,transcriber's ,notes ,in this ,plain ,text version of this e,book1 italics are enclosed within tildas1 superscripts and subscripts are enclosed in curly braces and preceded by a caret superscript or an underscore subscript4 ,other notes will be found at the end of this e,book4 ,,smithsonian ,,miscellaneous ,,collections ,,volume #gf1 ,,number #b ,,history ,,of ,,electric ,,light ,,by ,,henry ,,schroeder ,harrison1 ,new ,jersey ,illustration3 ,,for ,,the ,,increase ,,and ,,diffvsion ,,of ,,knowledge ,,among ,,men ,,smithsonian ,,institvtion ,,washington #ahdf 7,,publication #bgag7 ,,city ,,of ,,washington ,,published ,,by ,,the ,,smithsonian ,,institution ,,august #ae1 #aibc ,the ,lord ,baltimore ,press ,,baltimore1 ,,md41 ,u4 ,s4 ,a4 ,,contents ,,page ,list of ,illustrations v ,foreword ix ,chronology of ,electric ,light xi ,early ,records of ,electricity and ,magnetism #a ,machines ,generating ,electricity by ,friction #b ,the ,leyden ,jar #c ,electricity ,generated by ,chemical ,means #c ,improvement of ,volta's ,battery #e ,davy's ,discoveries #e ,researches of ,oersted1 ,ampre1 ,schweigger and ,sturgeon #f ,ohm's ,law #g ,invention of the ,dynamo #g ,daniell's ,battery #aj ,grove's ,battery #aa ,grove's ,demonstration of ,incandescent ,lighting #ab ,grenet ,battery #ac ,de ,moleyns' ,incandescent ,lamp #ac ,early ,developments of the ,arc ,lamp #ad ,joule's ,law #af ,starr's ,incandescent ,lamp #ag ,other ,early ,incandescent ,lamps #ai ,further ,arc ,lamp ,developments #bj ,development of the ,dynamo1 #ahdj-ahfj #bd ,the ,first ,commercial ,installation of an ,electric ,light #be ,further ,dynamo ,developments #bg ,russian ,incandescent ,lamp ,inventors #cj ,the ,jablochkoff 8,candle0 #ca ,commercial ,introduction of the ,differentially ,controlled ,arc ,lamp #cc ,arc ,lighting in the ,united ,states #cc ,other ,american ,arc ,light ,systems #dj 8,sub-,dividing the ,electric ,light0 #db ,edison's ,invention of a ,practical ,incandescent ,lamp #dc ,edison's ,three-,wire ,system #ec ,development of the ,alternating ,current ,constant ,potential ,system #ed ,incandescent ,lamp ,developments1 #ahhd-ahid #ef ,the ,edison 8,municipal0 ,street ,lighting ,system #fb ,the ,shunt ,box ,system for ,series ,incandescent ,lamps #fd ,the ,enclosed ,arc ,lamp #fe ,the ,flame ,arc ,lamp #fg ,the ,constant ,current ,transformer for ,series ,circuits #fi ,enclosed ,series ,alternating ,current ,arc ,lamps #fi ,series ,incandescent ,lamps on ,constant ,current ,transformers #gj ,the ,nernst ,lamp #ga ,the ,cooper-,hewitt ,lamp #gb ,the ,luminous or ,magnetite ,arc ,lamp #gd ,mercury ,arc ,rectifier for ,magnetite ,arc ,lamps #gg ,incandescent ,lamp ,developments1 #ahid-aijd #gh ,the ,moore ,tube ,light #gi ,the ,osmium ,lamp #hb ,the ,gem ,lamp #hb ,the ,tantalum ,lamp #hd ,invention of the ,tungsten ,lamp #he ,drawn ,tungsten ,wire #hg ,the ,quartz ,mercury ,vapor ,arc ,lamp #hh ,the ,gas-,filled ,tungsten ,lamp #hi ,types and ,sizes of ,tungsten ,lamps ,now ,made #ia ,standard ,voltages #ic ,cost of ,incandescent ,electric ,light #ic ,statistics ,regarding the ,present ,demand for ,lamps #id ,selected ,bibliography #ie ,,list ,,of ,,illustrations ,,page ,portion of the ,electrical ,exhibit in the ,united ,states ,national ,museum viii ,otto ,von ,guericke's ,electric ,machine1 #afej #b ,voltaic ,pile1 #agii #d ,faraday's ,dynamo1 #ahca #h ,pixii's ,dynamo1 #ahcb #i ,daniell's ,cell1 #ahcf #aj ,grove's ,cell1 #ahch #aa ,grove's ,incandescent ,lamp1 #ahdj #ac ,de ,moleyns' ,incandescent ,lamp1 #ahda #ad ,wright's ,arc ,lamp1 #ahde #ae ,archereau's ,arc ,lamp1 #ahdh #af ,starr's ,incandescent ,lamp1 #ahde #ah ,staite's ,incandescent ,lamp1 #ahdh #ai ,roberts' ,incandescent ,lamp1 #aheb #ai ,farmer's ,incandescent ,lamp1 #ahei #bj ,roberts' ,arc ,lamp1 #aheb #ba ,slater and ,watson's ,arc ,lamp1 #aheb #ba ,diagram of 8,differential0 ,method of ,control of an ,arc ,lamp #bb ,lacassagne and ,thiers' ,differentially ,controlled ,arc ,lamp1 #ahef #bc ,serrin's ,arc ,lamp1 #aheg #bd ,siemens' ,dynamo1 #ahef #be ,alliance ,dynamo1 #ahfb #bf ,wheatstone's ,self-,excited ,dynamo1 #ahff #bg ,gramme's ,dynamo1 #ahga #bh ,gramme's 8,ring0 ,armature #bh ,alteneck's ,dynamo with 8,drum0 ,wound ,armature1 #ahgb #bi ,lodyguine's ,incandescent ,lamp1 #ahgb #cj ,konn's ,incandescent ,lamp1 #ahge #cj ,bouliguine's ,incandescent ,lamp1 #ahgf #ca ,jablochkoff 8,candle10 #ahgf #cb ,jablochkoff's ,alternating ,current ,dynamo1 #ahgf #cc ,wallace-,farmer ,arc ,lamp1 #ahge #cd ,wallace-,farmer ,dynamo1 #ahge #cd ,weston's ,arc ,lamp1 #ahgf #ce ,brush's ,dynamo1 #ahgg #cf ,diagram of ,brush ,armature #cf ,brush's ,arc ,lamp1 #ahgg #cg ,thomson-,houston ,arc ,dynamo1 #ahgh #ch ,diagram of ,t-,h ,arc ,lighting ,system #ci ,thomson-,houston ,arc ,lamp1 #ahgh #dj ,thomson ,double ,carbon ,arc ,lamp #dj ,maxim ,dynamo #da ,sawyer's ,incandescent ,lamp1 #ahgh #db ,farmer's ,incandescent ,lamp1 #ahgh #db ,maxim's ,incandescent ,lamp1 #ahgh #dc ,edison's ,first ,experimental ,lamp1 #ahgh #dd ,diagram of ,constant ,current ,series ,system #de ,diagram of ,edison's ,multiple ,system1 #ahgi #de ,edison ,dynamo1 #ahgi #df ,edison's ,high ,resistance ,platinum ,lamp1 #ahgi #dg ,edison's ,high ,resistance ,platinum in ,vacuum ,lamp1 #ahgi #dg ,edison's ,carbon ,lamp of ,october #ba1 #ahgi #dh ,demonstration of ,edison's ,incandescent ,lighting ,system #di ,dynamo ,room1 ,s4 ,s4 ,columbia #ej ,original ,socket for ,incandescent ,lamps #ea ,wire ,terminal ,base ,lamp1 #ahhj #ea ,original ,screw ,base ,lamp1 #ahhj #eb ,improved ,screw ,base ,lamp1 #ahha #eb ,final ,form of ,screw ,base1 #ahha #ec ,diagram of ,edison's ,three ,wire ,system1 #ahha #ed ,diagram of ,stanley's ,alternating ,current ,multiple ,system1 #ahhe #ee ,standard ,edison ,lamp1 #ahhd #ef ,standard ,edison ,lamp1 #ahhh #ef ,standard ,edison ,lamp1 #ahid #eg ,various ,bases in ,use1 #ahib #eh ,thomson-,houston ,socket #ei ,westinghouse ,socket #ei ,adapters for ,edison ,screw ,sockets1 #ahib #fj ,various ,series ,bases in ,use1 #ahib #fa ,edison 8,municipal0 ,system1 #ahhe #fb ,edison 8,municipal0 ,lamp1 #ahhe #fc ,shunt ,box ,system1 #ahhg #fd ,enclosed ,arc ,lamp1 #ahic #fe ,open ,flame ,arc ,lamp1 #ahih #ff ,enclosed ,flame ,arc ,lamp1 #aijh #ff ,constant ,current ,transformer1 #aijj #fh ,series ,incandescent ,lamp ,socket with ,film ,cutout1 #aijj #gj ,nernst ,lamp1 #aijj #ga ,diagram of ,nernst ,lamp #gb ,cooper-,hewitt ,mercury ,vapor ,arc ,lamp1 #aija #gc ,diagram of ,cooper-,hewitt ,lamp for ,use on ,alternating ,current #gd ,luminous or ,magnetite ,arc ,lamp1 #aijb #ge ,diagram of ,series ,magnetite ,arc ,lamp #gf ,mercury ,arc ,rectifier ,tube for ,series ,magnetite ,arc ,circuits1 #aijb #gg ,early ,mercury ,arc ,rectifier ,installation #gh ,the ,moore ,tube ,light1 #aijd #gi ,diagram of ,feeder ,valve of ,moore ,tube #hj ,osmium ,lamp1 #aije #hb ,gem ,lamp1 #aije #hc ,tantalum ,lamp1 #aijf #hd ,tungsten ,lamp1 #aijg #hf ,drawn ,tungsten ,wire ,lamp1 #aiaa #hg ,quartz ,mercury ,vapor ,lamp1 #aiab #hh ,gas ,filled ,tungsten ,lamp1 #aiac #hi ,gas ,filled ,tungsten ,lamp1 #aibc #ij ,standard ,tungsten ,lamps1 #aibc #ib ,illustration3 ,,portion ,,of ,,the ,,electrical ,,exhibit ,,in ,,the ,,united ,,states ,,national ,,museum4 ,section devoted to the historical development of the electric light and dynamo4 ,,foreword ,in the year #ahhd a ,section of ,transportation was organized in the ,united ,states ,national ,museum for the purpose of preparing and assembling educational exhibits of a few objects of railroad machinery which had been obtained both from the ,centennial ,exhibition held in ,philadelphia in #ahgf and still earlier as incidentals to ethnological collections1 and to secure other collections relating to the railway industry4 ,from this beginning the section was expanded to include the whole field of engineering and is designated at present as the ,divisions of ,mineral and ,mechanical ,technology4 ,the growth and enlargement of the collections has been particularly marked in the fields of mining and mineral industries2 mechanical engineering1 especially pertaining to the steam engine1 internal combustion engine and locomotive2 naval architecture1 and electrical engineering1 particularly the development of the telegraph1 telephone and the electric light4 ,in the acquisition of objects visualizing the history of electric light the ,museum has been rather fortunate1 particularly as regards the developments in the ,united ,states4 ,thus mention may be made of the original ,patent ,office models of the more important dynamos1 arc lights and incandescent lights1 together with original commercial apparatus after these models2 a unit of the equipment used in the first commercially successful installation on land of an incandescent lighting system1 presented by ,joseph ,e4 ,hinds in whose engraving establishment in ,new ,york ,city the installation was made in #ahha2 and a large series of incandescent lights1 mainly originals1 visualizing chronologically the developments of the ,edison light from its inception1 presented at intervals since the year #ahih by the ,general ,electric ,company4 ,the object of all collections in the ,divisions is to visualize broadly the steps by which advances have been made in each field of engineering2 to show the layman the fundamental and general principles which are the basis for the developments2 and to familiarize the engineer with branches of engineering other than his own4 ,normally when a subject is completely covered by a collection of objects1 a paper is prepared and published describing the collection and the story it portrays4 ,in the present instance1 however1 on account of the uncertainty of the time of completing the collection1 if it is possible ever to bring this about1 it was thought advisable to publish ,mr4 ,schroeder's paper which draws upon the ,museum collection as completely as possible4 ,,carl ,w4 ,,mitman1 ,curator1 ,divisions of ,mineral and ,mechanical ,technology1 ,u4 ,s4 ,national ,museum4 ,,chronology ,,of ,,electric ,,light #ahjj--;,allesandro ,volta demonstrated his discovery that electricity can be generated by chemical means4 ,the ,,volt1 the unit of electric pressure1 is named in his honor for this discovery of the electric battery4 #ahjb--,sir ,humphry ,davy demonstrated that electric current can heat carbon and strips of metal to incandescence and give light4 #ahji--,sir ,humphry ,davy demonstrated that current will give a brilliant flame between the ends of two carbon pencils which are first allowed to touch each other and then pulled apart4 ,this light he called the 8arc0 on account of its arch shape4 #ahbj--;,andr ,marie ,ampre discovered that current flowing through a coiled wire gives it the properties of a magnet4 ,the ,,ampere1 the unit of flow of electric current1 is named in his honor for this discovery4 #ahbe--;,georg ,simon ,ohm discovered the relation between the voltage1 ampereage and resistance in an electric circuit1 which is called ,ohm's ,law4 ,the ,,ohm1 the unit of electric resistance1 is named in his honor for this discovery4 #ahca--,michael ,faraday discovered that electricity can be generated by moving a wire in the neighborhood of a magnet1 the principle of the dynamo4 #ahdj--,sir ,william ,robert ,grove demonstrated his experimental incandescent lamp in which platinum is made incandescent by current flowing through it4 #ahda--;,frederick ,de ,moleyns obtained the first patent on an incandescent lamp4 ,the burner was powdered charcoal operating in an exhausted glass globe4 #ahde--,thomas ,wright obtained the first patent on an arc light4 #ahde--;,j4 ,w4 ,starr invented an incandescent lamp consisting of a carbon pencil operating in the vacuum above a column of mercury4 #ahef--;,joseph ,lacassagne and ,henry ,thiers invented the 8differential0 method of control of the arc which was universally used twenty years later when the arc lamp was commercially established4 #ahfb--,the first commercial installation of an electric light4 ,an arc light was put in a lighthouse in ,england4 #ahff--,sir ,charles ,wheatstone invented the 8self-excited0 dynamo1 now universally used4 #ahgb--,lodyguine invented an incandescent lamp having a graphite burner operating in nitrogen gas4 #ahgf--,paul ,jablochkoff invented the 8electric candle10 an arc light commercially used for lighting the boulevards in ,paris4 #ahgg-h--;,arc light systems commercially established in the ,united ,states by ,william ,wallace and ,prof4 ,moses ,farmer1 ,edward ,weston1 ,charles ,f4 ,brush and ,prof4 ,elihu ,thomson and ,edwin ,j4 ,houston4 #ahgi--,thomas ,alva ,edison invented an incandescent lamp consisting of a high resistance carbon filament operating in a high vacuum maintained by an all glass globe4 ,these principles are used in all incandescent lamps made today4 ,he also invented a completely new system of distributing electricity at constant pressure1 now universally used4 #ahhb--,lucien ,goulard and ,john ,d4 ,gibbs invented a series alternating current system of distributing electric current4 ,this has not been commercially used4 #ahhf--,william ,stanley invented a constant pressure alternating current system of distribution4 ,this is universally used where current is to be distributed long distances4 #ahic--,louis ,b4 ,marks invented the enclosed carbon arc lamp4 #ahih--;,bremer's invention of the flame arc lamp1 having carbons impregnated with various salts1 commercially established4 #aijj--;,dr4 ,walther ,nernst's invention of the ,nernst lamp commercially established4 ,the burner consisted of various oxides1 such as zirconia1 which operated in the open air4 #aija--;,dr4 ,peter ,cooper ,hewitt's invention of the mercury arc light commercially established4 #aijb--,the magnetite arc lamp was developed by ,c4 ,a4 ,b4 ,halvorson1 ,jr4 ,this has a new method of control of the arc4 ,the negative electrode consists of a mixture of magnetite and other substances packed in an iron tube4 #aijd--;,d4 ,mc,farlan ,moore's invention of the ,moore vacuum tube light commercially established4 ,this consisted of a long tube1 made in lengths up to #bjj feet1 from which the air had been exhausted to about a thousandth of an atmosphere4 ,high voltage current passing through this rarefied atmosphere caused it to glow4 ,rarefied carbon dioxide gas was later used4 #aije--;,dr4 ,auer von ,welsbach's invention of the osmium incandescent lamp commercially established1 but only on a small scale in ,europe4 ,the metal osmium1 used for the filament which operated in vacuum1 is rarer and more expensive than platinum4 #aije--;,dr4 ,willis ,r4 ,whitney's invention of the ,gem incandescent lamp commercially established4 ,the carbon filament had been heated to a very high temperature in an electric resistance furnace invented by him4 ,the lamp was #be per cent more efficient than the regular carbon lamp4 #aijf--;,dr4 ,werner von ,bolton's invention of the tantalum incandescent lamp commercially established4 #aijg--;,alexander ,just and ,franz ,hanaman's invention of the tungsten filament incandescent lamp commercially established4 #aiaa--;,dr4 ,william ,d4 ,coolidge's invention of drawn tungsten wire commercially established4 #aiac--;,dr4 ,irving ,langmuir's invention of the gas-filled tungsten filament incandescent lamp commercially established4 ,,history ,,of ,,electric ,,light ,,by ,,henry ,,schroeder1 ,,harrison1 ,,new ,,jersey4 ,,early ,,records ,,of ,,electricity ,,and ,,magnetism ,about twenty-five centuries ago1 ,thales1 a ,greek philosopher1 recorded the fact that if amber is rubbed it will attract light objects4 ,the ,greeks called amber 8elektron10 from which we get the word 8electricity40 ,about two hundred and fifty years later1 ,aristotle1 another ,greek philosopher1 mentioned that the lodestone would attract iron4 ,lodestone is an iron ore 7,fe#c,o#d71 having magnetic qualities and is now called magnetite4 ,the word 8magnet0 comes from the fact that the best specimens of lodestones came from ,magnesia1 a city in ,asia ,minor4 ,plutarch1 a ,greek biographer1 wrote about #ajj ,a4 ,d41 that iron is sometimes attracted and at other times repelled by a lodestone4 ,this indicates that the piece of iron was magnetised by the lodestone4 ,in #aahj1 ,alexander ,neckham1 an ,english ,monk1 described the compass1 which probably had been invented by sailors of the northern countries of ,europe1 although its invention has been credited to the ,chinese4 ,early compasses probably consisted of an iron needle1 magnetised by a lodestone1 mounted on a piece of wood floating in water4 ,the word lodestone or 8leading stone0 comes from the fact that it would point towards the north if suspended like a compass4 ,william ,gilbert1 physician to ,queen ,elizabeth of ,england1 wrote a book about the year #afjj giving all the information then known on the subject4 ,he also described his experiments1 showing1 among other things1 the existence of magnetic lines of force and of north and south poles in a magnet4 ,robert ,norman had discovered a few years previously that a compass needle mounted on a horizontal axis would dip downward4 ,gilbert cut a large lodestone into a sphere1 and observed that the needle did not dip at the equator of this sphere1 the dip increasing to #ij degrees as the poles were approached4 ,from this he deduced that the earth was a magnet with the magnetic north pole at the geographic north pole4 ,it has since been determined that these two poles do not coincide4 ,gilbert suggested the use of the dipping needle to determine latitude4 ,he also discovered that other substances1 beside amber1 would attract light objects if rubbed4 ,,machines ,,generating ,,electricity ,,by ,,friction ,otto ,von ,guericke was mayor of the city of ,magdeburg as well as a philosopher4 ,about #afej he made a machine consisting of a ball of sulphur mounted on a shaft which could be rotated4 ,electricity was generated when the hand was pressed against the globe as it rotated4 ,he also discovered that electricity could be conducted away from the globe by a chain and would appear at the other end of the chain4 ,von ,guericke also invented the vacuum air pump4 ,in #agji1 ,francis ,hawksbee1 an ,englishman1 made a similar machine1 using a hollow glass globe which could be exhausted4 ,the exhausted globe when rotated at high speed and rubbed by hand would produce a glowing light4 ,this 8electric light0 as it was called1 created great excitement when it was shown before the ,royal ,society1 a gathering of scientists1 in ,london4 ,illustration3 ,,otto ,,von ,,guericke',s ,,electric ,,machine1 #afej4 ,a ball of sulphur was rotated1 electricity being generated when it rubbed against the hand4 ,stephen ,gray1 twenty years later1 showed the ,royal ,society that electricity could be conducted about a thousand feet by a hemp thread1 supported by silk threads4 ,if metal supports were used1 this could not be done4 ,charles du ,fay1 a ,frenchman1 repeated ,gray's experiments1 and showed in #agcc that the substances which were insulators1 and which ,gilbert had discovered1 would become electrified if rubbed4 ,those substances which ,gilbert could not electrify were conductors of electricity4 ,,the ,,leyden ,,jar ,the thought came to ,von ,kleist1 ,bishop of ,pomerania1 ,germany1 about #agde1 that electricity could be stored4 ,the frictional machines generated so small an amount of electricity 7though1 as is now known1 at a very high pressure--several thousand volts7 that he thought he could increase the quantity by storing it4 ,knowing that glass was an insulator and water a conductor1 he filled a glass bottle partly full of water with a nail in the cork to connect the machine with the water4 ,holding the bottle in one hand and turning the machine with the other for a few minutes1 he then disconnected the bottle from the machine4 ,when he touched the nail with his other hand he received a shock which nearly stunned him4 ,this was called the ,leyden jar1 the forerunner of the present condenser4 ,it received its name from the fact that its discovery was also made a short time after by experimenters in the ,university of ,leyden4 ,further experiments showed that the hand holding the bottle was as essential as the water inside1 so these were substituted by tin foil coatings inside and outside the bottle4 ,benjamin ,franklin1 ,american statesman1 scientist and printer1 made numerous experiments with the ,leyden jar4 ,he connected several jars in parallel1 as he called it1 which gave a discharge strong enough to kill a turkey4 ,he also connected the jars in series1 or 8in cascade0 as he called it1 thus establishing the principle of parallel and series connections4 ,noticing the similarity between the electric spark and lightning1 ,franklin in #ageb1 performed his famous kite experiment4 ,flying a kite in a thunderstorm1 he drew electricity from the clouds to charge ,leyden jars1 which were later discharged1 proving that lightning and electricity were the same4 ,this led him to invent the lightning rod4 ,,electricity ,,generated ,,by ,,chemical ,,means ,luigi ,galvani was an ,italian scientist4 ,about #aghe1 so the story goes1 his wife was in delicate health1 and some frog legs were being skinned to make her a nourishing soup4 ,an assistant holding the legs with a metal clamp and cutting the skin with a scalpel1 happened to let the clamp and scalpel touch each other4 ,to his amazement the frog legs twitched4 ,galvani repeated the experiment many times by touching the nerve with a metal rod and the muscle with a different metal rod and allowing the rods to touch1 and propounded the theory of animal electricity in a paper he published in #agia4 ,allesandro ,volta1 a professor of physics in the ,university of ,pavia1 ,italy1 read about ,galvani's work and repeated his experiments4 ,he found that the extent of the movement of the frog legs depended on the metals used for the rods1 and thus believed that the electric charge was produced by the contact of dissimilar metals with the moisture in the muscles4 ,to prove his point he made a pile of silver and zinc discs with cloths1 wet with salt water1 between them4 ,this was in #agii1 and he described his pile in ,march1 #ahjj1 in a letter to the ,royal ,society in ,london4 ,illustration3 ,,voltaic ,,pile1 #agii4 ,volta discovered that electricity could be generated by chemical means and made a pile of silver and zinc discs with cloths1 wet with salt water1 between them4 ,this was the forerunner of the present-day dry battery4 ,photograph courtesy ,prof4 ,chas4 ,f4 ,chandler ,museum1 ,columbia ,university1 ,new ,york4 ,this was an epoch-making discovery as it was the forerunner of the present-day primary battery4 ,volta soon found that the generation of electricity became weaker as the cloths became dry1 so to overcome this he made his 8crown of cups40 ,this consisted of a series of cups containing salt water in which strips of silver and zinc were dipped4 ,each strip of silver in one cup was connected to the zinc strip in the next cup1 the end strips of silver and zinc being terminals of the battery4 ,this was the first time that a continuous supply of electricity in reasonable quantities was made available1 so the ,,volt1 the unit of electrical pressure was named in his honor4 ,it was later shown that the chemical affinity of one of the metals in the liquid was converted into electric energy4 ,the chemical action of ,volta's battery is that the salt water attacks the zinc when the circuit is closed forming zinc chloride1 caustic soda and hydrogen gas4 ,the chemical equation is3 ,zn #b,na,cl #b;,h#b,o ,zn,cl#b #b,na,o,h ,h#b ,,improvement ,,of ,,volta',s ,,battery ,it was early suggested that sheets of silver and zinc be soldered together back to back and that a trough be divided into cells by these bimetal sheets being put into grooves cut in the sides and bottom of the trough4 ,this is the reason why one unit of a battery is called a 8cell40 ,it was soon found that a more powerful cell could be made if copper1 zinc and dilute sulphuric acid were used4 ,the zinc is dissolved by the acid forming zinc sulphate and hydrogen gas1 thus3 ,zn ,h#b,,so#d ,zn,s,o#d ,h#b ,the hydrogen gas appears as bubbles on the copper and reduces the open circuit voltage 7about #j4h volt per cell7 as current is taken from the battery4 ,this is called 8polarization40 ,owing to minute impurities in the zinc1 it is attacked by the acid even when no current is taken from the battery1 the impurities forming with the zinc a short circuited local cell4 ,this is called 8local action10 and this difficulty was at first overcome by removing the zinc from the acid when the battery was not in use4 ,,davy',s ,,discoveries ,sir ,humphry ,davy was a well-known ,english chemist1 and with the aid of powerful batteries constructed for the ,royal ,institution in ,london1 he made numerous experiments on the chemical effects of electricity4 ,he decomposed a number of substances and discovered the elements boron1 potassium and sodium4 ,he heated strips of various metals to incandescence by passing current through them1 and showed that platinum would stay incandescent for some time without oxidizing4 ,this was about #ahjb4 ,in the early frictional machines1 the presence of electricity was shown by the fact that sparks could be obtained4 ,similarly the breaking of the circuit of a battery would give a spark4 ,davy1 about #ahji1 demonstrated that this spark could be maintained for a long time with the large battery of #bjjj cells he had had constructed4 ,using two sticks of charcoal connected by wires to the terminals of this very powerful battery1 he demonstrated before the ,royal ,society the light produced by touching the sticks together and then holding them apart horizontally about three inches4 ,the brilliant flame obtained he called an 8arc0 because of its arch shape1 the heated gases1 rising1 assuming this form4 ,davy was given the degree of ,,ll4 ,d4 for his distinguished research work1 and was knighted on the eve of his marriage1 ,april #aa1 #ahab4 ,,researches ,,of ,,oersted1 ,,amp,,re1 ,,schweigger ,,and ,,sturgeon ,hans ,christian ,oersted was a professor of physics at the ,university of ,copenhagen in ,denmark4 ,one day in #ahai1 while addressing his students1 he happened to hold a wire1 through which current was flowing1 over a large compass4 ,to his surprise he saw the compass was deflected from its true position4 ,he promptly made a number of experiments and discovered that by reversing the current the compass was deflected in the opposite direction4 ,oersted announced his discovery in #ahbj4 ,andr ,marie ,ampre was a professor of mathematics in the ,ecole ,polytechnic in ,paris4 ,hearing of ,oersted's discovery1 he immediately made some experiments and made the further discovery in #ahbj that if the wire is coiled and current passed through it1 the coil had all the properties of a magnet4 ,these two discoveries led to the invention of ,schweigger in #ahbj1 of the galvanometer 7or 8multiplier0 as it was then called71 a very sensitive instrument for measuring electric currents4 ,it consisted of a delicate compass needle suspended in a coil of many turns of wire4 ,current in the coil deflected the needle1 the direction and amount of deflection indicating the direction and strength of the current4 ,ampre further made the discovery that currents in opposite directions repel and in the same directions attract each other4 ,he also gave a rule for determining the direction of the current by the deflection of the compass needle4 ,he developed the theory that magnetism is caused by electricity flowing around the circumference of the body magnetised4 ,the ,,ampere1 the unit of flow of electric current1 was named in honor of his discoveries4 ,in #ahbe it was shown by ,sturgeon that if a bar of iron were placed in the coil1 its magnetic strength would be very greatly increased1 which he called an electro-magnet4 ,,ohm',s ,,law ,georg ,simon ,ohm was born in ,bavaria1 the oldest son of a poor blacksmith4 ,with the aid of friends he went to college and became a teacher4 ,it had been shown that the rate of transfer of heat from one end to the other of a metal bar is proportional to the difference of temperature between the ends4 ,about #ahbe1 ,ohm1 by analogy and experiment1 found that the current in a conductor is proportional to the difference of electric pressure 7voltage7 between its ends4 ,he further showed that with a given difference of voltage1 the current in different conductors is inversely proportional to the resistance of the conductor4 ,ohm therefore propounded the law that the current flowing in a circuit is equal to the voltage on that circuit divided by the resistance of the circuit4 ,in honor of this discovery1 the unit of electrical resistance is called the ,,ohm4 ,this law is usually expressed as3 ,c ,e_/,r 8,c0 meaning current 7in amperes71 8,e0 meaning electromotive force or voltage 7in volts7 and 8,r0 meaning resistance 7in ohms74 ,this is one of the fundamental laws of electricity and if thoroughly understood1 will solve many electrical problems4 ,thus1 if any two of the above units are known1 the third can be determined4 ,examples3 ,an incandescent lamp on a #abj-volt circuit consumes #j4d ampere1 hence its resistance under such conditions is #cjj ohms4 ,several trolley cars at the end of a line take #ajj amperes to run them and the resistance of the overhead wire from the power house to the trolley cars is half an ohm2 the drop in voltage on the line between the power house and trolley cars is therefore #ej volts1 so that if the voltage at the power house were #fjj1 it would be #eej volts at the end of the line4 ,critics derided ,ohm's law so that he was forced out of his position as teacher in the ,high ,school in ,cologne4 ,finally after ten years ,ohm began to find supporters and in #ahda his law was publicly recognized by the ,royal ,society of ,london which presented him with the ,copley medal4 ,,invention ,,of ,,the ,,dynamo ,michael ,faraday was an ,english scientist4 ,born of parents in poor circumstances1 he became a bookbinder and studied books on electricity and chemistry4 ,he finally obtained a position as laboratory assistant to ,sir ,humphry ,davy helping him with his lectures and experiments4 ,he also made a number of experiments himself and succeeded in liquifying chlorine gas for which he was elected to a ,fellowship in the ,royal ,institution in #ahbd4 ,following up ,oersted's and ,ampre's work1 he endeavored to find the relation between electricity and magnetism4 ,finally on ,oct4 #ag1 #ahca1 he made the experiment of moving a permanent bar magnet in and out of a coil of wire connected to a galvanometer4 ,this generated electricity in the coil which deflected the galvanometer needle4 ,a few days after1 ,oct4 #bh1 #ahca1 he mounted a copper disk on a shaft so that the disk could be rotated between the poles of a permanent horseshoe magnet4 ,the shaft and edge of the disk were connected by brushes and wires to a galvanometer1 the needle of which was deflected as the disk was rotated4 ,a paper on his invention was read before the ,royal ,society on ,november #bd1 #ahca1 which appeared in printed form in ,january1 #ahcb4 ,illustration3 ,,faraday',s ,,dynamo1 #ahca4 ,faraday discovered that electricity could be generated by means of a permanent magnet4 ,this principle is used in all dynamos4 ,faraday did not develop his invention any further1 being satisfied1 as in all his work1 in pure research4 ,his was a notable invention but it remained for others to make it practicable4 ,hippolyte ,pixii1 a ,frenchman1 made a dynamo in #ahcb consisting of a permanent horseshoe magnet which could be rotated between two wire bobbins mounted on a soft iron core4 ,the wires from the bobbins were connected to a pair of brushes touching a commutator mounted on the shaft holding the magnet1 and other brushes carried the current from the commutator so that the alternating current generated was rectified into direct current4 ,illustration3 ,,pixii',s ,,dynamo1 #ahcb4 ,pixii made an improvement by rotating a permanent magnet in the neighborhood of coils of wire mounted on a soft iron core4 ,a commutator rectified the alternating current generated into direct current4 ,this dynamo is in the collection of the ,smithsonian ,institution4 ,e4 ,m4 ,clarke1 an ,englishman made1 in #ahcd1 another dynamo in which the bobbins rotated alongside of the poles of a permanent horseshoe magnet4 ,he also made a commutator so that the machine produced direct current4 ,none of these machines gave more than feeble current at low pressure4 ,the large primary batteries that had been made were much more powerful1 although expensive to operate4 ,it has been estimated that the cost of current from the #bjjj-;cell battery to operate the demonstration of the arc light by ,davy1 was six dollars a minute4 ,at present retail rates for electricity sold by lighting companies1 six dollars would operate ,davy's arc light about #ejj hours or #cj1jjj times as long4 ,,daniell',s ,,battery ,illustration3 ,,daniell',s ,,cell1 #ahcf4 ,daniell invented a battery consisting of zinc1 copper and copper sulphate4 ,later the porous cup was dispensed with1 which was used to keep the sulphuric acid formed separate from the solution of copper sulphate1 the two liquids then being kept apart by their difference in specific gravity4 ,it was then called the ,gravity ,battery and for years was used in telegraphy4 ,it was soon discovered that if the zinc electrode were rubbed with mercury 7amalgamated71 the local action would practically cease1 and if the hydrogen bubbles were removed1 the operating voltage of the cell would be increased4 ,john ,frederic ,daniell1 an ,english chemist1 invented a cell in #ahcf to overcome these difficulties4 ,his cell consisted of a glass jar containing a saturated solution of copper sulphate 7,cu,s,o#d74 ,a copper cylinder1 open at both ends and perforated with holes1 was put into this solution4 ,on the outside of the copper cylinder there was a copper ring1 located below the surface of the solution1 acting as a shelf to support crystals of copper sulphate4 ,inside the cylinder there was a porous earthenware jar containing dilute sulphuric acid and an amalgamated zinc rod4 ,the two liquids were therefore kept apart but in contact with each other through the pores of the jar4 ,the hydrogen gas given off by the action of the sulphuric acid on the zinc1 combined with the dissolved copper sulphate1 formed sulphuric acid and metallic copper4 ,the latter was deposited on the copper cylinder which acted as the other electrode4 ,thus the copper sulphate acted as a depolarizer4 ,the chemical reactions in this cell are1 ,in inner porous jar3 ,zn ,h#b,,so#d ,zn,s,o#d ,h#b ,in outer glass jar3 ,h#b ,cu,s,o#d ,h#b,,so#d ,cu ,this cell had an open circuit voltage of a little over one volt4 ,later the porous cup was dispensed with1 the two liquids being kept apart by the difference of their specific gravities4 ,this was known as the ,gravity cell1 and for years was used in telegraphy4 ,illustration3 ,,grove',s ,,cell1 #ahch4 ,this consisted of zinc1 sulphuric acid1 nitric acid and platinum4 ,it made a very powerful battery4 ,the nitric acid is called the depolarizer as it absorbs the hydrogen gas formed1 thus improving the operating voltage4 ,,grove',s ,,battery ,sir ,william ,robert ,grove1 an ,english ,judge and scientist1 invented a cell in #ahch consisting of a platinum electrode in strong nitric acid in a porous earthenware jar4 ,this jar was put in dilute sulphuric acid in a glass jar in which there was an amalgamated zinc plate for the other electrode4 ,this had an open circuit voltage of about #a4i volts4 ,the porous jar was used to prevent the nitric acid from attacking the zinc4 ,the nitric acid was used for the purpose of combining with the hydrogen gas set free by the action of the sulphuric acid on the zinc1 and hence was the depolarizing agent4 ,hydrogen combining with nitric acid forms nitrous peroxide and water4 ,part of the nitrous peroxide is dissolved in the water1 and the rest escapes as fumes which1 however1 are very suffocating4 ,the chemical equations of this cell are as follows3 ,in outer glass jar3 ,zn ,h#b,,so#d ,zn,s,o#d ,h#b ,in inner porous jar3 ,h#b #b;,,hno#c ,n#b,o#d #b;,h#b,o ,an interesting thing about ,grove's cell is that it was planned in accordance with a theory4 ,grove knew that the electrical energy of the zinc-sulphuric acid cell came from the chemical affinity of the two reagents1 and if the hydrogen gas set free could be combined with oxygen 7to form water--,h#b,o71 such chemical affinity should increase the strength of the cell4 ,as the hydrogen gas appears at the other electrode1 the oxidizing agent should surround that electrode4 ,nitric acid was known at that time as one of the most powerful oxidizing liquids1 but as it attacks copper1 he used platinum for the other electrode4 ,thus he not only overcame the difficulty of polarization by the hydrogen gas1 but also increased the voltage of the cell by the added chemical action of the combination of hydrogen and oxygen4 ,,grove',s ,,demonstration ,,of ,,incandescent ,,lighting ,in #ahdj ,grove made an experimental lamp by attaching the ends of a coil of platinum wire to copper wires1 the lower parts of which were well varnished for insulation4 ,the platinum wire was covered by a glass tumbler1 the open end set in a glass dish partly filled with water4 ,this prevented draughts of air from cooling the incandescent platinum1 and the small amount of oxygen of the air in the tumbler reduced the amount of oxidization of the platinum that would otherwise occur4 ,with current supplied by a large number of cells of his battery1 he lighted the auditorium of the ,royal ,institution with these lamps during one of the lectures he gave4 ,this lamp gave only a feeble light as there was danger of melting the platinum and platinum gives but little light unless operated close to its melting temperature4 ,it also required a lot of current to operate it as the air tended to cool the incandescent platinum4 ,the demonstration was only of scientific interest1 the cost of current being much too great 7estimated at several hundred dollars a kilowatt hour7 to make it commercial4 ,,grenet ,,battery ,it was discovered that chromic anhydride gives up oxygen easier than nitric acid and consequently if used would give a higher voltage than ,grove's nitric acid battery4 ,it also has the advantage of a lesser tendency to attack zinc directly if it happens to come in contact with it4 ,grenet developed a cell having a liquid consisting of a mixture of potassium bichromate 7,k#b;,cr#b,o#g7 and sulphuric acid4 ,a porous cell was therefore not used to keep the two liquids apart4 ,this had the advantage of reducing the internal resistance4 ,the chemical reaction was3 ,k#b;,cr#b,o#g 7potassium bichromate7 #g;,h#b,,so#d 7sulphuric acid7 #c,zn 7zinc7 #c,zn,s,o#d 7zinc sulphate7 ,k#b,,so#d 7potassium sulphate7 ,cr#b 7,,so#d7c 7chromium sulphate7 #g;,h#b,o 7water74 ,in order to prevent the useless consumption of zinc on open circuit1 the zinc was attached to a sliding rod and could be drawn up into the neck of the bottle-shaped jar containing the liquid4 ,illustration3 ,,grove',s ,,incandescent ,,lamp1 #ahdj4 ,grove made an experimental lamp1 using platinum for the burner which was protected from draughts of air by a glass tumbler4 ,,de ,,moleyns' ,,incandescent ,,lamp ,frederick ,de ,moleyns1 an ,englishman1 has the honor of having obtained the first patent on an incandescent lamp4 ,this was in #ahda and his lamp was quite novel4 ,it consisted of a spherical glass globe1 in the upper part of which was a tube containing powdered charcoal4 ,this tube was open at the bottom inside the globe and through it ran a platinum wire1 the end below the tube being coiled4 ,another platinum wire coiled at its upper end came up through the lower part of the globe but did not quite touch the other platinum coil4 ,the powdered charcoal filled the two coils of platinum wire and bridged the gap between4 ,current passing through this charcoal bridge heated it to incandescence4 ,the air in the globe having been removed as far as was possible with the hand air pumps then available1 the charcoal did not immediately burn up1 the small amount consumed being replaced by the supply in the tube4 ,the idea was ingenious but the lamp was impractical as the globe rapidly blackened from the evaporation of the incandescent charcoal4 ,illustration3 ,,de ,,moleyns' ,,incandescent ,,lamp1 #ahda4 ,this consisted of two coils of platinum wire containing powdered charcoal operating in a vacuum4 ,it is only of interest as the first incandescent lamp on which a patent 7,british7 was granted4 ,,early ,,developments ,,of ,,the ,,arc ,,lamp ,it had been found that most of the light of the arc came from the tip of the positive electrode1 and that the charcoal electrodes were rapidly consumed1 the positive electrode about twice as fast as the negative4 ,mechanisms were designed to take care of this1 together with devices to start the arc by allowing the electrodes to touch each other and then pulling them apart the proper distance4 ,this distance varied from one-eighth to three-quarters of an inch4 ,in #ahdj ,bunsen1 the ,german chemist who invented the bunsen burner1 devised a process for making hard dense carbon pencils which lasted much longer than the charcoal previously used4 ,the dense carbon from the inside of the retorts of gas making plants was ground up and mixed with molasses1 moulded into shape and baked at a high temperature4 ,bunsen also1 in #ahdc1 cheapened ,grove's battery by substituting a hard carbon plate in place of the platinum electrode4 ,illustration3 ,,wright',s ,,arc ,,lamp1 #ahde4 ,this lamp is also only of interest as the first arc lamp on which a patent 7,british7 was granted4 ,four arcs played between the five carbon discs4 ,thomas ,wright1 an ,englishman1 was the first to patent an arc lamp4 ,this was in #ahde1 and the lamp was a hand regulated device consisting of five carbon disks normally touching each other and rotated by clockwork4 ,two of the disks could be drawn outward by thumb screws1 which was to be done after the current was turned on thus establishing four arcs1 one between each pair of disks4 ,the next year1 #ahdf1 ,w4 ,e4 ,staite1 another ,englishman1 made an arc lamp having two vertical carbon pencils4 ,the upper was stationary4 ,the lower was movable and actuated by clockwork directed by ratchets which in turn were regulated by an electro-magnet controlled by the current flowing through the arc4 ,thus the lower carbon would be moved up or down as required4 ,archereau1 a ,frenchman1 made a very simple arc lamp in #ahdh4 ,the upper carbon was fixed and the lower one was mounted on a piece of iron which could be drawn down into a coil of wire4 ,the weight of the lower electrode was overbalanced by a counterweight1 so that when no current was flowing the two carbons would touch4 ,when current was turned on1 it flowed through the two carbons and through the coil of wire 7solenoid7 which then became energized and pulled the lower carbon down1 thus striking the arc4 ,two of these arc lamps were installed in ,paris and caused considerable excitement4 ,after a few weeks of unreliable operation1 it was found that the cost of current from the batteries was much too great to continue their use commercially4 ,the dynamo had not progressed far enough to permit its use4 ,illustration3 ,,archereau',s ,,arc ,,lamp1 #ahdh4 ,this simple arc was controlled by an electro-magnet1 and two lamps were installed for street lighting in ,paris1 current being obtained from batteries4 ,,joule',s ,,law ,joule was an ,englishman1 and in #ahdb began investigating the relation between mechanical energy and heat4 ,he first showed that1 by allowing a weight to drop from a considerable height and turn a paddle wheel in water1 the temperature of the water would increase in relation to the work done in turning the wheel4 ,it is now known that #ggh foot-pounds 7#a lb4 falling #ggh feet1 #aj lbs4 falling #gg4h feet or #ggh lbs4 falling one foot1 etc47 is the mechanical equivalent of energy equal to raising one pound of water one degree ,fahrenheit4 ,the rate of energy 7power7 is the energy divided by a unit of time2 thus one horsepower is #cc1jjj foot-pounds per minute4 ,joule next investigated the relation between heat and electric current4 ,he made a device consisting of a vessel of water in which there were a thermometer and an insulated coil of wire having a considerable resistance4 ,he found that an electric current heated the water1 and making many combinations of the amount and length of time of current flowing and of the resistance of the wire1 he deduced the law that the energy in an electric circuit is proportional to the square of the amount of current flowing multiplied by the length of time and multiplied by the resistance of the wire4 ,the rate of electrical energy 7electric power7 is therefore proportional to the square of current multiplied by the resistance4 ,the electrical unit of power is now called the ,,watt1 named in honor of ,james ,watt1 the ,englishman1 who made great improvements to the steam engine about a century ago4 ,thus1 watts ,c#b,r and substituting the value of ,r from ,ohm's law1 ,c ,e_/,r1 we get ,watts ,volts ,amperes ,the watt is a small unit of electric power1 as can be seen from the fact that #gdf watts are equal to one horsepower4 ,the kilowatt1 kilo being the ,greek word for thousand1 is #ajjj watts4 ,this term is an important one in the electrical industry4 ,for example1 dynamos are rated in kilowatts1 expressed as ,,kw2 the largest one made so far is #ej1jjj ,,kw which is #ff1fff horsepower4 ,edison's first commercial dynamo had a capacity of #f ,,kw although the terms watts and kilowatts were not in use at that time4 ,the ordinary sizes of incandescent lamps now used in the home are #be1 #dj and #ej watts4 ,,starr',s ,,incandescent ,,lamp ,illustration3 ,,starr',s ,,incandescent ,,lamp1 #ahde4 ,this consisted of a short carbon pencil operating in the vacuum above a column of mercury4 ,j4 ,w4 ,starr1 an ,american1 of ,cincinnati1 ,ohio1 assisted financially by ,peabody1 the philanthropist1 went to ,england where he obtained a patent in #ahde on the lamps he had invented1 although the patent was taken out under the name of ,king1 his attorney4 ,one is of passing interest only4 ,it consisted of a strip of platinum1 the active length of which could be adjusted to fit the battery strength used1 and was covered by a glass globe to protect it from draughts of air4 ,the other1 a carbon lamp1 was the first real contribution to the art4 ,it consisted of a rod of carbon operating in the vacuum above a column of mercury 7,torrecellium vacuum7 as in a barometer4 ,a heavy platinum wire was sealed in the upper closed end of a large glass tube1 and connected to the carbon rod by an iron clamp4 ,the lower end of the carbon rod was fastened to another iron clamp1 the two clamps being held in place and insulated from each other by a porcelain rod4 ,attached to the lower clamp was a long copper wire4 ,just below the lower clamp1 the glass tube was narrowed down and had a length of more than #cj inches4 ,the tube was then filled with mercury1 the bottom of the tube being put into a vessel partly full of mercury4 ,the mercury ran out of the enlarged upper part of the tube1 coming to rest in the narrow part of the tube as in a barometer1 so that the carbon rod was then in a vacuum4 ,one lamp terminal was the platinum wire extending through the top of the tube1 and the other was the mercury4 ,several of these lamps were put on exhibition in ,london1 but were not a commercial success as they blackened very rapidly4 ,starr started his return trip to the ,united ,states the next year1 but died on board the ship when he was but #be years old4 ,,other ,,early ,,incandescent ,,lamps ,illustration3 ,,staite',s ,,incandescent ,,lamp1 #ahdh4 ,the burner was of platinum and iridium4 ,illustration3 ,,roberts' ,,incandescent ,,lamp1 #aheb4 ,it had a graphite burner operating in vacuum4 ,in #ahdh ,w4 ,e4 ,staite1 who two years previously had made an arc lamp1 invented an incandescent lamp4 ,this consisted of a platinum-iridium burner in the shape of an inverted ,u1 covered by a glass globe4 ,it had a thumb screw for a switch1 the whole device being mounted on a bracket which was used for the return wire4 ,e4 ,c4 ,shepard1 another ,englishman1 obtained a patent two years later on an incandescent lamp consisting of a weighted hollow charcoal cylinder the end of which pressed against a charcoal cone4 ,current passing through this high resistance contact1 heated the charcoal to incandescence4 ,it operated in a glass globe from which the air could be exhausted4 ,m4 ,j4 ,roberts obtained an ,english patent in #aheb on an incandescent lamp4 ,this had a graphite rod for a burner1 which could be renewed1 mounted in a glass globe4 ,the globe was cemented to a metallic cap fastened to a piece of pipe through which the air could be exhausted4 ,after being exhausted1 the pipe1 having a stop cock1 could be screwed on a stand to support the lamp4 ,moses ,g4 ,farmer1 a professor at the ,naval ,training ,station at ,newport1 ,rhode ,island1 lighted the parlor of his home at #aa ,pearl ,street1 ,salem1 ,mass41 during ,july1 #ahei1 with several incandescent lamps having a strip of platinum for the burner4 ,the novel feature of this lamp was that the platinum strip was narrower at the terminals than in the center4 ,heat is conducted away from the terminals and by making the burner thin at these points1 the greater resistance of the ends of the burner absorbed more electrical energy thus offsetting the heat being conducted away4 ,this made a more uniform degree of incandescence throughout the length of the burner1 and ,prof4 ,farmer obtained a patent on this principle many years later 7#ahhb74 ,illustration3 ,,farmer',s ,,incandescent ,,lamp1 #ahei4 ,this experimental platinum lamp was made by ,professor ,farmer and several of them lighted the parlor of his home in ,salem1 ,mass4 ,,further ,,arc ,,lamp ,,developments ,during the ten years1 #ahej to #ahfj1 several inventors developed arc lamp mechanisms4 ,among them was ,m4 ,j4 ,roberts1 who had invented the graphite incandescent lamp4 ,in ,roberts' arc lamp1 which he patented in #aheb1 the lower carbon was stationary4 ,the upper carbon fitted snugly into an iron tube4 ,in the tube was a brass covered iron rod1 which by its weight could push the upper carbon down the tube so the two carbons normally were in contact4 ,an electro-magnet in series with the arc was so located that1 when energized1 it pulled up the iron tube4 ,this magnet also held the brass covered iron rod from pushing the upper carbon down the tube so that the two carbons were pulled apart1 striking the arc4 ,when the arc went out1 the iron tube dropped back into its original position1 the brass covered iron rod was released1 pushing the upper carbon down the tube until the two carbons again touched4 ,this closed the circuit again1 striking the arc as before4 ,illustration3 ,,roberts' ,,arc ,,lamp1 #aheb4 ,the arc was controlled by an electro-magnet which held an iron tube to which the upper carbon was fastened4 ,illustration3 ,,slater ,,and ,,watson',s ,,arc ,,lamp1 #aheb4 ,clutches were used for the first time in this arc lamp to feed the carbons4 ,in the same year 7#aheb7 ,slater and ,watson obtained an ,english patent on an arc lamp in which the upper carbon was movable and held in place by two clutches actuated by electro-magnets4 ,the lower carbon was fixed1 and normally the two carbons touched each other4 ,when current was turned on1 the electro-magnet lifted the clutches which gripped the upper carbon1 pulling it up and striking the arc4 ,this was the first time that a clutch was used to allow the carbon to feed as it became consumed4 ,henry ,chapman1 in #ahee1 made an arc in which the upper carbon was allowed to feed by gravity1 but held in place by a chain wound around a wheel4 ,on this wheel was a brake actuated by an electro-magnet4 ,the lower carbon was pulled down by an electro-magnet working against a spring4 ,when no current was flowing or when the arc went out1 the two carbons touched4 ,with current on1 one electro-magnet set the brake and held the upper carbon stationary4 ,the other electro-magnet pulled the lower carbon down1 thus striking the arc4 ,none of these mechanisms regulated the length of the arc4 ,it was not until #ahef that ,joseph ,lacassagne and ,henry ,thiers1 ,frenchmen1 invented the so-called 8differential0 method of control1 which made the carbons feed when the arc voltage1 and hence length1 became too great4 ,this principle was used in commercial arc lamps several years afterward when they were operated on series circuits1 as it had the added advantage of preventing the feeding of one arc lamp affecting another on the same circuit4 ,this differential control consists in principle of two electro-magnets1 one in series with1 and opposing the pull of the other which is in shunt with the arc4 ,the series magnet pulls the carbons apart and strikes the arc4 ,as the arc increases in length1 its voltage rises1 thereby increasing the current flowing through the shunt magnet4 ,this increases the strength of the shunt magnet and1 when the arc becomes too long1 the strength of the shunt becomes greater than that of the series magnet1 thus making the carbons feed4 ,illustration3 ,,diagram ,,of 8,,differential0 ,,method ,,of ,,control ,,of ,,an ,,arc ,,lamp4 ,this principle1 invented by ,lacassagne and ,thiers1 was used in all arc lamps when they were commercially introduced on a large scale more than twenty years later4 ,the actual method adopted by ,lacassagne and ,thiers was different from this1 but it had this principle4 ,they used a column of mercury on which the lower carbon floated4 ,the upper carbon was stationary4 ,the height of the mercury column was regulated by a valve connected with a reservoir of mercury4 ,the pull of the series magnet closed the valve fixing the height of the column4 ,the pull of the shunt magnet tended to open the valve1 and when it overcame the pull of the series magnet it allowed mercury to flow from the reservoir1 raising the height of the column bringing the carbons nearer together4 ,this reduced the arc voltage and shunt magnet strength until the valve closed again4 ,thus the carbons were always kept the proper distance apart4 ,in first starting the arc1 or if the arc should go out1 current would only flow through the shunt magnet1 bringing the two carbons together until they touched4 ,current would then flow through the contact of the two carbons and through the series magnet1 shutting the valve4 ,there were no means of pulling the carbons apart to strike the arc4 ,current flowing through the high resistance of the poor contact of the two carbons1 heated their tips to incandescence4 ,the incandescent tips would begin to burn away1 thus after a time starting an arc4 ,the arc1 however1 once started was maintained the proper length4 ,illustration3 ,,lacassagne ,,and ,,thiers' ,,differentially ,,controlled ,,arc ,,lamp1 #ahef4 ,the lower carbon floated on a column of mercury whose height was 8differentially0 controlled by series and shunt magnets4 ,in #aheg1 ,serrin took out his first patent on an arc lamp1 the general principles of which were the same as in others he made4 ,the mechanism consisted of two drums1 one double the diameter of the other4 ,both carbons were movable1 the upper one feeding down1 and the lower one feeding up1 being connected with chains wound around the drums4 ,the difference in consumption of the two carbons was therefore compensated for by the difference in size of the drums1 thus maintaining the location of the arc in a fixed position4 ,a train of wheels controlled by a pawl and regulated by an electro-magnet1 controlled the movement of the carbons4 ,the weight of the upper carbon and its holder actuates the train of wheels4 ,illustration3 ,,serrin',s ,,arc ,,lamp1 #aheg4 ,this type of arc was not differentially controlled but was the first commercial lamp later used4 ,both carbons were movable1 held by chains wound around drums which were controlled by ratchets actuated by an electro-magnet4 ,,development ,,of ,,the ,,dynamo1 #ahdj-ahfj ,during the first few years after #ahdj the dynamo was only a laboratory experiment4 ,woolrich devised a machine which had several pairs of magnets and double the number of coils in order to make the current obtained less pulsating4 ,wheatstone in #ahde patented the use of electro-magnets in place of permanent magnets4 ,brett in #ahdh suggested that the current1 generated in the coils1 be allowed to flow through a coil surrounding each permanent magnet to further strengthen the magnets4 ,pulvermacher in #ahdi proposed the use of thin plates of iron for the bobbins1 to reduce the eddy currents generated in the iron4 ,sinsteden in #ahea suggested that the current from a permanent magnet machine be used to excite the field coils of an electro-magnet machine4 ,in #ahee ,soren ,hjorth1 of ,copenhagen1 ,denmark1 patented a dynamo having both permanent and electro-magnets1 the latter being excited by currents first induced in the bobbins by the permanent magnets4 ,in #ahef ,dr4 ,werner ,siemens invented the shuttle wound armature4 ,this consisted of a single coil of wire wound lengthwise and counter sunk in a long cylindrical piece of iron4 ,this revolved between the magnet poles which were shaped to fit the cylindrical armature4 ,illustration3 ,,siemens' ,,dynamo1 #ahef4 ,this dynamo was an improvement over others on account of the construction of its 8shuttle0 armature4 ,,the ,,first ,,commercial ,,installation ,,of ,,an ,,electric ,,light ,in #ahfb a ,serrin type of arc lamp was installed in the ,dungeness lighthouse in ,england4 ,current was supplied by a dynamo made by the ,alliance ,company1 which had been originally designed in #ahej by ,nollet1 a professor of ,physics in the ,military ,school in ,brussels4 ,nollet's original design was of a dynamo having several rows of permanent magnets mounted radially on a stationary frame1 with an equal number of bobbins mounted on a shaft which rotated and had a commutator so direct current could be obtained4 ,a company was formed to sell hydrogen gas for illuminating purposes1 the gas to be made by the decomposition of water with current from this machine4 ,nollet died and the company failed1 but it was reorganized as the ,alliance ,company a few years later to exploit the arc lamp4 ,illustration3 ,,alliance ,,dynamo1 #ahfb4 ,this was the dynamo used in the first commercial installation of an arc light in the ,dungeness ,lighthouse1 ,england1 #ahfb4 ,about the only change made in the dynamo was to substitute collector rings for the commutator to overcome the difficulties of commutation4 ,alternating current was therefore generated in this first commercial machine4 ,it had a capacity for but one arc light1 which probably consumed less than ten amperes at about #de volts1 hence delivered in the present terminology not over #dej watts or about two-thirds of a horsepower4 ,as the bobbins of the armature undoubtedly had a considerable resistance1 the machine had an efficiency of not over #ej per cent and therefore required at least one and a quarter horsepower to drive it4 ,,further ,,dynamo ,,developments ,in the summer of #ahhf ,sir ,charles ,wheatstone constructed a self-excited machine on the principle of using the residual magnetism in the field poles to set up a feeble current in the armature which1 passing through the field coils1 gradually strengthened the fields until they built up to normal strength4 ,it was later found that this idea had been thought of by an unknown man1 being disclosed by a clause in a provisional #aheh ,english patent taken out by his agent4 ,wheatstone's machine was shown to the ,royal ,society in ,london and a paper on it read before the ,society on ,february #ad1 #ahfg4 ,the field coils were shunt wound4 ,illustration3 ,,wheatstone',s ,,self-,,excited ,,dynamo1 #ahff4 ,this machine was the first self-excited dynamo by use of the residual magnetism in the field poles4 ,dr4 ,werner ,siemens also made a self-excited machine1 having series fields1 a paper on which was read before the ,academy of ,sciences in ,berlin on ,january #ag1 #ahfg4 ,this paper was forwarded to the ,royal ,society in ,london and presented at the same meeting at which ,wheatstone's dynamo was described4 ,wheatstone probably preceded ,siemens in this re-discovery of the principle of self-excitation1 but both are given the merit of it4 ,however1 ,s4 ,a4 ,varley on ,december #bd1 #ahff1 obtained a provisional ,english patent on this1 which was not published until ,july1 #ahfg4 ,illustration3 ,,gramme',s ,,dynamo1 #ahga4 ,these were commercially used1 their main feature being the 8ring0 wound armature4 ,illustration3 ,,gramme',s 8,,ring0 ,,armature4 ,wire coils1 surrounding an iron wire core1 were all connected together in an endless ring1 each coil being tapped with a wire connected to a commutator bar4 ,in #ahgj ,gramme1 a ,frenchman1 patented his well-known ring armature4 ,the idea had been previously thought of by ,elias1 a ,hollander1 in #ahdb1 and by ,pacinnotti1 an ,italian1 as shown by the crude motors 7not dynamos7 they had made4 ,gramme's armature consisted of an iron wire core coated with a bituminous compound in order to reduce the eddy currents4 ,this core was wound with insulated wire coils1 all connected together in series as one single endless coil4 ,each coil was tapped with a wire connected to a commutator bar4 ,his first machine1 having permanent magnets for fields1 was submitted to the ,french ,academy of ,sciences in #ahga4 ,later machines were made with self-excited field coils1 which were used in commercial service4 ,they had1 however a high resistance armature1 so that their efficiency did not exceed #ej per cent4 ,illustration3 ,,alteneck',s ,,dynamo ,,with 8,,drum0 ,,wound ,,armature1 #ahgb4 ,the armature winding was entirely on the surface of the armature core1 a principle now used in all dynamos4 ,von ,hefner ,alteneck1 an engineer with ,siemens1 invented the drum wound armature in #ahgb4 ,the wires of the armature were all on the surface of the armature core1 the wires being tapped at frequent points for connection with the commutator bars4 ,thus in the early seventies1 commercial dynamos were available for use in arc lighting1 and a few installations were made in ,europe4 ,,russian ,,incandescent ,,lamp ,,inventors ,in #ahgb ,lodyguine1 a ,russian scientist1 made an incandescent lamp consisting of a 8,v0 shaped piece of graphite for a burner1 which operated in nitrogen gas4 ,he lighted the ,admiralty ,dockyard at ,st4 ,petersburg with about two hundred of these lamps4 ,in #ahgb the ,russian ,academy of ,sciences awarded him a prize of #ej1jjj rubles 7a lot of real money at that time7 for his invention4 ,a company with a capital of #bjj1jjj rubles 7then equal to about #ajj1jjj7 was formed but as the lamp was so expensive to operate and had such a short life1 about twelve hours1 the project failed4 ,illustration3 ,,lodyguine',s ,,incandescent ,,lamp1 #ahgb4 ,the burner was made of graphite and operated in nitrogen gas4 ,illustration3 ,,konn',s ,,incandescent ,,lamp1 #ahge4 ,in this lamp the graphite rods operated in a vacuum4 ,kosloff1 another ,russian1 in #ahge patented a graphite in nitrogen incandescent lamp1 which had several graphite rods for burners1 so arranged that when one failed another was automatically connected4 ,konn1 also a ,russian1 made a lamp similar to ,kosloff's except that the graphite rods operated in a vacuum4 ,bouliguine1 another ,russian1 in #ahgf made an incandescent lamp having a long graphite rod1 only the upper part of which was in circuit4 ,as this part burned out1 the rod was automatically pushed up so that a fresh portion then was in circuit4 ,it operated in a vacuum4 ,none of these lamps was commercial as they blackened rapidly and were too expensive to maintain4 ,illustration3 ,,bouliguine',s ,,incandescent ,,lamp1 #ahgf4 ,a long graphite rod1 the upper part of which only was in circuit1 operated in vacuum4 ,as this part burned out1 the rod was automatically shoved up1 a fresh portion then being in the circuit4 ,,the ,,jablochkoff 8,,candle0 ,paul ,jablochkoff was a ,russian army officer and an engineer4 ,in the early seventies he came to ,paris and developed a novel arc light4 ,this consisted of a pair of carbons held together side by side and insulated from each other by a mineral known as kaolin which vaporized as the carbons were consumed4 ,there was no mechanism1 the arc being started by a thin piece of carbon across the tips of the carbons4 ,current burned this bridge1 starting the arc4 ,the early carbons were about five inches long1 and the positive carbon was twice as thick as the negative to compensate for the unequal consumption on direct current4 ,this1 however1 did not work satisfactorily4 ,later the length of the carbons was increased1 the carbon made of equal thickness and burned on alternating current of about eight or nine amperes at about #de volts4 ,he made an alternating current generator which had a stationary exterior armature with interior revolving field poles4 ,several 8candles10 as they were called1 were put in one fixture to permit all night service and an automatic device was developed1 located in each fixture1 so that should one 8candle0 go out for any reason1 another was switched into service4 ,illustration3 ,,jablochkoff 8,,candle10 #ahgf4 ,this simple arc consisted of a pair of carbons held together side by side and insulated from each other by kaolin4 ,several boulevards in ,paris were lighted with these arc lights4 ,this arc lamp is in the collection of the ,smithsonian ,institution4 ,in #ahgf many of these 8candles0 were installed and later several of the boulevards in ,paris were lighted with them4 ,this was the first large installation of the arc light1 and was the beginning of its commercial introduction4 ,henry ,wilde made some improvements in the candle by eliminating the kaolin between the carbons which gave ,jablochkoff's arc its peculiar color4 ,wilde's arc was started by allowing the ends of the carbons to touch each other1 a magnet swinging them apart thus striking the arc4 ,illustration3 ,,jablochkoff',s ,,alternating ,,current ,,dynamo1 #ahgf4 ,this dynamo had a stationary exterior armature and internal revolving field poles4 ,alternating current was used for the ,jablochkoff 8candle0 to overcome the difficulties of unequal consumption of the carbons on direct current4 ,,commercial ,,introduction ,,of ,,the ,,differentially ,,controlled ,,arc ,,lamp ,about the same time ,lontin1 a ,frenchman1 improved ,serrin's arc lamp mechanism by the application of series and shunt magnets4 ,this is the differential principle which was invented by ,lacassagne and ,thiers in #ahee but which apparently had been forgotten4 ,several of these lamps were commercially installed in ,france beginning with #ahgf4 ,,arc ,,lighting ,,in ,,the ,,united ,,states ,illustration3 ,,wallace-,,farmer ,,arc ,,lamp1 #ahge4 ,this 8differentially controlled0 arc lamp consisted of two slabs of carbon between which the arc played4 ,in the original lamp the carbon slabs were mounted on pieces of wood held in place by bolts1 adjustment being made by hitting the upper carbon slab with a hammer4 ,this lamp is in the collection of the ,smithsonian ,institution4 ,illustration3 ,,wallace-,,farmer ,,dynamo1 #ahge4 ,this was the first commercial dynamo used in the ,united ,states for arc lighting4 ,this dynamo is in the collection of the ,smithsonian ,institution4 ,about #ahge ,william ,wallace of ,ansonia1 ,connecticut1 made an arc light consisting of two rectangular carbon plates mounted on a wooden frame4 ,the arc played between the two edges of the plates1 which lasted much longer than rods4 ,when the edges had burned away so that the arc then became unduly long1 the carbon plates were brought closer together by hitting them with a hammer4 ,wallace became associated with ,moses ,g4 ,farmer1 and they improved this crude arc by fastening the upper carbon plate to a rod which was held by a clutch controlled by a magnet4 ,this magnet had two coils in one1 the inner winding in series with the arc1 and outer one in shunt and opposing the series winding4 ,the arc was therefore differentially controlled4 ,illustration3 ,,weston',s ,,arc ,,lamp1 #ahgf4 ,this lamp is in the collection of the ,smithsonian ,institution4 ,they also developed a series wound direct current dynamo4 ,the armature consisted of a number of bobbins1 all connected together in an endless ring4 ,each bobbin was also connected to a commutator bar4 ,there were two sets of bobbins1 commutators and field poles1 the equivalent of two machines in one1 which could be connected either to separate circuits1 or together in series on one circuit4 ,the ,wallace-,farmer system was commercially used4 ,the arc consumed about #bj amperes at about #ce volts1 but as the carbon plates cooled the arc1 the efficiency was poor4 ,the arc flickered back and forth on the edges of the carbons casting dancing shadows4 ,the carbons1 while lasting about #ej hours1 were not uniform in density1 so the arc would flare up and cast off soot and sparks4 ,edward ,weston of ,newark1 ,new ,jersey1 also developed an arc lighting system4 ,his commercial lamp had carbon rods1 one above the other1 and the arc was also differentially controlled4 ,an oil dash pot prevented undue pumping of the carbons4 ,his dynamo had a drum-wound armature1 and had several horizontal field coils on each side of one pair of poles between which the armature revolved4 ,the system was designed for about #bj amperes1 each are taking about #ce volts4 ,illustration3 ,,brush',s ,,dynamo1 #ahgg4 ,this dynamo was used for many years for commercial arc lighting4 ,illustration3 ,,diagram ,,of ,,brush ,,armature4 ,the armature was not a closed circuit4 ,for description of its operation1 see text4 ,charles ,f4 ,brush made a very successful arc lighting system in #ahgh4 ,his dynamo was unique in that the armature had eight coils1 one end of each pair of opposite coils being connected together and the other ends connected to a commutator segment4 ,thus the armature itself was not a closed circuit4 ,the machine had two pairs of horizontal poles between which the coils revolved4 ,one end of the one pair of coils in the most active position was connected1 by means of two of the four brushes1 in series with one end of the two pairs of coils in the lesser active position4 ,the latter two pairs of coils were connected in multiple with each other by means of the brushes touching adjacent commutator segments4 ,the outside circuit was connected to the other two brushes1 one of which was connected to the other end of the most active pair of coils4 ,the other brush was connected to the other end of the two lesser active pairs of coils4 ,the one pair of coils in the least active position was out of circuit4 ,the field coils were connected in series with the outside circuit4 ,illustration3 ,,brush',s ,,arc ,,lamp1 #ahgg4 ,the carbons were differentially controlled4 ,this lamp was used for many years4 ,this lamp is in the collection of the ,smithsonian ,institution4 ,brush's arc lamp was also differentially controlled4 ,it was designed for about #aj amperes at about #de volts4 ,the carbons were copper plated to increase their conductivity4 ,two pairs of carbons were used for all-night service1 each pair lasting about eight hours4 ,a very simple device was used to automatically switch the arc from one to the other pair of carbons1 when the first pair was consumed4 ,this device consisted of a triangular-shaped piece of iron connected to the solenoid controlling the arc4 ,there was a groove on each of the outer two corners of this triangle1 one groove wider than the other4 ,an iron washer surrounded each upper carbon4 ,the edge of each washer rested in a groove4 ,the washer in the narrow groove made a comparatively tight fit about its carbon4 ,the other washer in the wider groove had a loose fit about its carbon4 ,pins prevented the washer from falling below given points4 ,both pairs of carbons touched each other at the start4 ,when current was turned on1 the solenoid lifted the triangle1 the loose-fitting washer gripped its carbon first1 so that current then only passed through the other pair of carbons which were still touching each other4 ,the further movement of the solenoid then separated these carbons1 the arc starting between them4 ,when this pair of carbons became consumed1 they could not feed any more so that the solenoid would then allow the other pair of carbons to touch1 transferring the arc to that pair4 ,illustration3 ,,thomson-,,houston ,,arc ,,dynamo1 #ahgh4 ,this dynamo was standard for many years4 ,this machine is in the collection of the ,smithsonian ,institution4 ,elihu ,thomson and ,edwin ,j4 ,houston in #ahgh made a very successful and complete arc light system4 ,their dynamo was specially designed to fit the requirements of the series arc lamp4 ,the ,thomson-,houston machine was a bipolar1 having an armature consisting of three coils1 one end of each of the three coils having a common terminal1 or 8,y0 connected1 as it is called4 ,the other end of each coil was connected to a commutator segment4 ,the machine was to a great extent self-regulating1 that is the current was inherently constant with fluctuating load1 as occurs when the lamps feed or when the number of lamps burning at one time should change for any reason4 ,this regulation was accomplished by what is called 8armature reaction10 which is the effect the magnetization of the armature has on the field strength4 ,close regulation was obtained by a separate electro-magnet1 in series with the circuit1 which shifted the brushes as the load changed4 ,as there were but three commutator segments1 one for each coil1 excessive sparking was prevented by an air blast4 ,illustration3 ,,diagram ,,of ,t-,h ,,arc ,,lighting ,,system4 ,the 8,t-,h0 7,thompson-,houston7 lamp employed the shunt feed principle4 ,the carbons were normally separated1 being in most types drawn apart by a spring4 ,a high resistance magnet1 shunted around the arc1 served to draw the carbons together4 ,this occurred on starting the lamp and thereafter the voltage of the arc was held constant by the balance between the spring and the shunt magnet4 ,as the carbon burned away the mechanism advanced to a point where a clutch was tripped1 the carbons brought together1 and the cycle repeated4 ,both the ,t-,h and ,brush systems were extensively used in street lighting1 for which they were the standard when the open arc was superseded by the enclosed4 ,,other ,,american ,,arc ,,light ,,systems ,illustration3 ,,thomson-,,houston ,,arc ,,lamp1 #ahgh4 ,this is an early model with a single pair of carbons4 ,illustration3 ,,thomson ,,double ,,carbon ,,arc ,,lamp4 ,this later model1 having two pairs of carbons1 was commercially used for many years4 ,this lamp is in the collection of the ,smithsonian ,institution4 ,beginning with about #ahhj1 several arc light systems were developed4 ,among these were the ,vanderpoele1 ,hochausen1 ,waterhouse1 ,maxim1 ,schuyler and ,wood4 ,the direct current carbon arc is inherently more efficient than the alternating current lamp1 owing to the fact that the continuous flow of current in one direction maintains on the positive carbon a larger crater at the vaporizing point of carbon4 ,this source furnishes the largest proportion of light1 the smaller crater in the negative carbon much less4 ,with the alternating current arc1 the large crater is formed first on the upper and then on the lower carbon4 ,on account of the cooling between alternations1 the mean temperature falls below the vaporizing point of carbon1 thus accounting for the lower efficiency of the alternating current arc4 ,illustration3 ,,maxim ,,dynamo4 ,this dynamo is in the collection of the ,smithsonian ,institution4 ,for this reason all these systems used direct current and the #aj ampere ultimately displaced the #bj ampere system4 ,the #aj ampere circuit was later standardized at #i4f amperes1 #ej volts per lamp4 ,the lamp therefore consumed #dhj watts giving an efficiency of about #ae lumens per watt4 ,this lamp gave an average of #ege candlepower 7spherical7 in all directions1 though it was called the #bjjj cp 7candlepower7 arc as under the best possible conditions it could give this candlepower in one direction4 ,later a #f4f ampere arc was developed4 ,this was called the 8#abjj cp0 lamp and was not quite as efficient as the #i4f ampere lamp4 8,,sub-,,dividing ,,the ,,electric ,,light0 ,while the arc lamp was being commercially established1 it was at once seen that it was too large a unit for household use4 ,many inventors attacked the problem of making a smaller unit1 or1 as it was called1 8sub-dividing the electric light40 ,in the ,united ,states there were four men prominent in this work3 ,william ,e4 ,sawyer1 ,moses ,g4 ,farmer1 ,hiram ,s4 ,maxim and ,thomas ,a4 ,edison4 ,these men did not make smaller arc lamps but all attempted to make an incandescent lamp that would operate on the arc circuits4 ,illustration3 ,,sawyer',s ,,incandescent ,,lamp1 #ahgh4 ,this had a graphite burner operating in nitrogen gas4 ,illustration3 ,,farmer',s ,,incandescent ,,lamp1 #ahgh4 ,the graphite burner operated in nitrogen gas4 ,this lamp is in the collection of the ,smithsonian ,institution4 ,sawyer made several lamps in the years #ahgh-gi along the lines of the ,russian scientists4 ,all his lamps had a thick carbon burner operating in nitrogen gas4 ,they had a long glass tube closed at one end and the other cemented to a brass base through which the gas was put in4 ,heavy fluted wires connected the burner with the base to radiate the heat1 in order to keep the joint in the base cool4 ,the burner was renewable by opening the cemented joint4 ,farmer's lamp consisted of a pair of heavy copper rods mounted on a rubber cork1 between which a graphite rod was mounted4 ,this was inserted in a glass bulb and operated in nitrogen gas4 ,maxim made a lamp having a carbon burner operating in a rarefied hydrocarbon vapor4 ,he also made a lamp consisting of a sheet of platinum operating in air4 ,,edison',s ,,invention ,,of ,a ,,practical ,,incandescent ,,lamp ,edison began the study of the problem in the spring of #ahgh4 ,he had a well-equipped laboratory at ,menlo ,park1 ,new ,jersey1 with several able assistants and a number of workmen1 about a hundred people all told4 ,he had made a number of well-known inventions1 among which were the quadruplex telegraph whereby four messages could be sent simultaneously over one wire1 the carbon telephone transmitter without which ,bell's telephone receiver would have been impracticable1 and the phonograph4 ,all of these are in use today1 so ,edison was eminently fitted to attack the problem4 ,illustration3 ,,maxim',s ,,incandescent ,,lamp1 #ahgh4 ,the carbon burner operated in a rarefied hydrocarbon vapor4 ,this lamp is in the collection of the ,smithsonian ,institution4 ,edison's first experiments were to confirm the failures of other experimenters4 ,convinced of the seeming impossibility of carbon1 he turned his attention to platinum as a light giving element4 ,realizing the importance of operating platinum close to its melting temperature1 he designed a lamp which had a thermostatic arrangement so that the burner would be automatically short circuited the moment its temperature became dangerously close to melting4 ,the burner consisted of a double helix of platinum wire within which was a rod4 ,when the temperature of the platinum became too high1 the rod in expanding would short circuit the platinum4 ,the platinum cooled at once1 the rod contracted opening the short circuit and allowing current to flow through the burner again4 ,his first incandescent lamp patent covered this lamp4 ,his next patent covered a similar lamp with an improved thermostat consisting of an expanding diaphragm4 ,both of these lamps were designed for use on series circuits4 ,illustration3 ,,edison',s ,,first ,,experimental ,,lamp1 #ahgh4 ,the burner was a coil of platinum wire which was protected from operating at too high a temperature by a thermostat4 ,the only system of distributing electricity1 known at that time1 was the series system4 ,in this system current generated in the dynamo armature flowed through the field coils1 out to one lamp after another over a wire1 and then back to the dynamo4 ,there were no means by which one lamp could be turned on and off without doing the same with all the others on the circuit4 ,edison realized that while this was satisfactory for street lighting where arcs were generally used1 it never would be commercial for household lighting4 ,he therefore decided that a practical incandescent electric lighting system must be patterned after gas lighting with which it would compete4 ,he therefore made an intensive study of gas distribution and reasoned that a constant pressure electrical system could be made similar to that of gas4 ,the first problem was therefore to design a dynamo that would give a constant pressure instead of constant current4 ,he therefore reasoned that the internal resistance of the armature must be very low or the voltage would fall as current was taken from the dynamo4 ,scientists had shown that the most economical use of electricity from a primary battery was where the external resistance of the load was the same as the internal resistance of the battery1 or in other words1 #ej per cent was the maximum possible efficiency4 ,illustration3 ,,diagram ,,of ,,constant ,,current ,,series ,,system4 ,this1 in #ahgh1 was the only method of distributing electric current4 ,illustration3 ,,diagram ,,of ,,edison',s ,,multiple ,,system1 #ahgi4 ,edison invented the multiple system of distributing electric current1 now universally used4 ,when ,edison proposed a very low resistance armature so that the dynamo would have an efficiency of #ij per cent at full load1 he was ridiculed4 ,nevertheless he went ahead and made one which attained this4 ,the armature consisted of drum-wound insulated copper rods1 the armature core having circular sheets of iron with paper between to reduce the eddy currents4 ,there were two vertical fields above and connected in shunt with the armature4 ,it generated electricity at about a hundred volts constant pressure and could supply current up to about #fj amperes at this pressure4 ,it therefore had a capacity1 in the present terminology1 of about #f kilowatts 7or #h horsepower74 ,illustration3 ,,edison ,,dynamo1 #ahgi4 ,edison made a dynamo that was #ij per cent efficient which scientists said was impossible4 ,this dynamo is in the collection of the ,smithsonian ,institution and was one of the machines on the steamship ,columbia1 the first commercial installation of the ,edison lamp4 ,a multiple system of distribution would make each lamp independent of every other and with a dynamo made for such a system1 the next thing was to design a lamp for it4 ,having a pressure of about a hundred volts to contend with1 the lamp1 in order to take a small amount of current1 must1 to comply with ,ohm's law1 have a high resistance4 ,he therefore wound many feet of fine platinum wire on a spool of pipe clay and made his first high resistance lamp4 ,he used his diaphragm thermostat to protect the platinum from melting1 and1 as now seems obvious but was not to all so-called electricians at that time1 the thermostat was arranged to open circuit instead of short circuit the burner when it became too hot4 ,this lamp apparently solved the problem1 and1 in order to protect the platinum from the oxygen of the air1 he coated it with oxide of zirconium4 ,unfortunately zirconia1 while an insulator at ordinary temperatures1 becomes1 as is now known1 a conductor of electricity when heated1 so that the lamp short circuited itself when it was lighted4 ,illustration3 ,,edison',s ,,high ,,resistance ,,platinum ,,lamp1 #ahgi4 ,this lamp had a high resistance burner1 necessary for the multiple system4 ,illustration3 ,,edison',s ,,high ,,resistance ,,platinum ,,in ,,vacuum ,,lamp1 #ahgi4 ,this experimental lamp led to the invention of the successful carbon filament lamp4 ,during his experiments he had found that platinum became exceedingly hard after it had been heated several times to incandescence by current flowing through it4 ,this apparently raised its melting temperature so he was able to increase the operating temperature and therefore greatly increase the candlepower of his lamps after they had been heated a few times4 ,examination of the platinum under a microscope showed it to be much less porous after heating1 so he reasoned that gases were occluded throughout the platinum and were driven out by the heat4 ,this led him to make a lamp with a platinum wire to operate in vacuum1 as he thought that more of the occluded gases would come out under such circumstances4 ,illustration3 ,,edison',s ,,carbon ,,lamp ,,of ,,october #ba1 #ahgi4 ,this experimental lamp1 having a high resistance carbon filament operating in a high vacuum maintained by an all-glass globe1 was the keystone of ,edison's successful incandescent lighting system4 ,all incandescent lamps made today embody the basic features of this lamp4 ,this replica is in the ,smithsonian ,institution exhibit of ,edison lamps4 ,the original was destroyed4 ,these lamps were expensive to make1 and1 knowing that he could get the requisite high resistance at much less cost from a long and slender piece of carbon1 he thought he might be able to make the carbon last in the high vacuum he had been able to obtain from the newly invented ,geissler and ,sprengel mercury air pumps4 ,after several trials he finally was able to carbonize a piece of ordinary sewing thread4 ,this he mounted in a one-piece all glass globe1 all joints fused by melting the glass together1 which he considered was essential in order to maintain the high vacuum4 ,platinum wires were fused in the glass to connect the carbonized thread inside the bulb with the circuit outside as platinum has the same coefficient of expansion as glass and hence maintains an airtight joint4 ,he reasoned that there would be occluded gases in the carbonized thread which would immediately burn up if the slightest trace of oxygen were present1 so he heated the lamp while it was still on the exhaust pump after a high degree of vacuum had been obtained4 ,this was accomplished by passing a small amount of current through the 8filament10 as he called it1 gently heating it4 ,immediately the gases started coming out1 and it took eight hours more on the pump before they stopped4 ,the lamp was then sealed and ready for trial4 ,illustration3 ,,demonstration ,,of ,,edison',s ,,incandescent ,,lighting ,,system4 ,showing view of ,menlo ,park ,laboratory ,buildings1 #ahhj4 ,on ,october #ba1 #ahgi1 current was turned into the lamp and it lasted forty-five hours before it failed4 ,a patent was applied for on ,november #dth of that year and granted ,january #bg1 #ahhj4 ,all incandescent lamps made today embody the basic features of this lamp4 ,edison immediately began a searching investigation of the best material for a filament and soon found that carbonized paper gave several hundred hours life4 ,this made it commercially possible1 so in ,december1 #ahgi1 it was decided that a public demonstration of his incandescent lighting system should be made4 ,wires were run to several houses in ,menlo ,park1 ,n4 ,j41 and lamps were also mounted on poles1 lighting the country roads in the neighborhood4 ,an article appeared in the ,new ,york ,herald on ,sunday1 ,december #ba1 #ahgi1 describing ,edison's invention and telling of the public demonstration to be given during the ,christmas holidays4 ,this occupied the entire first page of the paper1 and created such a furor that the ,pennsylvania ,railroad had to run special trains to ,menlo ,park to accommodate the crowds4 ,the first commercially successful installation of the ,edison incandescent lamps and lighting system was made on the steamship ,columbia1 which started ,may #b1 #ahhj1 on a voyage around ,cape ,horn to ,san ,francisco1 ,calif4 ,the carbonized paper filament of the first commercial incandescent lamp was quite fragile4 ,early in #ahhj carbonized bamboo was found to be not only sturdy but made an even better filament than paper4 ,the shape of the bulb was also changed from round to pear shape1 being blown from one inch tubing4 ,later the bulbs were blown directly from molten glass4 ,illustration3 ,,dynamo ,,room1 ,s4 ,s4 ,,columbia4 ,the first commercial installation of the ,edison ,lamp1 started ,may #b1 #ahhj4 ,one of these original dynamos is on exhibit at the ,smithsonian ,institution4 ,as it was inconvenient to connect the wires to the binding posts of a new lamp every time a burned out lamp had to be replaced1 a base and socket for it were developed4 ,the earliest form of base consisted simply of bending the two wires of the lamp back on the neck of the bulb and holding them in place by wrapping string around the neck4 ,the socket consisted of two pieces of sheet copper in a hollow piece of wood4 ,the lamp was inserted in this1 the two-wire terminals of the lamp making contact with the two-sheet copper terminals of the socket1 the lamp being rigidly held in the socket by a thumb screw which forced the socket terminals tight against the neck of the bulb4 ,illustration3 ,,original ,,socket ,,for ,,incandescent ,,lamps1 #ahhj4 ,illustration3 ,,wire ,,terminal ,,base ,,lamp1 #ahhj4 ,this crude form of lamp base fitted the original form of lamp socket pictured above4 ,this lamp is in the exhibit of ,edison lamps in the ,smithsonian ,institution4 ,this crude arrangement was changed in the latter part of #ahhj to a screw shell and a ring for the base terminals1 wood being used for insulation4 ,the socket was correspondingly changed4 ,this was a very bulky affair1 so the base was changed to a cone-shaped ring and a screw shell for terminals4 ,wood was used for insulation1 which a short time after was changed to plaster of ,paris as this was also used to fasten the base to the bulb4 ,it was soon found that the tension created between the two terminals of the base when the lamp was firmly screwed in the socket often caused the plaster base to pull apart1 so the shape of the base was again changed early in #ahha1 to the form in use today4 ,an improved method of connecting the ends of the filament to the leading-in wires was adopted early in #ahha4 ,formerly this was accomplished by a delicate clamp having a bolt and nut4 ,the improvement consisted of copper plating the filament to the leading-in wire4 ,illustration3 ,,original ,,screw ,,base ,,lamp1 #ahhj4 ,this first screw base1 consisting of a screw shell and ring for terminals with wood for insulation1 was a very bulky affair4 ,this lamp is in the exhibit of ,edison lamps in the ,smithsonian ,institution4 ,illustration3 ,,improved ,,screw ,,base ,,lamp1 #ahha4 ,the terminals of this base consisted of a cone shaped ring and a screw shell4 ,at first wood was used for insulation1 later plaster of paris which was also used to fasten the base to the bulb4 ,this lamp is in the exhibit of ,edison lamps in the ,smithsonian ,institution4 ,in the early part of the year #ahha the lamps were made 8eight to the horsepower40 ,each lamp1 therefore1 consumed a little less than #ajj watts1 and was designed to give #af candlepower in a horizontal direction4 ,the average candlepower 7spherical7 in all directions was about #gg per cent of this1 hence as the modern term 8lumen0 is #ab4eg spherical candlepower1 these lamps had an initial efficiency of about #a4g lumens per watt4 ,the lamps blackened considerably during their life so that just before they burned out their candlepower was less than half that when new4 ,thus their mean efficiency throughout life was about #a4a l-p-w 7lumens per watt74 ,these figures are interesting in comparison with the modern #ajj-watt gas-filled tungsten-filament lamp which has an initial efficiency of #ab4i1 and a mean efficiency of #aa4h1 l-p-w4 ,in other words the equivalent 7wattage7 size of modern lamp gives over seven times when new1 and eleven times on the average1 as much light for the same energy consumption as ,edison's first commercial lamp4 ,in the latter part of #ahha the efficiency was changed to 8ten lamps per horsepower10 equivalent to #b l-p-w initially4 ,two sizes of lamps were made3 #af cp for use on #aaj-volt circuits and #h cp for use either direct on #ee volts or two in series on #aaj-volt circuits4 ,illustration3 ,,final ,,form ,,of ,,screw ,,base1 #ahha4 ,with plaster of paris1 the previous form of base was apt to pull apart when the lamp was firmly screwed into the socket4 ,the form of the base was therefore changed to that shown1 which overcame these difficulties1 and which has been used ever since4 ,the lamp shown was standard for three years and is in the exhibit of ,edison lamps in the ,smithsonian ,institution4 ,,edison',s ,,three-,,wire ,,system ,the distance at which current can be economically delivered at #aaj volts pressure is limited1 as will be seen from a study of ,ohm's law4 ,the loss of power in the distributing wires is proportional to the square of the current flowing4 ,if the voltage be doubled1 the amount of current is halved1 for a given amount of electric power delivered1 so that the size of the distributing wires can then be reduced to one-quarter for a given loss in them4 ,at that time 7#ahha7 it was impossible to make #bbj-volt lamps1 and though they are now available1 their use is uneconomical1 as their efficiency is much poorer than that of #aaj-volt incandescent lamps4 ,edison invented a distributing system that had two #aaj-volt circuits1 with one wire called the neutral1 common to both circuits so that the pressure on the two outside wires was #bbj volts4 ,the neutral wire had only to be large enough to carry the difference between the currents flowing in the two circuits4 ,as the load could be so arranged that it would be approximately equal at all times on both circuits1 the neutral wire could be relatively small in size4 ,thus the three-wire system resulted in a saving of #fj per cent in copper over the two-wire system or1 for the same amount of copper1 the distance that current could be delivered was more than doubled4 ,illustration3 ,,diagram ,,of ,,edison',s ,,three-,,wire ,,system1 #ahha4 ,this system reduced the cost of copper in the multiple distributing system #fj per cent4 ,,development ,,of ,,the ,,alternating ,,current ,,constant ,,potential ,,system ,the distance that current can be economically distributed1 as has been shown1 depends upon the voltage used4 ,if1 therefore1 current could be sent out at a high voltage and the pressure brought down to that desired at the various points to which it is distributed1 such distribution could cover a much greater area4 ,lucien ,gaulard was a ,french inventor and was backed by an ,englishman named ,john ,d4 ,gibbs4 ,about #ahhb they patented a series alternating-current system of distribution4 ,they had invented what is now called a transformer which consisted of two separate coils of wire mounted on an iron core4 ,all the primary coils were connected in series1 which1 when current went through them1 induced a current in the secondary coils4 ,lamps were connected in multiple on each of the secondary coils4 ,an ,american patent was applied for on the transformer1 but was refused on the basis that 8more current cannot be taken from it than is put in40 ,while this is true if the word energy were used1 the transformer can supply a greater current at a lower voltage 7or vice versa7 than is put in1 the ratio being in proportion to the relative number of turns in the primary and secondary coils4 ,the transformer was treated with ridicule and ,gaulard died under distressing circumstances4 ,illustration3 ,,diagram ,,of ,,stanley',s ,,alternating ,,current ,,multiple ,,system1 #ahhe4 ,this system is now universally used for distributing electric current long distances4 ,information regarding the transformer came to the attention of ,william ,stanley1 an ,american1 in the latter part of #ahhe4 ,he made an intensive study of the scheme1 and developed a transformer in which the primary coil was connected in multiple on a constant potential alternating-current high-voltage system4 ,from the secondary coil a lower constant voltage was obtained4 ,an experimental installation was made at ,great ,barrington1 ,mass41 in the early part of #ahhf1 the first commercial installation being made in ,buffalo1 ,new ,york1 in the latter part of the year4 ,this scheme enabled current to be economically distributed to much greater distances4 ,the voltage of the high-tension circuit has been gradually increased as the art has progressed from about a thousand volts to over two hundred thousand volts pressure in a recent installation in ,california1 where electric power is transmitted over two hundred miles4 ,,incandescent ,,lamp ,,developments1 #ahhd-ahid ,in #ahhd the ring of plaster around the top of the base was omitted2 in #ahhf an improvement was made by pasting the filament to the leading-in wires with a carbon paste instead of the electro-plating method2 and in #ahhh the length of the base was increased so that it had more threads4 ,several concerns started making incandescent lamps1 the filaments being made by carbonizing various substances4 8,parchmentized0 thread consisted of ordinary thread passed through sulphuric acid4 8,tamadine0 was cellulose in the sheet form1 punched out in the shape of the filament4 ,squirted cellulose in the form of a thread was also used4 ,this was made by dissolving absorbent cotton in zinc chloride1 the resulting syrup being squirted through a die into alcohol which hardened the thread thus formed4 ,this thread was washed in water1 dried in the air and then cut to proper length and carbonized4 ,illustration3 ,,standard ,,edison ,,lamp1 #ahhd4 ,the ring of plaster around the neck of previous lamps was omitted4 ,this lamp is in the exhibit of ,edison lamps in the ,smithsonian ,institution4 ,illustration3 ,,standard ,,edison ,,lamp1 #ahhh4 ,the length of the base was increased so it had more threads4 ,this lamp is in the exhibit of ,edison lamps in the ,smithsonian ,institution4 ,the filament was improved by coating it with graphite4 ,one method1 adopted about #ahhh1 was to dip it in a hydrocarbon liquid before carbonizing4 ,another1 more generally adopted in #ahic was a process originally invented by ,sawyer1 one of the ,americans who had attempted to 8sub-divide the electric light0 in #ahgh-gi4 ,this process consisted of passing current through a carbonized filament in an atmosphere of hydrocarbon vapor4 ,the hot filament decomposed the vapor1 depositing graphite on the filament4 ,the graphite coated filament improved it so it could operate at #c lumens per watt 7initial efficiency74 ,lamps of #bj1 #bd1 #cb and #ej candlepower were developed for #aaj-volt circuits4 ,lamps in various sizes from #ab to #cf cp were made for use on storage batteries having various numbers of cells and giving a voltage of from #bj to #dj volts4 ,miniature lamps of from to #b cp for use on dry batteries of from #b to #e volts1 and #c to #f cp on #e to #ab volts1 were also made4 ,these could also be connected in series on #aaj volts for festoons4 ,very small lamps of cp of #b to #d volts for use in dentistry and surgery were made available4 ,these miniature lamps had no bases1 wires being used to connect them to the circuit4 ,illustration3 ,,standard ,,edison ,,lamp1 #ahid4 ,this lamp had a 8treated0 cellulose filament1 permitting an efficiency of #c lumens per watt which has never been exceeded in a carbon lamp4 ,this lamp is in the exhibit of ,edison lamps in the ,smithsonian ,institution4 ,lamps for #bbj-volt circuits were developed as this voltage was desirable for power purposes1 electric motors being used1 and a few lamps were needed on such circuits4 ,they are less efficient and more expensive than #aaj-volt lamps1 their use being justified however only when it is uneconomical to have a separate #aaj-volt circuit for lighting4 ,the lamps were made in sizes from #af to #ej candlepower4 ,illustration3 ,edison4 ,thomson-,houston4 ,westinghouse4 ,brush-,swan4 ,edi-,swan ,edi-,swan ,united ,states4 ,hawkeye4 7single contact74 7double contact74 ,ft4 ,wayne ,jenny4 ,mather or ,perkins4 ,loomis4 ,schaeffer or ,national4 ,indianapolis ,jenny4 ,siemens ,halske4 ,,various ,,standard ,,bases ,,in ,,use1 #ahib4 ,illustration3 ,,thomson-,,houston ,,socket4 ,illustration3 ,,westinghouse ,,socket4 ,electric street railway systems used a voltage in the neighborhood of #eej1 and lamps were designed to burn five in series on this voltage4 ,these lamps were different from the standard #aaj-volt lamps although they were made for about this voltage4 ,as they were burned in series1 the lamps were selected to operate at a definite current instead of at a definite voltage1 so that the lamps when burned in series would operate at the proper temperature to give proper life results4 ,such lamps would therefore vary considerably in individual volts1 and hence would not give good service if burned on #aaj-volt circuits4 ,the candelabra screw base and socket and the miniature screw base and socket were later developed4 ,ornamental candelabra base lamps were made for use direct on #aaj volts1 smaller sizes being operated in series on this voltage4 ,the former gave about #aj cp1 the latter in various sizes from #d to #h cp4 ,the miniature screw base lamps were for low volt lighting4 ,illustration3 ,thomson-,houston4 ,westinghouse4 ,,adapters ,,for ,,edison ,,screw ,,sockets1 #ahib4 ,next to the ,edison base1 the ,thomson-,houston and ,westinghouse bases were the most popular4 ,by use of these adapters1 ,edison base lamps could be used in ,t-,h and ,westinghouse sockets4 ,the various manufacturers of lamps in nearly every instance made bases that were very different from one another4 ,no less than fourteen different standard bases and sockets came into commercial use4 ,these were known as1 ,brush-,swan1 ,edison1 ,edi-,swan 7double contact71 ,edi-,swan 7single contact71 ,fort ,wayne ,jenny1 ,hawkeye1 ,indianapolis ,jenny1 ,loomis1 ,mather or ,perkins1 ,schaeffer or ,national1 ,siemens ,halske1 ,thomson-,houston1 ,united ,states and ,westinghouse4 ,in addition there were later larger sized bases made for use on series circuits4 ,these were called the ,bernstein1 ,heisler1 ,large ,edison1 ,municipal ,bernstein1 ,municipal ,edison1 ,thomson-,houston 7alternating circuit7 and ,thomson-,houston 7arc circuit74 ,some of these bases disappeared from use and in #aijj the proportion in the ,united ,states was about #gj per cent ,edison1 #ae per cent ,westinghouse1 #aj per cent ,thomson-,houston and #e per cent for all the others remaining4 ,a campaign was started to standardize the ,edison base1 adapters being sold at cost for the ,westinghouse and ,thomson-,houston sockets so that ,edison base lamps could be used4 ,in a few years the desired results were obtained so that now there are no other sockets in the ,united ,states but the ,edison screw type for standard lighting service4 ,this applies also to all other countries in the world except ,england where the bayonet form of base and socket is still popular4 ,illustration3 ,bernstein4 ,heisler4 ,thomson-,houston 7alternating current74 ,thomson-,houston ,municipal ,edison4 ,municipal ,bernstein4 7arc circuit74 ,,various ,,series ,,bases ,,in ,,use1 #ahib4 ,the above six bases have been superseded by the 8,large ,edison10 now called the ,mogul ,screw base4 ,,the ,,edison 8,,municipal0 ,,street ,,lighting ,,system ,illustration3 ,,edison 8,,municipal0 ,,system1 #ahhe4 ,high voltage direct current was generated1 several circuits operating in multiple1 three ampere lamps burning in series on each circuit4 ,photograph courtesy of ,association of ,edison ,illuminating ,companies4 ,the arc lamp could not practically be made in a unit smaller than the so-called 8#abjj candlepower0 7#f4f ampere7 or 8half0 size1 which really gave about #cej spherical candlepower4 ,a demand therefore arose for a small street lighting unit1 and ,edison designed his 8,municipal0 street lighting system to fill this requirement4 ,his experience in the making of dynamos enabled him to make a direct current bipolar constant potential machine that would deliver #ajjj volts which later was increased to #abjj volts4 ,they were first made in two sizes having an output of #ab and #cj amperes respectively4 ,incandescent lamps were made for #c amperes in several sizes from #af to #ej candlepower4 ,these lamps were burned in series on the #abjj-volt direct current system4 ,thus the #ab-;ampere machine had a capacity for four series circuits1 each taking #c amperes1 the series circuits being connected in multiple across the #abjj volts4 ,the number of lamps on each series circuit depended upon their size1 as the voltage of each lamp was different for each size1 being about #a volts per cp4 ,a popular size was the #cb-;candlepower unit1 which therefore required about #de volts and hence at #c amperes consumed about #ace watts4 ,allowing #e per cent loss in the wires of each circuit1 there was therefore #aadj of the #abjj volts left for the lamps4 ,hence about #be #cb-;candlepower or #ej #af-;candlepower lamps could be put on each series circuit4 ,different sizes of lamps could also be put on the same circuit1 the number depending upon the aggregate voltage of the lamps4 ,illustration3 ,,edison ,,municipal ,,lamp1 #ahhe4 ,inside the base was an arrangement by which the lamp was automatically short circuited when it burned out4 ,a device was put in the base of each lamp to short circuit the lamp when it burned out so as to prevent all the other lamps on that circuit from going out4 ,this device consisted of a piece of wire put inside the lamp bulb between the two ends of the filament4 ,connected to this wire was a very thin wire inside the base which held a piece of metal compressed against a spring4 ,the spring was connected to one terminal of the base4 ,should the lamp burn out1 current would jump from the filament to the wire in the bulb1 and the current then flowed through the thin wire to the other terminal of the base4 ,the thin wire was melted by the current1 and the spring pushed the piece of metal up short circuiting the terminals of the base4 ,this scheme was later simplified by omitting the wire1 spring1 etc41 and substituting a piece of metal which was prevented from short circuiting the terminals of the base by a thin piece of paper4 ,when the lamp burned out the entire #abjj volts was impressed across this piece of paper1 puncturing it and so short circuiting the base terminals4 ,should one or more lamps go out on a circuit1 the increase in current above the normal #c amperes was prevented by an adjustable resistance1 or an extra lot of lamps which could be turned on one at a time1 connected to each circuit and located in the power station under the control of the operator4 ,this system disappeared from use with the advent of the constant current transformer4 ,,the ,,shunt ,,box ,,system ,,for ,,series ,,incandescent ,,lamps ,illustration3 ,,shunt ,,box ,,system1 #ahhg4 ,lamps were burned in series on a high voltage alternating current1 and when a lamp burned out all the current then went through its 8shunt box10 a reactance coil in multiple with each lamp4 ,soon after the commercial development of the alternating current constant potential system1 a scheme was developed to permit the use of lamps in series on such circuits without the necessity for short circuiting a lamp should it burn out4 ,a reactance1 called a 8shunt box0 and consisting of a coil of wire wound on an iron core1 was connected across each lamp4 ,the shunt box consumed but little current while the lamp was burning4 ,should one lamp go out1 the entire current would flow through its shunt box and so maintain the current approximately constant4 ,it had the difficulty1 however1 that if several lamps went out1 the current would be materially increased tending to burn out the remaining lamps on the circuit4 ,this system also disappeared from use with the development of the constant current transformer4 ,,the ,,enclosed ,,arc ,,lamp ,up to #ahic the carbons of an arc lamp operated in the open air1 so that they were rapidly consumed1 lasting from eight to sixteen hours depending on their length and thickness4 ,louis ,b4 ,marks1 an ,american1 found that by placing a tight fitting globe about the arc1 the life of the carbons was increased ten to twelve times4 ,this was due to the restricted amount of oxygen of the air in the presence of the hot carbon tips and thus retarded their consumption4 ,the amount of light was somewhat decreased1 but this was more than offset by the lesser expense of trimming which also justified the use of more expensive better quality carbons4 ,satisfactory operation required that the arc voltage be increased to about #hj volts4 ,illustration3 ,,enclosed ,,arc ,,lamp1 #ahic4 ,enclosing the arc lengthened the life of the carbons1 thereby greatly reducing the cost of maintenance4 ,this lamp rapidly displaced the series open arc4 ,an enclosed arc lamp for use on #aaj-volt constant potential circuits was also developed4 ,a resistance was put in series with the arc for use on #aaj-volt direct current circuits1 to act as a ballast in order to prevent the arc from taking too much current and also to use up the difference between the arc voltage 7#hj7 and the line voltage 7#aaj74 ,on alternating current1 a reactance was used in place of the resistance4 ,the efficiencies in lumens per watt of these arcs 7with clear glassware71 all of which have now disappeared from the market1 were about as follows3 #f4f ampere #eaj watt direct current 7,d4,c47 series arc1 #h l-p-w4 #e4j ampere #eej watt direct current multiple 7#aaj-volt7 arc1 #d l-p-w4 #g4e ampere #edj watt alternating current 7,a4,c47 multiple 7#aaj-volt7 arc1 #d l-p-w4 ,illustration3 ,,open ,,flame ,,arc ,,lamp1 #ahih4 ,certain salts impregnated in the carbons produced a brilliantly luminous flame in the arc stream which enormously increased the efficiency of the lamp4 ,illustration3 ,,enclosed ,,flame ,,arc ,,lamp1 #aijh4 ,by condensing the smoke from the arc in a cooling chamber it was practical to enclose the flame arc1 thereby increasing the life of the carbons4 ,the reason for the big difference in efficiency between the series and multiple direct-current arc is that in the latter a large amount of electrical energy 7watts7 is lost in the ballast resistance4 ,while there is a considerable difference between the inherent efficiencies of the ,d4 ,c4 and ,a4 ,c4 arcs themselves1 this difference is reduced in the multiple ,d4 ,c4 and ,a4 ,c4 arc lamps as more watts are lost in the resistance ballast of the multiple ,d4 ,c4 lamp than are lost in the reactance ballast of the multiple ,a4 ,c4 lamp4 ,this reactance gives the ,a4 ,c4 lamp what is called a 8power-factor40 ,the product of the amperes 7#g4e7 times the volts 7#aaj7 does not give the true wattage 7#edj7 of the lamp1 so that the actual volt-amperes 7#hbe7 has to be multiplied by a power factor1 in this case about #fe per cent1 to obtain the actual power 7watts7 consumed4 ,the reason is that the instantaneous varying values of the alternating current and pressure1 if multiplied and averaged throughout the complete alternating cycle1 do not equal the average amperes 7measured by an ammeter7 multiplied by the average voltage 7measured by a volt-meter74 ,that is1 the maximum value of the current flowing 7amperes7 does not occur at the same instant that the maximum pressure 7voltage7 is on the circuit4 ,,the ,,flame ,,arc ,,lamp ,about #ahdd ,bunsen investigated the effect of introducing various chemicals in the carbon arc4 ,nothing was done1 however1 until ,bremer1 a ,german1 experimented with various salts impregnated in the carbon electrodes4 ,in #ahih he produced the so-called flame arc1 which consisted of carbons impregnated with calcium fluoride4 ,this gave a brilliant yellow light most of which came from the arc flame1 and practically none from the carbon tips4 ,the arc operated in the open air and produced smoke which condensed into a white powder4 ,the two carbons were inclined downward at about a #cj-;degree angle with each other1 and were of small diameter but long1 #ah to #cj inches1 having a life of about #ab to #ae hours4 ,the tips of the carbons projected through an inverted earthenware cup1 called the 8economizer10 the white powder condensing on this and acting not only as an excellent reflector but making a dead air space above the arc4 ,the arc was maintained at the tips of the carbons by an electro-magnet whose magnetic field 8blew0 the arc down4 ,two flame arc lamps were burned in series on #aaj-volt circuits4 ,they consumed #eej watts each1 giving an efficiency of about #ce lumens per watt on direct current4 ,on alternating current the efficiency was about #cj l-p-w4 ,by use of barium salts impregnated in the carbons1 a white light was obtained1 giving an efficiency of about #ah l-p-w on direct current and about #ae on alternating current4 ,these figures cover lamps equipped with clear glassware4 ,using strontium salts in the carbons1 a red light was obtained at a considerably lower efficiency1 such arcs on account of their color being used only to a limited extent for advertising purposes4 ,illustration3 ,,constant ,,current ,,transformer1 #aijj4 ,this converted alternating current of constant voltage into constant current1 for use on series circuits4 ,these arcs were remarkably efficient but their maintenance expense was high4 ,later1 about #aijh1 enclosed flame arcs with vertical carbons were made which increased the life of the carbons1 the smoke being condensed in cooling chambers4 ,however1 their maintenance expense was still high4 ,they have now disappeared from the market1 having been displaced by the very efficient gas-filled tungsten filament incandescent lamp which appeared in #aiac4 ,,the ,,constant ,,current ,,transformer ,,for ,,series ,,circuits ,about #aijj the constant current transformer was developed by ,elihu ,thomson4 ,this transforms current taken from a constant potential alternating current circuit into a constant alternating current for series circuits1 whose voltage varies with the load on the circuit4 ,the transformer has two separate coils2 the primary being stationary and connected to the constant potential circuit and the secondary being movable and connected to the series circuit4 ,the weight of the secondary coil is slightly underbalanced by a counter weight4 ,current flowing in the primary induces current in the secondary1 the two coils repelling each other4 ,the strength of the repelling force depends upon the amount of current flowing in the two coils4 ,the core of the transformer is so designed that the central part1 which the two coils surround1 is magnetically more powerful close to the primary coil than it is further away4 ,when the two coils are close together a higher voltage is induced in the secondary than if the later were further away from the primary coil4 ,in starting1 the two coils are pulled apart by hand to prevent too large a current flowing in the series circuit4 ,the secondary coil is allowed to gradually fall and will come to rest at a point where the voltage induced in it produces the normal current in the series circuit1 the repelling force between the two coils holding the secondary at this point4 ,should the load in the series circuit change for any reason1 the current in the series circuit would also change1 thus changing the force repelling the two coils4 ,the secondary would therefore move until the current in the series circuit again becomes normal4 ,the action is therefore automatic1 and the actual current in the series circuit can be adjusted within limits to the desired amount1 by varying the counterweight4 ,a dash pot is used to prevent the secondary coil from oscillating 7pumping7 too much4 ,in the constant current transformer1 the series circuit is insulated from the constant potential circuit4 ,this has many advantages4 ,a similar device1 called an automatic regulating reactance was developed which is slightly less expensive1 but it does not have the advantage of insulating the two circuits from each other4 ,,enclosed ,,series ,,alternating ,,current ,,arc ,,lamps ,the simplicity of the constant current transformer soon drove the constant direct-current dynamo from the market4 ,an enclosed arc lamp was therefore developed for use on alternating constant current4 ,two sizes of lamps were made2 one for #f4f amperes consuming #dej watts and having an efficiency of about #d lumens per watt1 and the other #g4e amperes1 #dhj watts and #e l-p-w 7clear glassware74 ,these lamps soon superseded the direct current series arcs4 ,they have now been superseded by the more efficient magnetite arc and tungsten filament incandescent lamps4 ,,series ,,incandescent ,,lamps ,,on ,,constant ,,current ,,transformers ,series incandescent lamps were made for use on constant current transformers superseding the 8,municipal0 and 8,shunt ,box0 systems4 ,the large ,edison1 now called the ,mogul ,screw base1 was adopted and the short circuiting film cut-out was removed from the base and placed between prongs attached to the socket4 ,illustration3 ,holder4 ,socket4 ,holder and socket4 ,,series ,,incandescent ,,lamp ,,socket ,,with ,,film ,,cutout1 #aijj4 ,the 8,large ,edison10 now called ,mogul ,screw1 base was standardized and the short circuiting device put on the socket terminals4 ,the transformers made for the two sizes of arc lamps1 produced #f4f and #g4e amperes and incandescent lamps1 in various sizes from #af to #ej cp1 were made for these currents so that the incandescent lamps could be operated on the same circuit with the arc lamps4 ,the carbon series incandescent lamp1 however1 was more efficient if made for lower currents1 so #c-1 #d- and #e-;ampere constant current transformers were made for incandescent lamps designed for these amperes4 ,later1 however1 with the advent of the tungsten filament1 the #f4f-;ampere series tungsten lamp was made the standard1 as it was slightly more efficient than the lower current lamps1 and was made in sizes from #cb to #djj cp4 ,when the more efficient gas-filled tungsten lamps were developed1 the sizes were further increased2 the standard #f4f-;ampere lamps now made are from #fj to #bejj cp4 ,,the ,,nernst ,,lamp ,dr4 ,walther ,nernst1 of ,germany1 investigating the rare earths used in the ,welsbach mantle1 developed an electric lamp having a burner1 or 8glower0 as it was called1 consisting of a mixture of these oxides4 ,the main ingredient was zirconia1 and the glower operated in the open air4 ,it is a non-conductor when cold1 so had to be heated before current would flow through it4 ,this was accomplished by an electric heating coil1 made of platinum wire1 located just above the glower4 ,as the glower became heated and current flowed through it1 the heater was automatically disconnected by an electro-magnet cut-out4 ,illustration3 ,,nernst ,,lamp1 #aijj4 ,the burners consisted mainly of zirconium oxide which had to be heated before current could go through them4 ,the resistance of the glower decreases with increase in current1 so a steadying resistance was put in series with it4 ,this consisted of an iron wire mounted in a bulb filled with hydrogen gas and was called a 8ballast40 ,iron has the property of increasing in resistance with increase in current flowing through it1 this increase being very marked between certain temperatures at which the ballast was operated4 ,the lamp was put on the ,american market in #aijj for use on #bbj-volt alternating current circuits4 ,the glower consumed #j4d ampere4 ,one1 two1 three1 four and six glower lamps were made1 consuming #hh1 #aif1 #bgd1 #cib and #ebh watts respectively4 ,as most of the light is thrown downward1 their light output was generally given in mean lower hemispherical candlepower4 ,the multiple glower lamps were more efficient than the single glower1 owing to the heat radiated from one glower to another4 ,their efficiencies1 depending on the size1 were from about #c to #e lumens per watt1 and their average candlepower throughout life was about #hj per cent of initial4 ,the lamp disappeared from the market about #aiab4 ,illustration3 ,,diagram ,,of ,,nernst ,,lamp4 ,,the ,,cooper-,,hewitt ,,lamp ,in #ahfj ,way discovered that if an electric circuit was opened between mercury contacts a brilliant greenish colored arc was produced4 ,mercury was an expensive metal and as the carbon arc seemed to give the most desirable results1 nothing further was done for many years until ,dr4 ,peter ,cooper ,hewitt1 an ,american1 began experimenting with it4 ,he finally produced an arc in vacuum in a one-inch glass tube about #ej inches long for #aaj volts direct current circuits1 which was commercialized in #aija4 ,the tube hangs at about #ae degrees from the horizontal4 ,the lower end contains a small quantity of mercury4 ,the terminals are at each end of the tube1 and the arc was first started by tilting the tube by hand so that a thin stream of mercury bridged the two terminals4 ,current immediately vaporized the mercury1 starting the arc4 ,a resistance is put in series with the arc to maintain the current constant on direct current constant voltage circuits4 ,automatic starting devices were later developed1 one of which consisted of an electro-magnet that tilted the lamp1 and the other of an induction coil giving a high voltage which1 in discharging1 started the arc4 ,illustration3 ,,cooper-,,hewitt ,,mercury ,,vapor ,,arc ,,lamp1 #aija4 ,this gives a very efficient light1 practically devoid of red but of high actinic value1 so useful in photography4 ,this lamp is particularly useful in photography on account of the high actinic value of its light4 ,its light is very diffused and is practically devoid of red rays1 so that red objects appear black in its light4 ,the lamp consumes #c amperes at #aaj volts direct current 7#che watts7 having an efficiency of about #ab lumens per watt4 ,the mercury arc is peculiar in that it acts as an electric valve tending to let current flow through it only in one direction4 ,thus on alternating current1 the current impulses will readily go through it in one direction1 but the arc will go out in the other half cycle unless means are taken to prevent this4 ,this is accomplished by having two terminals at one end of the tube1 which are connected to choke coils1 which in turn are connected to a single coil 7auto7 transformer4 ,the alternating current supply mains are connected to wires tapping different parts of the coil of the auto transformer4 ,the center of the coil of the auto transformer is connected through an induction coil to the other end of the tube4 ,by this means the alternating current impulses are sent through the tube in one direction1 one half cycle from one of the pairs of terminals of the tube1 the other half cycle from the other terminal4 ,thus pulsating direct current1 kept constant by the induction coil1 flows through the tube1 the pulsations overlapping each other by the magnetic action of the choke coils4 ,this alternating current lamp is started by the high voltage discharge method4 ,it has a #ej-;inch length of tube1 consuming about #djj watts on #aaj volts4 ,its efficiency is a little less than that of the direct current lamp4 ,illustration3 ,,diagram ,,of ,,cooper-,,hewitt ,,lamp ,,for ,,use ,,on ,,alternating ,,current4 ,the mercury arc is inherently for use on direct current1 but by means of reactance coils1 it can be operated on alternating current4 ,,the ,,luminous ,,or ,,magnetite ,,arc ,,lamp ,about #aija ,dr4 ,charles ,p4 ,steinmetz1 ,schenectady1 ,n4 ,y41 studied the effect of metallic salts in the arc flame4 ,dr4 ,willis ,r4 ,whitney1 also of ,schenectady1 and director of the research laboratory of the organization of which ,dr4 ,steinmetz is the consulting engineer1 followed with some further work along this line4 ,the results of this work were incorporated in a commercial lamp called the magnetite arc lamp1 through the efforts of ,c4 ,a4 ,b4 ,halvorson1 ,jr41 at ,lynn1 ,mass4 ,the negative electrode consists of a pulverized mixture of magnetite 7a variety of iron ore7 and other substances packed tightly in an iron tube4 ,the positive electrode is a piece of copper sheathed in iron to prevent oxidization of the copper4 ,the arc flame gives a brilliant white light1 and1 similar to the mercury arc1 is inherently limited to direct current4 ,it burns in the open air at about #ge volts4 ,the lamp is made for #d-;ampere direct current series circuits and consumes about #caj watts and has an efficiency of about #aa lumens per watt4 ,illustration3 ,,luminous ,,or ,,magnetite ,,arc ,,lamp1 #aijb4 ,this has a negative electrode containing magnetite which produces a very luminous white flame in the arc stream4 ,the negative 7iron tube7 electrode now has a life of about #cej hours4 ,later1 a higher efficiency1 #d-;ampere electrode was made which has a shorter life but gives an efficiency of about #ag l-p-w1 and a #f4f-;ampere lamp was also made giving an efficiency of about #ah l-p-w using the regular electrode4 ,this electrode in being consumed gives off fumes1 so the lamp has a chimney through its body to carry them off4 ,some of the fumes condense1 leaving a fine powder1 iron oxide1 in the form of rust4 ,the consumption of the positive 7copper7 electrode is very slow1 which is opposite to that of carbon arc lamps on direct current4 ,the arc flame is brightest near the negative 7iron tube7 electrode and decreases in brilliancy and volume as it nears the positive 7copper7 electrode4 ,illustration3 ,,diagram ,,of ,,series ,,magnetite ,,arc ,,lamp4 ,the method of control1 entirely different from that of other arc lamps1 was invented by ,halvorson to meet the peculiarities of this arc4 ,the peculiarities of the arc are such that ,halvorson invented an entirely new principle of control4 ,the electrodes are normally apart4 ,in starting1 they are drawn together by a starting magnet with sufficient force to dislodge the slag which forms on the negative electrode and which becomes an insulator when cold4 ,current then flows through the electrodes and through a series magnet which pulls up a solenoid breaking the circuit through the starting magnet4 ,this allows the lower electrode to fall a fixed distance1 about seven-eighths of an inch1 drawing the arc1 whose voltage is then about #gb volts4 ,as the negative electrode is consumed1 the length and voltage of the arc increases when a magnet1 in shunt with the arc1 becomes sufficiently energized to close the contacts in the circuit of the starting magnet causing the electrode to pick up and start off again4 ,,mercury ,,arc ,,rectifier ,,for ,,magnetite ,,arc ,,lamps ,illustration3 ,,mercury ,,arc ,,rectifier ,,tube ,,for ,,series ,,magnetite ,,arc ,,lamps1 #aijb4 ,the mercury arc converted the alternating constant current into direct current required by the magnetite lamp4 ,as the magnetite arc requires direct current for its operation1 the obvious way to supply a direct constant current for series circuits is to rectify1 by means of the mercury arc1 the alternating current obtained from a constant current transformer4 ,the terminals of the movable secondary coil of the constant current transformer are connected to the two arms of the rectifier tube4 ,one end of the series circuit is connected to the center of the secondary coil4 ,the other end of the series circuit is connected to a reactance which in turn is connected to the pool of mercury in the bottom of the rectifier tube4 ,one-half of the cycle of the alternating current goes from the secondary coil to one arm of the rectifier tube through the mercury vapor1 the mercury arc having already been started by a separate starting electrode4 ,it then goes to the pool of mercury1 through the reactance and through the series circuit4 ,the other half cycle of alternating current goes to the other arm of the rectifier tube1 through the mercury vapor1 etc41 and through the series circuit4 ,thus a pulsating direct current flows through the series circuit1 the magnetic action of the reactance coil making the pulsations of current overlap each other1 which prevents the mercury arc from going out4 ,illustration3 ,,early ,,mercury ,,arc ,,rectifier ,,installation4 ,,incandescent ,,lamp ,,developments1 #ahid-aijd ,with the development of a waterproof base in #aijj1 by the use of a waterproof cement instead of plaster of ,paris to fasten the base to the bulb1 porcelain at first and later glass being used to insulate the terminals of the base from each other1 lamps could be exposed to the weather and give good results4 ,electric sign lighting therefore received a great stimulus1 and lamps as low as #b candlepower for #aaj volts were designed for this purpose4 ,carbon lamps with concentrated filaments were also made for stereoptican and other focussing purposes4 ,these lamps were made in sizes from #bj to #ajj candlepower4 ,the arc lamp was more desirable for larger units4 ,the dry battery was made in small units of #b1 #c and #e cells1 so that lamps of about to #a candlepower were made for #b1 #c and #f volts1 for portable flashlights4 ,it was not however until the tungsten filament was developed in #aijg that these flashlights became as popular as they now are4 ,for ornamental lighting1 lamps were supplied in round and tubular bulbs1 usually frosted to soften the light4 ,illustration3 ,,the ,,moore ,,tube ,,light1 #aijd4 ,this consisted of a tube about #a inches in diameter and having a length up to #bjj feet1 in which air at about one thousandth part of atmospheric pressure was made to glow by a very high voltage alternating current4 ,,the ,,moore ,,tube ,,light ,geissler1 a ,german1 discovered sixty odd years ago1 that a high voltage alternating current would cause a vacuum tube to glow4 ,this light was similar to that obtained by ,hawksbee over two hundred years ago4 ,geissler obtained his high voltage alternating current by a spark coil1 which consisted of two coils of wire mounted on an iron core4 ,current from a primary battery passed through the primary coil1 and this current was rapidly interrupted by a vibrator on the principle of an electric bell4 ,this induced an alternating current of high voltage in the secondary coil as this coil had a great many more turns than the primary coil had4 ,scientists found that about #gj per cent of the electrical energy put into the ,geissler tube was converted into the actual energy in the light given out4 ,in #ahia ,mr4 ,d4 ,mc,farlan ,moore1 an ,american1 impressed with the fact that only one-half of one per cent of the electrical energy put into the carbon-incandescent lamp came out in the form of light1 decided to investigate the possibilities of the vacuum tube4 ,after several years of experiments and the making of many trial lamps1 he finally1 in #aijd1 made a lamp that was commercially used in considerable numbers4 ,illustration3 ,,diagram ,,of ,,feeder ,,valve ,,of ,,moore ,,tube4 ,as the carbon terminals inside the tube absorbed the very slight amount of gas in the tube1 a feeder valve allowed gas to flow in the tube1 regulating the pressure to within one ten thousandth part of an atmosphere above and below the normal extremely slight pressure required4 ,the first installation of this form of lamp was in a hardware store in ,newark1 ,n4 ,j4 ,it consisted of a glass tube #a inches in diameter and #ahj feet long4 ,air1 at a pressure of about one-thousand part of an atmosphere1 was in the tube1 from which was obtained a pale pink color4 ,high voltage 7about #af1jjj volts7 alternating current was supplied by a transformer to two carbon electrodes inside the ends of the tube4 ,the air had to be maintained within one ten-thousandth part of atmospheric pressure above and below the normal of one-thousandth1 and as the rarefied air in the tube combined chemically with the carbon electrodes1 means had to be devised to maintain the air in the tube at this slight pressure as well as within the narrow limits required4 ,this was accomplished by a piece of carbon through which the air could seep1 but if covered with mercury would make a tight seal4 ,as the air pressure became low1 an increased current would flow through the tube1 the normal being about a tenth of an ampere4 ,this accordingly increased the current flowing through the primary coil of the transformer4 ,in series with the primary coil was an electro-magnet which lifted1 as the current increased1 a bundle of iron wires mounted in a glass tube which floated in mercury4 ,the glass tube1 rising1 lowered the height of the mercury1 uncovering a carbon rod cemented in a tube connecting the main tube with the open air4 ,thus air could seep through this carbon rod until the proper amount was fed into the main tube4 ,when the current came back to normal the electro-magnet lowered the floating glass tube which raised the height of the mercury and covered the carbon rod1 thus shutting off the further supply of air4 ,as there was a constant loss of about #djj watts in the transformer1 and an additional loss of about #bej watts in the two electrodes1 the total consumption of the #ahj-;foot tube was about #bbej watts4 ,nitrogen gas gave a yellow light1 which was more efficient and so was later used4 ,on account of the fixed losses in the transformer and electrodes the longer tubes were more efficient1 though they were made in various sizes of from #dj to #bjj feet4 ,the #bjj-;foot tube1 with nitrogen1 had an efficiency of about #aj lumens per watt4 ,nitrogen gas was supplied to the tube by removing the oxygen from the air used4 ,this was accomplished by passing the air over phosphorous which absorbed the oxygen4 ,carbon dioxide gas 7,,co#b7 gave a pure white light but at about half the efficiency of nitrogen4 ,the gas was obtained by allowing hydrochloric acid to come in contact with lumps of marble 7calcium carbonate7 which set free carbon dioxide and water vapor4 ,the latter was absorbed by passing the gas through lumps of calcium chloride4 ,the carbon dioxide tube on account of its daylight color value1 made an excellent light under which accurate color matching could be done4 ,a short tube is made for this purpose and this is the only use which the ,moore tube now has1 owing to the more efficient and simpler tungsten filament incandescent lamp4 ,,the ,,osmium ,,lamp ,dr4 ,auer von ,welsbach1 the ,german scientist who had produced the ,welsbach gas mantle1 invented an incandescent electric lamp having a filament of the metal osmium4 ,it was commercially introduced in ,europe in #aije and a few were sold1 but it was never marketed in this country4 ,it was generally made for #ee volts1 two lamps to burn in series on #aaj-volt circuits1 gave about #be candlepower and had an initial efficiency of about #e lumens per watt4 ,it had a very fair maintenance of candlepower during its life1 having an average efficiency of about #e l-p-w4 ,osmium is a very rare and expensive metal1 usually found associated with platinum1 and is therefore very difficult to obtain4 ,burnt out lamps were therefore bought back in order to obtain a supply of osmium4 ,it is also a very brittle metal1 so that the lamps were extremely fragile4 ,illustration3 ,,osmium ,,lamp1 #aije4 ,this incandescent lamp was used in ,europe for a few years1 but was impractical to manufacture in large quantities as osmium is rarer and more expensive than platinum4 ,,the ,,gem ,,lamp ,dr4 ,willis ,r4 ,whitney1 of ,schenectady1 ,n4 ,y41 had invented an electrical resistance furnace4 ,this consisted of a hollow carbon tube1 packed in sand1 through which a very heavy current could be passed4 ,this heated the tube to a very high temperature1 the sand preventing the tube from oxidizing1 so that whatever was put inside the tube could be heated to a very high heat4 ,among his various experiments1 he heated some carbon filaments and found that the high temperature changed their resistance 8characteristic0 from negative to positive4 ,the ordinary carbon filament has a resistance when hot that is less than when it is cold1 which was reversed after heating it to the high temperature ,dr4 ,whitney was able to obtain4 ,these filaments were made into lamps for #aaj-volt service and it was found that they could be operated at an efficiency of #d lumens per watt4 ,the lamps also blackened less than the regular carbon lamp throughout their life4 ,illustration3 ,,gem ,,lamp1 #aije4 ,this incandescent lamp had a graphitized carbon filament obtained by the heat of an electric furnace1 so that it could be operated at #be per cent higher efficiency than the regular carbon lamp4 ,this lamp is in the exhibit of ,edison lamps in the ,smithsonian ,institution4 ,this lamp was put on the market in #aije and was called the ,gem or metallized carbon filament lamp as such a carbon filament had a resistance characteristic similar to metals4 ,at first it had two single hair pin filaments in series which in #aiji were changed to a single loop filament like the carbon lamp4 ,in #aije the rating of incandescent lamps was changed from a candlepower to a wattage basis4 ,the ordinary #af-;candlepower carbon lamp consumed #ej watts and was so rated4 ,the #ej-watt ,gem lamp gave #bj candlepower1 both candlepower ratings being their mean candlepower in a horizontal direction4 ,the ,gem lamp was made for #aaj-volt circuits in sizes from #dj to #bej watts4 ,the #ej-watt size was the most popular1 many millions of which were made before the lamp disappeared from use in #aiah4 ,the lamp was not quite as strong as the carbon lamp4 ,some ,gem lamps for series circuits were also made1 but these were soon superseded by the tungsten-filament lamp which appeared in #aijg4 ,,the ,,tantalum ,,lamp ,illustration3 ,,tantalum ,,lamp1 #aijf4 ,the tantalum filament could be operated at #ej per cent greater efficiency than that of the regular carbon incandescent lamp4 ,this lamp is in the exhibit of ,edison lamps in the ,smithsonian ,institution4 ,dr4 ,werner von ,bolton1 a ,german physicist1 made an investigation of various materials to see if any of them were more suitable than carbon for an incandescent-lamp filament4 ,after experimenting with various metals1 tantalum was tried4 ,tantalum had been known to science for about a hundred years4 ,von ,bolton finally obtained some of the pure metal and found it to be ductile so that it could be drawn out into a wire4 ,as it had a low specific resistance1 the wire filament had to be much longer and thinner than the carbon filament4 ,a great number of experimental lamps were made so that it was not until #aijf that the lamp was put on the market in this country4 ,it had an initial efficiency of #e lumens per watt and a good maintenance of candle power throughout its life1 having an average efficiency of about #d l-p-w4 ,the usual sizes of lamps were #dj and #hj watts giving about #bj and #dj candlepower respectively4 ,it was not quite as strong as the carbon lamp1 and on alternating current the wire crystallized more rapidly1 so that it broke more easily1 giving a shorter life than on direct current4 ,it disappeared from use in #aiac4 ,,invention ,,of ,,the ,,tungsten ,,lamp ,alexander ,just and ,franz ,hanaman in #aijb were laboratory assistants to the ,professor of ,chemistry in the ,technical ,high ,school in ,vienna4 ,just was spending his spare time in another laboratory in ,vienna1 attempting to develop a boron incandescent lamp4 ,in ,august of that year he engaged ,hanaman to aid him in his work4 ,they conceived the idea of making a lamp with a filament of tungsten and for two years worked on both lamps4 ,the boron lamp turned out to be a failure4 ,their means were limited2 ,hanaman's total income was #dd per month and ,just's was slightly more than this4 ,in #aijc they took out a ,german patent on a tungsten filament1 but the process they described was a failure because it produced a filament containing both carbon and tungsten4 ,the carbon readily evaporated and quickly blackened the bulb when they attempted to operate the filament at an efficiency higher than that possible with the ordinary carbon filament4 ,finally in the latter part of the next year 7#aijd7 they were able to get rid of the carbon and produced a pure tungsten filament4 ,tungsten had been known to chemists for many years by its compounds1 its oxides and its alloys with steel1 but the properties of the pure metal were practically unknown4 ,it is an extremely hard and brittle metal and it was impossible at that time to draw it into a wire4 ,just and ,hanaman's process of making a pure tungsten filament consisted of taking tungsten oxide in the form of an extremely fine powder1 reducing this to pure tungsten powder by heating it while hydrogen gas passed over it4 ,the gas combined with the oxygen of the oxide1 forming water vapor which was carried off1 leaving the tungsten behind4 ,the tungsten powder was mixed with an organic binding material1 and the paste was forced by very high pressure through a hole drilled in a diamond4 ,this diamond die was necessary because tungsten1 being so hard a substance1 would quickly wear away any other kind of die4 ,the thread formed was cut into proper lengths1 bent the shape of a hair pin and the ends fastened to clamps4 ,current was passed through the hair pin in the presence of hydrogen gas and water vapor4 ,the current heated the hair pin1 carbonized the organic binding material in it1 the carbon then combining with the moist hydrogen gas1 leaving the tungsten particles behind4 ,these particles were sintered together by the heat1 forming the tungsten filament4 ,patents were applied for in various countries1 the one in the ,united ,states on ,july #f1 #aije4 ,the two laboratory assistants in #aije finally succeeded in getting their invention taken up by a ,hungarian lamp manufacturer4 ,by the end of the year lamps were made that were a striking success for they could be operated at an efficiency of #h lumens per watt4 ,they were put on the ,american market in #aijg1 the first lamp put out being the #ajj-watt size for #aaj-volt circuits4 ,this was done by mounting several hair pin loops in series to get the requisite resistance1 tungsten having a low specific resistance4 ,the issue of the ,american patent was delayed owing to an interference between four different parties1 each claiming to be the inventor4 ,after prolonged hearings1 one application having been found to be fraudulent1 the patent was finally granted to ,just and ,hanaman on ,february #bg1 #aiab4 ,illustration3 ,,tungsten ,,lamp1 #aijg4 ,the original #ajj watt tungsten lamp was nearly three times as efficient as the carbon lamp1 but its 8pressed0 filament was very fragile4 ,this lamp is in the exhibit of ,edison lamps in the ,smithsonian ,institution4 ,this 8pressed0 tungsten filament was quite fragile1 but on account of its relatively high efficiency compared with other incandescent lamps1 it immediately became popular4 ,soon after its introduction it became possible to make finer filaments so that lamps for #fj1 #dj and then #be watts for #aaj-volt circuits were made available4 ,sizes up to #ejj watts were also made which soon began to displace the enclosed carbon arc lamp4 ,lamps were also made for series circuits in sizes from #cb to #djj candlepower4 ,these promptly displaced the carbon and ,gem series lamps4 ,the high efficiency of the tungsten filament was a great stimulus to flashlights which are now sold by the millions each year4 ,the lighting of railroad cars1 ,pullmans and coaches1 with tungsten lamps obtaining their current from storage batteries1 soon superseded the gas light formerly used4 ,in some cases1 a dynamo1 run by a belt from the car axle1 kept these batteries charged4 ,illustration3 ,,drawn ,,tungsten ,,wire ,,lamp1 #aiaa4 ,scientists had declared it impossible to change tungsten from a brittle to ductile metal4 ,this1 however1 was accomplished by ,dr4 ,coolidge1 and drawn tungsten wire made the lamp very sturdy4 ,this lamp is in the exhibit of ,edison lamps in the ,smithsonian ,institution4 ,,drawn ,,tungsten ,,wire ,after several years of patient experiment1 ,dr4 ,william ,d4 ,coolidge in the research laboratory of a large electrical manufacturing company at ,schenectady1 ,n4 ,y41 invented a process for making tungsten ductile1 a patent for which was obtained in ,december1 #aiac4 ,tungsten had heretofore been known as a very brittle metal1 but by means of this process it became possible to draw it into wire4 ,this greatly simplified the manufacture of lamps and enormously improved their strength4 ,such lamps were commercially introduced in #aiaa4 ,with drawn tungsten wire it was easier to coil and therefore concentrate the filament as required by focusing types of lamps4 ,the automobile headlight lamp was among the first of these1 which in #aiab started the commercial use of electric light on cars in place of oil and acetylene gas4 ,on street railway cars the use of tungsten lamps1 made possible on this severe service by the greater sturdiness of the drawn wire1 greatly improved their lighting4 ,furthermore1 as the voltage on street railway systems is subject to great changes1 the candlepower of the tungsten filament has the advantage of varying but about half as much as that of the carbon lamp on fluctuating voltage4 ,illustration3 ,,quartz ,,mercury ,,vapor ,,lamp1 #aiab4 ,the mercury arc if enclosed in quartz glass can be operated at much higher temperature and therefore greater efficiency4 ,the light is still deficient in red but gives a considerable amount of ultra-violet rays which kill bacteria and are very dangerous to the eye4 ,they can1 however1 be absorbed by a glass globe4 ,the lamp is not used as an illuminant in this country1 but is valuable for use in the purification of water4 ,,the ,,quartz ,,mercury ,,vapor ,,arc ,,lamp ,by putting a mercury arc in a tube made of quartz instead of glass1 it can be operated at a much higher temperature and thereby obtain a greater efficiency4 ,such a lamp1 however1 is still largely deficient in red rays1 and it gives out a considerable amount of ultra-violet rays4 ,these ultra-violet rays will kill bacteria and the lamp is being used to a certain extent for such purpose as in the purification of water4 ,these rays are very dangerous to the eyes1 but they are absorbed by glass1 so as an illuminant1 a glass globe must be used on the lamp4 ,these lamps appeared in ,europe about #aiab but were never used to any extent in this country as an illuminant4 ,they have an efficiency of about #bf lumens per watt4 ,quartz is very difficult to work1 so the cost of a quartz tube is very great4 ,the ordinary bunsen gas flame is used with glass1 but quartz will only become soft in an oxy-hydrogen or oxy-acetylene flame4 ,illustration3 ,,gas ,,filled ,,tungsten ,,lamp1 #aiac4 ,by operating a coiled filament in an inert gas1 ,dr4 ,langmuir was able to greatly increase its efficiency1 the gain in light by the higher temperature permissible1 more than offsetting the loss of heat by convection of the gas4 ,this lamp is in the exhibit of ,edison lamps in the ,smithsonian ,institution4 ,,the ,,gas-,,filled ,,tungsten ,,lamp ,the higher the temperature at which an incandescent lamp filament can be operated1 the more efficient it becomes4 ,the limit in temperature is reached when the material begins to evaporate rapidly1 which blackens the bulb4 ,the filament becoming thinner more quickly1 thus rupturing sooner1 shortens the life4 ,if1 therefore1 the evaporating temperature can by some means be slightly raised1 the efficiency will be greatly improved4 ,this was accomplished by ,dr4 ,irving ,langmuir in the research laboratories at ,schenectady1 ,n4 ,y41 by operating a tungsten filament in an inert gas4 ,nitrogen was first used4 ,the gas circulating in the bulb has the disadvantage of conducting heat away from the filament so that the filament was coiled4 ,this presented a smaller surface to the currents of gas and thereby reduced this loss4 ,the lamps were commercially introduced in #aiac and a patent was granted in ,april1 #aiaf4 ,illustration3 ,,gas ,,filled ,,tungsten ,,lamp1 #aibc4 ,this is the form of the lamp as at present made4 ,for #aaj-volt circuits the sizes range from #ej to #ajjj watts4 ,an increased amount of electrical energy is required in these lamps to offset the heat being conducted away by the gas4 ,this heat loss is minimized in a vacuum lamp1 the filament tending to stay hot on the principle of the vacuum bottle4 ,this loss in a gas filled lamp becomes relatively great in a filament of small diameter1 as the surface in proportion to the volume of the filament increases with decreasing diameters4 ,hence there is a point where the gain in temperature is offset by the heat loss4 ,the first lamps made were of #gej and #ajjj watts for #aaj-volt circuits4 ,later #ejj- and then #djj-watt lamps were made4 ,the use of argon gas1 which has a poorer heat conductivity than nitrogen1 made it possible to produce smaller lamps1 #ej-watt gas-filled lamps for #aaj-volt circuits now being the smallest available4 ,in the present state of the art1 a vacuum lamp is more efficient than a gas-filled lamp having a filament smaller than one consuming about half an ampere4 ,thus gas-filled lamps are not now practicable much below #ajj watts for #bbj volts1 #ej watts for #aaj volts1 #be watts for #fj volts1 #ae watts for #cj volts1 etc4 ,from the foregoing it will be seen that the efficiency of these lamps depends largely on the diameter of the filament4 ,there are other considerations1 which also apply to vacuum lamps1 that affect the efficiency4 ,some of these are3 the number of anchors used1 as they conduct heat away2 in very low voltage lamps having short filaments the relative amount of heat conducted away by the leading-in wires becomes of increasing importance1 etc4 ,the #ajjj-watt lamp for #aaj-volt circuits is now made for nearly #bj lumens per watt2 the #ej-watt lamp a little over #aj l-p-w4 ,the advent of the tungsten filament and especially the gas-filled lamp sounded the doom of all other electric illuminants except the magnetite and mercury arc lamps4 ,all other incandescent lamps have now practically disappeared4 ,the flame arc as well as the enclosed carbon arc lamp are hardly ever seen4 ,the simplicity of the incandescent lamp1 its cleanliness1 low first cost1 low maintenance cost and high efficiency of the tungsten filament have been the main reasons for its popularity4 ,,types ,,and ,,sizes ,,of ,,tungsten ,,lamps ,,now ,,made ,there are about two hundred different types and sizes of tungsten filament lamps now standard for various kinds of lighting service4 ,for #aaj-volt service1 lamps are made in sizes from #aj to #ajjj watts4 ,of the smaller sizes1 some are made in round and tubular-shaped bulbs for ornamental lighting4 ,in addition there are the candelabra lamps used in ornamental fixtures4 ,twenty-five- to five hundred-watt lamps are made with bulbs of special blue glass to cut out the excess of red and yellow rays and thus produce a light approximating daylight4 ,for #bbj-volt service lamps are made in sizes of from #be to #ajjj watts4 ,for sign lighting service1 #e-watt lamps of low voltage are made for use on a transformer located near the sign to reduce the #aaj volts alternating current to that required by the lamps4 ,lamps are made from #e to #ajj watts for #cj-volt service1 such as is found in train lighting and in gas engine driven dynamo sets used in rural homes beyond the reach of central station systems4 ,concentrated filament lamps are made for stereopticon and motion picture projection1 floodlighting1 etc41 in sizes from #ajj to #ajjj watts1 for street railway headlights in sizes below #ajj watts and for locomotive headlights in sizes from #ajj to #bej watts4 ,for series circuits1 used in street lighting1 lamps are made from #fj to #bejj candlepower4 ,miniature lamps cover those for flashlight1 automobile1 ,christmas-tree1 surgical and dental services1 etc4 ,they range1 depending on the service1 from to #ba candlepower1 and in voltage from #b to #bd4 ,illustration3 ,,standard ,,tungsten ,,lamps1 #aibc4 ,this illustrates some of the two hundred different lamps regularly made4 ,,standard ,,voltages ,mention has been made of #aaj-volt service1 #bbj-volt service1 etc4 ,in the days of the carbon incandescent lamp it was impossible to manufacture all lamps for an exact predetermined voltage4 ,the popular voltage was #aaj1 so lighting companies were requested in a number of instances to adjust their service to some voltage other than #aaj4 ,they were thus able to utilize the odd voltage lamps manufactured1 and this produced a demand for lamps of various voltages from #ajj to #acj4 ,arc lamps had a resistance 7reactance on alternating current7 that was adjustable for voltages between #ajj and #acj4 ,similarly a demand was created for lamps of individual voltages of from #bjj to #bfj4 ,the #bjj- to #bfj-volt range has simmered down to #bbj1 #bcj1 #bdj and #bej volts4 ,these lamps are not as efficient as the #aaj-volt type and their demand is considerably less1 as the #aaj-volt class of service for lighting is1 with the exception of ,england1 almost universal4 ,thus #aaj-volt service means #ajj to #acj volts in contra-distinction to #bjj to #bfj volts1 etc4 ,the drawn tungsten wire filament made it possible to accurately predetermine the voltage of the lamp1 so now that the carbon incandescent lamp is a thing of the past1 there is no need for so many different voltages4 ,several years ago standard voltages of #aaj1 #aae and #abj were recommended for adoption by all the electrical societies in the ,united ,states1 and practically all central stations have now changed their service to one of these voltages4 ,,cost ,,of ,,incandescent ,,electric ,,light ,in the early '#hj's current was expensive1 costing a consumer on the average about twenty cents per kilowatt hour4 ,the cost has gradually come down and the general average rate for which current is sold for lighting purposes is now about #d cents4 ,during the period #ahhj to #aije the average efficiency of carbon lamps throughout their life increased from about one to over #b lumens per watt and their list price decreased from one dollar to twenty cents4 ,the average amount of light obtained for one cent at first was about five candlepower hours and in #aijd it was increased to over thirty-six at the average rate then in effect4 ,the next year with the more efficient ,gem lamp #dd candle-hours could be had for one cent4 ,in #aijf the amount was increased to #ej with the tantalum lamp and with the tungsten lamp in #aijg1 even at its high price of #a4ej1 the amount was further increased to #fc4 ,since then the average cost of current has been reduced but slightly1 but the efficiency of the tungsten lamp has materially increased and its cost reduced so that it is now possible to obtain1 with the ordinary #dj-watt lamp #agj candle-hours for a cent4 ,if the gas-filled tungsten lamp were used the amount of light now obtained for a cent would depend upon the size1 which1 for the #ajjj-watt lamp1 would be #chb candle-hours4 ,,statistics ,,regarding ,,the ,,present ,,demand ,,for ,,lamps ,in the ,united ,states there are about #cej million incandescent and about two hundred thousand magnetite arc lamps now 7#aibc7 in use4 ,they are increasing about #aj per cent each year4 ,the annual demand for incandescent lamps for renewals and new installations is over #bjj millions1 exclusive of miniature lamps4 ,the use of incandescent lamps in all other countries put together is about equal that in the ,u4 ,s4 ,the average candlepower of standard lighting lamps has increased from #af1 which prevailed during the period prior to #aije1 to over #fj4 ,the average wattage has not varied much during the past twenty-odd years1 the average lamp now consuming about #ee watts4 ,this indicates that the public is utilizing the improvement in lamp efficiency by increased illumination4 ,the present most popular lamp is the #dj-watt size which represents #bj per cent of the total demand4 ,second in demand is the #be-watt at #ah per cent and third1 the #ej-watt at #ae per cent of the total in numbers4 ,while the aggregate demand of all the gas-filled tungsten lamps is a little over #bj per cent in numbers1 they represent1 on account of their greater efficiency and wattage1 over half the amount of total candlepower used4 ,in the ,united ,states about #he per cent of all lamps are for the #aaj-volt range4 ,about #e per cent for #bbj volts1 #b per cent for street series lighting1 #c per cent for street railway and #e per cent for trainlighting and miscellaneous classes of service4 ,,selected ,,bibliography ,,alglave ,,and ,,boulard1 8,the ,electric ,light10 translated by ,t4 ,o',connor ,sloane1 edited by ,c4 ,m4 ,lungren1 ,d4 ,appleton ,co41 ,new ,york1 #ahhd4 ,,barham1 ,g4 ,,basil1 8,the ,development of the ,incandescent ,electric ,lamp10 ,scott ,greenwood ,son1 ,london1 #aiab4 ,,dredge1 ,,james1 8,electric ,illumination10 #b vols41 ,john ,wiley ,sons1 ,new ,york1 #ahhb4 ,,durgin1 ,,william ,a41 8,electricity--,its ,history and ,development10 ,a4 ,c4 ,mc,clurg ,co41 ,chicago1 #aiab4 ,,dyer ,,martin1 8,edison1 ,his ,life and ,inventions10 #b vols41 ,harper ,bros41 ,new ,york1 #aiaj4 ,,guillemin1 ,,amedee1 8,electricity and ,magnetism10 edited by ,silvanus ,p4 ,thompson1 ,mc,millan ,co41 ,london1 #ahia4 ,,houston1 ,,edwin ,j41 8,electricity ,one ,hundred ,years ago and ,to-day10 ,the ,w4 ,j4 ,johnston ,co41 ,new ,york1 #ahid4 ,,houston ,,and ,,kennelly1 8,electric ,arc ,lighting10 ,mc,graw ,publishing ,co41 ,new ,york1 #aijf4 ,,hutchinson1 ,,rollin ,w41 ,,jr41 8,high ,efficiency ,electrical ,illuminants and ,illumination10 ,john ,wiley ,sons1 ,new ,york1 #aiaa4 ,,maier1 ,,julius1 8,arc and ,glow ,lamps10 ,whittaker ,co41 ,london1 #ahhf4 ,,pope1 ,,franklin ,,leonard1 8,evolution of the ,electric ,incandescent ,lamp10 ,boschen ,wefer1 ,new ,york1 #ahid4 ,,solomon1 ,,maurice1 8,electric ,lamps10 ,d4 ,van ,nostrand ,co41 ,new ,york1 #aijh4 ,transcriber's ,notes ,punctuation1 hyphenation1 and spelling were made consistent when a predominant preference was found in the original book2 otherwise they were not changed4 ,simple typographical errors were corrected2 unbalanced quotation marks were remedied when the change was obvious1 and otherwise left unbalanced4 ,illustrations in this e,book have been positioned between paragraphs4 ,in versions of this e,book that support hyperlinks1 the page references in the ,list of ,illustrations lead to the corresponding illustrations4 8,allesandro ,volta0 was printed that way4