Hot and Thermal Springs. 381 



der the equator ; only that at equal depths, the cold is compa. 

 ratively much greater near the poles than under the equator. 

 But he goes further, and concludes from this, that the deepest 

 abysses of the sea, as the summits of our mountains, are covered 

 with perpetual ice, even under the equator, and therefore con- 

 siders that so many facts are sufficient to overthrow the hypo- 

 thesis, now so generally adopted, of the existence of fire in the 

 centre of the earth.* 



Von Bucht came forward in opposition to this last conclusion, 

 and declared himself hostile to the formidable idea of the exist- 

 ence of such a crust of ice, which is by no means rendered ne- 

 cessary by observation. If, says this ingenious philosopher, the 

 internal cold is felt so near the surface of the sea, should it not 

 also be felt at those depths in the earth near the sea, which are 

 so distant from the surface that the latter can no more have any 

 heating effect on it ? But has there ever been found in the 



" Peron (Annales du Museum d'Hist. Nat., vol. v. p. 123 to 148, and 

 Journ. de Phys., vol. lix. p. 361) found several zoophytes, fished up from the 

 bottom of the sea on the coast oi New Holland, to be 6°.75 warmer than the 

 air and the surface of the sea. He puts the question, Whether the zoophytes 

 inhabiting the bottom of the sea live as the more perfect animals and plants 

 do, in a warmth peculiar to themselves, exceeding, at least in some cases, that 

 of the surrounding medium ? It is a matter of doubt whether plants do pos- 

 sess a warmth of their own (see Treviranus, Biologic, vnL v. p. 3 and follow- 

 ing). According to all observations, namely, those of Schiibler (Poggendorff s 

 Annal. vol. x. p. 581), this is by no means the case. Among animals, birds 

 have the highest temperature ; next to them the mammalia ; then the am- 

 phibia, fish, certain insects ; and lastly the molluscse, Crustacea, and the worms 

 (John Davy in the Edinb. Phil. Journ., vol. xiiL p. 300, and vol. xiv. 

 p. 38). But if, as J. Davy asserts (in a letter to H. Davy of the 18th May 

 )81C, in the Journ. of Science), the temperature even of fish is only 2°.025 

 to 2°.700 higher than that of the water, (see in opposition to this Von Hum- 

 boldt and Proven9al in the Mem. de la Soc d'Arc, vol. ii. p. 598), the tem- 

 perature of the zoophytes must be scarcely perceptibly higher than that of 

 the water. Should the zoophytes, notwithstanding, show a higher tempera- 

 ture, which, however, remains to be proved by more accurate observation, it 

 ought rather to be supposed that such heat is derived from the bottom be- 

 neath, and that they retain it longer than the surrounding water does, which, 

 by becoming specifically lighter, rises and carries its excess of heat to the sur- 

 face, than that it is a heat peculiar to itself 



t Gilbert's Annal. voL xx. p. 341. 



