Nov. 19, 1923 WILLIAMSON AND ADAMS: DENSITY IN EARTH 427 
denied. The proposed density distribution merely attempts to 
harmonize certain known facts regarding the mass and moment of 
inertia of the Earth, the velocities of earthquake waves, and the 
compressibilities of rocks. 
The distribution here described is shown graphically in Fig. 3 
(full-line curve). At the boundary between the various zones the 
corners are arbitrarily slightly rounded. This diagram also con- 
tains, for comparison, a plot of Goldschmidt’s distribution (dotted 
lines), and the density according to Laplace’s law (dashed line) with 
surface density 2.7. 
roe 
28 = 5 r vai 
% 
4S 
| 
| 
16 ~ t 1 
/2 1Z H — | 
fressure, itions of “Jega bars 
» 
8 = 4 T 
04 = : ar r 
0 P00 7600 Zoo 3200 4000 ZS0O S500 600 
Deplh 17 Hilomerers 
Fig. 5. Pressure as a function of depth, derived from the full-line curve of Fig. 3. 
Fig. 4 is intended to illustrate the segregation of iron toward the 
center and the fringe of pallasite surrounding the iron core. The 
depth of the surface layer—60 km—is shown to scale by the thickness 
of the outer circular line. 
Pressure in the Harth. The pressures corresponding to the present 
density distribution were obtained from the equation 
iii < 107° gp 
aan 2 a 
e 
