FS, in scric-s, and at ii-iiiature 26 coiinects test wiper 29 to the juiietiori of- relay 27 aiicl iyi,,i-net 28. Siiice all the lilies of the gi@o,,ip exce@pt tl-ie cal.lin(y Iiiie 1,,,ive earth coniaected to their test contacts, tinles,, the ivipei@s of FS are alrea,-Iy st,,tiidin- on this Iiiie relay 27 is shor'L-1-circuited aild mao;iiet 28 is energized and de-eiieruized to step the ivipers rolitid until the calliiig Iiiie is Toti@id. AVheil this occiirs, rel,,Ly 2'i is no loiauer short-circuited and eiieraizes, tliei-eby it its armature 30 completinilyacircuitforcoiinectii,t(yrelay3l. Rela), 31 upon energizing, at trm,,ttures 32 and 33 coiiiiects 'the sl3etki-n@@ leids throtigh, it armaiure 34 coiiii-ects ea@th to test iv;lpor 29 and at ai-ii-iature 35 prepares @i lockir@c-, eirciiit for itself. The coiiiiection of earth to i-viper 29 coi-npletes a circuit for the tipper i,vindino, of line relay 6 wl-iieh thereiipon eiierf-y;.zes fully ar@d at ariii,,t'Lures 11 ,Liid 12 disconnects conductors 1 and 2 froi-n its lower wil-iclin(@, qnd eai-th respectively. The circuit of i-elay 7 is t'@lereby 0I)ened a-,id iinless other calls have been iiiiiiafecl in the me,,intime, it commences to de-enero-ize TJpon theoper,,ttioii of armature 35, the folloivin(y cil@eliit is completed: eartb, arm,,tture 30 ancl its frorit contact, iviper 36' ancl the contact on whicli i'u is restin(y froi-it cont,,ict and ariiiatIlTe -lo 35, contact 22, wiper 21, front contact aiid ariiiature 15, series i-ela3, 19, stepping m,,ignet 20 to battery. The finder allotter FA is thus adi,anced oi-ie step and by tl-ie operation of series relay 19 tlae eiretiit a relay 23 is opened so that it cle-energizes ,tiid opens the c@rcuit of relay 27. Ul-iless aiiy ot-l-iei, c,,tlls are v@niting ittention relay 7 iiow de-eiiergizes ancl opeiis the circuit of relay 13 - which de-e-Tiergizes also. A circuit for restoriiig tlae fincler io allotter to noriiial is then coinpl@ted as foll.oi-,,s: eartlied iiiultil)le colitacts 36, wiper 18, back contact and armattire 15, relay 19, magnot 20 to battery. Since this eirciiit is coinpleted in.termitieiitly tinder the control ofj 'clie interrupter coiitact uiitil 'vi@'er IS ei-igages coiitact 17 -%ihich is now dead the switch is i-estorecl to iiormal in readiiiess to coinplete o'L-Iher connectioiis. Dui-@ino, tlae conversatioii the relays 6 ancl 31 ai,e lield tip by earth Ted bqck oi-i releise trunk conductor 37 from one of tl-ie iiumerical switebes. Wheii the c,,illiiicr party han(ys up Iii-, receiver this earth is relilovecl ancl r@'elays C) aii.,l 31 de-eneroize, ,ind the iiidi@ is fre(3cl. It iiiay theii be used t estibl'sli a coniiectioii by i-vay of the fin,-Ier FS' since ivlien earth is removed from condiietor 37, FS' -%vill iio longer test busy in the baiik of lu-Iie fiiider allotter FA'. Oiie impoi-taiit featuire of the arv,,tngeiii6iit sho vNn should be iioted, iiamely that the finder al.i@otter is stepped on after the callin-, iiiie ha's been Totind irrespective of wliether earth is fed back f rom the iiumeridal sw;_tch. li-i tho ordiiiary eourse, this ea-@,tli will be s'ent 1,740,559 3 back before the eart-l-i at armature 30 has been removecl, but iil case the truiik as@,ociated with tl-ie selected fincler shoulcl be ftulty, etrl-ll will not come back and relay ol ivill cle.-ellergize. The reiiioval of earth from test wiper 70 29 parti,,illy de-energizes relay 6, so that the circuit 6T relay 7 is ao-ain coiilpleted and siiice it is sloii, it Avill not iiive released dtirillo, this interval. Hence the fincler allotter Fx ivill again hunt for an iclle fidder, and t-Iiis 7 will theii operate to fiiid the calliiia I;Ine and the coiinection wil.1 be coliipleted thereover. The operation iihen ,L coiiiiection is extended from the grotip scri,ecl by the fiiiders stich as FS' is precisely simil-ar a'nd it -,vill be se,-ii 50 that as soon as the lilik has been taken in'Lo use by either FA or FA'. it is impossible for it to be seized over 'Uhe other path. Moreover it is not possible foi@ nlore th,,tii oiie connecting rel,,@y to be operated tt once since the illitial 35 energizin(y circuit is complete(I from the fiiider alotter. Fig. 3 depicts the baiik iiir;-iig of the - fii-ider all.o'L'ei,s FA a-,-id FA'. oiily the biiiii:s e,,-iga(-.-ed bN7 @L-h(., -@iipc-,@.,s 18 aiid 21 being shoi-vn. The f)o a-,e sli(-)wn as havip-(Y 25 poii:its ard t t(-,tal of IS ti@tii]@s are provicled of l@Ibich 7 are to e,-,Cli switch Pnd the rem,,tining foiir ,ire co@iiiv@on. Sirce the ntimber available to ea!ch sv@@.teli is oiily 11, they are iniil- f)5 tiplecl tavice rolind the b,,tnk so as to tvoicl turniiig to noi-mal, tlieve bel-Lig thils t,Nvo liornitl @,)csitioi-is. The lead 38 in Fig. 3 extends to the eG@iit@-,ct stich ,,is 9 of the common start 100 relav. T.ius I)y iiie, s of the invention one of the iro@'t serious disi,-Ivaiitages of si-iiall - c,,,pa,-ity filicler sv;-'tche@,, 1,.,,,s beeii overcome. It iiill be undei-slood, li(-,ivevcr, that the invention 105 is eqtialily tppl.le,,ible 'Lo laro-e c,,ipacity fiiiclers thou--h, as pointed out above, the (,reatest @,,dvaiitages of tl-ie al-i-ai-igement are to be foiind iii coiinectioii witli finclers of small cil),icity. 110 ll"liat is claiiiie(.1 is: 1. In a svstei-ii of- a tele hone systeiii, t. t)-i@oup o-f I'tiio fiiidei- sivi'uches divided into sub--rotip@,, stibscriber coiitrollecl n-Liiiierical s-@viteli-,s foi- entei-idinconnections 115 ,i certaiii iiiiiiiber of said last switches being allotted iiidii,idiiall.-@ to ,L corresponcling number Oi' si@,i@tc 'bes comprisiiig one sub<yi,oui), 9,iio'Ll).e r iiiiiiibei@ ol said switches eacli oi@ ivli;-cli - s coiiii-cted iii coi,.,in-ion rela- 120 t@on ,iitli a PILtral;ty o@'.' firder switches of anotlier stib-.g--otil). 2. Iii trii@king sys"-(,iii of a tolepl-ioiie systeiii, ,t of Ili-ie fiiider switebes divided ijito sitb-groiips, subs---riber controlled nii- 125 iiici,-eal siv"olies for extending coiinec'u'IORS, a cerilllin ruiliber o-l' said last switches beiiig c-.11,,)ttecl in.cliviettially to a corresi@onding nuniber of filidev switches comprising one subcroup, tinotlier nliliiber o'L s,,tid switches each t I-, e p@ - of aii e.-@:e,-ssive movement on re-

4 1,740,559 o I' 11,1;iieh is coiinected Nvitli. a plurality, of liti@(ler switches of anotlier sub-,,rotip,, aiid ,t tliir(I number of s,@tidsnvitelies each of ivhich is eqnnected, in coi-nnion relitioii a 4,-i-e@tter pliir,,Llity of finder sNAitelies of a third @'llb-gi-otip thaii iii the secoiicl. 3. In ,I triinkilig systein of a telel.)hone s ys teii-i, tt -ro@,ip of line finder sw-itelies divided i, @)to siii)---rotirs s,,ibsci-ibei@ c..)-- Litrollecl nu0. tile nnect i-ical s-witches for ex'ending co iong, ,t el-rtain iiiiiiaber of said last switches being allotted iiidividi.,,ally to a corresponding number of fincler sivit,.-hes c6i-nprising one sub(yi-oup ano]'Llier ntiriber of saict switches each L, of vihich is coll,@:,Iected with ,t pluralit-y of fi,ider switches of aiiother sub-group, and nie,-,Lns for calisin(y the saicl ii7Liiiierical switelles t'o be allotted for use by calling lines in ,i, definite order of priority in wh,ich order the 9-o sii@itches are access'ble froiii successively lar(,-er o-roul)s of'suibscribers7 ILies. 4. In a tru-nking s-v'stem of a telephone systein, 9, gi,oup of Iiiie fiiider switches divided i I nt,) sub-groups, sLiL-se-ILer coiitrolled liu,-3 r.,,erical sivitches for extending coiiiiections, .1 certain iiuiiiber of s,,tld snvitches beiii(r allotted individlially to a corresponding i-iuiiiber of finder switches con-iprising oiie sub,Uroup, aiiotlier ntimber of sai.d - ,AlTitches eqc'ii ,,,i o-L' which is connected ivith t plurality of finder sy@itches of tiiother sub-grolip, aiid means for calisipz the fiiider switches and the iiumerical switches to be used -Iii a definite o,@cler of priority. I 5. In a telephone system, finder switches for connecting ,t callin(y subscriber's line to o.qe of r,, groiip of first nuinerical s-witches, II-iel.iiis for efLiTsing the finders to be taken for tise iii a definite order of prioritl,, the finders ]@g -iieri al 4, @'Y first taken for use bei linked to nui c skvi;tches individual to them -v@,hile a iiuinber c,.f those taken into use thereafter are coniiectecl in common to ayiother niiinerical sivitch. -1 6. In a telephone svstem, groups of subscribers' lines, some of said groups being larger than others of said group.--, nuinerie,,tl switches, backwardly hunting switches for coiinecting subscribers' lines to said numeral 'tche r@,i swi s, and mearis for causing said ntimeral sivitches to be taken for use ip- t clefinite orcler of priority, in -",hicli order some of said ii:i,imei-al switches ,Lre access-Lble from stiecessively iarger groups of subscribers' lines than other of said nuii-iei-ical switches. 7. Iii a telephone, system, finder switches arraiiged in groups, a grotip of other svti 'ti@bes, iiieans for connectinocertain of said fincler snvitches to indivictuai ones of said other c') switches, aiid means, for connecting others of said find@ers in mliltiple to the other 8. In a telophone systera, a Oalling lixie, a plurality of, fliider swit-lhes having access to 65 8.aid 1-ine, other fiiider 8,witches a pltiral,.ty of nui-iierical si,,,itch,-s for exteiidiil,(, conneezm tion@ to called lines, certain of said niiiiierical switelies being iiidivi-dtial to certain of th@, fiiider switches Nvll-lle o,.hers are d'irectly coiii-iected without intervenln,- s-,viL-,ches to tt nuiiiber of the finder switelies, a-iid n-ieans for causin-- the first of the niiiyierical sivitches 'o be taken for use aliead of 'Lhose v,,hicli are co@-ial-p-o t n o a nuiiiber of th(, fipders. ys 9. In a, telepho-@le s tem eiilployino, bacl:",ardly hunting switches -Lor connectilig subsci-lbers' lines to numericil s@vitches, ilieans ineltidin(y aii allottine,, s,,vi'u-cl-i for catisin(y 4-lie iiuip-ericvl s-,vitches to be takei4 in@LO ii s, e i -n a definite ordei- of pl--iori-l@-v, ind me,,tiis for c,,tu')i,.-ig tl,-ie s,,Lid allotte., k"O' 'be iiioire-,l '-Lo q d;lsi' ti@ctii,e pos uloii ,tt any tili'le no fiiide-,, u,.icter its co-,itr6l is pei@forll--iipg a hunting operat-lo"l. 10. III ,t telopliope svsteiii, nui-,i.,-r@leal s%vitches for extendijig c'onnect:lbi-is, bacl@- s-vvarctly huliting sivitches for coiaiiecti,-lg the numerical switches to siibscribers' li@)eS, n-ieai-is includi-ng an allottitiu switch for causiiig the fiiiders aiid iiumerical s-",itches to be tiken into tise in a definite o@clor of prioritv, o .9 aiid finder coiltrolled iiaeans for Completi.111)" tt cireiiit for advai-ici@g the allotter respon@- ,,ive Lo the finder's comino, to rest on ,t calling fine. 11. Iil a telephone system, groups of 95 iDO' lines. ti correspondin- nuiilber of ('FOIII)S of tri-inl@s, ineans for enablin(Y the lines -of @71 oiie@ groul) to extencl CollneCtions oilly @,,ia t particular group of trii-illi:s a d for enabi; n 1119 the lines of more than oi-ie grotip to extend 100 co-@inections vi,,t a triink of another of said groups, 12. In a telephoiie svstem, a ealliiiy equipped Nvith .t combined line and cut o.,i rel,,iy, a finder switch hlving tccess to sa'd 105 I liiie, a seconcl relav, a cireiiit i.-icludip,@z s,,,id first and second relays coinpleted resro,-isi.ve to the initiation of a call for oi)erati-,-ig sai(-I, slecoiid rel@),y, ineans oper,,tted b@ said secoiid relay for parti,,tlly operating gaid firs'u@- elay 110 to thereby dis'uinoguish the calli-Tig line -11,- oin others to ivhich the finders have Lccess. aild said second relav at the stme tiiiie c,,tijsin(y the first relay to become full.), 6pei-ated by esel-,cted findei- to fipd tl-ie call- 115 caiising a pr ing line. 13. In a telephone system, groiips of giibscribei-s' lines of iariolis sizes, iiiiiiieri(@,,il s @iitches, and n-ieails f or causing said numer i - cal snvitches to be tal,-en for iise in t deftiiite 120 order of priority, in which orcier soii-le of said switches are accessible frolii stiecessively larger groups of subscribers' Iii),es than other of said switches. 14. The method of maint,,iininz a, pl,e125 scribed order of use of the finder switches of a _graded m-Lilti le finder slstein which conp sists: of connectin,& the finders to the bank@ of a ho= type distrib-Litor in said prescribed o:f starting @aid clistribiitor' 130 so

1,740,550 5 ii-om its home posil-lion responsive to the initiation of ,t call in search of the first ic[le Iiiider coliiiected to its baiiks; aiid ol retLiriiiii(- said distributoi- to if's lioiiie positioi-i iiiiiii(,cliately aftei- a filider lias beeii op(-@rated iiito coiinectioii %vith P. calling Iiiie. 15. In t tolepbone system, a group of line,@., ,t grotip of fi-, [ers liavi,.-io, access to sa'id IC n a distrlbtitor siiitch havii-tu a norifial posi10 tioll, iiieij:ls respoiisive to sirtiultan(,oiis calls i-.iitiated by a plurality of said iiiies T-or startiiig sa@ic[ to sels.,ct t fiiac-lei- to operate it i,,itc) coiin(@,e"lioi-i o,,ie of s@tid c-ci aiid f,)r ,@aic.1- to 15 ,,e@ Lec,t aiid opei@ate anot'lier finc'ter sivic(,,"@i iii-t@o coaiiiectio.n i@7itli aiiot'iler ope of said ca"ling l'Ir-es, aiid iiie@iiis i-cspoiisive to the estaT)Ilsiiinent of a coi-iiiection Ayitli the -.ast of sqict calling I.Iiies 'Lor i,eturiiiii(y said disli@ibiitor to its 2o noriiiall positioil. 16. in a telephoiie systeni, a group of lines, of f-iiider switches liaviiig access to saicl lines, .t distributor sai-itch liti,ii-io- a noi-posi'Li-on, iiieaiis responsive to the initi,,L25 tioii of a call on one of saic'[ lines f or operiting said clistributor out of its normal position tO seleel ai-id operite a finder into connectioii Nvitli said calling line, aiicl meai-is ilespoiisive to tlio establis'iiiiieiit of -@aid coiiiiectl,,@i 'i@or 3o rettirniiig said distributor to its jioi-nial position. 171. Iii a telephoiie system, a group of lines, ,t gi-oup of finder snvitches havl,ilg @-ccess to saicl lines, ,tdi-stributor swi'k-leh havina a -.-Liorn r) m,,tl positioii, q. stai-L, i-elay eiiergize-,-[ resl)oiisive to the initiatioii of t cill on one o-L said iiiies and deeiiergizecl whe-ti a finder co,,iiiects ii,ith that Iiiie, iiie,,tiis respoiisin,e to the eiiel,gizatioii of saicl start i-elay for operatiiig sa'ld 40 distributor otit of its iiormil positiop- to select ancl tioji ivith the ed by the deeiiei, or returnilig sition. 45 18. Iii t telephoiie syst(,jii iii w.tiieli tt lioill;iig type distr'b-Litor 's started 1rom iiormal I I 1 respoiisi ve to the initiatioii of a call on a iiiie to selectind control a finder, to find that line aiid theii relelse fi:olii the fincler, a retui-ii to i5o iioriiial circuit aiid a fiiider selectine, cireiiit iii silict distrlbtitor, a relay ei-iergized upon the initiation of a call to opeii saicl fori-ner ancl to close s,,ticl latter eircui'L, a trunk line outgoin,y from said finder, a relay in the finder 55 operited -v@lieii the calliii,-r Iiiie is Totitid 'L-o co-nnect that line to saicl trtink, means responsive to a sliecessftil opei-ation of s,,tid fincler relay for restorino- said first relalr aiid responsive to an uiis-Liecessful operation of said 60 finder relay for iiiailitaining saicl first relay energized, ,trid iiieaiis iii said distributor opei-ated over said finder selecting circuit aftc,.r saicl findei-- i-elay his been operated for selecting another finder for opei-ating it into co@i65 nection -with said calling line. 1 9. In a telephone system, a subscriber's line, a plurality of fincters having access to said lines, truilks outgoing 'Irom said fiiicters, a distribtitor havilip, a norinal position, a return to normal circuit in said distributoi@, 70 meai is responsive to tl-ie initiatioii of a call oii on,- of saicl lines for opening said return to norinal circuit and for starting said distribu tor otit of its noriiial position in search of an idle finder, meaiis in said dis'ributor 75 i,,spolisive to the fincling of an idle fincier for @3e izin(y and stai@ting that finder in selreh of sa@. d callin,- line, iiieans iii said fincler for c,@s @,@abl.isliiiig -,t cod-iieclion belunveeli saic-[ liiie anC L trunk, iiieans iii saict disti-lbutor respoil- 50 sive to the fiiic[er iin(ti,,ig said line for oper-,tt.iig said finder coniiec-'cing iiieaiis anc I for dis@ss ociatiiig s,,ii'd d'Is'Lr'lb,,itor froria said findei@ and foi, closin,,y said return to iioriii,,Ilclrcuit to retui-,,i @eict ctisL-ribu'Lor to normal. 85 20. In a te.',eplione systein, stibscribers'lines divid ect into a plurality of gi-oups, finder swite l-ies 1,@aviiio- access to said lines, said finders beii-ic,@- arraii(,-ed in groups correspoiiding to said Iiiie -poups, a pluralltv of trunks olit- 00 gOID.0 ' froii saict fincters, direct connections betaveen said -'Liiiders aiid trunks, the sum of tli(, n,,ii-iibers of ti-tinks available to said indi,7idii al Iiiie c,-t,oups is o-reater than the -tiumber of s,tid out(yoiiicy trtinl,:s. 95 21. Inaiiiidei's,,vltclisvsteminivhichsome fiiide r switel-ies are assigned to the individual use o-j' a oj--otip of lines ancl other finders assigii ed to different groups of lines are connect ed in n-itiltiple ivith eacli other, a fiiider 100 allott er, 1'heaiis i@esponsive to the initiation o-T t call by one of said Iiiies for starting said allott er in seareli of in idle fiiicler, and means for causing said ,illotter to select a finder ,tssign ed to ttie inclivicltial use of the li-,ie group 105 coiit, ,tii-iin(,-- the callin(y !,Ine if such a fiiidei22. In ,i 'Lelephone sys'uen-i in -,vhich a homing type clistrlbtitor is started froin normal resp onsive to the ii-iitiation of a call oii a - lipe 110 to select ,tlid control a fip-der to -Liiid that line Riid then releasc- from the finder, a return to nor mal circuit aiid a finder selector circuit iii said clistribiitoi-, and a relay ei-ier(yized ui)oii the initiatioii of a call to open s"aid for-Lmer 15 ,tiad to r@lose said latter circuit. In iaitness Nvhereo-f, I hereunto subscribe m3, iian-ie this 28th day of April, 1925. WILLIAM AITKEN. 120 125 is idle. t,

Pater,ted Dec. 24, 1929 12740@559 UNITED STATES PATENT OFFICE WILLIAM AITKEN, OF LONDON, ENGLAND, ASSIGNOR, 13Y MTESNE ASSIGNXENTS, TO AUTOMATIC ELECTRIC INC., OF CHICAGO, ILLINOIS, A CORPORATION OF DELAWARE GRADED FINDER SYSTEX Application filed May 21,1925, Serial No. 31,808, and in Gr,,,at Britain.A-iigust 21,1921. Rene-wed September The present invei-ition relates to telephoiie systems employing iutoinatic switches ,tncl is niore partictilarly concernecl with systems @inplo.l,in(y s-",itches of the backwari-Ily huntIII(, o@ fi@cler type. As is well kiiown, tlle fu,llctionperformedb theseswiteliesis'esseny tially sli-nilor to that of line-s-,witelies of the forwar(Il btinting Lvpe. blit the coiitrolling y arrangements miist of course be clift-erent ancl in creneral the qtiantities i.nvolvecl will be 10 li @, ffereiit ,ilso. When the switel-ies ,ire usecl for connectinff ,t ca,lling siibscriber's Iiiie ",ith a first numerical switch, if Iii-iesivitches aro used, they must be provided inclividtial to each cilling line and lience ,t large iiumber 15 are i@eqliirecl. These switches however, ,ire comp,tratively el-ieap and sin-tple to m,,tn-Lifacture -,tnd furtl-ier, the selector snvitches to which the line-s-witel-ies have ,tccess may be arr,,inged i-n coinparatively lar(ye groli-os, for 20 instance groiips of 25 so that the nlimber of expensive selector switebes is redliec,(l to a minimum. Witli finder-snvitches on the otber hand, if they ai,e arranued to be of larg@e 25 ca,pacity, a special switch construction is necessary if undtil.y long h-Li-nting time is to .be avof@lecl, wl-iile if they -.re st,,indard switelies of small capacity, not onl-.y miist a mucli larger niiinber be ei-n,,-)Ioyed, btit siiiee 30 e,@tch fincler-switch is uslially clirectly linli:ecl to a selector switch, the expensive selector s-",itches mlist also be provided iii greater qu,,tntity. The object of the preseiit invention is to overcome tlii-s drawback to the use of fincler35 switel-ies ancl to enable a sr,,iall. type of finclerswitch similar in codstructiori to a Iiiie switch to be employecl without Linduly inere,,tsing the ni-imber of i-i7Limerical switches to Ayltich 40 the fiiider-switel-ies are linkecl ' the invention, in a system .i-@ecorCliDO' tO employing 'hncler-switches which bunt for l,ines arrangecl in gi-oups corresponding to the capacity of each finder-switeli, some of ,15 the.filider-switches are connected to inclividtial terminals of the succeeding switchino, devices, wliile others are connected in m@iltiple to'the terminals of tl-ie succeecling switching device. 5o According to another f-eature of the inven29, 1928. tioli, in a svstem eiiiployi]-ig bacl@iv,-,rdlv hiinting swite'hes for connectina subscrilers' lines to numeric,,il s%vitches, the nlimerical s@ vitches are arrangecl to be taken itito use in a definite order of priority, ii-i -wliieh order the 55 swit ches are accessi.ble from s,,iccessively larg er groups of subscribers' Iii-ies. A ftirther feature of the inveiition is tl-tat in a system employino, fincler swltcl-ies for conn ecting a catling @tibsei-iber's line to ,i co first nl,.merical switch, tl-ie finclers are adal)ted to be taken into use in t definite order of priority, the finclers aclapted to be first tal@ en into use for connectiny with a callinlu li-ii,e beiii(Y linked to indiviclual sivitelaiiig (le- 6 -iose t, vices, while tl ,ken into use when all of the first eliss are busy are coqnected liq successively 1,,Irger grotips to s-witehing devices co,-nmo'n to M-ore ihan one fiiider. Tiie in@,ention be bet4l-er unclerstooci 70 from t'le fol-lowiii (y degeription of i prefe,-recl emb odiment t,-tlc--n in coriiinction iNi'L-h 'tlie tccom panvino, clra-%Vin(rs. It Avill be undcrstood that tli.@Ligh the foriii described concerns the nov el. arr,,tirigoi-iie-.its of finders for Colll)-ecL'Il-Ig 75 ,,iibs cril-ers' lines -@@o -.q,,-imerical s-,Yitches, tl,.io inve, ,itioii is not limite(t to such use -,qor to tl-io exac t eireiiit arranoe-Tilents sholvn. Re ferrin(y now to the clr-Lwin(ys, Fig. I sliows virious arrapgements of fi@-iders -wl-iich so are possible accordip!E@ to i,lie @ilventioi-i in illust rations A ai-id B 25 point -ii-,iders ai-e tisecl and in illtistration kO 50 1 oii-it finciers ,ire i - Lised. D and C re@7,I)ectii,ely slioiy two ,irran(- ei-aents of -wl-iat iiity be term-ed "(Yra@iiiig"' 85 Z, iTi the b,,inlcs of the finder allotters associated Aiitli the various groups. Fig . 2 is a eireiiit di,,tgriiii shoivi-Tig the actiia l coth-iectioiis ii,heii finders of t'Wo di (T'erent groups are coiinectecl in ilitiltiple to a go comi non stieceedino- switcla, wliile Fig.@3 shonvs I the wiring of the fincler allo't,ter banks. In illustration A there are slionvn tnvo grou ps of stibscribers' lines a and b, e,,ich uroti p comprising 9,5 lines -which are served 95 b@v five finder-switches. In each groul) it is ,ti,ra n(yed thtt by means of an allotter (not shown@) the fipcler-switches are taken into iis6 in a clefinite orcler of priority, f-or instance the tru-,ik lines asrociatecl with i-iic finders in 1.00

1,740,559 'iito t@@sc, i!Us 'c@l- IV, ffic is Iii@,yllt It 'I by 1 @-,iid wliieh are to tl,.e o, coii-it; o-"S ill b ai,e L'-t!Teii c,,ii-e of b3, Iiiies 3 ii)(I 4. The !I-ties 5 6 aid 7. hoiveier, 3 are to 'Che tTN-o I) Lit a--e o-nly ta,lceii 1-ie illo -Lise ti-ie 1;- iies i-T-i t Pre alrel@icly bi-@.9y. I'Z, be appreIrk C,- aled 'tliat The i.@,,vol-I is t',)e sq e as 'Uliat employeo, in'o-rpdiiig vs ,.tl),Dlied 'Lo Toriyard.ly liiin@L-ing sii,'I'Lclies. Illtistratioii 11 s'iaoii-s a possible arr,,i;iigen-iedt witli three gro,,ips of si-,,bsei-iber's lines -ieivhq --affic, so .t,@ c, (I a n cl e, v,, i t h ,)@ s o ii t lieavier tith,,,t eacli grollli,) is sei@ited by six: findelcS,,vil,-ches. iii this cos,- tjie fv.-o truenli:s 8 a.ii,-l 9 10 ind 1',-, 12 tn,,l 13,@ (1-1-@o-,ip ach rprotip, .i,re the ne@-.t ti-vf.) I-Ti o z@, 2o 14, 15 irid IS @-,@e comp-ioi ti-ie 1,,ist 'L-,,,,,-o l@') and 17 are co:-,imo-i'l to all three gi,olli)s. B@,, this a total of 11 "i@ui-iks i,@ to sevve for the tl-iree gr(,,ups as a(,,tipst IS if- eacii (Y',otip li,,id -1 alil its six "Iri,,nks inclivid-e.,,Lj', Iii, illtistration C the ii-Limbei-.s ai-e sl'o-litl f7 erer.t, 1),,,,t the 1,)riiiciple the stiiie. In tiais c,-,se tliei-e are t@yo gi-otips of stibscribers' ]@liies i in-,I g and e,,Lch C(,iyipriscs 50 zo li@-,ies. Uiicler these circi@iiisttices 9 @@.-.i,-Iers --re providecl to de,,l with lzlie ofe,-,cll groiil,) apd the first five d 24--98 are, inciiiiduo.@l, aiicl the To@cir ai,e colliamoli, so that -@ tot-,I of- 14 The illtistratioils D @ind E siioiy ii i eilt iiianner the groi-ipiny arraii,),eiiiert'. .Tl-,iese iiiiistrttions represent tiie bant@ t,,icts of the finder illottei-s oil-o of Nyiicil is vssociated Nvitli each group. In D --It is as4ci SUli'led that there are -i@'o-Lir (yi@o,,ips t-,ld @-i,-iiee -clioilters ancl tli,,tt si-x Riidet-s ti,e pi,ovide-,l to @Lake c,,ire of the trtffic iii eaciland moreover that the lioiiie pos-"i-o.,i o--F .2,1,ch P,J.Iotte,.- i-s at the bot'Lom o-i' eacli A,ei@t;etil- ro-,v o,-!-' contpets. It wiil be see,-@-i tlieii that tlio ill--,t two ceiitac'Ls ai@e, co-ni-iected t) ;ln,,.!ividiial i@r,de r ]:;,T-il@,s the 'Lli ircl a.-i,,l f o,.irtl@i c OD !I- ,I ct,,@ a re coiinected to links wliieh ai-e com,m,,,i, to t-wo L,,-rotips, thoii,,(4h the grotipiiig is diff-erent iii the 'Lwo cases, wh-lie tlae fiflih aiid sixtl-i ,)ositioils lead to finders -@,-h'lc'il are corimon to all fo-,,Ii@- o-i-olips. Ill ll.llistra@qon E foui- <-,-rotips ,incl, sevep ,,n(7t ii t'iii-s case tlc, coiane,@tion of 'Li@ie Iii-i,-Iers iii 1).ftil@s is Lri-'Lyed oii the fotir'Lli cont'lets. Fig. 2 shows . detailed circiiits for the caso in which two finders are@ con-iiected tolge'hcito a comiioii stieceedi-Tio, snvitch foi, ii,,is@.-ance a first selector. The circuits -,itotilcl not hoia,CO ever need alter,@ition if a lai- er ii.-Lii-nbe@, of finders were eriaplo ed in rntiltiple, the conY nections of the adCL1:tional s-witches ):)ein(y readily apptrent to those versed ir,@ tl-ie lirt. 'rhe finder-switel-ies representecl b@7 FS and i,G5 FS' aTe. mechanically icleiitical With,liresv,,itciies oT' well li:nown type, Nvi' uh w,.pei-s liaviii(y no norlicial positi.oli and iiiovin,- al@-v(gvs iii th-, sai-iie direction and having either 25 or 50 coptacts. A stiitable nuliiber of tlicse sivttclies ,ii-e provided T-or each eroup 70 of liiies and the order in -which these s itebes ii,e tqken into use is cletermine(-,l by t -finder allotter slich as FA. T-Jiis switcli is mechanically,identicil ",ith ,tny oT the finders except it is p o tha' r vided with a normal posit@ion 75 to -which it returns -when not actuially in use. The.leads I and 2 exteiid to a subst@iioii and incoll-iino; connections for this station are coii-ii)@eted froi-ii a connector over the leads 8 4 and 5. The combined line ancl cut ofr so rel,,ty 6 is arrat-iged to operate iii t",,-o sta.ges accordiiio; as to -whether it is energized over its top or bott6ill wincling. Stippose n6-w tl-iat tl-ie subscriber -Luider consicleration initiates a call. Whe@n he re. s5 iiaoves his receii7er, a eirc!ui:t is cojiapletect ,is, fol!onvs: bittery, both wilidin,-s of common stirt relay 7, lo-wer windin-- of line relay 6 of the e,@illino- Iiiie, back cont,,ict and armatiire 1,1, coiiductor 11 stibscriber's, loop, coiioo u cltietor 2, arinat re i2 ,incl its back contact elrth. Owin(y to the hi(-Ii resistance of this @n eirciiit, relay 6 does not operate blit relay 7 operates -,nd @-t -,Lriiiature 8 shor'u eireliits its high resi-qtance lower wijidino- Rela-v 9,5 6 then receives enotigh etirrent for it to ot@- erate its ai,mat-Lire 10 oiily. wl-ieteby tl-ie calling line is p'@lacecl, in condition to be fotind by the finder-sm7iteli tllotter., The operation of ,.i,iiiattlre 8 also coiiapletes i eireliit for re- 100 lay 13, ivl,,iieh thereupon enero,i.zes, and applies e,,trth at arii-iattire 14 to the test co-lit,-tcts@ @tsso-@iith ill the li-@ies in the groL@il:.)- e-,@,cept those actliall@, in tise. M-oreover, it armatliro 9 rela3, 7 comple'ues ,i circuit Ls follows: etrtli, 105 ariiiattire 9 iiid its front contact, norn-i-a-I contict 17 in the banli: of the allotter FA, honlino; wiper 18 bacl@: contact tnd ari-iiature 15 i,@;nding of series relay 19,, interril-pter contact and m@@io,inet 20 to'battery. The - wipers iio O'L the finder allotters ar-I thiis ,tdvanp@ed one' s top before the above eireiiit is opet-ied Lt ,irinature 15. The colitrol of the hunti , n(y operition is then ti@-ans@ferred to tha tcgt wipe-r 21 and this operation continues Unt'l "7iper 115 21 engages a contact, for instance the contaet 22 'Lo wl-iieh e,,trth is not coiiiaectecl. At arm. iture 16 a circuit is prepired for Iiiie relay 23 of the allotter, this eirc-Liit not beiiig ol)er@ ative foi- the pi-e@sent owing to: the fact that 120 it is open at arniattire 24; of series relay 19 'Its loD o- as. the allo-tter is hluiting to: fina a..n idle finder. Assuming that thei fiiicler FS is the one t',Ili:e" into use, relay 19 de-energizes wheii 125 the tllotter FA- comes to rest and coinpletes a @ircuit for rel,,ty 23 whicli there.upon ener-gizes an@l at: arli'l@ture,'25 co @mpletes a@ eir6uit for s'witching relay 27 of the finder al. lotter ,tnd steDT:)in g, mao,,net, 28 of the finder 20