8 Temperature of the Terrestrial Globe. 



trates the e? h and returns into the air. Considering, therefore, a 

 law similar this, which is established of itself in the interior of the 

 globe, I h? obtained the following results. 



In one ath of a year after the temperature at the surface is 

 raised to i iiean value, the earth begins to be heated ; the rays of 

 the sun j 3trate it during six months. Then the heat of the earth 

 takes an posite direction ; it comes out and is dissipated in the air 

 and ext lal space. Now the quantity of heat which undergoes 

 these VF .tions in the course of a year is expressed by the calculus. 

 If the c t of the earth was formed of a metallic substance of forged 

 iron, (t substance which I have chosen for an example, after hav- 

 ing m ured the specific coefficients,) the heat which produces 

 the su ssion of the seasons, would be for the climate of Paris, and 

 for a 5 ire meter of surface, equivalent to what would melt a cylin- 

 drical *luran of ice, having for its base this square meter, and a 

 heig' f about three meters and one tenth. Although the value 

 of coefficients for substances of which the globe is composed, 



has as yet been measured, we can easily see that they would 

 giv esult much less than we have just mentioned. It is propor- 

 tio to the square root of the product of the capacity for heat, 

 cc tered in relation to volume and the permeability. 



e will now consider the second cause of terrestrial heat, which, 



i e think, resides in the planetary spaces. The temperature of 



space exactly defined, is that which a thermometer would indi- 



, supposing the instrument placed in any part of the space occu- 



\ by the solar system, and the bodies which compose this system 



lihilated. 



We shall give a detail of the principal facts from which we have 

 scertained the existence of this heat, peculiar to the planetary 

 paces, which is independent of the presence of the sun, and of the 

 original heat which the earth has preserved. To obtain a knowledge 

 of this singular phenomenon, it is necessary to ascertain what would 

 be the thermometrical state of the terrestrial mass, if it received only 

 the heat from the sun. To facilitate this enquiry we may at first 

 leave the atmosphere out of the account. Now if there existed no 

 cause sufficient to give the planetary spaces a common and constant 

 temperature, that is, if the earth and all the bodies of the solar sys- 

 tem, were placed in space deprived of all heat, the phenomena ob- 

 served would be altogether contrary to what we now witness. The 

 polar regions would be subject to an intense cold and the decrease 



