ONE SOUTH WILLIAM STREET
                            NEW YORK
 
                                        October 11, 1939
 
Dear Mr. President:
 
              With approaching fulfillment of your plans in connection with revision of the
NeutralityAct, I trust that you may now be able to accord me the opportunity to present a
communication from Dr. Albert Einstein to you And other relevant material bearing on
experimental work by physicists with far-reaching significance for National Defense.
 
              Briefly, the experimentation that has been going on for half a dozen years on atomic
disintegration has culminated this year (a) in the discovery by Dr. Leo Szilard and Professor Fermi
that the element, uranium, could be split by neutrons and (b) in the opening up of the probability
of chain reactions, - that is, that in this nuclear process uranium itself may emit neutrons. This new
development in physics holds out the following prospects:
 
          1. The creation of a new source of energy which might 
          be utilized for purposes of power production;
 
          2. The liberation from such chain reaction of new radio-
          active elements, so that tons rather than grams of 
          radium could be made available in the medical field;
 
          3. The construction, as an eventua1 probability, of bombs 
          of hitherto unenvisaged potency and scope: As Dr. 
          Einstein observes, in the letter which I will leave 
          with you, "a single bomb of this type carried by boat 
          and exploded in a port might well destroy the whole 
          port together with some of the surrounding territory!"
 
              In connection, then, with the practical importance of this work - for power, healing and
national defense purposes - it needs to be borne in mind that our supplies of uranium are limited
and poor in quality as compared with the large sources of excellent uranium in the Belgian Congo
and, next in line, Canada and former Czechoslovakia. It has come to the attention of Dr. Einstein
and the rest of the group concerned with this problem that Germany has actually stopped the sale
of uranium from the Czechoslovakian mines it seized. This action must be related to the fact that
the son of the German Under-Secretary of State, Karl von Weizsaecker, had been an assistant at
the Kaiser Wilhelm Institute in Berlin