VI PREFACE. 



these studies. Why, then, should not these principles be taught to 

 them, it is pertinent to ask, if it be the great object of education to 

 prepare one to act well his part in life ? And in the case of those 

 who are not to pursue any art in which the principles of natural 

 science are brought into play, a knowledge of the phenomena that 

 abound around us in air, water, and earth is not only valuable as 

 information, and as a source of enjoyment, but also as a means of 

 mental culture. 



The questions in this and the previous parts I have put at the end 

 of the book, believing that when they are nearer to the text both 

 pupil and teacher are apt to depend on them too much. For this 

 reason also I have the numbers refer to the pages, while in the Index 

 I have the more definite reference to the paragraphs. In the Glos- 

 sary there are no definitions, but references to paragraphs where the 

 explanation of the terms can be found. W. HOOKER. 



January, 1SG5. 



