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- 

 torn ; experiment should shew us the same effect at the bottom of 

 the sea, at least from the depth where the temperature approaches to 



Zero. 



M 



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 go to a much greater depth to find them. 

 Now these low degrees of temperature communicated 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. 



cool 



torn 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 



