at the annunciator1 and that1 for convenience1 the annunciator box has also a receptacle for the battery4 ,the circuiting is shown diagramatically1 as it is called1 so as fully to explain how the lines are run4 ,two windows and a door are connected up with an annunciator having three drops1 or numbers #a1 #b1 #c4 ,the circuit runs from one pole of the battery to the bell and then to one post of the annunciator4 ,from the other post a wire runs to one terminal of the switch at the door or window4 ,the other switch terminal has a wire running to the other pole of the battery4 ,a1 ,b1 ,c represent the circuit wires from the terminals of the window and door switches1 to the annunciators4 ,it is entirely immaterial which side of the battery is connected up with the bell4 ,from the foregoing it will readily be understood how to connect up any ordinary apparatus1 remembering that in all cases the magnet must be brought into the electric circuit4 ,,chapter ,,viii ,,accumulators4 ,,storage ,,or ,,secondary ,,batteries ,,storing ,,up ,,electricity4--,in the foregoing chapters we have seen that1 originally1 electricity was confined in a bottle1 called the ,leyden jar1 from which it was wholly discharged at a single impulse1 as soon as it was connected up by external means4 ,later the primary battery and the dynamo were invented to generate a constant current1 and after these came the second form of storing electricity1 called the storage or secondary battery1 and later still recognized as accumulators4 ,,the ,,accumulator4--,the term accumulator is1 strictly speaking1 the more nearly correct1 as electricity is1 in reality1 stored in an accumulator4 ,but when an accumulator is charged by a current of electricity1 a chemical change is gradually produced in the active element of which the accumulator is made4 ,this change or decomposition continues so long as the charging current is on4 ,when the accumulator is disconnected from the charging battery or dynamo1 and its terminals are connected up with a lighting system1 or with a motor1 for instance1 a reverse process is set up1 or the particles re-form themselves into their original compositions1 which causes a current to flow in a direction opposite to that of the charging current4 ,it is immaterial to the purposes of this chapter1 as to the charging source1 whether it be by batteries or dynamos2 the same principles will apply in either case4 ,illustration3 ,fig4 #fb4 ,,accumulator ,,grids ,,accumulator ,,plates4--,the elements used for accumulator plates are red lead for the positive plates1 and precipitated lead1 or the well-known litharge1 for the negative plates4 ,experience has shown that the best way to hold this material is by means of lead grids4 ,fig4 #fb shows the typical form of one of these grids4 ,it is made of lead1 cast or molded in one piece1 usually square1 as at ,a1 with a wing or projection 7,b71 at one margin1 extending upwardly and provided with a hole 7,c74 ,the grid is about a quarter of an inch thick4 ,,the ,,grid4--,the open space1 called the grid1 proper1 comprises cross bars1 integral with the plate1 made in a variety of shapes4 ,fig4 #fb shows three forms of constructing these bars or ribs1 the object being to provide a form which will hold in the lead paste1 which is pressed in so as to make a solid-looking plate when completed4 ,,the ,,positive ,,plate4--,the positive plate is made in the following manner3 ,make a stiff paste of red lead and sulphuric acid2 using a solution1 say1 of one part of acid to two parts of water4 ,the grid is laid on a flat surface and the paste forced into the perforations with a stiff knife or spatula4 ,turn over the grid so as to get the paste in evenly on both sides4 ,the grid is then stood on its edge1 from #ah to #bj hours1 to dry1 and afterwards immersed in a concentrated solution of chloride of lime1 so as to convert it into lead peroxide4 ,when the action is complete it is thoroughly rinsed in cold water1 and is ready to use4 ,,the ,,negative ,,plate4--,the negative plate is filled1 in like manner1 with precipitated lead4 ,this lead is made by putting a strip of zinc into a standard solution of acetate of lead1 and crystals will then form on the zinc4 ,these will be very thin1 and will adhere together1 firmly1 forming a porous mass4 ,this1 when saturated and kept under water for a short time1 may be put into the openings of the negative plate4 ,illustration3 ,fig4 #fc4 ,,assemblage ,,of ,,accumulator ,,plates ,,connecting ,,up ,,the ,,plates4--,the next step is to put these plates in position to form a battery4 ,in ,fig4 #fc is shown a collection of plates connected together4 ,for simplicity in illustrating1 the cell is made up of glass1 porcelain1 or hard rubber1 with five plates 7,a71 ,a1 ,a representing the negative and ,b1 ,b the positive plates4 ,a base of grooved strips 7,c1 ,c7 is placed in the batteries of the cell to receive the lower ends of the plates4 ,the positive plates are held apart by means of a short section of tubing 7,d71 which is clamped and held within the plates by a bolt 7,e71 this bolt also being designed to hold the terminal strip 7,f74 ,in like manner1 the negative plates are held apart by the two tubular sections 7,g71 each of which is of the same length as the section ,d of the positives4 ,the bolt 7,h7 holds the negatives together as well as the terminal 7,i74 ,the terminals should be lead strips1 and it would be well1 owing to the acid fumes which are formed1 to coat all brass work1 screws1 etc41 with paraffine wax4 ,the electrolyte or acid used in the cell1 for working purposes1 is a pure sulphuric acid1 which should be diluted with about four times its weight in water4 ,remember1 you should always add the strong acid to the water1 and never pour the water into the acid1 as the latter method causes a dangerous ebullition1 and does not produce a good mixture4 ,put enough of this solution into the cell to cover the tops of the plates1 and the cell is ready4 ,illustration3 ,fig4 #fd4 ,,connecting ,,up ,,storage ,,battery ,,in ,,series ,,charging ,,the ,,cells4--,the charge of the current must never be less than #b4e volts4 ,each cell has an output1 in voltage1 of about #b volts1 hence if we have1 say1 #aj cells1 we must have at least #be volts charging capacity4 ,we may arrange these in one line1 or in series1 as it is called1 so far as the connections are concerned1 and charge them with a dynamo1 or other electrical source1 which shows a pressure of #be volts1 as illustrated in ,fig4 #fd1 or1 instead of this1 we may put them into two parallel sets of #e cells each1 as shown in ,fig4 #fe1 and use #ab4e volts to charge with4 ,in this case it will take double the time because we are charging with only one-half the voltage used in the first case4 ,the positive pole of the dynamo should be connected with the positive pole of the accumulator cell1 and negative with negative4 ,when this has been done run up the machine until it slightly exceeds the voltage of the cells4 ,thus1 if we have #ej cells in parallel1 like in ,fig4 #fd1 at least #abe volts will be required1 and the excess necessary should bring up the voltage in the dynamo to #ace or #adj volts4 ,illustration3 ,fig4 #fe4 ,,parallel ,,series ,illustration3 ,fig4 #ff4 ,,charging ,,circuit ,,the ,,initial ,,charge4--,it is usual initially to charge the battery from periods ranging from #cf to #dj hours1 and to let it stand for #ab or #ae hours1 after which to re-charge1 until the positive plates have turned to a chocolate color1 and the negative plates to a slate or gray color1 and both plates give off large bubbles of gas4 ,in charging1 the temperature of the electrolyte should not exceed #ajj ,fahrenheit4 ,when using the accumulators they should never be fully discharged4 ,,the ,,charging ,,circuit4--,the diagram 7,fig4 #ff7 shows how a charging circuit is formed4 ,the lamps are connected up in parallel1 as illustrated4 ,each #af-;candle-power #aje-volt lamp will carry #a_/b ampere1 so that1 supposing we have a dynamo which gives #aaj volts1 and we want to charge a #d-volt accumulator1 there will be #e-volt surplus to go to the accumulator4 ,if1 for instance1 you want the cell to have a charge of #b amperes1 four of these lamps should be connected up in parallel4 ,if #c amperes are required1 use #f lamps1 and so on4 ,,chapter ,,ix ,,the ,,telegraph ,the telegraph is a very simple instrument4 ,the key is nothing more or less than a switch which turns the current on and off alternately4 ,the signals sent over the wires are simply the audible sounds made by the armature1 as it moves to and from the magnets4 ,,mechanism ,,in ,,telegraph ,,circuits4--,a telegraph circuit requires three pieces of mechanism at each station1 namely1 a key used by the sender1 a sounder for the receiver1 and a battery4 ,,the ,,sending ,,key4--,the base of the sending instrument is six inches long1 four inches wide1 and three-quarters of an inch thick1 made of wood1 or any suitable non-conducting material4 ,the key 7,a7 is a piece of brass three-eighths by one-half inch in thickness and six inches long4 ,midway between its ends is a cross hole1 to receive the pivot pin 7,b71 which also passes through a pair of metal brackets 7,c1 ,d71 the bracket ,c having a screw to hold one of the line wires1 and the other bracket having a metal switch 7,e7 hinged thereto4 ,this switch bar1 like the brackets1 is made of brass1 one-half inch wide by one-sixteenth of an inch thick4 ,below the forward end of the key 7,a7 is a cross bar of brass 7,f71 screwed to the base by a screw at one end1 to receive the other line wire4 ,directly below the key 7,a7 is a screw 7,g71 so that the key will strike it when moved downwardly4 ,the other end of the bar 7,f7 contacts with the forward end of the switch bar 7,e7 when the latter is moved inwardly4 ,illustration3 ,fig4 #fg4 ,,telegraph ,,sending ,,key ,the forward end of the key 7,a7 has a knob 7,h7 for the fingers1 and the rear end has an elastic 7,i7 attached thereto which is secured to the end of the base1 so that1 normally1 the rear end is held against the base and away from the screw head 7,g74 ,the head 7,j7 of a screw projects from the base at its rear end4 ,key ,a contacts with it4 ,when the key ,a contacts with the screw heads ,g1 ,j1 a click is produced1 one when the key is pressed down and the other when the key is released4 ,you will notice that the two plates ,c1 ,f are connected up in circuit with the battery1 so that1 as the switch ,e is thrown1 so as to be out of contact1 the circuit is open1 and may be closed either by the key ,a or the switch ,e4 ,the use of the switch will be illustrated in connection with the sounder4 ,illustration3 ,fig4 #fh4 ,,telegraph ,,sounder ,when the key ,a is depressed1 the circuit of course goes through plate ,c1 key ,a and plate ,f to the station signalled4 ,,the ,,sounder4--,the sounder is the instrument which carries the electro-magnet4 ,in ,fig4 #fh this is shown in perspective4 ,the base is six inches long and four inches wide1 being made1 preferably1 of wood4 ,near the forward end is mounted a pair of electro-magnets 7,a1 ,a71 with their terminal wires connected up with plates ,b1 ,b'1 to which the line wires are attached4 ,midway between the magnets and the rear end of the base is a pair of upwardly projecting brackets 7,c74 ,between these are pivoted a bar 7,d71 the forward end of which rests between the magnets and carries1 thereon1 a cross bar 7,e7 which is directly above the magnets1 and serves as the armature4 ,the rear end of the base has a screw 7,f7 directly beneath the bar ,d of such height that when the rear end of the bar ,d is in contact therewith the armature ,e will be out of contact with the magnet cores 7,a1 ,a74 ,a spiral spring 7,g7 secured to the rear ends of the arm and to the base1 respectively1 serves to keep the rear end of the key normally in contact with the screw ,f4 ,,connecting ,,up ,,the ,,key ,,and ,,sounder4--,having made these two instruments1 we must next connect them up in the circuit1 or circuits1 formed for them1 as there must be a battery1 a key1 and a sounder at each end of the line4 ,in ,fig4 #fi you will note two groups of those instruments4 ,now observe how the wires connect them together4 ,there are two line wires1 one 7,a7 which connects up the two batteries1 the wire being attached so that one end connects with the positive terminal of the battery1 and the other end with the negative terminal4 ,illustration3 ,fig4 #fi4 ,a ,,telegraph ,,circuit ,the other line wire 7,b71 between the two stations1 has its opposite ends connected with the terminals of the electro-magnet ,c of the sounders4 ,the other terminals of each electro-magnet are connected up with one terminal of each key by a wire 7,d71 and to complete the circuit at each station1 the other terminal of the key has a wire 7,e7 to its own battery4 ,,two ,,stations ,,in ,,circuit4--,the illustration shows station #b telegraphing to station #a4 ,this is indicated by the fact that the switch ,f' of that instrument is open1 and the switch ,f of station #a closed4 ,when1 therefore1 the key of station #b is depressed1 a complete circuit is formed which transmits the current through wire ,e' and battery1 through line ,a1 then through the battery of station #a1 through wire ,e to the key1 and from the key1 through wire ,d1 to the sounder1 and finally from the sounder over line wire ,b back to the sounder of station #b1 completing the circuit at the key through wire ,d'4 ,when the operator at station #b closes the switch ,f'1 and the operator at station #a opens the switch ,f1 the reverse operation takes place4 ,in both cases1 however1 the sounder is in at both ends of the line1 and only the circuit through the key is cut out by the switch ,f1 or ,f'4 ,,the ,,double ,,click4--,the importance of the double click of the sounder will be understood when it is realized that the receiving operator must have some means of determining if the sounder has transmitted a dot or a dash4 ,whether he depresses the key for a dot or a dash1 there must be one click when the key is pressed down on the screw head ,g 7,fig4 #fb71 and also another click1 of a different kind1 when the key is raised up so that its rear end strikes the screw head ,j4 ,this action of the key is instantly duplicated by the bar ,d 7,fig4 #fh7 of the sounder1 so that the sounder as well as the receiver knows the time between the first and the second click1 and by that means he learns that a dot or a dash is made4 ,,illustrating ,,the ,,dot ,,and ,,the ,,dash4--,to illustrate3 ,let us suppose1 for convenience1 that the downward movement of the lever in the key1 and the bar in the sounder1 make a sharp click1 and the return of the lever and bar make a dull click4 ,in this case the ear1 after a little practice1 can learn readily how to distinguish the number of downward impulses that have been given to the key4 ,the ,morse ,telegraph ,code ,a 4 - ,n - 4 4 444 ,b - 444 ,o 44 #a 4 - - 4 ,c 44 4 ,p 44444 #b 44 - 44 ,d - 4 4 ,q 44 - 4 #c 444 - 4 ,e 4 ,r 4 44 #d 4444 - ,f 4 - 4 ,s 444 #e - - - ,g - - 4 ,t - #f 444444 ,h 4444 ,u 44 - #g - - 44 ,i 44 ,v 444 - #h - 4444 ,j - 4 - 4 ,w 4 - - #i - 44 - ,k - 4 - ,x 4 - 44 #j ---- ------ ,l -- ,y 44 44 ,m - - ,z 444 4 ,,example ,,in ,,use4--,let us take an example in the word electrical4 ,e ,l ,e ,c ,t ,r ,i ,c ,a ,l 4 -- 4 44 4 - 4 44 44 44 4 4 - -- ,the operator first makes a dot1 which means a sharp and a dull click close together2 there is then a brief interval1 then a lapse1 after which there is a sharp click1 followed1 after a comparatively longer interval1 with the dull click4 ,now a dash by itself may be an ,l1 a ,t1 or the figure #j1 dependent upon its length4 ,the short dash is ,t1 and the longest dash the figure #j4 ,the operator will soon learn whether it is either of these or the letter ,l1 which is intermediate in length4 ,in time the sender as well as receiver will give a uniform length to the dash impulse1 so that it may be readily distinguished4 ,in the same way1 we find that ,r1 which is indicated by a dot1 is followed1 after a short interval1 by two dots4 ,this might readily be mistaken for the single dot for ,e and the two dots for ,i1 were it not that the time element in ,r is not as long between the first and second dots1 as it ordinarily is between the single dot of ,e when followed by the two dots of ,i4 ,,chapter ,x ,,high ,,tension ,,apparatus1 ,,condensers1 ,,etc4 ,,induction4--,one of the most remarkable things in electricity is the action of induction--that property of an electric current which enables it to pass from one conductor to another conductor through the air4 ,another singular and interesting thing is that the current so transmitted across spaces changes its direction of flow1 and1 furthermore1 the tension of such a current may be changed by transmitting it from one conductor to another4 ,,low ,,and ,,high ,,tension4--,in order to effect this latter change--that is1 to convert it from a low tension to a high tension--coils are used1 one coil being wound upon the other2 one of these coils is called the primary and the other the secondary4 ,the primary coil receives the current from the battery1 or source of electrical power1 and the secondary coil receives charges1 and transmits the current4 ,for an illustration of this examine ,fig4 #gj1 in which you will note a coil of heavy wire 7,a71 around which is wound a coil of fine wire 7,b74 ,if1 for instance1 the primary coil has a low voltage1 the secondary coil will have a high voltage1 or tension4 ,advantage is taken of this phase to use a few cells1 as a primary battery1 and then1 by a set of ,induction ,coils1 as they are called1 to build up a high-tension electro-motive force1 so that the spark will jump across a gap1 as shown at ,c1 for the purpose of igniting the charges of gas in a gasoline motor2 or the current may be used for medical batteries1 and for other purposes4 ,illustration3 ,fig4 #gj4 ,,induction ,,coil ,,and ,,circuit ,the current passes1 by induction1 from the primary to the secondary coil4 ,it passes from a large conductor to a small conductor1 the small conductor having a much greater resistance than the large one4 ,,elastic ,,property ,,of ,,electricity4--,while electricity has no resiliency1 like a spring1 for instance1 still it acts in the manner of a cushion under certain conditions4 ,it may be likened to an oscillating spring acted upon by a bar4 ,referring to ,fig4 #ga1 we will assume that the bar ,a in falling down upon the spring ,b compresses the latter1 so that at the time of greatest compression the bar goes down as far as the dotted line ,c4 ,it is obvious that the spring ,b will throw the bar upwardly4 ,now1 electricity appears to have a kind of elasticity1 which characteristic is taken advantage of in order to increase the efficiency of the induction in the coil4 ,illustration3 ,fig4 #ga4 ,,illustrating ,,elasticity ,,the ,,condenser4--,to make a condenser1 prepare two pine boards like ,a1 say1 eight by ten inches and a half inch thick1 and shellac thoroughly on all sides4 ,then prepare sheets of tinfoil 7,b71 six by eight inches in size1 and also sheets of paraffined paper 7,c71 seven by nine inches in dimensions4 ,also cut out from the waste pieces of tinfoil strips 7,d71 one inch by two inches4 ,to build up the condenser1 lay down a sheet of paraffined paper 7,c71 then a sheet of tinfoil 7,b71 and before putting on the next sheet of paraffined paper lay down one of the small strips 7,d7 of tinfoil1 as shown in the illustration1 so that its end projects over one end of the board ,a2 then on the second sheet of paraffine paper lay another sheet of tinfoil1 and on this1 at the opposite end1 place one of the small strips 7,d71 and so on1 using from #ej to #ajj of the tinfoil sheets4 ,when the last paraffine sheet is laid on1 the other board is placed on top1 and the whole bound together1 either by wrapping cords around the same or by clamping them together with bolts4 ,illustration3 ,fig4 #gb4 ,,condenser ,you may now make a hole through the projecting ends of the strips1 and you will have two sets of tinfoil sheets1 alternately connected together at opposite ends of the condenser4 ,care should be exercised to leave the paraffine sheets perfect or without holes4 ,you can make these sheets yourself by soaking them in melted paraffine wax4 ,,connecting ,,up ,a ,,condenser4--,when completed1 one end of the condenser is connected up with one terminal of the secondary coil1 and the other end of the condenser with the other secondary terminal4 ,illustration3 ,fig4 #gc4 ,,high-,,tension ,,circuit ,in ,fig4 #gc a high-tension circuit is shown4 ,two coils1 side by side1 are always used to show an induction coil1 and a condenser is generally shown1 as illustrated1 by means of a pair of forks1 one resting within the other4 ,,the ,,interrupter4--,one other piece of mechanism is necessary1 and that is an ,interrupter1 for the purpose of getting the effect of the pulsations given out by the secondary coil4 ,a simple current interrupter is made as follows3 ,prepare a wooden base 7,a71 one inch thick1 six inches wide1 and twelve inches long4 ,upon this mount a toothed wheel 7,b71 six inches in diameter1 of thin sheet metal1 or a brass gear wheel will answer the purpose4 ,the standard 7,c71 which supports the wheel1 may be of metal bent up to form two posts1 between which the crankshaft 7,d7 is journaled4 ,the base of the posts has an extension plate 7,e71 with a binding post for a wire4 ,at the front end of the base is an ,l-shaped strip 7,f71 with a binding post for a wire connection1 and the upwardly projecting part of the strip contacts with the toothed wheel4 ,when the wheel ,b is rotated the spring finger 7,f7 snaps from one tooth to the next1 so that1 momentarily1 the current is broken1 and the frequency is dependent upon the speed imparted to the wheel4 ,illustration3 ,fig4 #gd4 ,,current ,,interrupter ,,uses ,,of ,,high-,,tension ,,coils4--,this high-tension coil is made use of1 and is the essential apparatus in wireless telegraphy1 as we shall see in the chapter treating upon that subject4 ,,chapter ,,xi ,,wireless ,,telegraphy ,,telegraphing ,,without ,,wires4--,wireless telegraphy is an outgrowth of the ordinary telegraph system4 ,when ,maxwell1 and1 later on1 ,hertz1 discovered that electricity1 magnetism1 and light were transmitted through the ether1 and that they differed only in their wave lengths1 they laid the foundations for wireless telegraphy4 ,ether is a substance which is millions and millions of times lighter than air1 and it pervades all space4 ,it is so unstable that it is constantly in motion1 and this phase led some one to suggest that if a proper electrical apparatus could be made1 the ether would thereby be disturbed sufficiently so that its impulses would extend out a distance proportioned to the intensity of the electrical agitation thereby created4 ,,surging ,,character ,,of ,,high-,,tension ,,currents4--,when a current of electricity is sent through a wire1 hundreds of miles in length1 the current surges back and forth on the wire many thousands of times a second4 ,light comes to us from the sun1 over #ij1jjj1jjj of miles1 through the ether4 ,it is as reasonable to suppose1 or infer1 that the ether can1 therefore1 convey an electrical impulse as readily as does a wire4 ,it is on this principle that impulses are sent for thousands of miles1 and no doubt they extend even farther1 if the proper mechanism could be devised to detect movement of the waves so propagated4 ,,the ,,coherer4--,the instrument for detecting these impulses1 or disturbances1 in the ether is generally called a coherer1 although detector is the term which is most satisfactory4 ,the name coherer comes from the first practical instrument made for this purpose4 ,illustration3 ,fig4 #ge4 ,,wireless ,,telegraphy ,,coherer ,,how ,,made4--,the coherer is simply a tube1 say1 of glass1 within which is placed iron filings4 ,when the oscillations surge through the secondary coil the pressure or potentiality of the current finally causes it to leap across the small space separating the filings and1 as it were1 it welds together their edges so that a current freely passes4 ,the bringing together of the particles1 under these conditions1 is called cohering4 ,fig4 #ge shows the simplest form of coherer4 ,the posts 7,a7 are firmly affixed to the base 7,b71 each post having an adjusting screw 7,c7 in its upper end1 and these screw downwardly against and serve to bind a pair of horizontal rods 7,d71 the inner ends of which closely approach each other4 ,these may be adjusted so as to be as near together or as far apart as desired4 ,e is a glass tube in which the ends of the rods 7,d7 rest1 and between the separated ends of the rods 7,d7 the iron filings 7,f7 are placed4 ,,the ,,decoherers4--,for the purpose of causing the metal filings to fall apart1 or decohere1 the tube is tapped lightly1 and this is done by a little object like the clapper of an electric bell4 ,in practice1 the coils and the parts directly connected with it are put together on one base4 ,,the ,,sending ,,apparatus4--,fig4 #gf shows a section of a coil with its connection in the sending station4 ,the spark gap rods 7,a7 may be swung so as to bring them closer together or farther apart1 but they must not at any time contact with each other4 ,the induction coil has one terminal of the primary coil connected up by a wire 7,b7 with one post of a telegraph key1 and the other post of the key has a wire connection 7,c71 with one side of a storage battery4 ,the other side of the battery has a wire 7,d7 running to the other terminal of the primary4 ,illustration3 ,fig4 #gf4 ,,wireless ,,sending ,,apparatus ,the secondary coil has one of its terminals connected with a binding post 7,e74 ,this binding post has an adjustable rod with a knob 7,f7 on its end1 and the other binding post 7,g71 which is connected up with the other terminal of the secondary coil1 carries a similar adjusting rod with a knob 7,h74 ,from the post 7,e7 is a wire 7,i71 which extends upwardly1 and is called the aerial wire1 or wire for the antenn1 and this wire also connects with one side of the condenser by a conductor 7,j74 ,the ground wire 7,k7 connects with the other binding post 7,g71 and a branch wire 7,l7 also connects the ground wire 7,k7 with one end of the condenser4 ,illustration3 ,fig4 #gg4 ,,wireless ,,receiving ,,apparatus ,,the ,,receiving ,,apparatus4--,the receiving station1 on the other hand1 has neither condenser1 induction coil1 nor key4 ,when the apparatus is in operation1 the coherer switch is closed1 and the instant a current passes through the coherer and operates the telegraph sounder1 the galvanometer indicates the current4 ,of course1 when the coherer switch is closed1 the battery operates the decoherer4 ,,how ,,the ,,circuits ,,are ,,formed4--,by referring again to ,fig4 #gf1 it will be seen that when the key is depressed1 a circuit is formed from the battery through wire ,b to the primary coil1 and back again to the battery through wire ,d4 ,the secondary coil is thereby energized1 and1 when the full potential is reached1 the current leaps across the gap formed between the two knobs 7,f1 ,h71 thereby setting up a disturbance in the ether which is transmitted through space in all directions4 ,it is this impulse1 or disturbance1 which is received by the coherer at the receiving station1 and which is indicated by the telegraph sounder4 ,,chapter ,,xii ,,the ,,telephone ,,vibrations4--,every manifestation in nature is by way of vibration4 ,the beating of the heart1 the action of the legs in walking1 the winking of the eyelid2 the impulses from the sun1 which we call light2 sound1 taste and color appeal to our senses by vibratory means1 and1 as we have hereinbefore stated1 the manifestations of electricity and magnetism are merely vibrations of different wave lengths4 ,,the ,,acoustic ,,telephone4--,that sound is merely a product of vibrations may be proven in many ways4 ,one of the earliest forms of telephones was simply a sound telephone1 called the ,acoustic ,telephone4 ,the principle of this may be illustrated as follows3 ,take two cups 7,a1 ,b71 as in ,fig4 #gh1 punch a small hole through the bottom of each1 and run a string or wire 7,c7 from the hole of one cup to that of the other1 and secure it at both ends so it may be drawn taut4 ,now1 by talking into the cup 7,a7 the bottom of it will vibrate to and fro1 as shown by the dotted lines and thereby cause the bottom of the other cup 7,b7 to vibrate in like manner1 and in so vibrating it will receive not only the same amplitude1 but also the same character of vibrations as the cup 7,a7 gave forth4 ,illustration3 ,fig4 #gh4 ,,acoustic ,,telephone ,illustration3 ,fig4 #gi4 ,,illustrating ,,vibrations ,,sound ,,waves4--,sound waves are long and short2 the long waves giving sounds which are low in the musical scale1 and the short waves high musical tones4 ,you may easily determine this by the following experiment3 ,stretch a wire1 as at ,b 7,fig4 #gi71 fairly tight1 and then vibrate it4 ,the amplitude of the vibration will be as indicated by dotted line ,a4 ,now1 stretch it very tight1 as at ,c1 so that the amplitude of vibration will be as shown at ,e4 ,by putting your ear close to the string you will find that while ,a has a low pitch1 ,c is very much higher4 ,this is the principle on which stringed instruments are built4 ,you will note that the wave length1 which represents the distance between the dotted lines ,a is much greater than ,e4 ,,hearing ,,electricity4--,in electricity1 mechanism has been made to enable man to note the action of the current4 ,by means of the armature1 vibrating in front of a magnet1 we can see its manifestations4 ,it is now but a step to devise some means whereby we may hear it4 ,in this1 as in everything else electrically1 the magnet comes into play4 ,illustration3 ,fig4 #hj4 ,,the ,,magnetic ,,field ,in the chapter on magnetism1 it was stated that the magnetic field extended out beyond the magnet1 so that if we were able to see the magnetism1 the end of a magnet would appear to us something like a moving field1 represented by the dotted lines in ,fig4 #hj4 ,the magnetic field is shown in ,fig4 #hj at only one end1 but its manifestations are alike at both ends4 ,it will be seen that the magnetic field extends out to a considerable distance and has quite a radius of influence4 ,,the ,,diaphragm ,,in ,a ,,magnetic ,,field4--,if1 now1 we put a diaphragm 7,a7 in this magnetic field1 close up to the end of the magnet1 but not so close as to touch it1 and then push it in and out1 or talk into it so that the sound waves strike it1 the movement or the vibration of the diaphragm 7,a7 will disturb the magnetic field emanating from the magnet1 and this disturbance of the magnetic field at one end of the magnet also affects the magnetic field at the other end in the same way1 so that the disturbance there will be of the same amplitude4 ,it will also display the same characteristics as did the magnetic field when the diaphragm 7,a7 disturbed it4 ,a ,,simple ,,telephone ,,circuit4--,from this simple fact grew the telephone4 ,if two magnets are connected up in the same circuit1 so that the magnetic fields of the two magnets have the same source of electric power1 the disturbance of one diaphragm will affect the other similarly1 just the same as the two magnetic fields of the single magnet are disturbed in unison4 ,,how ,,to ,,make ,a ,,telephone4--,for experimental and testing purposes two of these telephones should be made at the same time4 ,the case or holder 7,a7 may be made either of hard wood or hard rubber1 so that it is of insulating material4 ,the core 7,b7 is of soft iron1 #c_/h inch in diameter and #e inches long1 bored and threaded at one end to receive a screw 7,c7 which passes through the end of the case 7,a74 ,the enlarged end of the case should be1 exteriorly1 #b-a_/d inches in diameter1 and the body of the case #a inch in diameter4 ,illustration3 ,fig4 #ha4 ,,section ,,of ,,telephone ,,receiver ,interiorly1 the large end of the case is provided with a circular recess #a-c_/d inches in diameter and adapted to receive therein a spool which is1 diametrically1 a little smaller than the recess4 ,the spool fits fairly tight upon the end of the core1 and when in position rests against an annular shoulder in the recess4 ,a hollow space 7,f7 is thus provided behind the spool 7,d71 so the two wires from the magnet may have room where they emerge from the spool4 ,the spool is a little shorter than the distance between the shoulder 7,e7 and the end of the casing1 at ,g1 and the core projects only a short distance beyond the end of the spool1 so that when the diaphragm 7,h7 is put upon the end of the case1 and held there by screws 7,i7 it will not touch the end of the core4 ,a wooden or rubber mouthpiece 7,j7 is then turned up to fit over the end of the case4 ,illustration3 ,fig4 #hb4 ,,the ,,magnet ,,and ,,receiver ,,head ,the spool 7,d7 is made of hard rubber1 and is wound with ,no4 #bd silk-covered wire1 the windings to be well insulated from each other4 ,the two ends of the wire are brought out1 and threaded through holes 7,k7 drilled longitudinally through the walls of the case1 and affixed to the end by means of screws 7,l71 so that the two wires may be brought together and connected with a duplex wire 7,m74 ,as the screw 7,c71 which holds the core in place1 has its head hidden within a recess1 which can be closed up by wax1 the two terminals of the wires are well separated so that short-circuiting cannot take place4 ,,telephone ,,connections4--,the simplest form of telephone connection is shown in ,fig4 #hc4 ,this has merely the two telephones 7,a and ,b71 with a single battery 7,c7 to supply electricity for both4 ,one line wire 7,d7 connects the two telephones directly1 while the other line 7,e7 has the battery in its circuit4 ,illustration3 ,fig4 #hc4 ,,simple ,,telephone ,,connection ,,complete ,,installation4--,to install a more complete system requires1 at each end1 a switch1 a battery and an electro-magneto bell4 ,you may use1 for this purpose1 a bell1 made as shown in the chapter on bells4 ,fig4 #hd shows such a circuit4 ,we now dispense with one of the line wires1 because it has been found that the ground between the two stations serves as a conductor1 so that only one line wire 7,a7 is necessary to connect directly with the telephones of the two stations4 ,the telephones 7,b1 ,b'1 respectively7 have wires 7,c1 ,c'7 running to the pivots of double-throw switches 7,d1 ,d'71 one terminal of the switches having wires 7,e1 ,e'71 which go to electric bells 7,f1 ,f'71 and from the bells are other wires 7,g1 ,g'71 which go to the ground4 ,the ground wires also have wires 7,h1 ,h'71 which go to the other terminals of the switch 7,d1 ,d'74 ,the double-throw switch 7,d1 ,d'71 in the two stations1 is thrown over so the current1 if any should pass through1 will go through the bell to the ground1 through the wires 7,e1 ,g or ,e'1 ,g'74 ,illustration3 ,fig4 #hd4 ,,telephone ,,stations ,,in ,,circuit ,now1 supposing the switch 7,d'71 in station #b1 should be thrown over so it contacts with the wire 7,h'74 ,it is obvious that the current will then flow from the battery 7,i'7 through wires 7,h'1 ,c'7 and line 7,a7 to station #a2 then through wire ,c1 switch ,d1 wire ,e to the bell ,f1 to the ground through wire ,g4 ,from wire ,g the current returns through the ground to station #b1 where it flows up wire ,g' to the battery1 thereby completing the circuit4 ,illustration3 ,fig4 #he4 ,,illustrating ,,light ,,contact ,,points ,the operator at station #b1 having given the signal1 again throws his switch 7,d'7 back to the position shown in ,fig4 #hd1 and the operator at station #a throws on his switch 7,d71 so as to ring the bell in station #b1 thereby answering the signal1 which means that both switches are again to be thrown over so they contact with the battery wires 7,h and ,h'71 respectively4 ,when both are thus thrown over1 the bells 7,g1 ,g'7 are cut out of the circuit1 and the batteries are both thrown in1 so that the telephones are now ready for talking purposes4 ,,microphone4--,originally this form of telephone system was generally employed1 but it was found that for long distances a more sensitive instrument was necessary4 ,,light ,,contact ,,points4--,in #ahgg ,professor ,hughes discovered1 accidentally1 that a light contact point in an electric circuit augmented the sound in a telephone circuit4 ,if1 for instance1 a light pin1 or a nail 7,a1 ,fig4 #he7 should be used to connect the severed ends of a wire 7,b71 the sounds in the telephone not only would be louder1 but they would be more distinct1 and the first instrument made practically1 to demonstrate this1 is shown in ,fig4 #hf4 ,illustration3 ,fig4 #hf4 ,,microphone ,illustration3 ,fig4 #hg4 ,,transmitter ,,how ,,to ,,make ,a ,,microphone4--,this instrument has simply a base 7,a7 of wood1 and near one end is a perpendicular sounding-board 7,b7 of wood1 to one side of which is attached1 by wax or otherwise1 a pair of carbon blocks 7,c1 ,d74 ,the lower carbon block 7,c7 has a cup-shaped depression in its upper side1 and the upper block has a similar depression in its lower side4 ,a carbon pencil 7,e7 is lightly held within these cups1 so that the lightest contact of the upper end of the pencil with the carbon block1 makes the instrument so sensitive that a fly1 walking upon the sounding-board1 may be distinctly heard through the telephone which is in the circuit4 ,,microphone ,,the ,,father ,,of ,,the ,,transmitter4--,this instrument has been greatly modified1 and is now used as a transmitter1 the latter thereby taking the place of the pin 7,a71 shown in ,fig4 #he4 ,,automatic ,,cut-,,outs ,,for ,,telephones4--,in the operation of the telephone1 the great drawback originally was in inducing users of the lines to replace or adjust their instruments carefully4 ,when switches were used1 they would forget to throw them back1 and all sorts of trouble resulted4 ,it was found necessary to provide an automatic means for throwing in and cutting out an instrument1 this being done by hanging the telephone on the hook1 so that the act merely of leaving the telephone made it necessary1 in replacing the instrument1 to cut out the apparatus4 ,before describing the circuiting required for these improvements1 we show1 in ,fig4 #hg1 a section of a transmitter4 ,a cup-shaped case 7,a7 is provided1 made of some insulating material1 which has a diaphragm 7,b7 secured at its open side4 ,this diaphragm carries the carbon pencil 7,c7 on one side and from the blocks which support the carbon pencil the wires run to binding posts on the case4 ,of course the carbon supporting posts must be insulated from each other1 so the current will go through the carbon pencil 7,c74 ,,complete ,,circuiting ,,with ,,transmitter4--,in showing the circuiting 7,fig4 #hh7 it will not be possible to illustrate the boxes1 or casings1 which receive the various instruments4 ,for instance1 the hook which carries the telephone or the receiver1 is hinged within the transmitter box4 ,the circuiting is all that it is intended to show4 ,illustration3 ,fig4 #hh4 ,,complete ,,telephonic ,,circuit ,the batteries of the two stations are connected up by a wire 7,a71 unless a ground circuit is used4 ,the other side of each battery has a wire connection 7,b1 ,b'7 with one terminal of the transmitter1 and the other terminal of the transmitter has a wire 7,c1 ,c'7 which goes to the receiver4 ,from the other terminal of the receiver is a wire 7,d1 ,d'7 which leads to the upper stop contact 7,e1 ,e'7 of the telephone hook4 ,a wire 7,f1 ,f'7 from the lower stop contact 7,g1 ,g'7 of the hook goes to one terminal of the bell1 and from the other terminal of the bell is a wire 7,h1 ,h'7 which makes connection with the line wire 7,a74 ,in order to make a complete circuit between the two stations1 a line wire 7,i7 is run from the pivot of the hook in station #a to the pivot of the hook in station #b4 ,in the diagram1 it is assumed that the receivers are on the hooks1 and that both hooks are1 therefore1 in circuit with the lower contacts 7,g1 ,g'71 so that the transmitter and receiver are both out of circuit with the batteries1 and the bell in circuit2 but the moment the receiver1 for instance1 in station #a is taken off the hook1 the latter springs up so that it contacts with the stop 7,e71 thus establishing a circuit through the line wire 7,i7 to the hook of station #b1 and from the hook through line 7,f'7 to the bell4 ,from the bell1 the line 7,a7 carries the current back to the battery of station 7,a71 thence through the wire 7,b7 to the transmitter wire 7,c7 to receiver and wire 7,d7 to the post 7,e71 thereby completing the circuit4 ,when1 at station #b1 the receiver is taken off the hook1 and the latter contacts with the post 7,e'71 the transmitter and receiver of both stations are in circuit with each other1 but both bells are cut out4 ,,chapter ,,xiii ,,electrolysis1 ,,water ,,purification1 ,,electroplating ,,decomposing ,,liquids4--,during the earlier experiments in the field of electricity1 after the battery or cell was discovered1 it was noted that when a current was formed in the cell1 the electrolyte was charged and gases evolved from it4 ,a similar action takes place when a current of electricity passes through a liquid1 with the result that the liquid is decomposed--that is1 the liquid is broken up into its original compounds4 ,thus1 water is composed of two parts1 by bulk1 of hydrogen and of oxygen1 so that if two electrodes are placed in water1 and a current is sent through the electrodes in either direction1 all the water will finally disappear in the form of hydrogen and oxygen gases4 ,,making ,,hydrogen ,,and ,,oxygen4--,during this electrical action1 the hydrogen is set free at the negative pole and the oxygen at the positive pole4 ,a simple apparatus1 which any boy can make1 to generate pure oxygen and pure hydrogen1 is shown in ,fig4 #hi4 ,it is constructed of a glass or earthen jar 7,a71 preferably square1 to which is fitted a wooden top 7,b71 this top being provided with a packing ring 7,c71 so as to make it air-tight4 ,within is a vertical partition 7,d71 the edges of which1 below the cap1 fit tightly against the inner walls of the jar4 ,this partition extends down into the jar a sufficient distance so it will terminate below the water level4 ,a pipe is fitted through the top on each side of the partition1 and each pipe has a valve4 ,an electrode1 of any convenient metal1 is secured at its upper end to the top of the cap1 on each side of the partition4 ,these electrodes extend down to the bottom of the jar1 and an electric wire connects with each of them at the top4 ,illustration3 ,fig4 #hi4 ,,device ,,for ,,making ,,hydrogen ,,and ,,oxygen ,if a current of electricity is passed through the wires and the electrodes1 in the direction shown by the darts1 hydrogen will form at the negative pole1 and oxygen at the positive pole4 ,these gases will escape upwardly1 so that they will be trapped in their respective compartments1 and may be drawn off by means of the pipes4 ,,purifying ,,water4--,advantage is taken of this electrolytic action1 to purify water4 ,oxygen is the most wonderful chemical in nature4 ,it is called the acid-maker of the universe4 ,the name is derived from two words1 oxy and gen2 one denoting oxydation1 and the other that it generates4 ,in other words1 it is the generator of oxides4 ,it is the element which1 when united with any other element1 produces an acid1 an alkali or a neutral compound4 ,,rust4--,for instance1 iron is largely composed of ferric acid4 ,when oxygen1 in a free or gaseous state1 comes into contact with iron1 it produces ferrous oxide1 which is recognized as rust4 ,,oxygen ,,as ,a ,,purifier4--,but oxygen is also a purifier4 ,all low forms of animal life1 like bacteria or germs in water1 succumb to free oxygen4 ,by free oxygen is meant oxygen in the form of gas4 ,,composition ,,of ,,water4--,now1 water1 in which harmful germs live1 is one-third oxygen4 ,nevertheless1 the germs thrive in water1 because the oxygen is in a compound state1 and1 therefore1 not an active agent4 ,but if oxygen1 in the form of gas1 can be forced through water1 it will attack the germs1 and destroy them4 ,,common ,,air ,,not ,a ,,good ,,purifier4--,water may be purified1 to a certain extent1 by forcing common air through it1 and the foulest water1 if run over rocks1 will be purified1 in a measure1 because air is intermingled with it4 ,but common air is composed of four-fifths nitrogen1 and only one-fifth oxygen1 and1 as nitrogen is the staple article of food for bacteria1 the purifying method by air is not effectual4 ,,pure ,,oxygen4--,when1 however1 oxygen is generated from water1 by means of electrolysis1 it is pure2 hence is more active and is not tainted by a life-giving substance for germs1 such as nitrogen4 ,the mechanism usually employed for purifying water is shown in ,fig4 #ij4 ,a ,,water ,,purifier4--,the case 7,a1 ,fig4 #ij7 may be made of metal or of an insulating material4 ,if made of metal it must be insulated within with slate1 glass1 marble or hard rubber1 as shown at ,b4 ,the case is provided with exterior flanges 7,c1 ,d71 with upper and lower ends1 and it is mounted upon a base plate 7,e7 and affixed thereto by bolts4 ,the upper end has a conically-formed cap 7,f7 bolted to the flanges 7,c71 and this has an outlet to which a pipe 7,g7 is attached4 ,the water inlet pipe 7,h7 passes through the lower end of the case 7,a74 ,the electrodes 7,i1 ,j7 are secured1 vertically1 within the case1 separated from each other equidistant1 each alternate electrode being connected up with one wire 7,k71 and the alternate electrodes with a wire 7,l74 ,illustration3 ,fig4 #ij4 ,,electric ,,water ,,purifier ,when the water passes upwardly1 the decomposed or gaseous oxygen percolates through the water and thus attacks the germs and destroys them4 ,,the ,,use ,,of ,,hydrogen ,,in ,,purification4--,on the other hand1 the hydrogen also plays an important part in purifying the water4 ,this depends upon the material of which the electrodes are made4 ,aluminum is by far the best material1 as it is one of nature's most active purifiers4 ,all clay contains aluminum1 in what is known as the sulphate form1 and water passing through the clay of the earth thereby becomes purified1 because of this element4 ,,aluminum ,,electrodes4--,when this material is used as the electrodes in water1 hydrate of aluminum is formed1 or a compound of hydrogen and oxygen with aluminum4 ,the product of decomposition is a flocculent matter which moves upwardly through the water1 giving it a milky appearance4 ,this substance is like gelatine1 so that it entangles or enmeshes the germ life and prevents it from passing through a filter4 ,if no filter is used1 this flocculent matter1 as soon as it has given off the gases1 will settle to the bottom and carry with it all decomposed matter1 such as germs and other organic matter attacked by the oxygen1 which has become entangled in the aluminum hydrate4 ,,electric ,,hand ,,purifier4--,an interesting and serviceable little purifier may be made by any boy with the simplest tools1 by cutting out three pieces of sheet aluminum4 ,hard rolled is best for the purpose4 ,it is better to have one of the sheets 7,a71 the middle one1 thicker than the two outer plates 7,b74 ,illustration3 ,fig4 #ia4 ,,portable ,,electric ,,purifier ,let each sheet be #a-a_/b inches wide and #e-a_/b inches thick4 ,one-half inch from the upper ends of the two outside plates 7,b1 ,b7 bore bolt holes 7,c71 each of these holes being a quarter of an inch from the edge of the plate4 ,the inside plate 7,a7 has two large holes 7,d7 corresponding with the small holes 7,c7 in the outside plates4 ,at the upper end of this plate form a wing 7,e71 #a_/b inch wide and #a_/b inch long1 provided with a small hole for a bolt4 ,next cut out two hard-rubber blocks 7,f71 each #a-a_/b inches long1 #a inch wide and #c_/h inch thick1 and then bore a hole 7,g7 through each1 corresponding with the small holes 7,c7 in the plates 7,b74 ,the machine is now ready to be assembled4 ,if the inner plate is #a_/h inch thick and the outer plates each #a_/af inch thick1 use two small eighth-inch bolts #a-a_/d inches long1 and clamp together the three plates with these bolts4 ,one of the bolts may be used to attach thereto one of the electric wires 7,h71 and the other wire 7,i7 is attached by a bolt to the wing 7,e74 ,illustration3 ,figs4 #ib-ie4 ,,details ,,of ,,portable ,,purifier ,such a device will answer for a #aaj-volt circuit1 in ordinary water4 ,now fill a glass nearly full of water1 and stand the purifier in the glass4 ,within a few minutes the action of electrolysis will be apparent by the formation of numerous bubbles on the plates1 followed by the decomposition of the organic matter in the water4 ,at first the flocculent decomposed matter will rise to the surface of the water1 but before many minutes it will settle to the bottom of the glass and leave clear water above4 ,,purification ,,and ,,separation ,,of ,,metals4--,this electrolytic action is utilized in metallurgy for the purpose of producing pure metals1 but it is more largely used to separate copper from its base4 ,in order to utilize a current for this purpose1 a high ampere flow and low voltage are required4 ,the sheets of copper1 containing all of its impurities1 are placed within a tank1 parallel with a thin copper sheet4 ,the impure sheet is connected with the positive pole of an electroplating dynamo1 and the thin sheet of copper is connected with the negative pole4 ,the electrolyte in the tank is a solution of sulphate of copper4 ,the action of the current will cause the pure copper in the impure sheet to disintegrate and it is then carried over and deposited upon the thin sheet1 this action continuing until the impure sheet is entirely eaten away4 ,all the impurities which were in the sheet fall to the bottom of the tank4 ,other metals are treated in the same way1 and this treatment has a very wide range of usefulness4 ,,electroplating4--,the next feature to be considered in electrolysis is a most interesting and useful one1 because a cheap or inferior metal may be coated by a more expensive metal4 ,silver and nickel plating are brought about by this action of a current passing through metals1 which are immersed in an electrolyte4 ,,plating ,,iron ,,with ,,copper4--,we have room in this chapter for only one concrete example of this work1 which1 with suitable modifications1 is an example of the art as practiced commercially4 ,iron1 to a considerable extent1 is now being coated with copper to preserve it from rust4 ,to carry out this work1 however1 an electroplating dynamo1 of large amperage1 is required1 the amperage1 of course1 depending upon the surface to be treated at one time4 ,the pressure should not exceed #e volts4 ,the iron surface to be treated should first be thoroughly cleansed1 and then immediately put into a tank containing a cyanide of copper solution4 ,two forms of copper solution are used1 namely1 the cyanide1 which is a salt solution of copper1 and the sulphate1 which is an acid solution of copper4 ,cyanide is first used because it does not attack the iron1 as would be the case if the sulphate solution should first come into contact with the iron4 ,a sheet of copper1 termed the anode1 is then placed within the tank1 parallel with the surface to be plated1 known as the cathode1 and so mounted that it may be adjusted to or from the iron surface1 or cathode4 ,a direct current of electricity is then caused to flow through the copper plate and into the iron plate or surface1 and the plating proceeded with until the iron surface has a thin film of copper deposited thereon4 ,this is a slow process with the cyanide solution1 so it is discontinued as soon as possible1 after the iron surface has been completely covered with copper4 ,this copper surface is thoroughly cleaned off to remove therefrom the saline or alkaline solution1 and it is then immersed within a bath1 containing a solution of sulphate of copper4 ,the current is then thrown on and allowed so to remain until it has deposited the proper thickness of copper4 ,,direction ,,of ,,current4--,if a copper and an iron plate are put into a copper solution and connected up in circuit with each other1 a primary battery is thereby formed1 which will generate electricity4 ,in this case1 the iron will be positive and the copper negative1 so that the current within such a cell would flow from the iron 7in this instance1 the anode7 to the negative1 or cathode4 ,the action of electroplating reverses this process and causes the current to flow from the copper to the iron 7in this instance1 the cathode74 ,,chapter ,,xiv ,,electric ,,heating1 ,,thermo ,,electricity ,,generating ,,heat ,,in ,a ,,wire4--,when a current of electricity passes through a conductor1 like a wire1 more or less heat is developed in the conductor4 ,this heat may be so small that it cannot be measured1 but it is1 nevertheless1 present in a greater or less degree4 ,conductors offer a resistance to the passage of a current1 just the same as water finds a resistance in pipes through which it passes4 ,this resistance is measured in ohms1 as explained in a preceding chapter1 and it is this resistance which is utilized for electric heating4 ,,resistance ,,of ,,substances4--,silver offers less resistance to the passage of a current than any other metal1 the next in order is copper1 while iron is1 comparatively1 a poor conductor4 ,the following is a partial list of metals1 showing their relative conductivity3 ,silver #a4 ,copper #a4jd to #a4ji ,gold #a4ch to #a4da ,aluminum #a4fd ,zinc #c4gi ,nickel #d4fi ,iron #f4ef ,tin #h4i ,lead #ac4b ,german ,silver #ab4b to #ae ,from this table it will be seen that1 for instance1 iron offers six and a half times the resistance of silver1 and that ,german silver has fifteen times the resistance of silver4 ,this table is made up of strands of the different metals of the same diameters and lengths1 so as to obtain their relative values4 ,,sizes ,,of ,,conductors4--,another thing1 however1 must be understood4 ,if two conductors of the same metal1 having different diameters1 receive the same current of electricity1 the small conductor will offer a greater resistance than the large conductor1 hence will generate more heat4 ,this can be offset by increasing the diameter of the conductor4 ,the metal used is1 therefore1 of importance1 on account of the cost involved4 ,,comparison ,,of ,,metals4--,a conductor of aluminum1 say1 #aj feet long and of the same weight as copper1 has a diameter two and a quarter times greater than copper2 but as the resistance of aluminum is #ej per cent4 more than that of silver1 it will be seen that1 weight for weight1 copper is the cheaper1 particularly as aluminum costs fully three times as much as copper4 ,illustration3 ,fig4 #if4 ,,simple ,,electric ,,heater ,the table shows that ,german silver has the highest resistance4 ,of course1 there are other metals1 like antimony1 platinum and the like1 which have still higher resistance4 ,german silver1 however1 is most commonly used1 although there are various alloys of metal made which have high resistance and are cheaper4 ,the principle of all electric heaters is the same1 namely1 the resistance of a conductor to the passage of a current1 and an illustration of a water heater will show the elementary principles in all of these devices4 ,a ,,simple ,,electric ,,heater4--,in ,fig4 #if the illustration shows a cup or holder 7,a7 for the wire1 made of hard rubber4 ,this may be of such diameter as to fit upon and form the cover for a glass 7,b74 ,the rubber should be #a_/b inch thick4 ,two holes are bored through the rubber cup1 and through them are screwed two round-headed screws 7,c1 ,d71 each screw being #a-a_/b inches long1 so they will project an inch below the cap4 ,each screw should have a small hole in its lower end to receive a pin 7,e7 which will prevent the resistance wire from slipping off4 ,the resistance wire 7,f7 is coiled for a suitable length1 dependent upon the current used1 one end being fastened by wrapping it around the screw 7,c74 ,the other end of the wire is then brought upwardly through the interior of the coil and secured in like manner to the other screw 7,d74 ,caution must be used to prevent the different coils or turns from touching each other4 ,when completed1 the coil may be immersed in water1 the current turned on1 and left so until the water is sufficiently heated4 ,illustration3 ,figs4 #ig-ih4 ,,resistance ,,device ,,how ,,to ,,arrange ,,for ,,quantity ,,of ,,current ,,used4--,it is difficult to determine just the proper length the coil should be1 or the sizes of the wire1 unless you know what kind of current you have4 ,you may1 however1 rig up your own apparatus for the purpose of making it fit your heater1 by preparing a base of wood 7,a7 #h inches long1 #c inches wide and #a inch thick4 ,on this mount four electric lamp sockets 7,b74 ,then connect the inlet wire 7,c7 by means of short pieces of wire 7,d7 with all the sockets on one side4 ,the outlet wire 7,e7 should then be connected up with the other sides of the sockets by the short wires 7,f74 ,if1 now1 we have one #af-;candlepower lamp in one of the sockets1 there is a half ampere going through the wires 7,c1 ,f74 ,if there are two lamps on the board you will have #a ampere1 and so on4 ,by this means you may readily determine how much current you are using and it will also afford you a means of finding out whether you have too much or too little wire in your coil to do the work4 ,illustration3 ,fig4 #ii4 ,,plan ,,view ,,of ,,electric ,,iron ,,an ,,electric ,,iron4--,an electric iron is made in the same way4 ,the upper side of a flatiron has a circular or oval depression 7,a7 cast therein1 and a spool of slate 7,b7 is made so it will fit into the depression and the high resistance wire 7,c7 is wound around this spool1 and insulating material1 such as asbestos1 must be used to pack around it4 ,centrally1 the slate spool has an upwardly projecting circular extension 7,d7 which passes through the cap or cover 7,e7 of the iron4 ,the wires of the resistance coil are then brought through this circular extension and are connected up with the source of electrical supply4 ,wires are now sold for this purpose1 which are adapted to withstand an intense heat4 ,illustration3 ,fig4 #ajj4 ,,section ,,of ,,electric ,,iron ,the foregoing example of the use of the current1 through resistance wires1 has a very wide application1 and any boy1 with these examples before him1 can readily make these devices4 ,,thermo ,,electricity4--,it has long been the dream of scientists to convert heat directly into electricity4 ,the present practice is to use a boiler to generate steam1 an engine to provide the motion1 and a dynamo to convert that motion into electricity4 ,the result is that there is loss in the process of converting the fuel heat into steam2 loss to change the steam into motion1 and loss to make electricity out of the motion of the engine4 ,by using water-power there is less actual loss2 but water-power is not available everywhere4 ,,converting ,,heat ,,directly ,,into ,,electricity4--,heat may be converted directly into electricity without using a boiler1 an engine or a dynamo1 but it has not been successful from a commercial standpoint4 ,it is interesting1 however1 to know and understand the subject1 and for that reason it is explained herein4 ,,metals2 ,,electric ,,positive-,,negative4--,to understand the principle1 it may be stated that all metals are electrically positive-negative to each other4 ,you will remember that it has hereinbefore been stated that if1 for instance1 iron and copper are put into an acid solution1 a current will be created or generated thereby4 ,so with zinc and copper1 the usual primary battery elements4 ,in all such cases an electrolyte is used4 ,thermo-electricity dispenses with the electrolyte1 and nothing is used but the metallic elements and heat4 ,the word thermo means heat4 ,if1 now1 we can select two strips of different metals1 and place them as far apart as possible--that is1 in their positive-negative relations with each other1 and unite the end of one with one end of other by means of a rivet1 and then heat the riveted ends1 a current will be generated in the strips4 ,if1 for instance1 we use an iron in conjunction with a copper strip1 the current will flow from the copper to the iron1 because copper is positive to iron1 and iron negative to copper4 ,it is from this that the term positive-negative is taken4 ,the two metals most available1 which are thus farthest apart in the scale of positive-negative relation1 are bismuth and antimony4 ,illustration3 ,fig4 #aja4 ,,thermo-,,electric ,,couple ,in ,fig4 #aja is shown a thermo-electric couple 7,a1 ,b7 riveted together1 with thin outer ends connected by means of a wire 7,c7 to form a circuit4 ,a galvanometer 7,d7 or other current-testing means is placed in this circuit4 ,a lamp is placed below the joined ends4 ,,thermo-,,electric ,,couples4--,any number of these couples may be put together and joined at each end to a common wire and a fairly large flow of current obtained thereby4 ,one thing must be observed3 ,a current will be generated only so long as there exists a difference in temperature between the inner and the outer ends of the bars 7,a1 ,b74 ,this may be accomplished by water1 or any other cooling means which may suggest itself4 ,,chapter ,,xv ,,alternating ,,currents1 ,,choking ,,coils1 ,,transformers1 ,,converters ,,and ,,rectifiers ,,direct ,,current4--,when a current of electricity is generated by a cell1 it is assumed to move along the wire in one direction1 in a steady1 continuous flow1 and is called a direct current4 ,this direct current is a natural one if generated by a cell4 ,,alternating ,,current4--,on the other hand1 the natural current generated by a dynamo is alternating in its character--that is1 it is not a direct1 steady flow in one direction1 but1 instead1 it flows for an instant in one direction1 then in the other direction1 and so on4 ,a direct-current dynamo such as we have shown in ,chapter ,,iv1 is much easier to explain1 hence it is illustrated to show the third method used in generating an electric current4 ,it is a difficult matter to explain the principle and operation of alternating current machines1 without becoming1 in a measure1 too technical for the purposes of this book1 but it is important to know the fundamentals involved1 so that the operation and uses of certain apparatus1 like the choking coil1 transformers1 rectifiers and converters1 may be explained4 ,,the ,,magnetic ,,field4--,it has been stated that when a wire passes through the magnetic field of a magnet1 so as to cut the lines of force flowing out from the end of a magnet1 the wire will receive a charge of electricity4 ,illustration3 ,fig4 #ajb4 ,,cutting ,a ,,magnetic ,,field ,to explain this1 study ,fig4 #ajb1 in which is a bar magnet 7,a74 ,if we take a metal wire 7,b7 and bend it in the form of a loop1 as shown1 and mount the ends on journal-bearing blocks1 the wire may be rotated so that the loop will pass through the magnetic field4 ,when this takes place1 the wire receives a charge of electricity1 which moves1 say1 in the direction of the darts1 and will make a complete circuit if the ends of the looped wire are joined1 as shown by the conductor 7,d74 ,,action ,,of ,,the ,,magnetized ,,wire4--,you will remember1 also that we have pointed out how1 when a current passes over a wire1 it has a magnetic field extending out around it at all points1 so that while it is passing through the magnetic field of the magnet 7,a71 it becomes1 in a measure1 a magnet of its own and tries to set up in business for itself as a generator of electricity4 ,but when the loop leaves the magnetic field1 the magnetic or electrical impulse in the wire also leaves it4 ,,the ,,movement ,,of ,a ,,current ,,in ,a ,,charged ,,wire4--,your attention is directed1 also1 to another statement1 heretofore made1 namely1 that when a current from a charged wire passes by induction to a wire across space1 so as to charge it with an electric current1 it moves along the charged wire in a direction opposite to that of the current in the charging wire4 ,now1 the darts show the direction in which the current moves while it is approaching and passing through the magnetic field4 ,but the moment the loop is about to pass out of the magnetic field1 the current in the loop surges back in the opposite direction1 and when the loop has made a revolution and is again entering the magnetic field1 it must again change the direction of flow in the current1 and thus produce alternations in the flow thereof4 ,let us illustrate this by showing the four positions of the revolving loop4 ,in ,fig4 #ajc the loop 7,b7 is in the middle of the magnetic field1 moving upwardly in the direction of the curved dart 7,a71 and while in that position the voltage1 or the electrical impulse1 is the most intense4 ,the current used flows in the direction of the darts 7,c7 or to the left4 ,in ,fig4 #ajd1 the loop 7,a7 has gone beyond the influence of the magnetic field1 and now the current in the loop tries to return1 or reverse itself1 as shown by the dart 7,d74 ,it is a reaction that causes the current to die out1 so that when the loop has reached the point farthest from the magnet1 as shown in ,fig4 #aje1 there is no current in the loop1 or1 if there is any1 it moves faintly in the direction of the dart 7,e74 ,illustration3 ,figs4 #ajc-ajf4 ,,illustrating ,,alternations ,,current ,,reversing ,,itself4--,when the loop reaches its lowest point 7,fig4 #ajf7 it again comes within the magnetic field and the current commences to flow back to its original direction1 as shown by darts 7,c74 ,,self-,,induction4--,this tendency of a current to reverse itself1 under the conditions cited1 is called self-induction1 or inductance1 and it would be well to keep this in mind in pursuing the study of alternating currents4 ,you will see from the foregoing1 that the alternations1 or the change of direction of the current1 depends upon the speed of rotation of the loop past the end of the magnet4 ,illustration3 ,figs4 #ajg-ajh4 ,,form ,,for ,,increasing ,,alternations ,instead1 therefore1 of using a single loop1 we may make four loops 7,fig4 #ajg71 which at the same speed as we had in the case of the single loop1 will give four alternations1 instead of one1 and still further1 to increase the periods of alternation1 we may use the four loops and two magnets1 as in ,fig4 #ajh4 ,by having a sufficient number of loops and of magnets1 there may be #dj1 #ej1 #fj1 #hj1 #ajj or #abj such alternating periods in each second4 ,time1 therefore1 is an element in the operation of alternating currents4 ,let us now illustrate the manner of connecting up and building the dynamo1 so as to derive the current from it4 ,in ,fig4 #aji1 the loop 7,a7 shows1 for convenience1 a pair of bearings 7,b74 ,a contact finger 7,c7 rests on each1 and to these the circuit wire 7,d7 is attached4 ,do not confuse these contact fingers with the commutator brushes1 shown in the direct-current motor1 as they are there merely for the purpose of making contact between the revolving loop 7,a7 and stationary wire 7,d74 ,illustration3 ,fig4 #aji4 ,,connection ,,of ,,alternating ,,dynamo ,,armature ,,brushes ,,in ,a ,,direct-,,current ,,dynamo4--,the object of the brushes in the direct-current dynamo1 in connection with a commutator1 is to convert this inductance of the wire1 or this effort to reverse itself into a current which will go in one direction all the time1 and not in both directions alternately4 ,to explain this more fully attention is directed to ,figs4 #aaj and #aaa4 ,let ,a represent the armature1 with a pair of grooves 7,b7 for the wires4 ,the commutator is made of a split tube1 the parts so divided being insulated from each other1 and in ,fig4 #aaj1 the upper one1 we shall call and designate the positive 77 and the lower one the negative 7-74 ,the armature wire 7,c7 has one end attached to the positive commutator terminal and the other end of this wire is attached to the negative terminal4 ,illustration3 ,fig4 #aaj4 ,,direct ,,current ,,dynamo ,one brush 7,d7 contacts with the positive terminal of the commutator and the other brush 7,e7 with the negative terminal4 ,let us assume that the current impulse imparted to the wire 7,c7 is in the direction of the dart 7,f1 ,fig4 #aaj74 ,the current will then flow through the positive 77 terminal of the commutator to the brush 7,d71 and from the brush 7,d7 through the wire 7,g7 to the brush 7,e71 which contacts with the negative 7-7 terminal of the commutator4 ,this will continue to be the case1 while the wire 7,c7 is passing the magnetic field1 and while the brush 7,d7 is in contact with the positive 77 terminal4 ,but when the armature makes a half turn1 or when it reaches that point where the brush 7,d7 contacts with the negative 7-7 terminal1 and the brush 7,e7 contacts with the positive 77 terminal1 a change in the direction of the current through the wire 7,g7 takes place1 unless something has happened to change it before it has reached the brushes 7,d1 ,e74 ,illustration3 ,fig4 #aaa4 ,,circuit ,,wires ,,in ,,direct ,,current ,,dynamo ,now1 this change is just exactly what has happened in the wire 7,c71 as we have explained4 ,the current attempts to reverse itself and start out on business of its own1 so to speak1 with the result that when the brushes 7,d and ,e7 contact with the negative and positive terminals1 respectively1 the surging current in the wire 7,c7 is going in the direction of the dart 7,h7--that is1 while1 in ,fig4 #aaj1 the current flows from the wire 7,c7 into the positive terminal1 and out of the negative terminal into the wire 7,c71 the conditions are exactly reversed in ,fig4 #aaa4 ,here the current in wire ,c flows into the negative 7-7 terminal1 and from the positive 77 terminal into the wire ,c1 so that in either case the current will flow out of the brush ,d and into the brush ,e1 through the external circuit 7,g74 ,it will be seen1 therefore1 that in the direct-current motor1 advantage is taken of the surging1 or back-and-forth movement1 of the current to pass it along in one direction1 whereas in the alternating current no such change in direction is attempted4 ,,alternating ,,positive ,,and ,,negative ,,poles4--,the alternating current1 owing to this surging movement1 makes the poles alternately positive and negative4 ,to express this more clearly1 supposing we take a line 7,a1 ,fig4 #aab71 which is called the zero line1 or line of no electricity4 ,the current may be represented by the zigzag line 7,b74 ,the lines 7,b7 above zero 7,a7 may be designated as positive1 and those below the line as negative4 ,the polarity reverses at the line ,a1 goes up to ,d1 which is the maximum intensity or voltage above zero1 and1 when the current falls and crosses the line ,a1 it goes in the opposite direction to ,e1 which is its maximum voltage in the other direction4 ,in point of time1 if it takes one second for the current to go from ,c to ,f1 on the down line1 then it takes only a half second to go from ,c to ,g1 so that the line ,a represents the time1 and the line ,h the intensity1 a complete cycle being formed from ,c1 ,d1 ,f1 then through ,f1 ,e1 ,c1 and so on4 ,illustration3 ,fig4 #aab4 ,,alternating ,,polarity ,,lines ,,how ,,an ,,alternating ,,dynamo ,,is ,,made4--,it is now necessary to apply these principles in the construction of an alternating-current machine4 ,fig4 #aac is a diagram representing the various elements1 and the circuiting4 ,illustration3 ,fig4 #aac4 ,,alternating ,,current ,,dynamo ,let ,a represent the ring or frame containing the inwardly projecting field magnet cores 7,b74 ,c is the shaft on which the armature revolves1 and this carries the wheel 7,d71 which has as many radially disposed magnet cores 7,e7 as there are of the field magnet cores 7,b74 ,the shaft 7,c7 also carries two pulleys with rings thereon4 ,one of these rings 7,f7 is for one end of the armature winding1 and the other ring 7,g7 for the other end of the armature wire4 ,,the ,,windings4--,the winding is as follows3 ,one wire1 as at ,h1 is first coiled around one magnet core1 the turnings being to the right4 ,the outlet terminal of this wire is then carried to the next magnet core and wound around that1 in the opposite direction1 and so on1 so that the terminal of the wire is brought out1 as at ,i1 all of these wires being connected to binding posts 7,j1 ,j'71 to which1 also1 the working circuits are attached4 ,,the ,,armature ,,wires4--,the armature wires1 in like manner1 run from the ring 7,g7 to one armature core1 being wound from right to left1 then to the next core1 which is wound to the right1 afterward to the next core1 which is wound to the left1 and so on1 the final end of the wire being connected up with the other ring 7,f74 ,the north 7,n7 and the south 7,s7 poles are indicated in the diagram4 ,,choking ,,coil4--,the self-induction in a current of this kind is utilized in transmitting electricity to great distances4 ,wires offer resistance1 or they impede the flow of a current1 as hereinbefore stated1 so that it is not economical to transmit a direct current over long distances4 ,this can be done more efficiently by means of the alternating current1 which is subject to far less loss than is the case with the direct current4 ,it affords a means whereby the flow of a current may be checked or reduced without depending upon the resistance offered by the wire over which it is transmitted4 ,this is done by means of what is called a choking coil4 ,it is merely a coil of wire1 wound upon an iron core1 and the current to be choked passes through the coil4 ,to illustrate this1 let us take an arc lamp designed to use a #ej-volt current4 ,if a current is supplied to it carrying #ajj volts1 it is obvious that there are #ej volts more than are needed4 ,we must take care of this excess of #ej volts without losing it1 as would happen were we to locate a resistance of some kind in the circuit4 ,this result we accomplish by the introduction of the choking coil1 which has the effect of absorbing the excessive #ej volts1 the action being due to its quality of self-induction1 referred to in the foregoing4 ,illustration3 ,fig4 #aad4 ,,choking ,,coil ,in ,fig4 #aad1 ,a is the choking coil and ,b an arc lamp1 connected up1 in series1 with the choking coil4 ,,the ,,transformer4--,it is more economical to transmit #aj1jjj volts a long distance than #a1jjj volts1 because the lower the pressure1 or the voltage1 the larger must be the conductor to avoid loss4 ,it is for this reason that #ejj volts1 or more1 are used on electric railways4 ,for electric light purposes1 where the current goes into dwellings1 even this is too high1 so a transformer is used to take a high-voltage current from the main line and transform it into a low voltage4 ,this is done by means of two distinct coils of wire1 wound upon an iron core4 ,illustration3 ,fig4 #aae4 ,a ,,transformer ,in ,fig4 #aae the core is ,o-shaped1 so that a primary winding 7,a71 from the electrical source1 can be wound upon one limb1 and the secondary winding 7,b7 wound around the other limb4 ,the wires1 to supply the lamps1 run from the secondary coil4 ,there is no electrical connection between the two coils1 but the action from the primary to the secondary coil is solely by induction4 ,when a current passes through the primary coil1 the surging movement1 heretofore explained1 is transmitted to the iron core1 and the iron core1 in turn1 transmits this electrical energy to the secondary coil4 ,,how ,,the ,,voltage ,,is ,,determined4--,the voltage produced by the secondary coil will depend upon several things1 namely1 the strength of the magnetism transmitted to it2 the rapidity1 or periodicity of the current1 and the number of turns of wire around the coil4 ,the voltage is dependent upon the length of the winding4 ,but the voltage may also be increased1 as well as decreased4 ,if the primary has1 we will say1 #ajj turns of wire1 and has #bjj volts1 and the secondary has #ej turns of wire1 the secondary will give forth only one-half as much as the primary1 or #ajj volts4 ,if1 on the other hand1 #djj volts would be required1 the secondary should have #bjj turns in the winding4 ,,voltage ,,and ,,amperage ,,in ,,transformers4--,it must not be understood that1 by increasing the voltage in this way1 we are getting that much more electricity4 ,if the primary coil1 with #ajj turns1 produces a current of #bjj volts and #ej amperes1 which would be #bjj #ej #aj1jjj watts1 and the secondary coil has #ej turns1 we shall have #ajj volts and #ajj amperes3 #ajj 7,v47 #ajj 7,a47 #aj1jjj watts4 ,or1 if1 on the other hand1 our secondary winding is composed of #bjj turns1 we shall have #djj volts and #be amperes1 #djj 7volts7 #be 7amperes7 also gives #aj1jjj watts4 ,necessarily1 there will be some loss1 but the foregoing is offered as the theoretical basis of calculation4 ,,chapter ,,xvi ,,electric ,,lighting ,the most important step in the electric field1 after the dynamo had been brought to a fairly workable condition1 was its utilization to make light4 ,it was long known prior to the discovery of practical electric dynamos1 that the electric current would produce an intense heat4 ,ordinary fuels under certain favorable conditions will produce a temperature of #d1ejj degrees of heat2 but by means of the electric arc1 as high as six1 eight and ten thousand degrees are available4 ,the fact that when a conductor1 in an electric current1 is severed1 a spark will follow the drawing part of the broken ends1 led many scientists to believe1 even before the dynamo was in a practical shape1 that electricity1 sooner or later1 would be employed as the great lighting agent4 ,when the dynamo finally reached a stage in development where its operation could be depended on1 and was made reversible1 the first active steps were taken to not only produce1 but to maintain an arc between two electrodes4 ,it would be difficult and tedious to follow out the first experiments in detail1 and it might1 also1 be useless1 as information1 in view of the present knowledge of the science4 ,a few steps in the course of the development are1 however1 necessary to a complete understanding of the subject4 ,reference has been made in a previous chapter to what is called the ,electric ,arc1 produced by slightly separated conductors1 across which the electric current jumps1 producing the brilliantly lighted area4 ,this light is produced by the combustion of the carbon of which the electrodes are composed4 ,thus1 the illumination is the result of directly burning a fuel4 ,the current1 in passing from one electrode to the other1 through the gap1 produces such an intense heat that the fuel through which the current passes is consumed4 ,carbon in a comparatively pure state is difficult to ignite1 owing to its great resistance to heat4 ,at about #g1jjj degrees it will fuse1 and pass into a vapor which causes the intense illumination4 ,the earliest form of electric lighting was by means of the arc1 in which the light is maintained so long as the electrodes were kept a certain distance apart4 ,to do this requires delicate mechanism1 for the reason that when contact is made1 and the current flows through the two electrodes1 which are connected up directly with the coils of a magnet1 the cores1 or armatures1 will be magnetized4 ,the result is that the electrode1 connected with the armature of the magnet1 is drawn away from the other electrode1 and the arc is formed1 between the separated ends4 ,as the current also passes through a resistance coil1 the moment the ends of the electrodes are separated too great a distance1 the resistance prevents a flow of the normal amount of current1 and the armature is compelled to reduce its pull4 ,the effect is to cause the two electrodes to again approach each other1 and in doing so the arc becomes brighter4 ,it will be seen1 therefore1 that there is a constant fight between the resistance coil and the magnet1 the combined action of the two being such1 that1 if properly arranged1 and with powers in correct relation to each other1 the light may be maintained without undue flickering4 ,such devices are now universally used1 and they afford a steady and reliable means of illumination4 ,many improvements are made in this direction1 as well as in the ingredients of the electrodes4 ,a very novel device for assuring a perfect separation at all times between the electrodes1 is by means of a pair of parallel carbons1 held apart by a non-conductor such as clay1 or some mixture of earth1 a form of which is shown in ,fig4 #aaf4 ,the drawing shows two electrodes1 separated by a non-conducting material1 which is of such a character that it will break down and crumble away1 as the ends of the electrodes burn away4 ,illustration3 ,fig4 #aaf4 ,parallel ,carbons4 ,this device is admirable where the alternating current is used1 because the current moves back and forth1 and the two electrodes are thus burned away at the same rate of speed4 ,in the direct or continuous current the movement is in one direction only1 and as a result the positive electrode is eaten away twice as fast as the negative4 ,this is the arc form of lamp universally used for lighting large spaces or areas1 such as streets1 railway stations1 and the like4 ,it is important also as the means for utilizing searchlight illumination1 and frequently for locomotive headlights4 ,arc lights are produced by what is called the series current4 ,this means that the lamps are all connected in a single line4 ,this is illustrated by reference to ,fig4 #aag1 in which ,a represents the wire from the dynamo1 and ,b1 ,c the two electrodes1 showing the current passing through from one lamp to the next4 ,illustration3 ,fig4 #aag4 ,arc-,lighting ,circuit4 ,a high voltage is necessary in order to cause the current to leap across the gap made by the separation of the electrodes4 ,,the ,,incandescent ,,system4--,this method is entirely different from the arc system4 ,it has been stated that certain metals conduct electricity with greater facility than others1 and some have higher resistance than others4 ,if a certain amount of electricity is forced through some metals1 they will become heated4 ,this is true1 also1 if metals1 which1 ordinarily1 will conduct a current freely1 are made up into such small conductors that it is difficult for the current to pass4 ,illustration3 ,fig #aah4 ,interrupted ,conductor4 ,in the arc method high voltage is essential2 in the incandescent plan1 current is the important consideration4 ,in the arc1 the light is produced by virtue of the break in the line of the conductor2 in the incandescent1 the system is closed at all times4 ,supposing we have a wire ,a1 a quarter of an inch in diameter1 carrying a current of1 say1 #ejj amperes1 and at any point in the circuit the wire is made very small1 as shown at ,b1 in ,fig4 #aah1 it is obvious that the small wire would not be large enough to carry the current4 ,the result would be that the small connection ,b would heat up1 and1 finally1 be fused4 ,while the large part of the wire would carry #ejj amperes1 the small wire could not possibly carry more than1 say1 #aj amperes4 ,now these little wires are the filaments in an electric bulb1 and originally the attempt was made to have them so connected up that they could be illuminated by a single wire1 as with the arc system above explained1 one following the other as shown in ,fig4 #aag4 ,illustration3 ,fig4 #aai4 ,incandescent ,circuit4 ,it was discovered1 however1 that the addition of each successive lamp1 so wired1 would not give light in proportion to the addition1 but at only about one-fourth the illumination1 and such a course would1 therefore1 make electric lighting enormously expensive4 ,this knowledge resulted in an entirely new system of wiring up the lamps in a circuit4 ,this is explained in ,fig4 #aai4 ,in this figure ,a represents the dynamo1 ,b1 ,b the brushes1 ,c1 ,d the two line wires1 ,e the lamps1 and ,f the short-circuiting wires between the two main conductors ,c1 ,d4 ,it will be observed that the wires ,c1 ,d are larger than the cross wires ,f4 ,the object is to show that the main wires might carry a very heavy amperage1 while the small cross wires ,f require only a few amperes4 ,this is called the multiple circuit1 and it is obvious that the entire amperage produced by the dynamo will not be required to pass through each lamp1 but1 on the other hand1 each lamp takes only enough necessary to render the filament incandescent4 ,this invention at once solved the problem of the incandescent system and was called the subdivision of the electric light4 ,by this means the cost was materially reduced1 and the wiring up and installation of lights materially simplified4 ,but the divisibility of the light did not1 by any means1 solve the great problem that has occupied the attention of electricians and experimenters ever since4 ,the great question was and is to preserve the little filament which is heated to incandescence1 and from which we get the light4 ,the effort of the current to pass through the small filament meets with such a great resistance that the substance is heated up4 ,if it is made of metal there is a point at which it will fuse1 and thus the lamp is destroyed4 ,it was found that carbon1 properly treated1 would heat to a brilliant white heat without fusing1 or melting1 so that this material was employed4 ,but now followed another difficulty4 ,as this intense heat consumed the particles of carbon1 owing to the presence of oxygen1 means were sought to exclude the air4 ,this was finally accomplished by making a bulb of glass1 from which the air was exhausted1 and as such a globe had no air to support combustion1 the filaments were finally made so that they would last a long time before being finally disintegrated4 ,the quest now is1 and has been1 to find some material of a purely metallic character1 which will have a very high fusing point1 and which will1 therefore1 dispense with the cost of the exhausted bulb4 ,some metals1 as for instance1 osmium1 tantalum1 thorium1 and others1 have been used1 and others1 also1 with great success1 so that the march of improvements is now going forward with rapid strides4 ,,vapor ,,lamps4--,one of the directions in which considerable energy has been directed in the past1 was to produce light from vapors4 ,the ,cooper ,hewitt mercury vapor lamp is a tube filled with the vapor of mercury1 and a current is sent through the vapor which produces a greenish light1 and owing to that peculiar color1 has not met with much success4 ,it is merely cited to show that there are other directions than the use of metallic conductors and filaments which will produce light1 and the day is no doubt close at hand when we may expect some important developments in the production of light by means of the ,hertzian waves4 ,,directions ,,for ,,improvements4--,electricity1 however1 is not a cheap method of illumination4 ,the enormous heat developed is largely wasted4 ,the quest of the inventor is to find a means whereby light can be produced without the generation of the immense heat necessary4 ,man has not yet found a means whereby he can make a heat without increasing the temperature1 as nature does it in the glow worm1 or in the firefly4 ,a certain electric energy will produce both light and heat1 but it is found that much more of this energy is used in the heat than in the light4 ,what wonderful possibilities are in store for the inventor who can make a heatless light6 ,it is a direction for the exercise of ingenuity that will well repay any efforts4 ,curious ,superstitions ,concerning ,electricity ,electricity1 as exhibited in light1 has been the great marvel of all times4 ,the word electricity itself comes from the thunderbolt of the ancient ,god ,zeus1 which is known to be synonymous with the thunderbolt and the lightning4 ,magnetism1 which we know to be only another form of electricity1 was not regarded the same as electricity by the ancients4 ,iron which had the property to attract1 was first found near the town of ,magnesia1 in ,lydia1 and for that reason was called magnetism4 ,later on1 a glimmer of the truth seemed to dawn on the early scientists1 when they saw the resemblance between the actions of the amber and the loadstone1 as both attracted particles4 ,and here another curious thing resulted4 ,amber will attract particles other than metals4 ,the magnet did not2 and from this imperfect observation and understanding1 grew a belief that electricity1 or magnetism would attract all substances1 even human flesh1 and many devices were made from magnets1 and used as cures for the gout1 and to affect the brain1 or to remove pain4 ,even as early as #b1ejj years before the birth of ,christ the ,chinese knew of the properties of the magnet1 and also discovered that a bar of the permanent magnet would arrange itself north and south1 like the mariners' compass4 ,there is no evidence1 however1 that it was used as a mariner's compass until centuries afterwards4 ,but the matter connected with light1 as an electrical development1 which interests us1 is its manifestations to the ancients in the form of lightning4 ,the electricity of the earth concentrates itself on the tops of mountains1 or in sharp peaks1 and accounts for the magnificent electrical displays always found in mountainous regions4 ,some years ago1 a noted scientist1 ,dr4 ,siemens1 while standing on the top of the great pyramid of ,cheops1 in ,egypt1 during a storm1 noted that an electrical discharge flowed from his hand when extended toward the heavens4 ,the current manifested itself in such a manner that the hissing noise was plainly perceptible4 ,the literature of all ages and of all countries shows that this manifestation of electrical discharges was noted1 and became the subject of discussions among learned men4 ,all these displays were regarded as the bolts of an angry ,god1 and historians give many accounts of instances where1 in ,his anger1 ,he sent down the lightning to destroy4 ,among the ,romans ,jupiter thus hurled forth his wrath2 and among many ancient people1 even down to the time of ,charlemagne1 any space struck by lightning was considered sacred1 and made consecrated ground4 ,from this grew the belief that it was sacrilegious to attempt to imitate the lightning of the sky--that ,deity would visit dire punishment on any man who attempted to produce an electric light4 ,virgil relates accounts where certain princes attempted to imitate the lightning1 and were struck by thunderbolts as punishments4 ,less than a century ago ,benjamin ,franklin devised the lightning rod1 in order to prevent lightning from striking objects4 ,the literature of that day abounds with instances of protests made1 on the part of those who were as superstitions as the people in ancient times1 who urged that it was impious to attempt to ward off ,heaven's lightnings4 ,it was argued that the lightning was one way in which the ,creator manifested ,his displeasure1 and exercised ,his power to strike the wicked4 ,when such writers as ,pliny will gravely set forth an explanation of the causes of lightning1 as follows in the paragraph below1 we can understand why it inculcated superstitious fears in the people of ancient times4 ,he says3 ,most men are ignorant of that secret1 which1 by close observation of the heavens1 deep scholars and principal men of learning have found out1 namely1 that they are the fires of the uppermost planets1 which1 falling to the earth1 are called lightning2 but those especially which are seated in the middle1 that is about ,jupiter1 perhaps because participating in the excessive cold and moisture from the upper circle of ,saturn1 and the immoderate heat of ,mars1 that is next beneath1 by this means he discharges his superfluity1 and therefore it is commonly said1 ',that ,jupiter shooteth and darteth lightning4' ,therefore1 like as out of a burning piece of wood a coal flieth forth with a crack1 even so from a star is spit out1 as it were1 and voided forth this celestial fire1 carrying with it presages of future things2 so that the heavens showeth divine operations1 even in these parcels and portions which are rejected and cast away as superfluous4 ,,chapter ,,xvii ,,power1 ,,and ,,various ,,other ,,electrical ,,manifestations ,it would be difficult to mention any direction in human activity where electricity does not serve as an agent in some form or manner4 ,man has learned that the ,creator gave this great power into the hands of man to use1 and not to curse4 ,when the dynamo was first developed it did not appear possible that it could generate electricity1 and then use that electricity in order to turn the dynamo in the opposite direction4 ,it all seems so very natural to us now1 that such a thing should practically follow2 but man had to learn this4 ,let us try to make the statement plain by a few simple illustrations4 ,by carefully going over the chapter on the making of the dynamo1 it will be evident that the basis of the generation of the current depends on the changing of the direction of the flow of an electric current4 ,look at the simple horse-shoe magnet4 ,if two of them are gradually moved toward each other1 so that the north pole of one approaches the north pole of the other1 there is a sensible attempt for them to push away from each other4 ,if1 however1 one of them is turned1 so that the north pole of one is opposite the south pole of the other1 they will draw together4 ,in this we have the foundation physical action of the dynamo and the motor4 ,when power is applied to an armature1 and it moves through a magnetic field1 the action is just the same as in the case of the hand drawing the north and the south pole of the two approaching magnets from each other4 ,the influence of the electrical disturbance produced by that act permeated the entire winding of the field and armature1 and extended out on the whole line with which the dynamo was connected4 ,in this way a current was established and transmitted1 and with proper wires was sent in the form of circuits and distributed so as to do work4 ,but an electric current1 without suitable mechanism1 is of no value4 ,it must have mechanism to use it1 as well as to make it4 ,in the case of light1 we have explained how the arc and the incandescent lamps utilize it for that purpose4 ,but now1 attempting to get something from it in the way of power1 means another piece of mechanism4 ,this is done by the motor1 and this motor is simply a converter1 or a device for reversing the action of the electricity4 ,attention is called to ,figs4 #abj and #aba4 ,let us assume that the field magnets ,a1 ,a are the positives1 and the magnets ,b1 ,b the negatives4 ,the revolving armature has also four magnet coils1 two of them1 ,c1 ,c1 being positive1 and the other two1 ,d1 ,d1 negative1 each of these magnet coils being so connected up that they will reverse the polarities of the magnets4 ,illustration3 ,figs4 #abj-aba4 ,,action ,,of ,,magnets ,,in ,a ,,dynamo ,now in the particular position of the revolving armature1 in ,fig4 #abj1 the magnets of the armature have just passed the respective poles of the field magnets1 and the belt ,e is compelled to turn the armature past the pole pieces by force in the direction of the arrow ,f4 ,after the armature magnets have gone to the positions in ,fig4 #aba1 the positives ,a try to draw back the negatives ,d of the armature1 and at the same time the negatives ,b repel the negatives ,d1 because they are of the same polarities4 ,this repulsion of the negatives ,a1 ,b continues until the armature poles ,c1 ,d have slightly passed them1 when the polarities of the magnets ,c1 ,d are changed2 so that it will be seen1 by reference to ,fig4 #abb1 that ,d is now retreating from ,b1 and ,c is going away from ,a--that is1 being forced away contrary to their natural attractive influences1 and in ,fig4 #abc1 when the complete cycle is nearly finished1 the positives are again approaching each other and the negatives moving together4 ,illustration3 ,figs4 #abb-abc4 ,,cycle ,,action ,,in ,,dynamo ,in this manner1 at every point1 the sets of magnets are compelled to move against their magnetic pull4 ,this explains the dynamo4 ,now take up the cycle of the motor1 and note in ,fig4 #abd that the negative magnets ,d of the armature are closely approaching the positive and negative magnets1 on one side2 and the positive magnets ,c are nearing the positive and negatives on the other side4 ,the positives ,a1 therefore1 attract the negatives ,d1 and the negative ,b exert a pull on the positives ,c at the same time4 ,the result is that the armature is caused to revolve1 as shown by the dart ,g1 in a direction opposite to the dart in ,fig4 #abj4 ,illustration3 ,figs4 #abd-abe4 ,,action ,,of ,,magnets ,,in ,,motor ,when the pole pieces of the magnets ,c1 ,d are about to pass magnets ,a1 ,b1 as shown in ,fig4 #abe1 it is necessary to change the polarities of the armature magnets ,c1 ,d2 so that by reference to ,fig4 #abf1 it will be seen that they are now indicated as ,c-1 and ,d1 respectively1 and have moved to a point midway between the poles ,a1 ,b 7as in ,fig4 #abe71 where the pull on one side1 and the push on the other are again the same1 and the last ,figure #abg shows the cycle nearly completed4 ,the shaft of the motor armature is now the element which turns the mechanism which is to be operated4 ,to convert electrical impulses into power1 as thus shown1 results in great loss4 ,the first step is to take the steam boiler1 which is the first stage in that source which is the most common and universal1 and by means of fuel1 converting water into steam4 ,the second is to use the pressure of this steam to drive an engine2 the third is to drive the dynamo which generates the electrical impulse2 and the fourth is the conversion from the dynamo into a motor shaft4 ,loss is met with at each step1 and the great problem is to eliminate this waste4 ,illustration3 ,figs4 #abf-abg4 ,,positions ,,of ,,magnets ,,in ,,motor ,the great advantage of electrical power is not in utilizing it for consumption at close ranges1 but where it is desired to transmit it for long distances4 ,such illustrations may be found in electric railways1 and where water power can be obtained as the primal source of energy1 the cost is not excessive4 ,it is found1 however1 that even with the most improved forms of mechanism1 in electrical construction1 the internal combustion engines are far more economical4 ,transmission of ,energy ,one of the great problems has been the transmission of the current to great distances4 ,by using a high voltage it may be sent hundreds of miles1 but to use a current of that character in the cars1 or shops1 or homes1 would be exceedingly dangerous4 ,to meet this requirement transformers have been devised1 which will take a current of very high voltage1 and deliver a current of low tension1 and capable of being used anywhere with the ordinary motors4 ,,the ,,transformer4--,this is an electrical device made up of a core or cores of thin sheet metal1 around which is wound sets of insulated wires1 one set being designed to receive the high voltage1 and the other set to put out the low voltage1 as described in a former chapter4 ,these may be made where the original output is a very high voltage1 so that they will be stepped down1 first from one voltage to a lower1 and then from that to the next lower stage4 ,this is called the ,step down transformer1 and is now used over the entire world1 where large voltages are generated4 ,,electric ,,furnaces4--,the most important development of electricity in the direction of heat is its use in furnaces4 ,as before stated1 an intense heat is capable of being generated by the electric current1 so that it becomes the great agent to use for the treatment of refractory material4 ,in furnaces of this kind the electric arc is the mechanical form used to produce the great heat1 the only difference being in the size of the apparatus4 ,the electric furnace is simply an immense form of arc light1 capable of taking a high voltage1 and such an arc is enclosed within a suitable oven of refractory material1 which still further conserves the heat4 ,,welding ,,by ,,electricity4--,the next step is to use the high heat thus capable of being produced1 to fuse metals so that they may be welded together4 ,it is a difficult matter to unite two large pieces of metal by the forging method1 because the highest heat is required1 owing to their bulk1 and in addition immense hammers1 weighing tons1 must be employed4 ,electric welding offers a simple and easy method of accomplishing the result1 and in the doing of which it avoids the oxidizing action of the forging heat4 ,instead of heating the pieces to be welded in a forge1 as is now done1 the ends to be united are simply brought into contact1 and the current is sent through the ends until they are in a soft condition1 after which the parts are pressed together and united by the simple merging of the plastic condition in which they are reduced by the high electric heat4 ,this form of welding makes the most perfect joint1 and requires no hammering1 as the mass of the metal flows from one part or end to the other2 the unity is a perfect one1 and the advantage is that the metals can be kept in a semi-fluid state for a considerable time1 thus assuring a perfect admixture of the two parts4 ,with the ordinary form of welding it is necessary to drive the heated parts together without any delay1 and at the least cooling must be reheated1 or the joint will not be perfect4 ,the smallest kinds of electric heating apparatus are now being made1 so that small articles1 sheet metal1 small rods1 and like parts can be united with the greatest facility4 ,,chapter ,,xviii ,x-,,ray1 ,,radium1 ,,and ,,the ,,like ,the camera sees things invisible to the human eye4 ,its most effective work is done with beams which are beyond human perception4 ,the photographer uses the ,actinic rays4 ,ordinary light is composed of the seven primary colors1 of which the lowest in the scale is the red1 and the highest to violet4 ,those below the red are called the ,infra-red1 and they are the ,hertzian waves1 or those used in wireless telegraphy4 ,those above the violet are called ,ultra-violet1 and these are employed for ,x-ray work4 ,the former are produced by the high tension electric apparatus1 which we have described in the chapter relating to wireless telegraphy2 and the latter1 called also the ,roentgen rays1 are generated by the ,crookes' ,tube4 ,this is a tube from which all the atmosphere has been extracted so that it is a practical vacuum4 ,within this are placed electrodes so as to divert the action of the electrical discharge in a particular direction1 and this light1 when discharged1 is of such a peculiar character that its discovery made a sensation in the scientific world4 ,the reason for this great wonder was not in the fact that it projected a light1 but because of its character4 ,ordinary light1 as we see it with the eye1 is capable of being reflected1 as when we look into a mirror at an angle4 ,the ,x-ray will not reflect1 but instead1 pass directly through the glass4 ,then1 ordinary light is capable of refraction4 ,this is shown by a ray of light bending as it passes through a glass of water1 which is noticed when the light is at an angle to the surface4 ,the ,x-ray will pass through the water without being changed from a straight line4 ,the foregoing being the case1 it was but a simple step to conclude that if it were possible to find a means whereby the human eye could see within the ultra-violet beam1 it would be possible to see through opaque substances4 ,from the discovery so important and far reaching it was not long until it was found that if the ultra-violet rays1 thus propagated1 were transmitted through certain substances1 their rates of vibration would be brought down to the speeds which send forth the visible rays1 and now the eye is able to see1 in a measure at least1 what the actinic rays show4 ,this discovery was but the forerunner of a still more important development1 namely1 the discovery of radium4 ,the actual finding of the metal was preceded by the knowledge that certain minerals1 and water1 as well1 possessed the property of radio-activity4 ,radio-activity is a word used to express that quality in metals or other material by means of which obscure rays are emitted1 that have the capacity of discharging electrified bodies1 and the power to ionize gases1 as well as to actually affect photograph plates4 ,certain metals had this property to a remarkable degree1 particularly uranium1 thorium1 polonium1 actinium1 and others1 and in #ahih the ,curies1 husband and wife1 ,french chemists1 isolated an element1 very ductile in its character1 which was a white metal1 and had a most brilliant luster4 ,pitchblende1 the base metal from which this was extracted1 was discovered to be highly radio-active1 and on making tests of the product taken from it1 they were surprised to find that it emitted a form of energy that far exceeded in calculations any computations made on the basis of radio-activity in the metals hitherto examined4 ,but this was not the most remarkable part of the developments4 ,the energy1 whatever it was1 had the power to change many other substances if brought into close proximity4 ,it darkens the color of diamonds1 quartz1 mica1 and glass4 ,it changes some of the latter in color1 some kinds being turned to brown and others into violet or purple tinges4 ,radium has the capacity to redden the skin1 and affect the flesh of persons1 even at some considerable distance1 and it is a most powerful germicide1 destroying bacteria1 and has been found also to produce some remarkable cures in diseases of a cancerous nature4 ,the remarkable similarity of the rays propagated by this substance1 with the ,x-rays1 lead many to believe that they are electrical in their character1 and the whole scientific world is now striving to use this substance1 as well as the more familiar light waves of the ,roentgen tube1 in the healing of diseases4 ,it is not at all remarkable that this use of it should first be considered1 as it has been the history of the electrical developments1 from the earliest times1 that each successive stage should find advocates who would urge its virtues to heal the sick4 ,it was so when the dynamo was invented1 when the high tension current was produced2 and electrical therapeutics became a leading theme when transmission by induction became recognized as a scientific fact4 ,it is not many years since the ,x-rays were discovered1 and the first announcement was concerning its wonderful healing powers4 ,this was particularly true in the case of radium1 but for some reason1 after the first tests1 all experimenters were thwarted in their theories1 because the science1 like all others1 required infinite patience and experience4 ,it was discovered1 in the case of the ,x-ray1 that it must be used in a modified form1 and accordingly1 various modifications of the waves were introduced1 called the m and the n rays1 as well as many others1 each having some peculiar qualification4 ,in time1 no doubt1 the investigators will find the right quality for each disease1 and learn how to apply it4 ,thus1 electricity1 that most alluring thing which1 in itself1 cannot be seen1 and is of such a character that it cannot even be defined in terms which will suit the exact scientific mind1 is daily bringing new wonders for our investigation and use4 ,it is1 indeed1 a study which is so broad that it has no limitations1 and a field which never will be exhausted4 ,,the ,,end ,,glossary ,,of ,,words ,,used ,,in ,,text ,,of ,,this ,,volume ,acid4 ,accumulator material is sulphuric acid1 diluted with water4 ,active ,that part of the material in accumulator plates ,material4 which is acted upon by the electric current4 ,accumulator4 ,a cell1 generally known as a storage battery1 which while it initially receives a charge of electricity1 is nevertheless1 of such a character1 owing to the active material of which it is made1 that it accumulates1 or1 as it were1 generates electricity4 ,aerial ,wire1 ,the wire which1 in wireless telegraphy1 is carried or ,conductor4 up into the air to connect the antenn with the receiving and sending apparatus4 ,alarm1 ,burglar4 ,a circulating system in a building1 connected up with a bell or other signaling means4 ,alloy4 ,a mixture of two or more metals2 as copper and zinc to make brass2 nickel and zinc to form ,german silver4 ,alternating ,current4 ,a current which goes back and forth in opposite directions1 unlike a direct current which flows continuously in one direction over a wire4 ,alternation4 ,the term applied to a change in the direction of an alternating current1 the frequency of the alternations ranging up to #bj1jjj or more vibrations per second4 ,amber4 ,a resin1 yellow in color1 which when rubbed with a cloth1 becomes excited and gives forth negative electricity4 ,ammeter4 ,an instrument for measuring the quantity or flow of electricity4 ,ampere4 ,the unit of current2 the term in which strength of the current is measured4 ,an ampere is an electromotive force of one volt through a resistance of one ohm4 ,annunciator4 ,a device which indicates or signals a call given from some distant point4 ,anode4 ,the positive terminal in a conducting circuit1 like the terminal of the carbon plate in a battery4 ,it is a plate in an electroplating bath from which the current goes over to the cathode or negative plate or terminal4 ,arc4 ,a term employed to designate the gap1 or the current which flows across between the conductors1 like the space between the two carbons of an arc lamp1 which gives the light4 ,armature4 ,a body of iron1 or other suitable metal1 which is in the magnetic field of a magnet4 ,armature ,bar4 ,the piece which holds the armature4 ,also one of a series of bars which form the conductors in armature windings4 ,armature ,coil4 ,the winding around an armature1 or around the core of an armature4 ,armature ,core4 ,the part in a dynamo or motor which revolves1 and on which the wire coils are wound4 ,astatic 7,galvanometer74 ,that which has no magnetic action to direct or divert anything exterior to it4 ,atom4 ,the ultimate particle of an elementary substance4 ,attraction4 ,that property of matter which causes particles to adhere1 or cohere1 to each other4 ,it is known under a variety of terms1 such as gravitation1 chemical affinity1 electro-magnetism and dynamic attraction4 ,automatic ,cut-out4 ,a device which acts through the operation of the mechanism with which it is connected4 ,it is usually applied to a device which cuts out a current when it overcharges or overloads the wire4 ,bath4 ,in electroplating1 the vessel or tank which holds the electroplating solution4 ,battery4 ,a combination of two or more cells4 ,battery1 ,dry4 ,a primary battery in which the electrolyte is made in a solid form4 ,battery1 ,galvanic4 ,a battery which is better known by the name of the ,voltaic ,pile1 made up of zinc and copper plates which alternate1 and with a layer of acidulated paper between each pair of plates4 ,battery1 ,storage4 ,a battery which accumulates electricity generated by a primary battery or a generator4 ,brush4 ,a term applied to the conducting medium that bears against the cylindrical surface of a commutator4 ,buzzer4 ,an electric call produced by a rapidly moving armature of an electro-magnet4 ,cable4 ,a number of wires or conductors assembled in one strand4 ,candle-power4 ,the amount of light given by the legal-standard candle4 ,this standard is a sperm candle1 which burns two grains a minute4 ,capacity4 ,the carrying power of a wire or circuit1 without heating4 ,when heated there is an overload1 or the capacity of the wire is overtaxed4 ,capacity1 ,storage4 ,the quantity of electricity in a secondary battery when fully charged1 usually reckoned in ampere hours4 ,carbon4 ,a material1 like coke1 ground or crushed1 and formed into sticks or plates by molding or compression4 ,it requires a high heat to melt or burn1 and is used as electrodes for arc lamps and for battery elements4 ,it has poor conductivity1 and for arc lamps is coated with copper to increase its conductivity4 ,cell1 ,electrolytic4 ,a vessel containing an electrolyte for electroplating purposes4 ,charge4 ,the quantity of electricity on the surface of a body or conductor4 ,chemical ,change4 ,when a current passes through electrodes in a solution1 a change takes place which is chemical in its character4 ,adding sulphuric acid to water produces heat4 ,if electrodes of opposite polarity are placed in such an acid solution1 a chemical change is produced1 which is transformed into electricity4 ,choking ,coil4 ,an instrument in a circuit which by a form of resistance regulates the flow of the current1 or returns part of it to the source of its generation4 ,counter-electromotive ,force4 ,cells which are inserted in opposition to a battery to reduce high voltage4 ,circuit1 ,astatic4 ,a circuit in an instrument so wound that the earth's magnetism will not affect it4 ,circuit ,breaker4 ,any instrument in a circuit which cuts out or interrupts the flow of a current4 ,circuit1 ,external4 ,a current flows through a wire or conductor1 and also along the air outside of the conductor1 the latter being the external circuit4 ,circuit ,indicator4 ,an instrument1 like a galvanometer1 that shows the direction in which a current is flowing through a conductor4 ,circuit1 ,return4 ,usually the ground return1 or the negative wire from a battery4 ,circuit1 ,short4 ,any connection between the mains or parallel lines of a circuit which does not go through the apparatus for which the circuit is intended4 ,coherer4 ,a tube1 or other structure1 containing normally high resistance particles which form a path or bridge between the opposite terminals of a circuit4 ,coil4 ,a wire1 usually insulated1 wound around a spool4 ,coil1 ,induction4 ,one of a pair of coils designed to change the voltage of a current of electricity1 from a higher to a lower1 or from a lower to a higher electro-motive force4 ,coil1 ,resistance4 ,a coil so wound that it will offer a resistance to a steady current1 or reduce the flow of electricity4 ,commutator4 ,a cylinder on the end of the armature of a dynamo or motor and provided with a pair of contact plates for each particular coil in the armature1 in order to change the direction of the current4 ,compass4 ,an apparatus which indicates the direction or flow of the earth's magnetism4 ,condenser4 ,a device for storing up electro-static charges4 ,conductance4 ,that quality of a conductor to carry a current of electricity1 dependent on its shape for the best results4 ,conduction4 ,the transmission of a current through a rod1 wire or conductor4 ,conductivity4 ,that quality which has reference to the capacity to conduct a current4 ,conductor4 ,any body1 such as a bar1 rod1 wire1 or machine1 which will carry a current4 ,connector4 ,a binding post1 clamp1 screw1 or other means to hold the end of a wire1 or electric conductor4 ,contact4 ,to unite any parts in an electric circuit4 ,controller4 ,the handle of a switchboard1 or other contact making and breaking means in a circuit4 ,converter4 ,an induction coil in an alternating circuit for changing potential difference1 such as high alternating voltage into low direct current voltage4 ,convolution4 ,to wind like a clock spring4 ,core4 ,the inner portion of an electro-magnet4 ,the inside part of an armature wound with wire4 ,core1 ,laminated4 ,when the core is built up of a number of separate pieces of the same material1 but not insulated from each other4 ,coulomb4 ,the unit of electrical quantity4 ,it is the quantity passed by a current of one ampere intensity in one second of time4 ,couple1 ,electric4 ,two or more electrodes in a liquid to produce an electric force4 ,current1 ,alternating4 ,a natural current produced by the action of electro-magnets4 ,it is a succession of short impulses in opposite directions4 ,current1 ,constant4 ,a current which is uniformly maintained in a steady stream4 ,current1 ,induced4 ,a current produced by electro-dynamic induction4 ,current ,meter4 ,an apparatus for indicating the strength of a current4 ,an ammeter4 ,current1 ,oscillating4 ,a current which periodically alternates4 ,current1 ,periodic4 ,a periodically varying current strength4 ,current1 ,undulating4 ,a current which has a constant direction1 but has a continuously varying strength4 ,decomposition4 ,the separation of a liquid1 such as an electrolyte1 into its prime elements1 either electrically or otherwise4 ,deflection4 ,the change of movement of a magnetic needle out of its regular direction of movement4 ,demagnetization4 ,when a current passes through a coil wound on an iron core1 the core becomes magnetized4 ,when the current ceases the core is no longer a magnet4 ,it is then said to be demagnetized4 ,it also has reference to the process for making a watch non-magnetic so that it will not be affected when in a magnetic field4 ,density4 ,the quantity of an electric charge in a conductor or substance4 ,depolarization4 ,the removal of magnetism from a permanent magnet1 or a horse-shoe magnet1 for instance4 ,it is generally accomplished by applying heat4 ,deposition1 ,the act of carrying metal from one pole of a cell to ,electrolysis4 another pole1 as in electroplating4 ,detector4 ,mechanism for indicating the presence of a current in a circuit4 ,diaphragm4 ,a plate in a telephone1 which1 in the receiver1 is in the magnetic field of a magnet1 and in a transmitter carries the light contact points4 ,dielectric4 ,a non-conductor for an electric current1 but through which electro-static induction will take place4 ,for example3 glass and rubber are dielectrics4 ,discharge4 ,the current flowing from an accumulator4 ,disintegration4 ,the breaking up of the plate or active material4 ,disruptive4 ,a static discharge passing through a dielectric4 ,duplex ,wire4 ,a pair of wires usually twisted together and insulated from each other to form the conducting circuit of a system4 ,dynamic ,electricity4 ,the term applied to a current flowing through a wire4 ,dynamo4 ,an apparatus1 consisting of core and field magnets1 which1 when the core is turned1 will develop a current of electricity4 ,earth ,returns4 ,instead of using two wires to carry a circuit1 the earth is used for what is called the return circuit4 ,efficiency4 ,the total electrical energy produced1 in which that wasted1 as well as that used1 is calculated4 ,elasticity4 ,that property of any matter which1 after a stress1 will cause the substance to return to its original form or condition4 ,electricity has elasticity1 which is utilized in condensers1 as an instance4 ,electricity1 ,lightning1 and1 in short1 any current or electrical ,atmospheric4 impulse1 like wireless telegraphic waves1 is called atmospheric4 ,electricity1 ,electricity with a low potentiality and large current ,voltaic4 density4 ,electrification4 ,the process of imparting a charge of electricity to any body4 ,electro-chemistry4 ,the study of which treats of electric and chemical forces1 such as electric plating1 electric fusing1 electrolysis1 and the like4 ,electrode4 ,the terminals of a battery1 or of any circuit2 as1 for instance1 an arc light4 ,electrolyte4 ,any material which is capable of being decomposed by an electric current4 ,electro-magnetism4 ,magnetism which is created by an electric current4 ,electrometer4 ,an instrument for measuring static electricity1 differing from a galvanometer1 which measures a current in a wire that acts on the magnetic needle of the galvanometer4 ,electro-motive ,voltage1 which is the measure or unit of e4 m4 f4 ,force4 7,e4 ,m4 ,f47 ,electroscope4 ,a device for indicating not only the presence of electricity1 but whether it is positive or negative4 ,electro-static ,surfaces separated by a dielectric for opposite ,accumulator4 charging of the surface4 ,element4 ,in electricity a form of matter1 as1 for instance1 gold1 or silver1 that has no other matter or compound4 ,original elements cannot be separated1 because they are not made up of two or more elements1 like brass1 for instance4 ,excessive ,charge4 ,a storage battery charged at too high a rate4 ,excessive ,discharge4 ,a storage battery discharged at too high a rate4 ,excessive ,overcharge4 ,charging for too long a time4 ,exciter4 ,a generator1 either a dynamo or a battery1 for exciting the field of a dynamo4 ,exhaustive ,discharge4 ,an excessive over-discharge of an accumulator4 ,f4 ,the sign used to indicate the heat term ,fahrenheit4 ,fall of ,voltage4 ,the difference between the initial and the final voltage in a current4 ,field4 ,the space or region near a magnet or charged wire4 ,also the electro-magnets in a dynamo or motor4 ,flow4 ,the volume of a current going through a conductor4 ,force1 ,electro-magnetic4 ,the pull developed by an electro-magnet4 ,frictional ,a current produced by rubbing dissimilar ,electricity4 substances together4 ,full ,load4 ,the greatest load a battery1 accumulator or dynamo will sustain4 ,galvanic4 ,pertaining to the electro-chemical relations of metals toward each other4 ,galvanizing4 ,the art of coating one metal with another1 such1 for instance1 as immersing iron in molten zinc4 ,galvanometry4 ,an instrument having a permanently magnetized needle1 which is influenced by a coil or a wire in close proximity to it4 ,galvanoscope4 ,an instrument1 like a galvanometer1 which determines whether or not a current is present in a tested wire4 ,generator4 ,a term used to generally indicate any device which originates a current4 ,german ,silver4 ,an alloy of copper1 nickel and zinc4 ,graphite4 ,one form of carbon4 ,it is made artificially by the electric current4 ,grid4 ,the metallic frame of a plate used to hold the active material of an accumulator4 ,gravity4 ,the attraction of mass for mass4 ,weight4 ,the accelerating tendency of material to move toward the earth4 ,gutta ,percha4 ,caoutchouc1 which has been treated with sulphur1 to harden it4 ,it is produced from the sap of tropical trees1 and is a good insulator4 ,harmonic ,receiver4 ,a vibrating reed acted on by an electro-magnet1 when tuned to its pitch4 ,high ,e4 ,m4 ,f4 ,a term to indicate currents which have a high voltage1 and usually low amperage4 ,igniter4 ,mechanism composed of a battery1 induction coil and a vibrator1 for making a jump spark1 to ignite gas1 powder1 etc4 ,i4 ,h4 ,p4 ,abbreviation1 which means ,indicated ,horse ,power4 ,impulse4 ,a sudden motion of one body acting against another4 ,an electro-magnetic wave magnetizing soft iron1 and this iron attracting another piece of iron1 as an example4 ,incandescence1 ,a conductor heated up by a current so it will ,electric4 glow4 ,induced ,current4 ,a current of electricity which sets up lines of force at right angles to the body of the wire through which the current is transmitted4 ,induction1 ,magnetic4 ,a body within a magnetic field which is excited by the magnetism4 ,installation4 ,everything belonging to an equipment of a building1 or a circuiting system to do a certain thing4 ,insulation4 ,a material or substance which resists the passage of a current placed around a conductor4 ,intensity4 ,the strength of a magnetic field1 or of a current flowing over a wire4 ,internal ,resistance4 ,the current strength of electricity of a wire to resist the passage4 ,interrupter4 ,a device in a wire or circuit for checking a current4 ,it also refers to the vibrator of an induction coil4 ,joint4 ,the place where two or more conductors are united4 ,joint ,resistance4 ,the combined resistance offered by two or more substances or conductors4 ,jump ,spark4 ,a spark1 disruptive in its character1 between two conducting points4 ,initial ,charge4 ,the charge required to start a battery4 ,kathode1 or ,cathode4 ,the negative plate or side of a battery4 ,the plate on which the electro deposit is made4 ,key4 ,the arm of a telegraph sounder4 ,a bar with a finger piece1 which is hinged and so arranged that it will make and break contacts in an electric circuit4 ,keyboard4 ,a switch-board2 a board on which is mounted a number of switches4 ,kilowatt4 ,a unit1 representing #a1jjj watts4 ,an electric current measure1 usually expressed thus3 ,k4,w4 ,kilowatt ,hour4 ,the computation of work equal to the exertion of one kilowatt in one hour4 ,knife ,switch4 ,a bar of a blade-like form1 adapted to move down between two fingers1 and thus establish metallic connections4 ,laminated4 ,made up of thin plates of the same material1 laid together1 but not insulated from each other4 ,lamp ,arc4 ,a voltaic arc lamp1 using carbon electrodes1 with mechanism for feeding the electrodes regularly4 ,lamp1 ,incandescent4 ,a lamp with a filament heated up to a glow by the action of an electric current4 ,the filament is within a vacuum in a glass globe4 ,leak4 ,loss of electrical energy through a fault in wiring1 or in using bare wires4 ,load4 ,the ampere current delivered by a dynamo under certain conditions4 ,low ,frequency4 ,a current in which the vibrations are of few alternations per second4 ,magnet4 ,a metallic substance which has power to attract iron and steel4 ,magnet ,bar4 ,a straight piece of metal4 ,magnet ,coil4 ,a coil of wire1 insulated1 surrounding a core of iron1 to receive a current of electricity4 ,magnet ,core4 ,a bar of iron adapted to receive a winding of wire4 ,magnet1 ,field4 ,a magnet in a dynamo4 ,a motor to produce electric energy4 ,magnet1 ,permanent4 ,a short steel form1 to hold magnetism for a long time4 ,magnetic ,adherence4 ,the adherence of particles to the poles of a magnet4 ,magnetic ,that quality of a metal which draws metals4 ,also ,attraction and the pulling action of unlike poles for each ,repulsion4 other1 and pushing away of like poles when brought together4 ,magnetic ,force4 ,the action exercised by a magnet of attracting or repelling4 ,magnetic ,pole4 ,the earth has ,north and ,south magnetic poles4 ,the south pole of a magnetic needle is attracted so it points to the north magnetic pole2 and the north pole of the needle is attracted to point to the south magnetic pole4 ,magneto-generator4 ,a permanent magnet and a revolving armature for generating a current4 ,maximum ,voltage4 ,the final voltage after charging4 ,molecule4 ,invisible particles made up of two or more atoms of different matter4 ,an atom is a particle of one substance only4 ,morse ,sounder4 ,an electric instrument designed to make a clicking sound1 when the armature is drawn down by a magnet4 ,motor-dynamo4 ,a motor and a dynamo having their armatures connected together1 whereby the motor is driven by the dynamo1 so as to change the current into a different voltage and amperage4 ,motor-transformer4 ,a motor which delivers the current like a generator4 ,needle4 ,a bar magnet horizontally poised on a vertical pivot point1 like the needle of a mariner's compass4 ,negative ,amber1 when rubbed1 produces negative electricity4 ,electricity4 ,a battery has positive as well as negative electricity4 ,negative ,element4 ,that plate in the solution of a battery cell which is not disintegrated4 ,normal4 ,the usual1 or ordinary4 ,the average4 ,in a current the regular force required to do the work4 ,north ,pole1 ,the term applied to the force located near ,electric4 the north pole of the globe1 to which a permanent magnet will point if allowed to swing freely4 ,o4 ,abbreviation for ,ohm4 ,ohm4 ,the unit of resistance4 ,equal to the resistance of a column of mercury one square millimeter in cross section1 and #ajf4bd centimeters in length4 ,ohm's ,law4 ,it is expressed as follows3 #a4 ,the current strength is equal to the electro-motive force divided by its resistance4 #b4 ,the electro-motive force is equal to the current strength multiplied by the resistance4 #c4 ,the resistance is equal to the electro-motive force divided by the current strength4 ,overload4 ,in a motor an excess of mechanical work which causes the armature to turn too slowly and produces heat4 ,phase4 ,one complete oscillation4 ,the special form of a wave at any instant1 or at any interval of time4 ,plate1 ,condenser4 ,in a static machine it is usually a plate of glass and revoluble4 ,plate1 ,negative4 ,the plate in a battery1 such as carbon1 copper or platinum1 which is not attacked by the solution4 ,plating1 ,electro-4 ,the method of coating one metal with another by electrolysis4 ,polarity4 ,the peculiarity1 in a body1 of arranging itself with reference to magnetic influence4 ,parallel4 ,when a number of cells are coupled so that their similar poles are grouped together4 ,that is to say1 as the carbon plates1 for instance1 are connected with one terminal1 and all the zinc plates with the other terminal4 ,polarization4 ,when the cell is deprived of its electro-motive force1 or any part of it1 polarization is the result4 ,it is usually caused by coating of the plates4 ,porosity4 ,having small interstices or holes4 ,positive ,current4 ,one which deflects a needle to the left4 ,positive ,any current flowing from the active element1 ,electricity4 such as zinc1 in a battery4 ,the negative electricity flows from the carbon to the zinc4 ,potential1 ,electric4 ,the power which performs work in a circuit4 ,potential ,energy4 ,that form of force1 which1 when liberated1 does or performs work4 ,power ,unit4 ,the volt-amperes or watt4 ,primary4 ,the induction coil in induction machines1 or in a transformer4 ,push ,button4 ,a thumb piece which serves as a switch to close a circuit while being pressed inwardly4 ,quantity4 ,such arrangement of electrical connections which give off the largest amount of current4 ,receiver4 ,an instrument in telephony and telegraphy which receives or takes in the sound or impulses4 ,relay4 ,the device which opens or closes a circuit so as to admit a new current which is sent to a more distant point4 ,repulsion1 ,that tendency in bodies to repel each other when ,electric4 similarly charged4 ,resilience4 ,the springing back to its former condition or position4 ,electricity has resilience4 ,resistance4 ,the quality in all conductors to oppose the passage of a current4 ,resistance ,coil4 ,a coil made up of wire which prevents the passage of a current to a greater or less degree4 ,resistance1 ,the counter force in an electrolyte which seeks ,electrolytic4 to prevent a decomposing current to pass through it4 ,resistance3 ,internal1 ,the opposing force to the movement of a current ,external4 which is in the cell or generator4 ,this is called the internal4 ,that opposite action outside of the cell or generator is the external4 ,resonator1 ,an open-circuited conductor for electrically ,electric4 resounding or giving back a vibration1 usually exhibited by means of a spark4 ,rheostat4 ,a device which has an adjustable resistance1 so arranged that while adjusting the same the circuit will not be open4 ,safety ,fuse4 ,a piece of fusible metal of such resistance that it breaks down at a certain current strength4 ,saturated4 ,when a liquid has taken up a soluble material to the fullest extent it is then completely saturated4 ,secondary4 ,one of the two coils in a transformer1 or induction coil4 ,secondary ,plates4 ,the brown or deep red plates in a storage battery when charged4 ,self-excited4 ,producing electricity by its own current4 ,series4 ,arranged in regular order4 ,from one to the other directly4 ,if lamps1 for instance1 should be arranged in circuit on a single wire1 they would be in series4 ,series1 ,multiple4 ,when lamps are grouped in sets in parallel1 and these sets are then connected up in series4 ,series ,windings4 ,a generator or motor wound in such a manner that one of the commutator brush connections is joined to the field magnet winding1 and the other end of the magnet winding joined to the outer circuit4 ,shunt4 ,going around4 ,shunt ,winding4 ,a dynamo in which the field winding is parallel with the winding of the armature4 ,snap ,switch4 ,a switch so arranged that it will quickly make a break4 ,sounder4 ,the apparatus at one end of a line actuated by a key at the other end of the line4 ,spark ,coil4 ,a coil1 to make a spark from a low electro-motive force4 ,spark1 ,electric4 ,the flash caused by drawing apart the ends of a conductor4 ,specific ,gravity4 ,the weight or density of a body4 ,static ,electricity4 ,generated by friction4 ,also lightning4 ,any current generated by a high electro-motive force4 ,strength of ,current4 ,the quantity of electricity in a circuit4 ,synchronize4 ,operating together2 acting in unison4 ,terminal4 ,the end of any electric circuit or of a body or machine which has a current passing through it4 ,thermostat1 ,electric4 ,an electric thermometer4 ,usually made with a metal coil which expands through the action of the electricity passing through it1 and1 in expanding1 it makes a contact and closes a circuit4 ,transformer4 ,the induction coil with a high initial ,e4 ,m4 ,f4 changes into a low electro-motive force4 ,unit4 ,a standard of light1 heat1 electricity1 or of other phenomena4 ,vacuum4 ,a space from which all matter has been exhausted4 ,vibrator4 ,mechanism for making and breaking circuits in induction coils or other apparatus4 ,volt4 ,the unit of electro-motive force4 ,voltage4 ,electro-motive force which is expressed in volts4 ,voltaic4 ,a term applied to electric currents and devices4 ,volt-meter4 ,an apparatus for showing the difference of potential1 or ,e4 ,m4 ,f4 in the term of volts4 ,watt4 ,the unit of electrical activity4 ,the product of amperes multiplied by volts4 ,watt ,hour4 ,one watt maintained through one hour of time4 ,waves1 ,electric ,waves in the ether caused by electro-magnetic ,magnetic4 disturbances4 ,x-rays4 ,the radiation of invisible rays of light1 which penetrate or pass through opaque substances4 ,yoke1 or ,bar4 ,a soft iron body across the ends of a horseshoe magnet1 to enable the magnet to retain its magnetism an indefinite time4 ,zinc ,battery4 ,a battery which uses zinc for one of its elements4 ,,index ,a ,accumulated1 #ca4 ,accumulation1 #bi4 ,accumulator cell1 #hg4 ,accumulators1 #hb1 #hh1 #hi4 ,accumulators1 plates1 #hc4 ,acid1 #cd1 #cg1 #abe4 ,acid maker1 #abe4 ,acid1 sulphuric1 #ca1 #hd4 ,acidulated1 #ee4 ,acidulated water1 #cd4 ,acoustics1 #aaj4 ,actinic rays1 #ahd1 #ahe4 ,actinium1 #ahf4 ,active element1 #hb4 ,adjustable rod1 #ajg4 ,adjusting screw1 #gj1 #ga1 #gb1 #gc1 #ajf4 ,aerial wire1 #ajh4 ,agents1 #ac1 #cb4 ,alarms1 burglar1 #aa1 #gf1 #hj4 ,alkali1 #abe4 ,alkaline1 #cg4 ,alternate1 #abg4 ,alternating1 #ch1 #adi1 #aej1 #aec1 #aed1 #aee1 #aef4 ,alternating current1 #ade4 ,alternating periods1 #adi4 ,alternations1 #adg4 ,aluminum1 #abh1 #abi1 #ace1 #acg4 ,aluminum hydrate1 #abi4 ,amber1 #e1 #aga4 ,ammeter1 #g1 #hh4 ,amperage1 #ch1 #fa1 #fb1 #acb1 #aei1 #afj1 #afh4 ,ampere1 #g1 #cg1 #fj1 #fc1 #aci1 #adj1 #afg4 ,amplitude1 #aaa4 ,annunciator1 #fe1 #gd1 #gf1 #gi1 #hj1 #ha4 ,annunciator bells1 #aa4 ,anode1 #ce1 #acc1 #acd4 ,antenn1 #ajh4 ,antimony #acg1 #adc4 ,anvil1 #ac1 #ad4 ,apparatus1 #aa1 #eg1 #ajf1 #aci1 #ade4 ,arc1 #afc1 #ahb4 ,arc lighting1 #ch1 #afe4 ,arc system1 #aff4 ,armature1 #ah1 #be1 #ch1 #dj1 #db1 #dc1 #de1 #df1 #dg1 #dh1 #ec1 #ee1 #gj1 #gb1 #gc1 #gd1 #ij1 #ic1 #aab1 #aea1 #aeb1 #aee1 #afc1 #agf1 #agg1 #agh1 #agi1 #ahj4 ,armature brush1 #dh4 ,armature post1 #ga4 ,armature1 vertical1 #ge4 ,armature winding1 #db1 #dc1 #aef4 ,asbestos1 #adj4 ,astatic galvanometer1 #ajh4 ,atmosphere1 #ahd4 ,attract1 #cj4 ,attracted1 #gb4 ,attraction1 #ba1 #be4 ,attractive1 #agh4 ,automatic1 #abj4 ,auxiliary1 #dd4 ,awls1 #ad4 ,b ,bacteria1 #abf1 #ahg4 ,bar1 cross1 #ff4 ,bar1 horizontal1 #df4 ,bar1 parallel switch1 #fg4 ,bar1 switch1 #fe1 #fh4 ,base block1 #ff4 ,batteries1 #aa1 #ic1 #abb4 ,battery1 #bi1 #cj1 #cb1 #ce1 #cf1 #df1 #dg1 #hj1 #ha1 #hb1 #hc1 #he1 #hf1 #hh1 #ib1 #id1 #ie1 #ajg1 #ajh1 #aaf1 #aag1 #aah1 #aba1 #acd1 #adb4 ,battery charging1 #hb4 ,bearings1 #de1 #df4 ,bells1 #fe1 #gc1 #gf1 #abb4 ,bells1 electric1 #gj4 ,bench1 #ac1 #ae1 #ag4 ,binding post1 #eb1 #gj1 #ga1 #gb1 #ajc1 #ajg1 #ajh1 #aba4 ,binding screw1 #fe1 #ff4 ,bismuth1 #ah1 #adc4 ,bit1 #ac4 ,blue vitriol1 #eg4 ,brass plate1 #gg1 #gh4 ,brazing1 #ag1 #fe4 ,bridge1 #eb4 ,brush holder1 #df4 ,brushes1 #dh1 #aej1 #aea1 #aec1 #afg4 ,burglar1 #aa4 ,burglar alarm1 #gf1 #hj4 ,buttons1 contact1 #hj4 ,buttons1 push1 #fe1 #fh1 #fi1 #gj1 #gf1 #gi4 ,c ,calorimeter1 #ef4 ,cancerous1 #ahg4 ,candle power1 #hi1 #aci4 ,cap1 removable1 #gc4 ,cap screws1 #db4 ,carbon1 #ce1 #aai1 #aba1 #afb1 #afc1 #afi4 ,carbon block1 #abj4 ,carbon pencil1 #aai4 ,cathode1 #ce1 #cf1 #acc1 #acd4 ,cell1 #bi1 #cc4 ,cell1 accumulator1 #hg4 ,cell1 charging1 #hg4 ,channel1 #dc4 ,channel1 concave1 #dj4 ,charged1 #abj4 ,charged battery1 #hb4 ,charging circuit1 #hb1 #hi4 ,charging source1 #hc4 ,charged wire1 #adg4 ,chemical1 #eg4 ,chisels1 #ac4 ,chloride of lime1 #hd4 ,choked1 #aeg4 ,choking coils1 #ade1 #adf1 #aef1 #aeh4 ,circuit1 #cc1 #fi1 #gc1 #gf1 #gh1 #hj1 #ha1 #ij1 #ib1 #ic1 #aji1 #aac1 #aaf1 #aba1 #abb1 #aca1 #acd1 #adc1 #aef4 ,circuit1 primary1 #ii4 ,circuit1 secondary1 #ii4 ,circuiting1 #ha1 #aee4 ,circuiting system1 #gi4 ,clapper arm1 #gj4 ,closed rings1 #bf4 ,coherer1 #aje1 #ajh1 #aji4 ,cohering1 #ajf4 ,coils1 #ah1 #bf1 #eb1 #ee1 #gd1 #afj4 ,coils1 choking1 #ade1 #adf1 #aef1 #aeh4 ,coils1 induction1 #ii1 #ajb4 ,coils1 primary1 #aji4 ,coils1 secondary1 #ajb1 #aji4 ,coincide1 #db4 ,cold1 #ad4 ,collecting surfaces1 #cj4 ,collector1 #ca4 ,column1 #fa4 ,combustion1 #afi4 ,commutator1 #dd1 #df1 #aea1 #aeb4 ,commutator brushes1 #df4 ,commutator plates1 #de4 ,compass1 #bb1 #bd1 #agb4 ,composition1 #hc1 #abd4 ,compound wound1 #dg4 ,concave channel1 #dj4 ,condenser1 #ih1 #ajj1 #aja1 #ajb1 #ajh4 ,conduct1 #f1 #ajh4 ,conduction1 #ace1 #acf1 #ach1 #aff1 #agj4 ,conduction current1 #bg4 ,conductor1 #ba1 #ca1 #cc1 #fc1 #ih1 #aaf1 #afa1 #afb4 ,conduit1 #gb4 ,conically formed1 #abf4 ,conjunction1 #adc4 ,connecting wire1 #eh4 ,connection1 #gb1 #gf4 ,construction1 magnet1 #ci4 ,consumption1 #ahj4 ,contact1 #abb1 #abc1 #aeb1 #afb4 ,contact finger1 #aej4 ,contact plate1 #fg1 #fh1 #gi4 ,contact screws1 #ic4 ,contact surface1 #ff4 ,continuous1 #ade4 ,converter1 #agf4 ,converting1 #adb1 #ade1 #adf4 ,copper1 #ah1 #cd1 #cf1 #fe1 #ff1 #acb1 #acc1 #acd1 #ace1 #acf1 #acg1 #adb1 #adc4 ,copper cyanide1 #acc4 ,copper plate1 #cc1 #ce1 #eh1 #fg4 ,copper sulphate1 #eg4 ,copper voltameter1 #ee1 #eg4 ,core1 #bg1 #bh1 #cf1 #ci1 #dj1 #aae4 ,core1 magnet1 #ge1 #ic4 ,counter1 clock-wise1 #ea4 ,coupled1 #cf4 ,crank1 #cj4 ,crookes' tube1 #ahd4 ,cross bar1 #eb1 #ff4 ,crown of cups1 #cb4 ,crystal1 #he4 ,current1 #f1 #g1 #ac1 #ah1 #bf1 #bg1 #bh1 #ce1 #cf1 #cg1 #ch1 #dg1 #ej1 #ea1 #eb1 #ee1 #ef1 #eg1 #eh1 #ei1 #fb1 #fc1 #gj1 #gb1 #gc1 #ij1 #ie1 #ih1 #aje1 #ajh1 #aaf1 #acc1 #acd1 #ace1 #acf1 #ach1 #aci1 #adj1 #ada1 #adb1 #adc1 #adg1 #adh1 #adi1 #aej1 #aeb1 #aec1 #aeg1 #afj1 #afa1 #afc1 #afe1 #aff1 #agj4 ,current1 alternating1 #aej4 ,current changing1 #hb4 ,current conduction1 #bg4 ,current1 continuous1 #afd4 ,current1 direct1 #ade1 #aej4 ,current direction1 #ej4 ,current1 exterior1 #ej1 #aej4 ,current1 reversing1 #adh4 ,current strength1 #g1 #eg4 ,current testing1 #adc4 ,cut-out1 #abj4 ,cutter1 #ad4 ,cutting1 lines of force1 #ch4 ,cylinder1 #dd4 ,cylindrical1 #dc4 ,d ,dash1 #ie1 #ig4 ,decoherer1 #ajf1 #ajh4 ,decomposed1 #eg1 #abh4 ,decomposes1 #ee4 ,decomposing1 #abc4 ,decomposition1 #ab1 #ce1 #hb4 ,deflected1 #ed4 ,degree1 #ace1 #afb4 ,demagnetized1 #bd1 #gb4 ,deposited1 #eh1 #acc4 ,depression1 #ae1 #adj4 ,detecting current1 #di4 ,detector1 #di1 #eb1 #ed1 #aje4 ,devices1 measuring1 #bg4 ,diagrams1 #df1 #dh1 #gi1 #hi4 ,diagrammatically1 #ha4 ,diamagnetic1 #ai4 ,diametrically1 #aad4 ,diaphragm1 #aab1 #aac1 #aaf1 #abj1 #abb4 ,diamonds1 #ahf4 ,diluted1 #hf4 ,direct current1 #ch1 #adj4 ,direction of current1 #ej4 ,direction of flow1 #ih4 ,discharge1 #agb4 ,disintegrate1 #acb4 ,disk1 #dc4 ,dissimilar1 #cg4 ,disturbance1 #agf4 ,dividers1 #ad4 ,divisibility1 #afh4 ,dot1 #if1 #ig4 ,dot and dash1 #if4 ,double click1 #ie4 ,double line1 #fe4 ,double-pole switch1 #fe4 ,double-throw switch1 #aag4 ,drawing1 #bj4 ,drill1 ratchet1 #ac4 ,drops1 #ha4 ,ductile1 #ahf4 ,duplex wire1 #aae4 ,dynamo1 #g1 #bg1 #ch1 #db1 #df1 #dh1 #fb1 #hb1 #hc1 #hg1 #hi1 #acb1 #ada1 #adb1 #ade1 #aej1 #aee1 #afa1 #afe1 #afg1 #age1 #agf1 #ahj1 #ahg4 ,dynamo fields1 #dj1 #da4 ,e ,earth1 #bb4 ,elasticity1 #ajj1 #adb4 ,electric1 #f1 #ca1 #di1 #ej1 #gf1 #gh1 #ha1 #aca1 #adb1 #aeh1 #afb1 #agc1 #agf4 ,electric arc1 #fc1 #afc4 ,electric bell1 #ai1 #fi1 #gj1 #ga1 #gb1 #ajf1 #aag4 ,electric bulbs1 #afg4 ,electric circuit1 #aah4 ,electric fan1 #ee4 ,electric field1 #gf4 ,electric hand purifier1 #abi4 ,electric heating1 #ace1 #acg1 #afa4 ,electric iron1 #acj1 #ada4 ,electric lamp socket1 #aci4 ,electric light1 #ef1 #ff4 ,electric lighting1 #afa4 ,electric power1 #aac4 ,electric welding1 #ahc4 ,electrical1 #h1 #aa1 #fe1 #if1 #ih1 #ajd1 #ada1 #aei1 #ahj1 #ahd1 #ahg4 ,electrical impulses1 #aje1 #adg1 #adh4 ,electrical manifestations1 #age4 ,electrically1 #cb1 #gj4 ,electricity1 #e1 #f1 #g1 #h1 #i1 #ab1 #ac1 #ah1 #ba1 #bf1 #bg1 #bh1 #bi1 #ch1 #di1 #ed1 #fj1 #fa1 #fb1 #hb1 #ig1 #ih1 #ajj1 #ajd1 #aaj1 #aab1 #aaf1 #abc1 #abd1 #acc1 #acd1 #acf1 #ach1 #ade1 #adf1 #adg1 #aed1 #aef1 #afj1 #aff1 #agj1 #aga1 #agb1 #age1 #ahb1 #ahg4 ,electricity measuring1 #di4 ,electricity1 thermo-1 #adb4 ,electrified1 #cg1 #ahf4 ,electro-chemical1 #ee4 ,electrode1 #ce1 #abd1 #abg1 #abh1 #afa1 #afb1 #afc1 #afd1 #afe1 #ahd4 ,electrolysis1 #g1 #abc1 #abf1 #acb4 ,electrolyte1 #cc1 #ce1 #cf1 #eg1 #hf1 #hh1 #abc1 #acb1 #adb4 ,electrolytic1 #ee1 #abc1 #abe4 ,electro-magnet1 #ei1 #gh4 ,electro-magnetic1 #g1 #bd1 #be1 #bi1 #cg1 #ee1 #ib1 #ic1 #id4 ,electro-magnetic force1 #g4 ,electro-magnetic rotation1 #g4 ,electro-magnetic switch1 #aaf4 ,electro-meter1 #g4 ,electro-motive force1 #cg1 #fc1 #ii4 ,electroplate1 #ab1 #ch1 #dh1 #abc1 #acb1 #acd4 ,electro-positive-negative1 #adb1 #adc4 ,elements1 #cf1 #hc4 ,engine energy1 #agj1 #ahj4 ,equidistant1 #abg4 ,ether1 #ajd4 ,example1 #fa4 ,excited1 #dg4 ,extension plate1 #ajc4 ,exterior1 #c4 ,exterior magnetic1 #bg4 ,external1 #cg4 ,external circuit1 #aec4 ,external current1 #ej4 ,external resistance1 #cg4 ,f ,factor1 #fa4 ,ferrous oxide1 #abe4 ,field1 #df1 #dg4 ,field1 dynamo1 #dj1 #da4 ,field magnet cores1 #aee4 ,field1 magnetic1 #ch4 ,field of force1 #cc4 ,field wire1 #dh4 ,filament1 #afh1 #afi1 #agj4 ,filter1 #abh4 ,flat iron1 #adj4 ,flocculent1 #abh4 ,force1 #ej4 ,formulated1 #ai4 ,friction1 #cb4 ,frictional1 #f1 #g1 #bi4 ,fuse1 #afi4 ,g ,galvani1 #g4 ,galvanic1 #g1 #bc1 #cj4 ,galvanometer1 #g1 #di1 #ajh1 #adc4 ,galvanoscope1 #ee1 #eh1 #ei4 ,gaseous1 #abh4 ,gasoline1 #ii4 ,gas stove1 #ag4 ,gelatine1 #abh4 ,generate1 #bi1 #ch1 #acd1 #acf1 #ade4 ,generated1 #ee4 ,generating1 #cb1 #acd4 ,generation1 #agj4 ,generator1 #cb1 #abe1 #adg4 ,german silver1 #acf1 #acg4 ,germicide1 #ahg4 ,gimlets1 #ag4 ,glass1 #cj1 #hf1 #abf1 #ahf4 ,gold1 #ace4 ,grid1 #hd4 ,ground circuit1 #aba4 ,gunpowder1 #f4 ,h ,hack-saw1 #ad4 ,hammer1 #ac4 ,heart-shaped switch1 #gg4 ,heater1 #acf4 ,heating1 #ac1 #ch4 ,hertzian rays1 #agj4 ,hertzian wave1 #ahd4 ,high tension1 #ch1 #ajb1 #ahd4 ,high tension apparatus1 #ih4 ,high tension coils1 #ajc4 ,high voltage1 #aeh4 ,horizontal bar1 #df4 ,horseshoe magnet1 #bb1 #bd1 #age4 ,hydrate of aluminum1 #abi4 ,hydrogen1 #ce1 #abc1 #abe1 #abh4 ,i ,igniting1 #ii4 ,illumination1 #afb1 #afc1 #afe1 #afg1 #agj4 ,immersed1 #acc4 ,impulses1 #fj1 #fb1 #if1 #ajd1 #aji1 #aeb1 #agi4 ,incandescent1 #aff1 #afh4 ,induced1 #bh4 ,inductance1 #adi1 #aej4 ,induction1 #bg1 #cg1 #ih1 #adg4 ,induction coils1 #ii1 #ajb1 #ajf4 ,influences1 #agh4 ,initial charge1 #hh4 ,insulated1 #bg1 #bh1 #dj1 #dc1 #eb1 #ee1 #gc1 #aae1 #aea1 #ahj4 ,insulating1 #ff1 #fi1 #abj1 #adj1 #afd4 ,insulating material1 #aad4 ,insulation1 #dj1 #aaf4 ,instruments1 #di1 #id1 #aab1 #aah1 #abj4 ,instruments1 measuring1 #h4 ,intensity1 #ee1 #fj1 #ajd1 #aed4 ,interior1 magnetic1 #bc4 ,internal resistance1 #cg4 ,interruption1 #ajb1 #ajc4 ,installation1 #afh4 ,ionize1 #ahf4 ,iron1 #ai1 #acb1 #acc1 #acf1 #adb1 #aga4 ,isolated1 #ahf4 ,j ,jar1 #bi1 #ca1 #cb4 ,journal1 #df4 ,journal block1 #af1 #adf4 ,jump spark1 #ii4 ,k ,key1 #ij1 #ia1 #ie4 ,key1 sending1 #ij4 ,knob1 #cb4 ,knob1 terminal1 #ca4 ,l ,laboratory1 #i4 ,lead1 #ca1 #acf4 ,lead1 precipitated1 #hc1 #he4 ,lead1 red1 #hc1 #hd4 ,lever switching1 #fg4 ,light1 #ajd4 ,light method1 #ef4 ,lighting1 #i1 #ch4 ,lighting circuit1 #dh4 ,lighting system1 #hb4 ,lightning1 #f1 #aga1 #agb1 #agc4 ,lightning rod1 #agc4 ,lime1 chloride of1 #hd4 ,line of force1 #adf4 ,line wire1 #abb4 ,line1 magnetic1 #bb1 #bc4 ,liquid1 #cb4 ,litharge1 #hc4 ,loadstone1 #ag4 ,locomotives1 #afe4 ,low tension1 #ch1 #ih1 #ajb1 #agi4 ,m ,magnet bar1 #bj4 ,magnet core1 #af1 #ge1 #ic4 ,magnet1 electro1 #ei1 #gh4 ,magnet1 horseshoe1 #bb1 #be1 #age4 ,magnet lines1 #bb1 #bc4 ,magnet1 permanent1 #be1 #ch1 #df1 #ej1 #agb4 ,magnet1 reversed1 #bj4 ,magnet1 steel1 #ec4 ,magnet1 swinging1 #ec4 ,magnetic1 #g1 #ai1 #bj1 #ba1 #bb1 #be1 #aac1 #agh4 ,magnetic construction1 #ci4 ,magnetic exterior1 #bg4 ,magnetic field1 #bb1 #bd1 #bg1 #ch1 #ej1 #aab1 #adf1 #adh1 #aee4 ,magnetic interior1 #bc4 ,magnetic pull1 #ei4 ,magnetic radiator1 #cg4 ,magnetism1 #ai1 #ed1 #ajd1 #aaj1 #aei1 #aga4 ,magnetized1 #ah1 #be1 #bg1 #ej4 ,magnetized wire1 #adf4 ,magnets1 #ac1 #ad1 #ah1 #ai1 #bj1 #ba1 #bb1 #bc1 #bd1 #be1 #ci1 #ea1 #ec1 #ed1 #gj1 #ga1 #gc1 #ge1 #ha1 #ij1 #ic1 #aab1 #aac1 #aae1 #adg1 #aej1 #afc1 #agf1 #agg1 #agh4 ,main conductor1 #ca4 ,mandrel1 #ae1 #af4 ,manganese1 #ai4 ,manifestations1 #ai4 ,mariner1 #agb4 ,material1 non-conducting1 #ij4 ,maximum1 #aed4 ,measure1 #ee1 #ef1 #fj1 #fb4 ,measurement1 #fb4 ,measuring devices1 #bg4 ,measuring instruments1 #h4 ,mechanism1 #dg1 #ahj4 ,medical batteries1 #ii4 ,mercury1 #fc1 #afi4 ,metal base1 #gc4 ,mica1 #ahf4 ,microphone1 #aah1 #aai1 #abj4 ,millimeter1 #fc4 ,minus1 #cd4 ,minus sign1 #ba4 ,morse code1 #gf4 ,motor1 #g1 #ba1 #bg1 #df1 #dg1 #fb1 #hb1 #ii1 #aej1 #agf1 #ahj4 ,mouthpiece1 #aae4 ,mouthpiece rays1 #ahh4 ,moving field1 #aag4 ,multiple1 #afh4 ,musical scale1 #aaa4 ,n ,negative1 #ba1 #ce1 #cf1 #fh1 #hc1 #hf1 #hg1 #id1 #abe1 #aea1 #aeb1 #aed1 #afe1 #agg1 #agh1 #agi4 ,neutral1 #abe4 ,neutral plate1 #hd4 ,nickel1 #acf4 ,nickel plating1 #acb4 ,nitrate of silver1 #fb4 ,nitrogen1 #abf4 ,non-conducting material1 #ij4 ,non-conductor1 #afd4 ,non-magnetic1 #ai4 ,north pole1 #bj1 #ba1 #bb1 #bc1 #be1 #ej1 #ed1 #aef4 ,number plate1 #ge4 ,n-ray1 #ahh4 ,o ,ohms1 #fj1 #fc4 ,ohms1 international1 #fc4 ,ohms law1 #g4 ,operator1 #ie1 #aah4 ,oscillating1 #ii1 #aje4 ,osmium1 #afi4 ,oxides1 #abe4 ,oxidizing1 #ahc4 ,oxygen1 #ce1 #abc1 #abe1 #abf1 #abh1 #abi1 #afi4 ,p ,packing ring1 #abd4 ,paraffine1 #ef1 #ajj1 #aja1 #ajb4 ,paraffine wax1 #hf4 ,parallel1 #hg1 #hh1 #hi4 ,parallel switch bar1 #fg4 ,parallel wires1 #bh1 #di4 ,partition1 #abd4 ,peon1 #ac4 ,percolate1 #abh4 ,periodicity1 #aei4 ,periods of alternations1 #adi4 ,permanent1 #ah1 #ai1 #ej4 ,permanent magnet1 #be1 #ch1 #df1 #ej1 #agb4 ,phase1 #ai4 ,phenomenon1 #bg1 #fe4 ,photograph1 #ahf4 ,physical1 #ba4 ,pile1 voltaic1 #cc4 ,pipe1 #fa4 ,pitchblende1 #ahf4 ,pivot pin1 #ec4 ,pivotal1 #bb4 ,plane1 #ac4 ,plate1 #eg1 #ic4 ,plate1 contact1 #fg1 #fh1 #gi4 ,plate1 copper1 #cc1 #ce1 #eh1 #fg4 ,plate1 negative1 #hd4 ,plate1 number1 #ge4 ,plate1 positive1 #hd1 #hh4 ,plate1 zinc1 #cc4 ,platinum1 #ac1 #eg1 #acg4 ,pliers1 #ad4 ,plus sign1 #ba1 #bd4 ,pointer1 #ec4 ,polarity1 #aed1 #agg1 #agh1 #agi4 ,polarization1 #ce4 ,pole1 north1 #bj1 #ba1 #bb1 #bc1 #be1 #ej1 #ed1 #aef4 ,pole piece1 #dj1 #db4 ,pole1 south1 #bj1 #ba1 #bb1 #be1 #ej1 #ed1 #aef4 ,poles1 #agg1 #agi4 ,polonium1 #ahf4 ,porcelain1 #hf4 ,porous1 #he4 ,positive1 #d1 #ba1 #be1 #cf1 #dj1 #fh1 #hc1 #hf1 #hg1 #id1 #abc1 #abe1 #aea1 #aeb1 #aec1 #aee1 #afe4 ,post1 binding1 #eb1 #ga4 ,potentiality1 #aje1 #aji4 ,power1 #ch1 #ahf4 ,power1 candle1 #hi1 #aci4 ,precipitate of lead1 #hc1 #he4 ,precision1 #g4 ,pressure1 #hg4 ,primary1 #ce1 #fb1 #ih1 #acd1 #adb1 #aei1 #ahd4 ,primary battery1 #g1 #ii4 ,primary circuit1 #ii4 ,primary coil1 #ajf1 #aji4 ,prime conductor1 #f4 ,projected1 #ahe4 ,propagated1 #aje1 #ahe4 ,properties1 #ee4 ,purification1 #abc1 #abh4 ,purifier1 #abf1 #aca4 ,push button1 #fe1 #fh1 #fi1 #gj1 #gf1 #gi4 ,q ,quantity1 #ee1 #fj1 #fa1 #ach4 ,quartz1 #ahf4 ,r ,radio-activity1 #ahf4 ,radium1 #ahd1 #ahe1 #ahg1 #ahh4 ,ratchet drill1 #ac4 ,reaction1 #adh4 ,receiver1 #ab1 #ij1 #ig1 #aba1 #abb4 ,receiving station1 #aji4 ,rectangular1 #fi4 ,rectifiers1 #adf4 ,red lead1 #hc1 #hd4 ,reel1 #ac4 ,reflected1 #ahe4 ,refraction1 #ahe4 ,refractory1 #ahb4 ,register1 #eg4 ,removable1 #ed4 ,removable cap1 #gc4 ,repel1 #bj4 ,repulsion1 #ba1 #abh4 ,reservoir1 #fa1 #fb4 ,resiliency1 #ii4 ,resistance1 #g1 #cf1 #cg1 #fj1 #fc1 #ii1 #ace1 #acf1 #acg1 #ach1 #adj1 #ada1 #aef1 #aeg1 #afc1 #aff1 #afh4 ,resistance bridge1 #g4 ,resistance1 external1 #cg4 ,resistance1 internal1 #cg4 ,rheostat1 #g4 ,reversed1 #bj1 #ej1 #aec4 ,reversible1 #afc4 ,reversing1 #agf4 ,reversing switch1 #fg4 ,revolubly1 #df4 ,revolve1 #agi4 ,revolving1 #agg4 ,roentgen rays1 #ahd4 ,roentgen tube1 #ahg4 ,rotation1 #adi4 ,rubber1 #dj1 #df1 #gg1 #aae1 #abf1 #acj1 #ach4 ,s ,sad-irons1 #ac4 ,saline1 #acc4 ,sanitation1 #ab4 ,saturated1 #he4 ,screw1 #ae4 ,screw1 binding1 #fe1 #ff4 ,screw-driver1 #ad4 ,screw1 set1 #gb4 ,sealing wax1 #ec4 ,secondary1 #fb1 #ih1 #aje1 #aeh1 #aei1 #afj4 ,secondary circuit1 #ii4 ,secondary coil1 #ajg1 #ajh4 ,self-induction1 #adi1 #aef4 ,sender1 #ij1 #ig4 ,sending apparatus1 #ajf4 ,sending key1 #ij4 ,separately excited1 #df4 ,series-wound1 #dg4 ,severed magnet1 #bj4 ,sewage1 #ab4 ,shaft1 #cj4 ,shears1 #ad1 #ag4 ,shellac1 #dj4 ,shunt-wound1 #dg4 ,signal1 #aah4 ,silver1 #ai1 #fc1 #abe4 ,silver nitrate1 #fb4 ,socket1 #ed1 #aci4 ,soldering1 #ad4 ,soldering iron1 #ag4 ,solution1 #ee1 #eg1 #fb1 #fc1 #hd1 #hf1 #acc1 #acd1 #adb4 ,sounder1 #ij1 #ib1 #ie1 #if4 ,sounding board1 #aai4 ,source1 charging1 #hc4 ,south pole1 #bj1 #ba1 #bb1 #be1 #ej1 #ed1 #aef4 ,spark gap1 #ajb1 #ajf4 ,spark jump1 #ii4 ,spring finger1 #fi4 ,square1 #ad1 #ag4 ,standard1 #fb1 #fc4 ,station1 #id1 #ie1 #aag1 #abb4 ,steel1 #ah1 #ai4 ,steel magnet1 #ec4 ,sterilized1 #ab4 ,stirrup1 #ge4 ,stock bit1 #ac4 ,stock contact1 #aba4 ,storage1 #hb4 ,storage battery1 #ajg4 ,storing1 #hb4 ,substances1 #ace4 ,sulphate1 #ee1 #abh1 #acc4 ,sulphur1 #ai4 ,sulphuric acid1 #ca1 #hd4 ,sulphuric acid voltameter1 #ee1 #eg4 ,superstition1 #aga1 #agc4 ,surging1 #aec1 #aed4 ,swinging magnet1 #ec4 ,swinging switch blade1 #fg4 ,switch blades1 #ff4 ,switches1 #fe1 #ff1 #gj1 #gg1 #gh1 #ij1 #aag4 ,switches1 bar1 #fe1 #fh1 #ij1 #ia4 ,switches1 bar1 parallel1 #fg4 ,switches1 heart-shaped1 #gh4 ,switches1 piece1 #gg4 ,switches1 reversing1 #fg4 ,switches1 sliding1 #fg1 #hj4 ,switches1 terminal1 #h4 ,switches1 two-pole1 #fe4 ,system1 circuiting1 #gi4 ,t ,tail-piece1 #af4 ,tantalum1 #afi4 ,telegraph1 #aa1 #ij1 #if4 ,telegraph key1 #ajf4 ,telegraph sounder1 #ajh1 #aji4 ,telegraphing1 #id4 ,telephone1 #ab1 #aaj1 #aac1 #aag1 #aah1 #aai1 #abj4 ,telephone circuit1 #aah4 ,telephone connections1 #aaf4 ,telephone hook1 #abb4 ,temperature1 #ef1 #hh1 #acd1 #afa1 #agj4 ,tension1 high1 #ch1 #ajb1 #ahd4 ,tension1 low1 #ch1 #ih1 #ajb1 #agi4 ,terminal1 #ca1 #cd1 #ce1 #dj1 #dh1 #hb1 #hf1 #ic1 #ie1 #ajg1 #aaf1 #aba1 #abb1 #aea1 #aeb1 #aec1 #aed1 #aef4 ,terminal knob1 #ca4 ,terminal1 secondary1 #ajb4 ,terminal switch1 #ha4 ,theoretical1 #afj4 ,therapeutics1 #ahg4 ,thermo-electric couples1 #adf4 ,thermo-electricity1 #ace4 ,thermometer1 #ef4 ,thorium1 #afi1 #ahf4 ,thunderbolt1 #aga1 #agc4 ,tin1 #acf4 ,tinfoil1 #ca1 #aja4 ,tools1 #aa1 #ac1 #ag4 ,torch1 brazing1 #ag4 ,transformer1 #ade1 #adf1 #aeh1 #aei1 #ahj1 #ahb4 ,transformer1 step-down1 #ahb4 ,transmission1 #ch1 #ahg4 ,transmit1 #fc1 #ie1 #aeg4 ,transmitter1 #ab1 #abj1 #aba1 #abb1 #abc4 ,transverse1 #af1 #eb4 ,transversely1 #dc4 ,trigger1 #ge4 ,tripod1 #ca4 ,tubular1 #dd1 #de4 ,two-pole switch1 #fe4 ,u ,ultra-violet1 #ahe4 ,uranium1 #ahf4 ,v ,vacuum1 #ahd4 ,vapor lamps1 #afi4 ,velocity1 #fj1 #gc4 ,vertical armature1 #ge4 ,vibration1 #aaj1 #aaa1 #aac4 ,vibratory1 #aaj4 ,vise1 #ac4 ,voltage1 #cg1 #ch1 #fj1 #fa1 #fb1 #fc1 #hg1 #hh1 #ii1 #adg1 #aed1 #afe1 #ahj1 #ahb4 ,voltage1 high1 #aeh4 ,voltaic1 #bi1 #cb4 ,voltaic pile1 #cc4 ,voltameter1 #g1 #eh1 #hh4 ,voltameter1 sulphuric1 acid1 #ee1 #eg4 ,volts1 #fj1 #fb1 #hg1 #hi1 #acb1 #aeh1 #aei4 ,w ,water1 #abc1 #ach1 #add4 ,water power1 #adb4 ,watts1 #fj1 #fa1 #afj4 ,wave lengths1 #ajd1 #aaj4 ,weight1 #di4 ,welding1 #ac1 #ahb4 ,winding1 #ah1 #dj1 #dg1 #eh1 #aei1 #aif4 ,winding reel1 #ad4 ,window connection1 #gf4 ,window frame1 #gh4 ,wire1 #f1 #ah1 #ba1 #bf1 #bh1 #aef4 ,wire1 circuiting1 #gi4 ,wire coil1 #dj4 ,wire lead1 #gj4 ,wire1 parallel1 #bh1 #di4 ,wireless1 #ab4 ,wireless telegraphy1 #ajc1 #ajd1 #ahd4 ,wiring1 #hj4 ,wiring1 window1 #gg4 ,workshop1 #aa1 #ag4 ,wound1 compound1 #dh4 ,wound-series1 #dg4 ,wound-shunt1 #dg4 ,x ,x-ray1 #ahd1 #ahe1 #ahg1 #ahh4 ,z ,zinc1 #ag1 #cd1 #ce1 #he1 #ace4 ,zinc plates1 #cc4 ,,the ,,how-,,to-,,do-,,it ,,books ,,carpentry ,,for ,,boys ,a book which treats1 in a most practical and fascinating manner all subjects pertaining to the ,king of ,trades2 showing the care and use of tools2 drawing2 designing1 and the laying out of work2 the principles involved in the building of various kinds of structures1 and the rudiments of architecture4 ,it contains over two hundred and fifty illustrations made especially for this work1 and includes also a complete glossary of the technical terms used in the art4 ,the most comprehensive volume on this subject ever published for boys4 ,,electricity ,,for ,,boys ,the author has adopted the unique plan of setting forth the fundamental principles in each phase of the science1 and practically applying the work in the successive stages4 ,it shows how the knowledge has been developed1 and the reasons for the various phenomena1 without using technical words so as to bring it within the compass of every boy4 ,it has a complete glossary of terms1 and is illustrated with two hundred original drawings4 ,,practical ,,mechanics ,,for ,,boys ,this book takes the beginner through a comprehensive series of practical shop work1 in which the uses of tools1 and the structure and handling of shop machinery are set forth2 how they are utilized to perform the work1 and the manner in which all dimensional work is carried out4 ,every subject is illustrated1 and model building explained4 ,it contains a glossary which comprises a new system of cross references1 a feature that will prove a welcome departure in explaining subjects4 ,fully illustrated4 ,price #fj cents per volume ,,the ,,new ,,york ,,book ,,company #adg ,,fourth ,,avenue ,,new ,,york ---------------------------------------- ------------------------- ,transcriber's ,note4 ,every effort has been made to replicate this text as faithfully as possible1 including obsolete and variant spellings and other inconsistencies4 ,minor punctuation and printing errors have been corrected4 ,the first page of the original book is an advertisement4 ,the page was moved to the end of the text4 ,some hyphenation inconsistencies in the text were retained3 #af-;candle-power and #af-;candlepower1 ,electromotive and electro-motive1 ,electro-meter and ,electrometer1 ,horseshoe and horse-shoe1 ,switchboard and switch-board1 ,two occurrences of ',colorimeter' for ',calorimeter' repaired4 ---------------------------------------- -------------------------