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i.-----oueclassified and approved for release by NSA on.__ _ _. 

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• c REF ID:A72380 

Extract from latter dated 

24 .lug. 1950 from Bagalin 

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With regard to the r.1 .. 209: There is a chance tbat the machine for 

T01l m:r be f'1nlahed in about a months time. I rill keep 7011 poatad an 

the progress. 

low '11th regard to the action of the new displace:asnt mechanimn 

'le have still a bsr drum, it carries nov 30 bars, and these bars are 

used not onl,y for the diq>laaement of the t71>a 1::heel, but also for the 

displacement or the key 'l'beels, 1ih1cb are displaced in the same 'Ri7 as 

the tJPe vheel, ioeo with a driving tooth on the bare, over an 

inte:rmad1a17 gear wheel, the proper 1'unctio~L£g being &ssured 't"ith the 

aid of the as.ma kind ot check pa. ul as is usad tor the type ~hefllo The 

bars therefore are normal.l1' provided with two driv:L~g teeth, one for 

one of ths keT weals and th~ -other tor th!l type tJheelo The bars are 

displacecl f'rom their inactive to their active position !.n the samo _,. aa 1n the M•209, i.e. with the aid or guide &fZilS, which are positic•1od 

bJ the pina in the k97 wh.eels, e.nd which a~" on myvaable l1::gs o:i th!? 

bars. \lhile the lugs are moveable: the driving teffth fox:• tha cUspl.!.oament 

ot the key wheels have to be fixed (cd aside from 1the di!ficult;r ~ 

e.rranging moveable driving teeth, thsra would be tob many nodif'i&hla 

element-a in tha machine). To oe candid, I do net. kno\1 e.s yet t'"M.ch. 

groupings of the driving teeth for the kEIJ" 7~sela 1iill be the no~-t 

ef'tect1ve, and therefore n are arranging them en the prGtotyps 1n the 

manner, that the first fin bars carr;v driving teeth to work with kar 

wheel !UO l, t.he na:.:t five bars to work with k9" '\'ihael n:o 2, etc .. , 11ith 

t ive bars tor each k~ llheelo We also put 1?1 one special cL-iving 

tooth on one of the 'bars 1n each of tha ab: groups, which is in active 

position, 11he11 the bar is 1n its ina~t:ive positiono Th'.lll nha:i none 

at the g-ilide arms displace the bare, all tho six key 'I.meals 'ilill b3 

diaple.ccd one step. O'l tho- encloss-d ro.:gb e:keteh I "1..aV'e eh.om tl .. o 

30 bars, and have indicated. en them the driving teoth for 1..he type T.heol 

and the driving t9eth tor the key 'llfheels, a.."':.d also an arrangement of tha 

lugs, chosen at :randomo You will find that tnie na;1 disple.cing mocb.a.~ism (\1hich .a.a davelopsd ror uea with our new teleciphering 

cachines) works on a novel principle1 while the key wheals and the 

position of the pins deter:uine which of the b~rs are to b9 displaced 

each timo, the bars and the pOEition of tha driving teeth Deter:nine, 

which of the key wheels are to be cisplacad and how much. We have thus 

&n intaraction between drum bars and key w1a~ls. 

As I have already mentioned, we do not !O'lO'!" s.s yin. hov tha tlri:ving 

teeth for the ke7 wheals should be best gro~ped, but this ~ill oi' course 

be ma.de subject of a :it:.udy. ProbabJ.,- the g,'l•:>upinga should not bs made 

identical for the different key wheels, and thora woulC. proba~ al30 

be no reason for placing driving teeth for tne kayo ~heels on all tha 

bars, as the number or displacement combina-r.io~s is only 61. (lrl'lich should 

in itself be plentr). 

I hope that this :f'irst 11 le£aon" he.a n~t been complats~ unintelli• 

gible, ancl I trust 70u will as.c ma ror 9%Pla.r1ation o: such poi'"l\.e which 

n~not be clear wO 70Uo 

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