64 THEORY OF THE EARTH. 



our intention to criticise their authors ; on the con- 

 trary, we are ready to admit that these systems 

 have generally been conceived by men ol science 

 and genius, none of whom were ignorant of the facts 

 on which they reasoned, and several of whom had 

 made extensive journeys for the purpose of examin- 

 ing them. 



Whence comes it then, that there should be so 

 much contrariety in the solutions of the same prob- 

 lem, that are given by men who proceed upon the 

 same principles ? This may have been occasioned 

 by the conditions of the problem never having been 

 all taken into consideration; by which it has re- 

 mained hitherto indeterminate, and susceptible of 

 many solutions all equally good, when such or 

 such conditions are abstracted ; and all equally bad, 

 when a new condition comes to be known, or when 

 the attention is directed to some known condition, 

 which had been formerly neglected. 



21. Statement of the Nature and Conditions of the 

 Problem to be solved. 



To quit the language of mathematics, it may be 

 asserted, that almost all the authors of these sys- 

 tems, confining their attention to certain difficul- 

 ties by which they were struck more forcibly than 

 by others, have endeavoured to solve these in a 

 way more or less probable, and have allowed 

 others to remain unnoticed, equally numerous and 

 equally important. For example, the only diffi- 



