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ratios. Harrison Brown of the University of Chicago, mentor to the next person we
ferent countries, minds were converging: to measure the age of the Earth, use the
primordial lead in meteorites. But in the aftermath of a devastating world war, only
the United States had the scientists, methods, instruments, and funds to do the ex-
periments.
Brown had worked during the war on the Manhattan Project, one of whose ma-
jor tasks was to separate the two isotopes of uranium, which was necessary since
the rarer U-235 is the only one of the pair that can engender a neutron-based chain
reaction. In order to monitor how well the separation had succeeded, scientists
analyzed the abundance of the uranium isotopes using a mass spectrometer. When
Brown returned to the University of Chicago after the war, he knew that scientists
could also use a “mass spec” to measure the isotopic composition of lead in met-
eorites.
FIGURE 4
. Clair Cameron Patterson (1922-1995).
Source
: Courtesy of the Archives, Califor-
nia Institute of Technology.
Brown soon moved to the California Institute of Technology, where he joined
forces with just the right person to undertake the measurements: a graduate student
tion's fine liberal arts colleges, Grinnell, earned a master's degree at the University
of Iowa, and when the war began, joined the Manhattan Project, where he learned
mass spectrometry.
Brown assured Patterson that the use of meteorites would be “duck soup” and
one of these assurances would come true. Patterson's research took seven years
and required the building of an entire new laboratory and the invention of novel
techniques.
Brown had based his optimism as to how long the work would take on chemical
analyses that had shown that iron meteorites contain enough lead to make it easy
