Some recent work by E. Fermi and L. Szilard, which has been communicated to me in manuscript, leads me to expect that the element uranium may be turned into a new and important source of energy in the immediate future. Certain aspects of the situation which has arisen seem to call for watchfulness and, if necessary, quick action on the part of the Administration. This new phenomena would also lead to the construction of bombs. . . . A single bomb of this type, carried by boat and exploded in a port, might very well destroy the whole port, together with some of the surrounding territory. However, such bombs might very well prove to be too heavy for transportation by air.
Source: Ltr. to Pres. F.D. Roosevelt, Aug.2,1939, resulting in funds to develop the atom bomb
Contributed by: Zaady