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Perce bare SJ 
J. R. Mayer on Celestial Dynamics. 405 
If we assume the earth to possess a very great capacity for 
heat, equal in fact to that of its volume of water, which when 
calculated for equal weights = 0°184, the above discussion leads 
to the conclusion that the difference of temperature of the con- 
stituent parts, and of the earth after their union, or, in other 
words, the heat generated by the collision of these parts, may 
Tange, according to their relative magnitude, from 0° to 32,000 
or even to 47,000°! 
‘With the number of parts which thus mechanically combine, 
the quantity of heat developed increases. Far greater still would 
have been the generation of heat if the constituent parts had 
moved in separate orbits round the sun before their union, and 
had accidentally approached and met each other. For various 
reasons, however, this latter supposition is not very probable. 
Several facts indicate that our earth was once a fiery liqui 
ass, which has since cooled gradually, down to a comparatively 
inconsiderable depth from the surface, to its present tempera- 
tu he first proof of this is the form of the earth. “The 
form of the earth is its history.” According to the most careful | 
measurements, the flattening at the poles is exactly such as a 
liquid mass rotating on its axis with the velocity of the earth 
would possess; from this we may conclude that the earth, at the 
time it received its rotatory motion, was in a liquid state; and, 
after much controversy, it may be considered as settled that this 
liquid condition was not that of an aqueous solution, but of a 
7 
well is 671 metres in depth, and its water 34° warm. 
Thermal springs furnish a striking proof of the high temper- 
ature existing in the interior of the earth. Scientific men are 
agreed that the aqueous deposits from the atmosphere, rain, 
il, dew, and snow, are the sole causes of the formation of 
springs, The water, obeying the laws of gravity, percolates 
through the earth wherever it can, and reappears at the surface 
in places of a lower situation. When water sinks to consider- 
able depths through vertical crevices in the rocks, it acquires the 
temperature of the surrounding strata, and returns as a thermal 
eS to the surface. 
c 
om waters are frequently distinguished from the water of 
ordinary springs merely by their possessing a higher tempera- 
