20 State of Earth’s Interior. 
In the foregoing I decline to fix the limits to any one of the five 
regions of the section, and content myself with showing that they 
must all find a place, and in precisely the order named, and for the 
reasons named. 
All the above is strictly in accordance with observed facts, and 
as strictly in accordance with the laws of heat under pressure, both 
acting on the same matter at the same time. 
L have strictly refrained from special theories, and thereby have 
avoided personalities. 
SOURCES OF EARTH’S INTERNAL HEAT. 
First. The source of the primary heat of this internal mass was 
the arrestment of the cosmic motion of the atoms, by centralization 
under the laws of gravity and rotary motion of the mass about 
Earth’s axis. The free descent along the line of the axis must 
have resulted in an exceedingly high motion, and this motion was 
arrested at the centre, and in the growing nucleus, forming by 
their union. 
Second. The heat, thus evolved, initiated chemical action among 
these atoms thus rushing in. These were the sources of the original 
nuclear heat. 
When the mass was solidified, the heat was so high that very 
many of the superficial elements existed in their gaseous state only, 
forming an envelope around the central heated mass. 
Finally, when this central mass had so far lost its fiery energy 
as to permit their descent in a liquid state, they descended in the 
order of their respective heat-endurance. Now, in their turn, 
they began to solidify, and form the outer crust. 
Last of all, when the outer coating of this outer crust had 
reached the proper temperature, the water began to condense on 
the tops of all jutting peaks. Chemical action again set in as this 
water reached the alkine minerals. Here was another accession of 
heat. 
In due time Earth became productive of living organisms. 
Water began to tear down the incipient mountain ridges, carry the 
debris down into the young ocean, and there form the sedimentary 
rocks. The thin crust frequently bent beneath their accumulating 
weight, and brought these half-formed rocks within the influence 
of this internal heat. Chemical action again, to a greater or less 
degree, modified them, and they were hardened into rocks. 
