‘The Evolution of Inductive Loading for Rell System ‘Telephone Facil Br THOMAS SHAW PART Vis CONTINUOUS LOADING erat CONTINUOUS tating 2, the aa of wan dated hctance, wae sto! theoretically jn the Ball Syste several yea ‘lone tort wore sas om ex loading. Taisenry work of John Stame Stone, then memset of the hesdgnarters technical etal! of the “American Dall Telephone Company, rested the ise to him on March 897 of «US. Pat (375295) deseribing 8 "bimetalc”wice cable, ‘Later or, when the commercial deveigpeat was aatorae, cos cane Siorations made it dasieable to start wilh oratory experiments on an leeticaly equvalne” artical lise sing sll large inductance 1 placing these esperments, Hsmoe erarme arent the any all stipulate ducts could tad wie Use be gli aerial es ayia, mural, on. Rrengiion of the raps a lage inherent in thee f ange esmnts of eactance, and of the Aleence of limations rputdng the maritate of indortanre that could te provided in ofr, then fa the devel ema ta the ax stato prben of suing eta ens relation ¢9 waeleneth ‘This theoretis problem was quickly alow hy GA. Carpal wha was then in eharge af the projet, a acing Tie bortery arte) Mo wa designed to detonate he petal of i-kalng (aly in 1899), The Hill Systm evelopment werk on contingase leading wt then ee peal for seme tne ‘During the nest tro decade, cil loading was fond to be economically suited to all Holl Systen ses or fluive ning, ven short intr roliate semaine rales reste at hale water erssngs of rivers ond Bays: Shorty ster the Fist World War, however, Zt beesane necessary to ulertake the development of contin lo! eae to moet em argent Ikan fue telephone trrvicaion with Cio, Fxplortery cheort ial ‘dies and labortory investiga Bad en sme shorty belo t3e ‘err, oe were discontinue? during che war, Tue esponatry work nud Cansleratio of the posoble one ofa nem nickeLitoa magsti alloy which 1222 ue mens, soearae Teme, Jove, oeTOMER 1951 tras then under dveostaent Uy she Sesouch Deparment ofthe Wester lect Cand ees on oer ew yaa a peemello” Key is projet nequined Cres dont amare cakes rang rath from won 1H nautical ses, eack ing «rea te! Tonge than any prevoiely ese! fr teehee etre, al large action of the oute mas ia deep ruler suc riser clepth somewhat over 00 Testo epee aoteting dng eileen ny Under te great nv omsaute Savane, are! te eomictions that Srould be encounters ding intl arin subsrqvent maintenance SSork, prevented col Ling from rceving ensiration, Maveaver, the treat water psire an elated consideration nf pape insulated cable ‘Since the cables were tence forsee im Ieephona revit connecting ‘reat pt inthe United Stres with Hava ad emote pint in Cuba, the overall ystensdesgh seqnernen weve very Fania, In adition tor tyonay telephone cre i rach re, provision algo as mad for thon cuir talegtap ect have he wie vane, and for direct current rol lerasiy bem te rie. Tene even fequzerent bre ‘hfe pecleas vegnrng “ler Eater esevfrere al other yes ‘of montiece tortion “The Funcarsntl design wos seule ¢ decison to Insta: single cure, contiwensy onde, alls sig gortacper- na ad basing seoncentesysterra9per spc eapped story einai muitos, Tor use asa retun eral, (These cabs were she Sis 20 be iestaled Wil ais eofore? Tran wine type contro tawling vas cesen lage Tocacse the des prrt inativice entee did wat ae eulieat the or the editions) revatan! development wor, and the adionsl ma Toctaring ywoptrations, tat owl howe brs vecessry in ocet to ost pemmallty tape sling, Tae monulbetring sitution presented seis problems Devause twas nceesr te ps er maectre neo, ssn American company had fice: (ae aig deepest snbmarive ele Moreaver kon-mize type cornwall las prope by C. B Kearap™ of hear) was oli the Paropann telephone er avn hen use in Several short submarine ens oaneundeteromnd bles The Ccban Sena rabes ner savuason he central cope soedactor Ina eiameter of bat 0.130 aah. Abo sic ws only wrapped a single Jager of DAM el ella wie ard there Ines of guutaporeba type ingultin bing tot chiskacss of abou 0.135 ish. A thin coppoe spe Ainccty on this once foisted protetion ays lanage by she tere, fovea Saiourins Fees Cais Spt bvonmox er ixnuenve Lansise rat and was pott of che system of copper tapes pzeviously weatonel bic “The feline perma of the ions ange mera was about 115. Tae dsteuied inductance of about 38 milihenrys per natal ile resulted in 2 low nonin inpadunce of sla 118 hs. Phe energy les iil ang atl wee the pencil avr Tit the op a te ‘working Fecuency band to about 40 cytes. AL IN) cyeles per second The bee lie rguielet wes he ender nyt 22 db fr che mean vale fle het al ete eae, AU SIMD eles ft ae bon 2.2 tes a8 ‘Spice linitasians prevent a ato cawslee shesipin ant deasion nore. Conpzehensive infonnation tcgacing all feacures of Le projec ix fen inn 19221, F AK. Paper” propane ny Meets, WH Martin Adres ae BW. Keadall. Engineers of the AT. & T.Co. and WE. (Co, wer sespnsile forthe elctial design af heals, metal f opens tion, and arangement ofthe repeaters and other termi appaeatae. The Calls ete amufurturid late in 1920 anal tale eary bn 12) by The ‘Teleyosph Connicuton ad Maintenance Go Ti of Landon, forthe Cr DbareAmrican Tecphoae ané Telegraph Conpauy. Te Iter aganiztion ie jointly owned by cke A, 7, & Ta and che Cuban Teleokare Co, itary of the Iteration) Ts 1 Ct DOM None Londed Cabo: Shae ie BL eae were aie for erser lelplene operation flayely because of exccaive loses and an inear distortion st lip rogues), i Levene veteran during 1930 to inal fourth cable between Key West an Havana in wider to nget the demas for akin utes, Advantage was taken of aances nh communica oe rl, aulable a improved cable ulation (parapata pov e pustels and aul: telephone systoms, co desig a wo hae caesar ‘which and be aveebe for carrer operation. he intial cane setup provided es rarer teenie crite arn rype CL satem wie he orighnlly Ine devekyial or openowise Lives Say 192, aever-rarel sem in sulsitutal. Compecensive infarction regan Fe 13 oad suse of the 3 charnel eae alee syste oan ins 1982 4.1. B. Bag hy Moses AE, Garin al Chew High Sons Transcenie Led Tloraph Caber During the ist World War wen the row for fatessing the message- angina eajly of ecstng non aed tramoceenic tlegranh cables be- ae urge le ll Star engineers ene moe te prem fal ‘ane to the vans tat ov ain reece fo the existing art would be nosesary to ve auch bette sabe, 1224 an wrax svete szeacel.jorweat, ocroors 1ST 4 Joly 1919 the coating intron thie prob exyeal ed in Werte Keri poopimal wx ermal contiauses Ioad-ng re tuansocenic telegraph sales, Since thi reoarzabie new magnetic allay? Thad bean invented and developed ry Wile Elect engnens hy were beady fan vth ils extrardinary hig penmcablity eaeeactriis land ad conden x he ability to wei ia providing high fmpedanee Ting wbich would wake precio w geal cease ib mesegessrying capacity. Lawing with izobovire ov nt ve any advantage in elem [ieph spel, brrause of is la permeability. Totusive wssarch ork fully started on the perso oe! vale design and natin job Tes, aco Ea slate termi meatus aod operating praia. The deren tained ther efor eae i dzlosores to the Western Union Telegraph Company mearline Cap gest ncrece i Teegiaph signaling sje thac could be ine ith the prope! we penal lading Tr sure the elegrank Comauty wadenrrangerntswith tbe Tele: CConsteucton acd Mecnonanee Company Lit. nf Lao for tae an Tnvture sod installation of 120ae eal length srg, lding material sapnlied by the Western Elsie Company aad applied and treat wer the dincton of Westrn Eleirie ener In Octobe: 1923 this esper= sexta ley was lids ceep water eae the south shore of Kerra. Tae faa installation teste occe or ontidakory tha tho Wester Ua company ltrungel foe the manafctave ad stallion 42200 ileal onset New York with Horta in tae vues Ae with tie teil Teng, the loading Tater wes supplies by the Wenser lectsic Compu, al it W36 ape ‘lel and stated ancer Wesern Electric supervision. "The new cable wos hil curing September 121 Aller coi est ments in he trminal paras a spond of ower 1900 eters por minite ‘hes liane, This seal about four times Phe earring capacity of an Ctinayy nonleeded ble of he sme length At the palne nv slate Inout of gener] theory i inca: he ellact of the indovtanre i bo tppos tie seting up of & curent d to maintin it once it Tas been (tablished, shor prescviag a ceirite wave Fone ab ch sil in palse ltavels ee thecale, The individ a the sana pats is real, Abd this be rue ghee speed errs posible ‘the permally acing material we applies in tp fre eso ee sonoma steanced copper svuluctor. The tape was 166 i thick abd 11125 ine wide. The alloy woe sompueed of about 39% af wikel sve 21% of ronan stall amount of manganco, uitnbly hs treated. It prove In infetance of aboot St miliary pee ail, slightly ver 12 times that tana ly the nse of fran wire inthe Cube cables previously describe "The permeability ofthe losing waa about 2300, = hut 20 ces that of eveuuiioN oF snpoerve rosme ims the fron wire oxi the Ca aes Ab cian thre othe cable not prevonry mention wan layer of ics insulating mata (under the regula gutta percha insulation) which protected the stain-senitioe rally Ira the steses caused by hydrosctic presare in te great Hepths ofthe ren ‘Demend for ether high speed kaded submarine esblee quickly flowed the suerte tiny of ie New Vor Hata elie and seers were installed during 1926 aching tna of st 15,060 ier of highspeed Cables, The new installations induded the Havts-Easdcn exble manaiec- burt ssw! intlled by the Nerddeutsche Seekabeiwecke AG. for the Drelsch AUlatincie ‘Telogepbeogesslech‘t, and tae New York ly Reterts-Penannee cable rovfnctret ard natal hy the Ts C&M Conjany forthe Western Union Telegaph Compeny, hese ret icsbr ‘ales wl an inpvosed irm of permalloy supaled by tae Westem Pletr Conspanconcsbing about 80%, nickel, 178% ix, 2% chrom aml 1159; wnyatese. Ts coy Sad an ints} peesbilty of above 3700 and provid higher inpodanoe ceding an that ueed an tart bih-epee ibe, In eoneectence, the Tower cables ere cable of sg al 2300 fears per minus ‘Other high-speed continous ule rales, alle i 1936 sd subse exon yrs el perlay malarial unulaeturel wer Westera Eerie CConspany astent cena, in some Faarers ede pial Tein Tene Compreiersive infumetion sganiing cll features of the high-speed cable prnets specifically meutioneé alive is give in two peers by O. 1: rely bla in 1925" ad 1926 eapectves Ts png, t shold be observed teat the pee oy lot can ler digcutson were-not intended fon, ond were aoe eile or elepline foonsniniston. Far thie purpone © new fay of magnets aley’, the Iremirvars, wa develops Their composition sented. on 17% rick 25M aly 2% ino, 7.8% mayen, end 05% manganese, When bed aca thin lang tap, tht ley as lected and euagetie ropes apecaly sitar felt transrnn lling very Tw yer Thich very advantages inthe canto ofall ores meigca i 4 Props Pransotionte Petephowe Cable During the hie 1921s, chee was worktl oot desea of & pees leaind exile suitable for view Trequeney lelepioay betwesn Nesfound Tan an Tread (1800 nats) zs). TE was of te single core type mith 2 eowntrc return conductor. Four layers of very chin peeminvar t2pe 1205 me mane sue reoMEAT owe, aezoMee 1951 provid dh stag, and the ed conductor as insulated with pora ita, Te sulablity 9f the desig fer wei deep eter wes veel by Temporary droping » Demte lth on the set aor ina dep water section he Ray of Use "The general Iusiese depression of the ely 198D% resulted fn a post onan of te ele pote hese fi gue ast. Later on the project Wor jantouad fader enue, ithe face of improvements nas Silat Fado telephone tomvmusesion, 40 expensive nena Po raery ingle conetetion raid huge Be juste ition infor ion moznting this cable projet facade in De (0. B Buckley's 1912 paper, "Tae Future of Toareomnie Telephony,” Consit'ng the A8nl Kelvin Lectin Helow be bation of Bet Enginoene® Continuous Loading fr Roper taseatsd elepne Cabes Tape wed Wiee Looting: When perwalliy abd peanisvar best became vais, thote-bal sitios were undertaken to detrine the prosprts ‘a ssonome ompetiiry wil all lading ov only pape isu “ephone cables. spermato wes given bo the Use of the mage tec lloe ir stains whee si ling fe me wmv, amet, fn fhtimacine nfeneite vallen ac aiver creings, neyo he eels sighfectency Curie oh ine speation, Nowe of shee tad, heres, [Bue sitcont promis fo watrace comical einer ws eonapived Pomaty Lead During !ve rile 1920s, the Boll Tee phone Taluralories statou research work om a madal bee concept 6 Continuo leading cst el perma, which gave soe promise MT Tiny Tee expensive thar "apne fo aluy tape oie fodng The froees ili Le cletclsie epost sams 6 wal je prwtione af niche sw or on he copper condor, anu the se ef Upevil iat trecervenslo wis she ceated chanicteri frenetic and Mevtees, puoperie of srrallay. Indus eons, nelle were devised for separeting tie coments wagaeti aves fram Vie sesh, tad foe Tncaking i inte hay Taina aceninvoys peeves, go ae a ncure the host advantages pospertiss for trephine emi stevie, abd we verbal enya hel he euywrivantsl wots Os concent ou all per condctors pcp bncause of the tow sine mrs plobians, end ely become Sch nanbivations appeated to Howe Pw best jaospees af coxzpeti wi Co any rv the pea cost sandal. QB. The snout opera Toy touting mista requir to pve @ sooced inductance per un length is ne, fect fet of the condustordizspeter) Te vecuieseuts rand the posites of using ac tnplat“euding inthe exchange atce senees wore given print iv tw eoetieal im soalerlrply aco of ce eatenive ie of sll const cables Ths wee ics sere artim aa of bg lghewelgnt lectroplase ooding on ine wines Ot ea Dogue) ae subtites for ange sie nies without bling. provide satiety soucions ould. be sored out forte ecu Dalai ad nrapuete antl probes. The Trlance problem arses fom the eel of scuting sulcientunonity sang the Load condactrs nant me wine ad ate the Sn pais This is complicate by the sentvity ofthe pernalloy continuous Iceding fo magnetention by stevly and inert siperpoeed sialing ftrents, Up the Iageraae erehange ble wes that are pot aw se ‘estesvely without coi ling, the competative cet eetimates were tractive for the eectiopatd lacing. ‘The intwbity uf contnuots Ladng en esse general fact, since itis not fens to decease or increase the weight of 9 loeding after searchin, it oer ta Recomm ckange om tearamisten seqite ‘rents mae desea by changes in peclormanee sarees atertians invivu yous. Aly hese noah! be bfx cor ori eka, einen in oer sien haa viet in area hace neroeary tn Fave heed aed no Ia rinits within the same onble ‘Theontically, we o she Hesisity Hitations of the eeu aig, ould be valued by using eal aud in emainason wi Hn ope to tester it raneeion range, However Pie wold sede the wish the “tsnsnssinn band blot tno: obtains le with tye ex loncing 9b crit Sin fusing contin haligg—te seat elle te etl eg Fomple fost nf Ue rata of stat eluctanee a el idan (Combinations of high ette, los tapedance, col loading with low in ‘itunes ominous lading coud be designe to have satfasory band ‘silt peers, Fora given rade of tansy perforant, however, ‘ch eumbinations appear tobe inorently more expesive tha ell oading br continuous loading by themseve. The enperinental work on eletrplce!continaous losing for exchange svat scarab inerntenty rng the DAYS At ve ime dil the prnpects nf securing, sila overall anemia oorlormarce, at ete which wuul encourage competi ts chain, suv tr be salle wanton a all at stained tack te any Alito teckel poublems vues AV Te eyelet prc has rot bean permanently abandooed, ha Une iscontinced fn Ue ate Toots acest ofthe gest peace mane gn ork 1208 me nook evstias nemTeNe peasnd, OctORDE 1951 “Tae we of es trplatelaading ota eile For eit loa on tl. ables, or on incidental sles in openice liesy id rot appear to 2 Atcactive when te sot abinats an the compe eqaemeats en circuit Tale, webiliyy rowlin” tortion and lesiiity were Wien ito acco. Santry Enough hae been told in the yroaling gages to support the elie statements regarding the Jow irsparance of coninuows lading inthe front of te Bell Sytem ative to Eat of cl lente. bsiauly, the Ices stained yy the iniemivedevelopaneat and in the wery extensive Che of economieal yes of ei ang is an aperant face i this ius ion, Tat these exten of se eelaions ao nat eve bo «lack of terest i contin losing ell demonstrated by the Tell System inate ix ‘leveloping the permaloyotinuoutleding tat made igh speed velgeaphy practicable in long submacinetlegreph enbls se by the other develop nt ork sire a is review. PART VI; EXTENT OF USE AND PCONOMIC SIGNIFICANCE Istoncenow {Up to now, ths acrouat of cit ote oe ben in tonas of incvideal developer sols sigacenc 9 repel ty La rir at ed curent dlevelopments fn edlatd ld, st wae: infomation regard thir importatce an extent of ue. Te sr apes to sop ae cnaiyee some gener statisis regi te total amonnt st nallag which hae Been she, is rough Inga of the Emportonc a” oil baring inthe growth ofthe Bell Tel phine Syst, Some portal yualentions of te aastice are come Inerted upon indo he esantaton of acta gure ine satistics here given sl lcussed ae for the os extensive and st ingortact applcalinas of cil Ing, namely, for vale ecuency Toading ow eal irate. They are group in two pinclpal cetegore: {1} orphan ty axl sed on ron qe exchange ate cables ane toe rebivaly very sual extent om tll exblee, and (2) side ict al ‘cil anton ell wed opel ung dstance ap ateoeban tol Cables, ae tn a elatively very smal extent a entrance cables in open wire Hes aclu lag eden exchange eables "ut used age Bend in prin satis up tothe end of 1949. The ev nta signianee of Pe pcan Rgutce that they mansore Ie the dine of mentierone the Gutent cemnrels for aliens cae elites tequted by the gr of he telephone’ syste, ah the ap vorveey 9p ryprene rou to ‘nen ecumulhted tor demand. In general, the lading als were nam facture to met spine ents orders iaaalaclare for sare nai ck in slcigalin 9 Sata nner exe weldom anderen, except daring steroid bend. this bas practical) A ofthe coi tha: were manulscturl wae neal nthe telephone plant ‘The production statics of couse include risidrale numer colle whien weve insted shovly aftr ssanulaturs wal whieh were taker ‘ato orice many years ater ofelitate te uo ove tarsi systems tha reid diferent types fri wet pee ewe career systems on the ubleaded cil vale Grete Tw gover, complete posting ‘complements wete not teh ut of service in prepration for earier sy tems operation; ie, lage traction ofthe inner Iain emai in the ages in which they wete originally potted ud installed, sal te later eis iv the sie ees ane lp servi. ti impartant to remember Ut he displace ostng ens payed an Important pazt im the improve ment and gto of telephone tervie in ther own period of conimerca ie. The unavalaiity of xls epiing deuce lending oaks inooible to xoply accurate informacion regurding the total nase 9 lenlng coil no being used fr regular tclephove service. It ee pelle, hooey, that azout 04% or more ofall tho eo eable col that have en rearsactoredl ane in sevie, or feted in circuits hick il be esse oon a cic yrovth rectines ‘hem. The corespondie percentage figure fee rernge ane el probably ghee, The outer of loading cols lake out of service esnnse ot incoiere defers hat were not detertod in the faciry ajc tele or which bets anor consequence faerie ijt, or whick hive be fed erste of ebeclesence, 2 ‘ery smal fection of he total member a cil thst ave been manasctored Ie Bell Syston nae CGexesar Posverion Stuns, Voici Pmigtency Cantar LOMtins ‘Te gral total preetion fine fap the el of 190) forall type of oiceveaquney Laing ce for Bell Sper wo i of the onder of B07 talion. Aparosinately $46 of this total (alt 1278000 re) ar nae Panton pe vols, used ast entirely a exer ye area nomequnded fable, Neatly 9.500000 cus ace side cout or phsstom loeding calls {sed on cs tcl aid tll etn rales, Ajonmirtely Thre qua. ‘ern of the gad total have Ly mature hing he sk to deca te greatly varying tas in the geuwll of lads sil prodaction are stow, (2) in terme of aecunulaee total prado thug 3910 fe 120 nm eae evsnrw wrMIRAE yoraNAL, OeOHE 19SL “Tale NIX ad (b) So ml tose Ting tae pri’ 1920-1019, potted ia Fig 38 Arse Pretoa Toate Inger, Cie evonage and yk gael annuel prodeion prin 19a} sere very sell lave 1 te Cae 19 1949 peo ered sy the char. Far example tae spaximor sarual prosuction of sil cuit [tne shart tll ete cols eer fy TES us the wae year 198, aad ‘te sranum anol poston toms exchange ne ale ie Bus | BE Nee Mlcdea Ea ah a prior to 1923 yas i the wer yese 1917+ Thus, with occasions! exceptions, the prafueton dats for t8e years pele 9 1920 cont no be amsartely puted on the care withowt ssi 4 eonusing sae “ile heginning, te ve of lang weal relative to it aubeeqvent xe because ihe le System ral plane wats ml, For nly a decade te Expnding toll cle pt ios yet esis than she exchange plant. Prom then on, ir che te decal rial 1919-1982, toll ele loading domizae