102 Geology as a means of culhire — A. Winchell. 
set forth, and at what finality will it end? No one can fail to- 
understand that these are lofty inquiries; and that any well 
grounded responses must lift our thoughts into the realm of 
sublime truth. But the history of the earth's cooling unrolls a 
vista through the past eternity. No human intelligence has- 
been witness of the events. The future career of the cooling 
globe lies in the folded possibilities of events unreal and stretch- 
ing into the eternity lying in the oj^posite direction. 
But these lofty questions are not unanswerable. The events 
of terrestrial history succeed according to methods which lie re- 
vealed. There is no uncertain caprice in their order and rela- 
tionships. Physical events run in grooves. What we observe 
discloses a trend which may be followed in either direction. By 
observation we have learned the laws of cooling, and the ele- 
mental and climatic changes which depend on changes of tem- 
perature. If the earth be a cooling globe we may with confidence 
deduce its conditions and their concomitances in the earlier 
stages of cooling. Here our reasoning becomes deductive. We 
proceed from the inductive principle of a cooling globe, and 
from the primary principles of thermodynamics, and retrace the 
cooling history. We see in imagination as we recede, a warmer 
terrestrial surface, a more tropical climate, and, in correlation,, 
more tropical plants and animals. We strengthen and verify 
the deduction by the inductive data afforded by the successively 
deeper sheets of ocean sediment. Farther on in the I'etrospect^ 
the sediments are but beginning to accumulate. The mountains 
are still in embryo; the ocean is universal. As the scroll of 
terrestrial history continues to unfold, the ocean itself is noticed 
at its natal epoch; the clouds are discharging the ocean from 
their bosom. Here the possibilities of inductive confirmation 
disappear. Earlier than this no enduring rocky forms had ex- 
isted. The greater heat had reduced all terrestrial matter to a 
fluid state, which retained no records. This is the starting 
point of inductive geology. 
But this is not the starting point of the process of cooling. 
With the eye of imagination under the calm guidance of the 
reasoning powers, we behold in the remoter past, a world of 
firemist, with the beginning of a central nucleus of molten 
matter. In the profounder depths of the eternity past, the fire- 
