US1972199A - Telephone installation - Google Patents

Description

Sept. 4, 1934. MERK TELEPHONE INSTALLATION Filed Feb. 14; 1933 5 Sheets-Sheet 1 4 r. v W 1/ 8 0 M 4 r. llw

e I y b z' I 6'7 .IFII Fr 6 9/ Ir a, Q a; w a s Sept. 4, 1934.

F. MERK TELEPHONE INSTALLATION Filed Feb. 14, 1933 3 Sheets-Sheet 2 life/"neg:

se t."4,.1934. F ME K 1,972,199

' TELEPHONE INSTALLATION Filed Feb. 14, 193:5 s sheets-sheet s Patented Sept. 4, 1934 UNITED. stares TELEP-IIONE INSTALLATION Friedrich- Merk, F1-ankfort-onthe-Main,

- Germany Y Application February14, 1933, 'Serial No. 656,731

v In Germany February 17, 1932 6 Claims. (01. 179 1s) The invention relates to telephonic selectors for groups of subscriber's lines and aims toprovide an improved selector arrangementor means and principle of making connections. 7 Such groups are characterized bye very unequal ratio of the subscribers lines to the. connecting lines associated with them. The ratio is very disproportionate because the use of the subscribers lines is small and cannot be increased, whereas the connecting lines should be used ,as much as possible in so far as the-presence of .a larger number of subscribers lines allows it. This requirement is satisfied if the. ratio of the subscribers lines to the connecting linesassociated with them is about 100 to 5 for ordinary traffic and about 100 to 9 for heavy traflic. V Selector devices for subscriber groups have hitherto been of two difierent or what might be called opposite constructions. In one case, the devices for the outgoing and incoming-traffic to and from subscribers are made as small but very numerous selectors, whereas in the other case, for the same purpose, considerably fewer, but very large and costly selectors are used. In so far as in this way the said ratio is satisfied, the result is only less economical than it is eflicient. The object of the invention is a technical and economical and, atthe same time,- satisfactory construction and arrangement of the-selector device for subscriber groups. This is brought about by, a multiple connection arrangement'in which however, if desired, suitable also for pre-selectors together with a staggering of some of the selectable lines. In any case, with the connection-aris to say, withoutadditional distributing switches.

This is the main advantage of the invention It is;

This connection arrangement is mainly intended for use in call seekers and line selectors; It is rangement, an eificiency is obtained which allows a grouping together of the lines in the ratio men-. tioned at the beginning to be obtained directly in the multiple having selectorsof medium size, that obtained together with another big advantage which consists in that the connection arrangement can also be used for line selectors and-can itself be .easily inserted-in selector systems :with subscribers lines divided into groups of ten. Altogether, the inyention'makes it possible to restrict the selectors for the incoming and outgoing subscriber trailic to approximately the same small number that has already beenobtained in the switchingstep of the selector groups in a differentv connection arrangement. (See German Pats ents Nos. 227,561 and 279,020.) It will facilitate understanding to here state that no particular type or constructionoi selector is required for the purposesof the invention, such is quite immaterial. It is necessary. only that the selector have a contact field so constructed that two equally large conductoror line groups may be connected with it. This might nec essitate making the selector twiceas large, that-.is, providing additional brush-sets andcontacts for double the number of 4 connections, but there would 'of course beno diiliculty in so doing. In other wordsin place of the usual type of selector: having a part contact field, the invention cons: templates or presumes a selector having a .200, part, contact field. A selector suitably adapted 'or adaptable to the purpose is, shown for example-in my prior Patent -No.11,912,(l87 dated 'MaySO, 1933, referring particularly'to Figs. 1 andS. The invention will be best understood'by further description withreference to the, attached draws: ings illustrating the same diagrammatically.

In said drawings: 7 Fig. 1 represents several groups of selectable; lines as connecting with associated, groups ofv selecting lines;- 1 .Fig. 1a represents a reverseconnectingarrange-:-

ment; p 1

Fig. 2 represents an arrangementwherein thev selectable lines are divided into sub-groups; Fig. Zarepresents a reverse switching arrangement of-this sub-group division; Figs. 3 and 3a illustrate the. above mentioned arrangement for a larger number of. selector,

l' -P I I Fig. 4 represents an improved fOIlIl'Of connec-: tion arrangement for a multiple of 'linesin accord: ance with the principleinvolved; Q I Fig. 4a illustrates a modification of the'latter andexemplifiesa practicable table of symbols advantageously used; Fig. 5 illustrates an adaptation of the ccnnec-.; tions of the preceding figure with only five groups of selectors,'together'with a table;

Fig. 6 exemplifies possible combinations of the table symbols;

Fig. '7 exemplifies variations of the table of Fig. 6; and

Fig. 8 is a further illustration of the table use.

In Figure l, the lines A, B and C indicate three groups of subscribers lines which cyclically connect together any two partial multiples marked with small circles I, II of three call seeking groups. The lines a, b, 0, indicate three groups of connecting lines to which are connected the call seeking groups indicated by arrows. The arrow-heads give the engaging position of the call seeker. Here, as in all the following figures, selectors with a zero position are assumed, so that the arrowheads indicate, at the same time, the sequence for the covering of the partial multiplesI andII lying one below the other. As a consequence of the visible restriction of the groups of linesA, B and C, each of these groups in one of the call seeking groups appears in the partial multiple I and in the other in the partial multiple II, The calls from any subscriber group can thus be made from any two groups of call seekers, By a suitable setting up of the starting circuit for the call seekers, the calls, for example, from the subscriber group A, can be made from the (appropriate) call seeking group a until all call seekers in this group are occupied. During" this time, further incoming calls from the the same subscriber group A are transferred by the starting circuit switched'in in the meantime to the call seeking group b for auxiliary operation. The call seeking group b can thus obtain the desired assistancebecause the subscribers of the group B can obtain any necesany assistance from the call seeking group 0.

Should there be no third call seeking group 0 and the multiple switch be made merely with two groups of call seekers a and b, the subscriber group, B would no longer be able to deal with a call'during the occupancy of thetwo' call seeking groups a and b. The multiple of the call seeking groups a and I would, in this case be a usual restricted multiple of the line groups A and B, which does not fall within the scope otthe invention. The

invention providesr'noreover a line multiple for the selector groups, the groups of lines of which are made accessiblein different combinations. In the construction of such line multiples, at least three groups of selectors asin Figure 1 are neces- In this way, it will thus first be possible, with the same number and size'of selectors in the groups, to be able to inake proportionately more calls than with only two groups. If, for example, five calls seekers are associated with each of the subscriber groups A, B, C, with the subscriber group A, ten calls canbe made from the call seeking groups a and b together, while at the same time, in the subscriber group B, five further callscan be made through the call seeker of the group c. I

In the reverse connection arrangement of Figure 1a in which the selecting and the selectable lines are oppositely arranged, groups of subscriber's lines are again indicated at A, B and C,

which end at preselectors indicated by their arrows, while in the selector multiple there are two groups I and II of the connecting' linesa, b, c. This connection arrangement, as regards the use of the connecting lines, operates like that of Figure 1. As regards the letters given together beneath the connection diagram of this and the other figures, an explanation is given later. I

In Figure 2, contrary to Figure l, the groups of subscribers lines are divided into sub-groups A1 operation. i

to A4, B1 to B4 and C1 to C4. Accordingly, the partial multiples I, II are also divided up into sub-groups. The several arrows branching from the connecting lines a, b, 0, represent the sets of brushes of the call seekers in the form of multiple brush selectors or of small call seekers connected in parallel, both of which arein themselvesknown. Upon a call being made from oneloi' the subscriber groups,the brush set of a call seeker of the particular sub-group appertaining to the appropriate call should always, in any case, be efiective. For the rest, theswitch device operates as regards the use of the connecting lines a, b, c, similarly to that of Figure 1,- that is to say, the use of the connecting lines will in this case not be influenced by the divisionof the subscriber lines into sub- A1-to.A4, B1 to B4, C1 to C4 indicate sub-groups of preselectors, to which corresponds the multiple of Figure, 1a, and thus has likewise the same Figures 8 and 3a illustrate the or the above mentioned switch arrang'ernenttora larger num: ber of groups of selectors and lines, the' increase of which enlarges theefllciencyof the connection arrangement.- Ifit'is-assumedin Figure that there are again five call seekers inthe subscriber groups, twenty calls are now possiblesimiih tane'ous'ly in three neighbouring subscriber groups, namely, ror example, ten calls in the sub: scriber groups A1 to A4 which are made'through the call-seekers of the groupsof lines "aand -b; five calls in the subscriber groups 131 to B4 which are made from the call seekers of-the"groups-ot lines o, and further, "five-calls in the subscriber groups C1 to G4 which are" made from the-call seekers-of the groups of lines d. In'th'e' remaining subscriber groups,- simultaneous calls fareiike wise possible in similar fashion; 'Ihe'sameap plies also to the'connections in Figure 3a. The group orlines in these two and in' the following similar figures enter'ingat the left in the first selector group forms the continuation er-tne group of lines on theright leaving the last group of selectors. I j w At this stage will be seen the remarkable prop erty of the connection arrangement in accordah ce' with the invention, namely, that the individual subscriber groups are continually operated by the connecting devices of the following subscriber group at the same-rate at'which theirown com necting devices are taken from" them by the previous subscriber group. compensation of the connection arrangement in accorda'nce with the invention arises out of'the correspondir' 'g or identical construction or thepartial multipleS'If II of theselector groups." This compensation of the connection device is also'apparent fromthe fact that no alteration'is made in [the efiiciencyii the partial multlpl'es'I, II were arranged in' lth reverse sequence in all theselector-group'sor if in Figure 3, the calls were distributed-from the sub scriber groups alternatel'y' to their owd'and to the following call seeker groupsas again'wasindicated in Figures 3o, namely withthe connecting lines of the partial multiplesI and II arranged in a mixed sequence.

The identical construction of the partial-mul tiples is of particular'importance ror tne efficiency and general "use of the connection a'r-' More will be said about this later.

rangement in accordance with, the finventio'ni.

'' Inv the connection *arrangemer'its previously" mentioned, having subscriber "lines divided into sub-groups (-Figures2, 3, and 2a, 3a), the'selectable groups of. lines in an. sub-groups of their partial multiples. I,. II are connected in" a similar way-at any two selector groups In the same way, in the individual selector groups, a combination of theirmultiplesioccurs' w'ith'any two similar:selectablegroups of linesfi. This identical connecting isirillustrated in thedrawings by the parallel running of the lines which indicate the selectablegroups of'linesu I J L.

The invention is not restricted to this identical parallelconnection of the partial multiplesI, :II in thesub=groups of the: individualgroups of subs'c'r'ibers'lines; :On the contrary, the existence of sub-groups ofsubscribers lines can be utilized to allow ach'ange-in the combination of the partial multiples I and II to occur also in the sub-groups ofthe subscribers lines. 'In this way, a double variation in the combination (mixing) of the selectable' groups. of 'lines in .the partial multiples I and II, iszobtained, namely, once'between the selector groups andin addition within the selector groups. This-form) of construction is advantageous as regards the accessibility and the utilization of the connecting lines; I

Figure 4 shows thisimproved form of constructionrof the connectionarrangement in accordance with-the invention forwselec'tors Swith subscriber line's-Kin the'multiple.. Ifithis form of construci' tion is compared with :the corresponding one in Figure-3, itwill be seen thatthe connecting lines for the subscriber groups in the partial multiple I oflitsown selector group are unaltered whereas the conne'cting'lines inthe partial multiple II for the sub-groups of each group. of subscribers lines whathas already been shown, namely," that with their-arrangement of Figure '3, .upon' the same assumptions, a subscriber group has simultaneously ten connections; it can now be, established that this number is increased in the arrangement U of Figure 4 to twentyefive. For example,- any sub-' scribe'r in the. subscriber-groups A1 toA4 couldcomnect to any one of the five call seekers of the group of connecting lines a and-then any .five subscribers in-each of the sub-groups A1, A2, A3 and A4,: could connect to any-of allxthecall seekers .of

the subsequent foursubscriber or connecting line groups b toe. wrThisgives'together'the ,mentioned: twenty-five simultaneous connections of the subscriber groups A1'to'A4. If this examination is continued; it is seen that'with calls from five neighbouring subscribed groups,- the whole of the call seekersand connecting lines of groups a, b, i, could .be connected at the same time: The mentioned. number "of connections occurs, to be sure, only under specially favourable circumstances, butit serves; in any case, as a comparison of appreciating the advance made by thearrangement if Figure 4 compared with that of Figure 3. i L V In the: reversed form of the same connection arrangement. for preselectors of Figure 4a, the previously mentioned modification in the line junctions in the partial multiple II is indicated by the obliquely running branches'of the groups Loi connecting lines a,'b;c

For the explanation of the operation of the connection arrangement of Figure 4a, the sloping branches of the groups of lines a, b, c, .i. may, for the moment, be imagined not to be present so that the vertically running branches within the selector groups consist merely of independent, pure line multiples. These multiples may be regarded as the first half of bundles of double the number of lines. It is known that the first half bundles of line, if they are small and, for.ex-'

ample, contain only five to ten lines, cope with about of the greatest traffic of the groups of double the number of lines. If this supposition that the groupsof lines a, b, c, con-' stitute an independent first half of a bundle is maintained, there can be no doubt that this half bundle with the partial multiple I copes alone with the greatest traific of the busy hour with a remainder of about 10%. The use of the half bundle thus obtained is so good that it is fully satisfactory and does not require any further improvement, as for the excess traffic that cannot be coped with by the half bundles, a group assistance is provided. The carrying into effect of this assistance is due to the fact that within a large number of selector groups, the average trafilc during the busy hour is smaller 'thanthe previously assumed greatest traffic of one selector] group and that accordingly also the excess'trafiic is smaller than 10% of the latter. In accorcL ance with the invention therefore, the obliquely running branches in Figure 4a of the same groups of lines a, b, c with the partial multiple II provided are for the auxiliary groups. The selectors themselves have accordingly a contact field which would, in any case, be necessary in the usual total bundle, while the multiplied groups of lines in the selectors are restricted for the same trafiic density to half the number of lines.

The table in Figure 4a shows a scheme for making up the connection arrangement by a juxtaposition of the symbols of the selecting and selectable groups of lines. The combinations of letters show with which selectable groups of lines theindividual sub-groups of selectors, or their leads, are related. For example, the term Alab, indicates that the sub-selector group Al can con,-

nect with the two line groups a and b. If all the letter combinations are therefore considered i.. .iivill be seen that they are combinations of second lineswhich return from the last to the first group.

of selectors. The form and arrangement of the combinations in Figure '7 agree entirely with those in Figure 4a. The connection diagram of Figure 4a can therefore be obtained directly also iron: Figure 7 if like figures are joined to each other by lines and for each letter a point is placed as a symbol for a partial multiple.

'. A similar analytical deduction should now be made for the connection arrangement of Figurc 4 For this purpose, the capital letters occurring in the combinations in the table of Figure 4a, are grouped with the individual small letters, a, b, c. In this way, for example for the letter a. from the individual transverse rows of the table ofxFigureAa, the/new seriesof combinations a (A1ll-i-A2H2+A3G3+A4F4) issobtained.. This expressionindicates that the-group of lines a now representing a selector group can be, connected to the combination: pairsflof:sub-2v groups of linesv in the bracketsxwhich previously were sub-groups of preselectors-j similarlys'series f combinations can bemade for thelother groups-of conductors b,.c i. The'series' are collected in the table of Figure4 and correspond with the appropriate connection arrangement;

Thiscontains nine groups of selectors .With thirty-six sub-groups of lines in the multiple',=whi1e in Figure 4a,.on the contrary,athirty-six.' subgroups of selectors with ninegroups of lines in. the multiple are contained. each groupof selectors of Figure 4, there :are four sub-groups of subscriber linescombined in pairs; Theyra're corresponding inversions of the combinations contained in Figure 4c and showthesmall let ters exchanged with the corresponding capital letters. The previous similarity between the combinations of Figures 4 and 4a. shows the ex.-: istenceof the same law of formation alsozfor. both connection arrangements, so'that these can beconnected with the same effeotiveness m If, in' the arrangements of Figures .41and"'4a' generally the series n=l to n=10 is given to -the subgroup number; this'gives for-the group num-. berand for thesumof all combinations ot'sec-z ond class without'repetition resulting therefrom the numbers given in the table of liigure- 8.unde1; the'headingsQn-l-l or n(2n+1); n=1 beingthe smallest 1 value with which" the invention is-con-l corned. This value corresponds to the connec-'= tions of Figures 1-, 2 and 11a,@2a.-:. 11.:4 is 'rthe: basicvalue for the connections of Figures'iand' 4m The value n=10 is;practically of -special:

interest because it applies to. selector systems" 1 with decimal group sub-division. In this case,-

there are groups each with 10 groups 01.10 as sub-groups, the multiple of which, full; use, of all combinations of 21 groups of. 100. To each group of 100, there are thuspaccording to.

the density of the trafiic, 5.-to'.9 connecting lines which are either simple Lpresel'ecto'rs w'ith:10 to 18 contacts or 5-to 9 call seeker'sswith'acontact field for twice 100 lines. As eall seekers;.ifdee sired rotary lever selectors could -be' used with l a multiple for twice 100 lines. Theconnectiofi arrangement l gives, with '21 groups of-100,' emciency which approximates to that-"of the 'known double preselector arrangement and err--v ceeds thatof the largestmechanicalslelector for 500 lines provided. call seekers and line. lCliOlS. t f'j 1:. exactadherence to the number's givenior: the groups and the"subgro ups the table; of- Figure'8 is not necessary An-addition to' the:

number of groups relatively to a given number of sub-groups can, in any case, not =be-harmful but only useful. In this respect, reference is made to an earlier statement-made in connection with Figures 3 and 3a. "A subtraction-from 'the.

i number of groups relatively to a given number the following speciaLfeatures in. the 'arrange-i Variations from the previous ment'otl'igure 5. .."The snbagmupo ot thee: pen! of selector-3,; for example A1 and B4, com-ninth: some groups or connecting lines, but the multiple oiall the m1ecb0rimumflw0flded'b! then:- ventiom: makes? dinerent oombimtiom. Time; the :efliciency: oi the varrangement o! FigurerS, apart Iromie. email remains therefore; at: a satisfactory level compnretwith thatlofxFigure lmv t For the use of the connection. in accordance. .with the ,lnvmtion for line selectors, the 1v arrangements tor :with' subscriber lines in .the multiple oome into question. In this connection, it is stressedthnt there is nothing different :inthe makingoithe so that all the previously mentioned characteristics when callseekers are used when line selectors used. As multiple. switches with auxiliary groups havenothithertoheen unknown in; line selectors es. for as: can be: it maybe shown-on the hneisoi Figure 4 how any seized sub-group or. lines, fol-example B1, B2, BI or B-canibe reached!! number selection without translation." choice of these subof lines depends in the first plecmin the known won on. there beingo. @tree :line in; the prearranged group or seleotoraand thus ailineleleetocc! group b-iscove'redz'. :Then,'by. the eeleotionot apenultb mate .-number,.:the setting line-solemn on one oLthesnidimb-mumof linerBl, 32.83. B4-followsvand. hereaxter through eflml number selectionesthe setting; of 01th desired individunl line dthe' lpwoorinte m. This oes on as longiae thereon lumcient lmo selectors-lathe continue, and thin: the no case, earlier wlththo. majority- 201.: calls which during the NI! hourl.-: c-gForlfurthercalle, nde'llntflm to of line selectors is'necessmt'f thilpurpoee the .spe'cinlconstruction dgitht mining; multiple prepares particular grouped! lmoloieotnn nameiy,-zthe selector group c for cells toll, groupsidior calls to 82; calls Ito. -B3,""nnd* lastly. the amour. m l II? calls to: B4.;i-a1t-wili 'bez'leenn-om this ,exn'mfle, m that-dn= the rows of line'eelector m mold togethen-the intervaibetween thole mom g'roupe iorawhichm deviationdi necoclary for: e call to itake place and m ior-thea=celi -inc1eaees in?" witnthe m number=-otthe desired sub-ground; es With the penultimate number 1 'me Ilopinzccu nectings'path ior-eacli -devinted call ll: thne obyiousl-y: determined simplyyhy selection without With this out in multiple. shitting-i oil the leads, it is immaterial how the lead selector melt and the means tor-adjusting theielector has therefore not i been shown oi' desci'ibed in detail.

When' using the switching errengement 0! Fig- 5 ure 3"for lineselectora, there is no difference a regards copingwith the from the-previous-case. It, asiprrevimuly, the mlncriber InhgroupsBif to B4 ere-called, the meiority of the connectiona agoinrun through the Mill muiti- 1 pic I-o1' the group"of line b, where the. above mentionedsubscriberieuh groupe in figures 3 and are-similarly connected. Only inreepect of the deviation oi the calls i'orexceooxtrnmo in Figure? is there any dlflerenee from thev previouscase, which however; iecimplifledhecnme the subscriber sub-groupem' mam creel! connected identically inlthe partial multiplen of the-next followinggroupot line selector: 0. Thtmin Figure 3, only two connecting potln come into ones-u.

tion for all calls from any particular group of subscribers, one of which leads to the group of line selectors which is directly selected by a group selector, or must be deviated over the next following group of line selectors in the row of connections if such are present. In order to be able to find the desired subscriber both in the multiple I and also in the partial multiple II, under the same conditions of numerical selection it is necessary that the subscriber lines be connected in both partial multiples in the same numerical sequence.

I claim:-

1. A telephone installation comprising selectors divided into groups and lines divided into groups, said lines being adapted to be reached through the selectors and the selectors of each group being provided with a contact field adapted to connect the lines of two groups of lines of equal size, two groups of lines being connected in the contact field of the selectors of one group of selectors, and each of these groups of lines being in addition connected in the contact field of the selectors of another selector group, the combination of line groups connected in the contact fields of the selectors varying from selector group to selector group.

2. A telephone installation comprising selectors divided into groups and lines divided into groups, said lines being adapted to be reached by the selectors and the selectors of each group being provided with a contact field adapted to connect the lines of two groups of lines of equal size; said contact field consisting of two partial multiple fields of equal size, the lines of a group of lines being connected in the first partial multiple field of the selectors of a group of selectors, these lines being connected in addition in the second partial multiple field of the selectors of another group of selectors and the lines of one of the second group of lines being connected in the second partial multiple field of the selectors of the first said group of selectors, these lines being in addition connected in the first partial multiple of the selectors of a third selector group.

3. A telephone installation comprising selectors divided into groups and lines divided into groups and sub-groups, said lines being adapted to be reached by said selectors, the selectors of each group being provided with a contact field adapted to connect the lines of two groups of lines of the same size; said contact field consisting of two partial multiple fields of the same size subdivided into sub-fields corresponding to the sub-groups of lines, the lines of the sub-groups of one group of lines being connected in the subfields of the first partial multiple field of the selectors of one selector group, these lines in addition being connected in the corresponding subfields of the second partial multiple field of the selectors of another group of selectors and the lines of the sub-groups of a second group of lines being connected in the sub-fields of the second 7 partial multiple of the selectors of the first said group of selectors, these lines in addition being connected in the corresponding sub-fields of the first partial multiple field of a third group of selectors.

4. A telephone installation comprising selectors divided into groups and lines divided into groups and sub-groups, said lines being adapted to be reached .by said selectors, the selectors of each group being provided with a contact field adapted to connect the lines of two groups of lines of the same size; this contact field consisting of two partial multiple fields of the same size, subdivided into sub-fields corresponding to the subgroups of the lines, the lines of the sub-groups of one group of lines being connected in the subfields of the first partial multiple field of the selectors of one group of selectors, these lines in addition being connected in the sub-fields of the second partial multiple field of the selectors of several other groups of selectors.

5. A telephone installation comprising selectors divided into groups and lines divided into groups and sub-groups, said lines being adapted to be reached by said selectors, the selectors of each group being provided with a contact field adapted to connect the lines of two groups of lines of the same size; this contact field consisting of two partial multiple fields of the same size divided into sub-fields corresponding to the sub-groups of the lines, the lines of the sub-groups of one of the first group of lines being connected in the sub-fields of the first partial multiple field of the selectors of one group of selectors, these lines in addition being connected in the sub-fields of the second partial multiple field of the selectors of several other selector groups alternately from sub-group to sub-group and in the sub-fields of the second partial multiple field of the selectors of each selector group only connected the lines of a single sub-group of this group of lines.

6. A telephone installation'comprising selectors divided into groups and subscribers lines divided into groups, said lines being adapted to be reached by said selectors, the selectors of each group being provided with a contact field adapted to connect the lines of two groups of lines of equal size, this contact field consisting of two partial multiple fields of equal size, the lines of two groups of lines being connected in the first and second partial multiple fields of the selectors of a group of selectors corresponding to the turn of their call numbers, the lines of said line group connected in the first partial multiple field of the selectors of said selector group being connected in addition in the second partial field of the selectors of a second selector group and the lines of the line group connected in the second partial multiple field oi the selectors of said selector group being connected-inthe first partial field of the selectors of a third selector group, each corresponding to the turn of their call numbers.

FRIEDRICH NIERK.

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