Temperature of the Globe. 337 



rate conception of nature," and a just view of the conse- 

 quences to be drawn from well-arranged facts. If we attempt to 

 conceive the problem of the distribution of temperature in its 

 most general sense, we may imagine the planetary heat either (as 

 in the present oxydised, hardened surface of the earth) to be a 

 consequence of the position in relation to a central body, which 

 excites heat ; or (as in the first state of the condensation of matter 

 dissolved in the form of vapour) the consequence of internal 

 processes of oxidation, precipitation, change of capacity, or elec- 

 tro-magnetic currents. Many geognostical phenomena, which 

 I have mentioned in another paper, seem to indicate such a de- 

 velopement of internal heat, produced by our planet itself. More- 

 over, the doubts raised against the peculiar heat in mines in 

 both parts of the world, have been entirely removed by recent 

 experiments of an ingenious astronomer M. Arago, on water 

 rising up through deep borings in what are called Artesian Wells. 

 The greater the depth from which the water ascends, the warmer 

 it has been found. In this case, there can be no suspicion of 

 strata of air sinking down and being condensed, and consequent- 

 ly disengaging heat ; nor can the neighbourhood of men, or of the 

 lanterns of miners, exercise an influence in this case. The waters 

 carry along with them the heal which they have acquired by a 

 long continued contact with rocky masses at different depths. 



These important observations shew how, independently of the 

 obliquity of the ecliptic in the earhest, and, as it were, youthful 

 state of our planet; the tropical temperature and tropical vege- 

 tation could arise under every zone, and continue, till, by the 

 radiation of heat from the hardened surface of the earth, and by 

 the gradual filling up of the veins with heterogeneous minerals 

 a state was formed, in which (as Fourier has shewn in a pro- 

 found mathematical work) the heat of the surface, and of the 

 atmosphere, depends merely upon the position of the planet to- 

 wards a central body, the sun. We gladly resign to other na- 

 tural philosophers the task to decide, how deep below the oxi- 

 dised and hardened surface of the earth the melted fluid masses 

 lie, which are poured out through the apertures of volcanoes, 

 which periodically agitate the continents and the bottom of the 

 ocean, and force hot mineral springs upwards through clefts in 

 granite and porphyry. The depth of our mines is too inconsi- 



