14 INTRODUCTORY OBSERVATIONS. 



regard to accuracy ; and true generalisations are in con- 

 sequence extremely rare. 



One section (IV) of the present volume will stUl be de- At. /. /t.y 

 voted to " general remarks," in order to prepare the x. y; 7~ 

 minds of beginners who may use the volume, to under- 

 stand the groupings of details which are to follow those 

 remarks. But as that section, though general, will truly 

 be founded upon elaborated details, the remarks will so 

 far approximate to true generalisations, quite as much as 

 to generalities only. The numerical statements and 

 summaries cannot indeed be put forth as rigidly exact ; 

 but they wiU be sufficiently near to exactness, to claim 

 acceptance as something more sound than the merely 

 vague generalities here objected against, as being almost 

 useless in science. 



