Measures for Progress: A History of the National Bureau of Standards

HEAVY WATER 363
research, in which the Bureau ought to become He and his
committee hesitated.
In April 1940, when the committee met at the Bureau for a second
time, with Pegram and Fermi also in attendance, it learned that only the
U235 isotope of uranium fissioned under bombardment by neutrons of thermal
(slow) velocities—a significant discovery, provided U235 could be sufficiently
concentrated. And it heard that a large section of the Kaiser Wilhelm Insti-
tute in Berlin had recently been set aside for research on uranium. Yet on
that occasion, and at another meeting in June, the committee adjourned with-
out making any definite recommendation except that funds should be sought
to support further investigation of isotope separation and the possibility of
a chain reaction with U235.'85
A month later the committee, with Pegram, Urey, Jesse W. Beams of
Virginia, Merle A. Tuve of the Carnegie Institution, Ross Gunn of the Naval
Research Laboratory, and Gregory Breit of Wisconsin as new members under
Dr. Briggs's chairmanship, became the Uranium (or S—i) Section of the
National Defense Research Committee (NDRC), set up by the President under
Dr. Vannevar Bush to mobilize science for war.lSG As with other research
for national defense turned over to it, NDRC was to contract for S—i research
and thereby accelerate the program.
Responsible for formulation of the S—i program, Briggs at once urged
support for the determination of the fundamental physical constants of
uranium and graphite and experimentation in the chain reaction. Fermi
began his first uranium and graphite pile at Columbia. Urey, with Briggs's
encouragement, continued his study of heavy water as a graphite substitute in
a chain reaction.187
In June i94i, as the scope of research expanded, NDRC was sub-
ordinated to the Office of Scientific Research and Development (OSRD),
established to direct the entire research resources of the Nation and close the
gap between research and procurement for national defense. The S—i
Section, now directly under Dr. James B. Conant as head of NDRC, but with
Dr. Briggs continuing as chairman, was transferred to OSRD. When in
September i94i reports of British progress in nuclear research aroused con-
cern over the lack of results here, Samuel K. Allison of Chicago, Edward U.
184 Continued investigation of heavy water had been the first area of research that the
Visiting Committee in 1934 strongly recommended be discontinued at the Bureau. See
above, p 34.5.
181 Henry D. Smyth, Atomic Energy for Military Purposes (Princeton University Press,
1945), pp. 48—49; Hewlett and Anderson, pp. 22—23.
188 A facsimile of the letter from the President to Dr. Bush appears in Robert E. Sher-
wood, Roosevelt and Hopkins: an Intimate History (New York: Harper, 1948), pp.
155—156.
187 Hewlett and Anderson, pp. 26—29. -