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IN RllPLY Rllirl!R TO 

REF ID:A4l4BS.8h I ' \.__) I '- _ _, ....---, 

, '.,_ -------------------------------.. -- (: \ / WAR DEPARTMENT, 

I .limg.\Jle.e.J!.\J¥J-·DIVJSION 

and Rese&l"Oh 

Jom1ho 

OFFICE OF THE CHIEF SIGNAL OFFICER, 

WASHINGTON. 

30 September, 1919 

Office, Ohi•f Sipl Oftlaor of the M:rrqJ 

l• In conlpliame with yom: tel~blo request :noe1wd ~steraav, 

tbe Oh1et 9~1 Officer 41reote ne to f'Ul'nlsh you with a atatemant oonoe:rnSng 

tbe Signal Carps method of allotting parts ot the et1pbsr tapes used, in conneotlon 

with the. Printing ~legraph Cipher to the various oft:iOee eo that 1n one dayts 

busi mss no overlap w111 oocut. 

2. As JOll have ah'eacly 'been 1nfo'l'ltB4t tbs nAtt tape is the lon~r 

ot the t_, te.J;ea. l.et '0:8 sq, for el'.BDiPleo that tbe "A" tape ms a total of 

691 c.tarsotere am th& "B" tape bas a total ot 590. The total nDDG.ler ot Oha.raoters wbicb oan be produoed b1 t'.bese tapes 1s evidctlf 591 tines 590 or 

M8t690. 'Rhle munbe:t Of oom1mt1ou is oaloulated to l:e more tha.n enough tor 

one day's bueineas of all tov sts.tlom, vrh1ch we as&mm U1 tb1s example 

ls the total Jmmbel' ot Printlt8 !elegt'a.ph ets.Uons to be provided with a oipber 

kB1• Aas-1ng that both "A" and "B" tapes are started w1tb the Se.Jl9 setting, 

"001"• and assuming that both tapes uale one revolutlon, wJ:en we :reach the 

592114 o?araater we age.in find on t?a "A" tape ttOOl" but an tb& "B" tape "002.n 

-BY the sane prooe&e when one mol"e revolution of tbe "A" tape ha.e been completed 

so th&t 1 t again rs els "001" o the "B" tape :reading will be "003." If we aasmm 

that tho iq'e businesa ot all f'olDl stations is •qiial, it w111 be o'bVia11sly 

neceeeoy to allot t of the totnl number of possible combtuatlons or abOut 

87,172 comblmt i(lle to eanb station. In otmr ~l"de, if we were t;o sit down 

and make one long singls tape by constantly add1D8 thO "A" tape and the "B" tape 

togetlSr until we bad returned to the point Wb)re tbe setting "00ln on the "A" 

tape woa.ld coin.old& 8'1.6Ctly \-d. th the eettll@ "001fl on tlle "B" tape we would 

bllve a third to.pe Of 34Bt690 oblraotars which we could out into qliarte:rs aJld 

assign tbe fil'et quarter to "A" statian, the seoond quarter to QB" eta.ti.on nnd 

the third quarter to "Cf etetion end the ~rth quarter to "D11 station, or 

What 1a more comrenient arli pre.otical. we ea.n divide the total number Of 

Ohamotfl}rs on the "A• tape by tour and thus dsteJ'!ni!le the etm-tiq: points 

on the tape to be assl~d to the tour etatlom. ~ 591 divided by 4 

gives 14'1 plua so t:tat tbe s1artlng points are 14'l ohanoters ~t on the 

"A" tape. It is quite obY1ous that b;v starting the "A" station, for example, 

with "001" as its "A" settitU an4 wlth 0 001 .. ae 1te "B" setting, and starting 

the "»" station. de;,v'e bllainees With setting 147 on the "A" tape Bl'ld CtOOl" 

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~~~~-:--~~~&~p-pr~o-ve_d~fo_r_R_e_1e_a_s_e_b_v_N_s_A_o_n~11_-_1_s-_2_0_14~p-u-rs_u_a_nt_t_o_E_.o~.-13_5_2~a~-,......,.--~~~j 
s _: I' f} " 0 r~' "1 

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IN REPLY REl'ER TO 

WAR DEPARTMENT, 

D OFFICE OF THE CHIEF SIGNAL OFFICER, 

-----------Oii-"tlii ~'BW ~1.l!tt and sta'l"Ung nc•~.m.th 294 OD the "A" tape and 9 001" 

91' the 0 1\11 ta.[8 ·and starting "])" station ·wi 01 tb.& eettlng 441 OD t:te 11A8 tape 

and n00l9 OD tbe 11:81' t&Je• m will haw i:nslU'ed tbe allooaticm at *Of tbs total 

number of oombimtions t.o each station w1 tb>ut 6117 overlap taking plaoe 

between. the tm"t alloted/ to tbe"A" station and tbat alloted to any otbar 

station. 1f the stations start to enclpmr each COl'l9$Utive nessage at the point 

wbere each ~ceeCng rressage stops. !'o flb• that thiS. le so. tlere is append,4 

hereto a table based 'lll>Oll tie su:ppasi t\an that th~ 0 A", tape is 12 Clharuoters : 

long an4 the *'B9 tape ie 11 dlaractas lone. au!l tmt 132 Cbaraeton will ooverthe entire d.a.?1 8 bu.siness ot the ibm' stations. By 0111" nl.e, if there ware 

tow stat1om9 we might instmot aA-n e~lon to start setdlng its d~e bwlness 

with the setting 11001n- an tbe "'A0 tape and "001" an the "B"' tape; the ... J)D 

station W1 th the setting "0041' on the "A0 tape BJJd "001" on tJ:leftlft tapi; the 

"C" st.atlcm wt tb tm setting -00"11' on tbe nAn tape. "001"e>n ttle "B" tape, antle 

the D~ station wl th the setting "010"· on th& "A" tape and "001" on tlle ".8" 

tap,e, Gild• by this meam. as seen from the table appended. we would ha:ve assur~ the allotmnt t.o each &t&.ti<JD at exactly 1t ot tle total ntmller of 

Characters. obtainable by the combimtion ot tl:es~ two ta119s. 

The i-e4 IJ&l"kS in the table in'lioate the limits of the combinations 

assigned to each station. In this case. ne by O'm' rule, the total number 

ot aoob'l.nations '-5 obtained by multiplying. tba total nmri:ler of obaraeters 

on "A" tape by the total mmber of cha'3C·ten on "B" ta.De• giving us 132 

cqmb1nat1 (llS, 1: Of v.bicb are allotec1 to caC'h one of the stations.. lt' is 

seen firom this tab~ that if the clal'·e business ls o-cmf'lmd by order to the 

ba.m1 Qf- characters ~oted to each staUon, tb.e1"9 will le no overlap 1n Sfl'8 

plao~ •. f!e table.· ot c.ourse. Should be rea4 hom top to bottom in eae.b 

eolJJlllD amt the col'GDl11S should ba rea<l in Ol"4er ft'Om left to right, so as to . obtain a ·co~lete sequence, Of co:d>f.mtions as thEW would aotuelly a.!>PSar by 

the a&U t1 an of these two tapes. 

3. It ia to be noted that in praotice we do not asGignthe 

combination "001" en tJ& 8 A0 tape as a stsrt1ag point_ for any station. If 

tm> tai:eo were UH4, "A" '181 and nr 486 long fOl" .example, it is q,uite possible 

tbat the allotment to tbe four statiom would read _ 

"A" , n.a• 

"A" station 029 ~l 4 upon as ti. d.aiJ'*'a 

'Wsiness tor eaoh ~~~ ~"'1• r&ral1J being requtrecl to handle 

lllDl'& business ttlan~tifnhel\\15med1'ifo grester- aUotmmt of combinatiom. 

depending upon how 'l!ISDY nessages cov.14 ~ aG8'iHI• 

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--- -- - --"-------------. 0IV19 ION 

WAR DEPARTMENT, 

OFFICE OF THE·CHIEF SIGNAL OFFICER, 

' WA8HINCJTON. 

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4. In case this ellpleZt.atiOJ'l ls '1ot sa.t1sfaot0r1. a-eqmst tmt 

you G:umaan!oat$ fUl'ttler on tlB sa.bJ ecst., · 

f 

J. o. MSa.bo:rgn&, ~ieut. uoi., o~l uoii.s 

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REF ID:A414BBB2