XVI PREFACE. 



pathological laws of caloric was essential to 

 the completion of his undertaking ; which at 

 that time he supposed would not require more 

 than twelve months : 



" But more advanced, beheld, with strange surprise, 

 New distant scenes of endless science rise." 



The performance of this task required a 

 vastly greater amount of laborious research 

 than he was prepared to expect, until he had 

 proceeded too far to desist. In the mean 

 time he had the satisfaction of perceiving that, 

 with every additional knowledge of facts, he 

 was conducted to a more elevated point of 

 view, and to more comprehensive generaliza- 

 tions : the consequence of which has been, that 

 in the Preliminary Chapter, he has entered 

 more fully into the rationale of geological and 

 astronomical phenomena, than he had ven- 

 tured to do in the second and third Books. 



In addition to the many difficulties encoun- 

 tered at every step, much precious time was 

 lost owing to ill health, by which the work 

 has been still further and most painfully de- 

 layed, to the disappointment of the Pub- 

 lisher, whose liberality and forbearance merit 

 the grateful acknowledgments of the Author. 



