Remarks on the Geology of Maine. 69 



more elevated ; it would arise from the contact of the air, and 

 from the radiant heat of the stars, smi, earth and atmosphere ; but 

 the first of these could have little influence, from the extreme 

 tenuity of the fluid ; so that the mean temperature indicated by 

 the thermometer would difler very little from that which it would 

 indicate if it were removed from the atmosphere and placed a 

 short distance above it. 



*at ^ff •&• -^ .u, .SA. 



1r TT TT •Jr TT TV 



Note. — In the proceedings of the Academy, on the 17th of 

 April last, the following passage occurs : 



" M. Poisson presented a supplement to his work, entitled The- 

 orie Mathematique de la Chaleur. This supplement is consti- 

 tuted of the Memoir upon the Temperature of the solid parts of 

 the Glohe, of the Atmosphere, and of those regions of space tra- 

 versed by the Earth, which was inserted in the Compte Rendu 

 de la seance de I'Academie of the 30th of January last ; and to 

 which the author has added several notes, relating, principally, to 

 the temperature of the earth and of space, at diflerent epochs. 

 One of these notes contains the complete determination of the 

 laws of refrigeration of a sphere of very great diameter, as the 

 earth, for example, which has not before been deduced from the- 

 ory. Another contains an example of the calculation of the tem- 

 peratures and densities of the atmospherick layers, regard being 

 had to the propagation of heat from layer to layer, and to the con- 

 ditions which terminate the atmosphere ; that is, to the condition 

 of an elastic force which is nothing in the upper layer of the at- 

 mosphere ; which can only result from a temperature of this layer 

 proper to its liquefaction." 



Art. III. — Miscellaneous Remarks on certain portions of the Ge~ 

 ology of Maine, in a letter from Dv. Charles T. Jackson, to 

 the Editor, dated Boston, Nov. 13/A, 1837. 



TO PROF. B. SILLIMAN. 



Sir — I HAVE lately returned home after spending five months 

 in the continuation of the geological survey of Maine, two months 

 of which time has been spent in the forests of the public lands of 

 that state. 



