16 Temperature of the Terrestrial Globe. 
solutely stationary. But if this be true, it is impossible that there 
should be found at the bottom of the ocean, beds of water lighter 
than the superior beds, and consequently currents could never be 
produced. 
If on the contrary the 400 degrees of temperature which would 
be found at the bottom of the sea, in case the surface at the bottom 
was covered with terra firma, are still freely discharged into the ocean, 
then, this heat, especially about the protuberances which are more or 
less elevated above the mean level of the bottom, would form, in- 
deed, currents which would mingle the inferior and superior temper- 
atures as M. Fourier admits. But then it is indubitable that the 
mean inferior temperatures are always a little higher than the superi- 
or, as takes place in a boiler full of water when heated from the bot- 
tom; experiment should shew us the same effect at the bottom of 
the sea, at least from the depth where the temperature approaches to 
Zero. Further, the theory of M. Fourier tends to prove that even 
the 400 degrees above cited can only give out very low degrees of 
heat in the ocean, because the 400 degrees have not, for ages exist- 
ed at the surface of the earth which supports the ocean but that it 
would be necessary to goto a much greater depth to find them. 
Now these low degrees of temperature carmmanteaed to the inferi- 
or beds of oceans, are not capable of producing any sensible cur- 
rents, still less those rapid currents which M. Fourier appears to 
admit. ‘Thus the internal heat of the earth admitted in the hypothe- 
sis, can in no wise cause the low temperature of the bottom of the 
waters. 
But the illustrious geometrician has recourse to the polar regions. 
Let us see if the solution of the enigma can be found there, and first 
what are the means, and what ought they to produce. At the lati- 
tude of 70° to 71° the mean temperature is equal to Zero, and it is 
from the water between that point and the poles, that we should ex- 
pect to find the desired refrigeration. We cannot suppose the mean 
temperature of this to be less than—5° C.; in as much as the poles 
are actually covered if not with earth, at least with ice of an enorm- 
ous thickness, which weakens the radiation of the heat of the water 
found below. Such are then the means whose effect is to cool the bot- 
tom of the sea to the temperature of Zero of the thermometer, what 
mean temperature should we admit the entire ocean to have, as the 
proper heat, given to it by the incandescent globe, if the refrigera- 
tion by the polar waters had not taken place? we have found this 
