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was used to gauge when the hot globe had cooled to the same tem-
perature. This Buffon did by placing one hand on each globe and
judging when they were at the same surface temperature. Once he
was satisfied they matched each other he read off his watch the time
that it had taken the hot globe to reach the temperature of the control
globe. This method was not without problems. There was a danger
that he could seriously burn one of his palms, and he noted that if the
surface texture differed between the two 'bullets' then their respective
temperatures were difficult to compare. His results can be seen in
Table 7.1 .
Being a conscientious scientist he tried to replicate the experi-
ments on the same spheres several times, but failed: with each succes-
sive heating event each sphere lost weight as some metal spalled off the
surface. Buffon had to rely on the results from the first run in each case.
Extrapolating these results to a globe the size of the Earth,
Buffon concluded that 'it would take 42,964 years, 221 days, to cool
only to the point where it would cease to burn, and 86,667 years and
132 days, to cool to the actual temperature.' This was considerably
more than the 50,000 years that Newton had suggested for the possible
duration of global cooling, and completely off the scale of the biblical
chronologers!
Did Buffon moderate his timescale in any way? He did, realising
that the Earth was not a mass of iron, and that the presence of other
materials would affect the cooling rate. In addition, the atmosphere
might have acted as a buffer to heat loss, rather like a lagging jacket
wrapped around a domestic hot water cylinder, and if the Earth cooled
in a vacuum this might have had some effect on the resultant cooling
time. Armed with these ideas Buffon carried out heating and cooling
experiments on a variety of materials, clay, marls, marble, stone, lead
and tin that he had moulded or formed into spheres. His 2-inch sphere
of clay took 38minutes to cool to hand-touch, the one of 2.5-inches
48minutes, and that of 3 inches cooled in 1 hour 15minutes. These
times are less than those recorded for the iron spheres. He then heated
1-inch spheres of different material close to the melting point of tin
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