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To a OIC, Projects Section, Cl'Jptolog1o Branch 

'· .,/ Sub jeot I Proposed S7atem Por Guaranteeing A Minimum C7ole Of 

Great Length In AnJ Irregular Motion Rotor System 

A• It ia propoaed tbat an1 tho~uahl.7 1rregula motion 

a7atem whatsoever be used, 1nclwl1ng $1gaba tJje, or patterns 

ot notohe• and COM motion. 'fb1a ayate,m aball be dev1aed ·;~ 

aol•lJ tor erratic motion, with no aaor1tic1n~ of unpred1ct- ab111ty to insure &.Am1n1~wn 0101e. 1 ~ " cq t..,. ~ 

Be It 1• ful'ther proposed that aJe1mple device be in• 

olucled aa deaorlbed below which •ball tiave a definite known 

period. Tb11 device will 1n effect interrupt the erratlo 

motion ot the rotor1, 1n an irregular {manner aocordiDJ to 1ta 

known cyol•• 81noe tb1a device baa one function onlJ and 1• 

to involve no oontr1but1on to aecur1tj •• a dota11 of erratic 

motion, 1ta oomponenta, notches, etc. •hall be fixed 1n the 

moat expedient ~at.tern. 

--;:;)~"t<. ~~ --

I propose 4 l/S" tb1ok aluminum 411ka each atta;~:g to a , ~ · ~-, "'"', stamped. c;ear wnea1 ot the type found 1n the ••209• ,_gear 3: · - ,. ii · shall" u 4-n\Jlliln ·pr~ to each other and of euob a number tbat . · . 'the- product ot tbe flu will be a c;,cle long enough to permit - - -fl-.- _~, ~ . · .. hour operation at maximum apee4 without reaett1ng and with• \ 

out repetition ot the cyol•• Number• eucb aa •a• 461 ,9, 51,......_ ; fulfill these requirement•• · -

These di•kl lhall be on a common •haft and advanced. ii o. -.• ~ 

tooth 

at a given 

for each 

point 1tep aa 

of 

in 

the 

the 

machine• 

M•209• 'l'he;y aball each , ~ , , , ' 

Thero shall be on tbe per1metera of these 41aa a autt1cent numl:>or of notc~ea so that at a 51ven percentage of the 

time tour notcbea will be a1multaneoual7 ettect1,,... Whe"ever 

tbia oonditlon oooura the interrupter aball operate bys 

•• Deny1nc atepp1ng of one or more relat1ve17 ta1t roto~a 

or- ~~ntrol rotors. 

b• Oi~ ~1 atepp1ng a relatively slow t-otor. 

c.OA l1 rever11ns any· 1' or a: of the rotora, 1.e., if 

rotor 2, tor example, was by reason of the atepp1ng a7atem aet to move, 1t would not, 1f 1t wae not aet 

to move, it would• Thia removes to the greateat deBl'ee predictability ot the action of a rotor becauae 

ot the known interrupter aettingJ a diaadvantage of 

•• and b. 

9 __ ~.. l t "" 4 t 1 . -""' Irregu ar pa terns are no ou~ec to the nterruptere 

;- ~.t.91'• on a siven d1ak ev817" f1tth~poas1ble notch 

.\.... -·• , would not be ettect1~e• ,~';.'!. .. example'_, 

eclassifi ed and a roved for release b ursuantto E .0. 1352 
e a W R~f.rn:~Q2,ll·,.I' U, :.n.1 ... -"' \,,._;; .. ~~ W A I OP. •"'I-· - I 

S1noe W... funct1on~1• limited, t:ke ild;t:i@:!i#~r need 

add no compl1cat1ona to the aett1ng of the machine 

either tor each meaeaae, or da11J• It could have a 

pin in each d1ak, 10 that at tbe end of each message 

a button coul4 be pressed and·bave a11~~~41aka automat1cally return to the same setting. ·c,1..,. ,1 r. 

Thia device would permit 6zteater tlex1b111ty of 

systems, a1noe they could be uaed cont1nuoual7 on 

lino without fear ot ultimate depth.a tor extended 

periods of time• 

I>av14 Wagner lat. Lt., Signal Corpe Oryptolog1c Branch