'B 4sk Doc- i Zr f vJ-S vvk - cc boctr er14-s GE L S FlED j cF 88o32g MS Bf I' HC 4 - DECLASSIRfD C Tlaar V r President I hand you herewith the report of the I ational academy of Sciences Committee on Uranium Bombs This American report proves to be somewhat more conservative than the 3riti h report the findings of which I summarized for you and ago ' 'allace a few%eeks This may be due to the fact that the Committee included some hard-headed engineers in addition to very distinguished physicists The present report estimates that the bombs will-be somewhat less effective than the British computations showed although still exceedingly powerful It predicts a longer interval before production could be started It also estimates total ooste much higher than the British figures although their costs are at present necessarily based on vary rough estimates P'evertheless the matter as presented de- cidedly calls for serious attention - I am now forming a carefully chosen engineering group to study plans for possible production I am also taking steps to further accelerate those parts of the research in physics which are aimed at furnishing data for design of a possible plant In accordance with your instructions I have stated the status of the subject to Secretary Stimson and general I arshall and I will keep them and also r ' lallace posted and give them copies of this report Considerations of policy as distinguished from technical matters are being limited to this small group and Dr Conant I have however discussed the financial problem which may be faced later with r Smith S1 t OLur 'a v%1-S A ti t r ca b o c k r l c p DECLASS'FlED e of r'y 63 y21- 4S DECLASSIFIED $1201$ 45 czf H 11 r1C_ kA ' t Ct rl --- 1 will be glad of course at any time to exthe matheplain any part of this report to you where matical language may need interpretation or to supplement this treatment of the subject with further data a copy of I plan with due caution to placesince we have this report in the hands of the British aspects the had full interchange on the scientificinstruct meofothersubject unless of course you should wise On the long-range aspects of this subject which I will wait are so full of dangers and possibilities to be instructed by you before taking any step which would commit us to any specific program Respectfully yours