432 ON THE DIFFUSION OF HEAT 



that amid all the revolutions of the heavenly bodies, an or- 

 der exists whence the irregularities arising from their mutual 

 actions do not increase, but are so adjusted, that when they 

 reach certain limits they recede, and within this state of oscil- 

 lation the stability of the entire system is for ever secured. It 

 would gratify the mind, could it be shewn, that a similar sys- 

 tem exists with regard to the subordinate parts ; or if not, that 

 a state of permanence in these parts will be ultimately esta- 

 blished, compatible with the operation of that more general 

 law under which the order of the universe is maintained. In 

 the structure of the globe, however, and in the operations to 

 which it is subject, there are evident causes of disintegration, 

 which seem incompatible with a. state of permanence, and from 

 which, in the progress of time, those arrangements which con- 

 stitute it a habitable world must apparently be subverted. For 

 the Huttonian Theory has been claimed the praise, (with what 

 justice need not here be inquired), of unfolding a system of 

 renovation corresponding to this waste. In the opposte Theo- 

 ry, no similar attempt has been made ; its object has been 

 merely to trace the arrangements which exist in the mineral 

 kingdom, and from these to infer the order and mode in 

 which they have been framed ; nor have any causes been 

 pointed out, as, indeed, none seem to follow from the princi- 

 ples of the theory, by which that disintegration, the occur- 

 rence of which in past periods is so clearly marked, and the 

 operation of which, even at present, is to be traced, may be re- 

 paired. 



If the view, however, which has been given of the relation 

 of the temperature of the earth to solar heat be just, this defi- 

 ciency may perhaps be supplied. Inequality of temperature 

 is the great source of change and of disintegration at the sur- 

 face ; the expansion and contraction from alternations of heat 



and 



