Geophysical Abstracts 152 January-March 1953

50 GEOPHYSICAL ABSTRACTS 152, JANUARY-MARCH 1953
to be the same as that of meteors, one-third iron, uranium, thorium, potassium,
and actinouranium, and two-thirds stony material. As the basic premise the earth
is assumed to have been formed by a cold process, so a homogenous distribution
of radioactive substances in the initial phase of the process seems quite probable.
Constant density and heat capacity of the earth, independent of the depth, are
also assumed.
The intensity of radioactive heat production computed from recent determina­
tions of decay constants, resulted in greater heat generation in the beginning of
geologic history than at the present time. Applying the method of images, ex­
pressions were derived for the temperature in the center of the earth for the past
time, for different assumed ages of the earth; for the variation of temperature
with depth. The great thermal inertia of the earth, due to very low heat con­
ductivity, leads to conditions where the exterior surface is cooling, while near the
center the temperature continues to rise. The computed quantities are presented
in the form of rapidly converging series. S. T. V.
14353. Bikitake, Tsuneji. Electrical conductivity and temperature in the earth :
Tokyo Univ. Earthquake Research Inst. Bull., v. 30, pt. 1, p. 13-24, 1952.
Eikitake's previous work on determining the temperature distribution within
the earth from the distribution of electrical conductivity and the theory of
ionic crystals is revised for greater accuracy and to take into account changes
in physical conditions above and below the so-called 20° discontinuity. Consider­
ing the pressure-effect of the conductivity it is found that the temperature is
probably 1,000 K just below the crust and then increases almost proportionally to
depth, the rate being estimated as 1.4 K per km. This distribution is roughly
consistent with the density and bulk modulus distribution determined by Bul-
len. M. 0. R.
INSTRUMENTS AND METHODS OF MEASUREMENT
14354. Tavernier, Paul, and Prache, Pierre. Influence de la pression sur la re-
sistivite" d'une thermistance [Effect of pressure on the resistivity of a
thermistor] : Jour. Physique et Radium, tome 13, no. 7-S-9, p. 423-426,
1952.
Experiments indicate the variation in resistance expressed as the fractional
change &R/Ro, of a thermistor subjected to pressures P up to 5,000 kg per cm2
is given by &R/Ro= 4.6 XIO"6 P and is independent of temperature in the range
between 30 and 70 C.' The correction to rough data is of the order of 0.01 de­
gree for pressure of 100 kg per cm2. Details of the experimental set up are
given. M. G. R.
OBSERVED TEMPERATURES IN THE CRUST AND HEAT FLOW
14355. Revelle, Roger, Maxwell, Arthur E., and Bullard, E. C. Heat flow through
the floor of the eastern North Pacific Ocean: Nature, v. 170, no. 4318, p.
199, 1952.
The thermal gradient at 6 places in the eastern north Pacific ocean floor was
found to be about 1.2X10~6 cal/cm2/sec. This is the same order of magnitude as
in continental areas. A possible explanation is that the heat is generated by
radioactivity, the total amount beneath a unit area of continent or ocean being
the same when summed to a depth of a few hundred kilometers. M. (7. R.