INTRODUCTION 



WHEN I was a boy in a country school a forward-looking teacher 

 placed in the school a textbook entitled " Natural Philosophy." 



This book was a storehouse of information. It described in 

 simple language various kinds of natural phenomena. It was 

 an introduction to the science of interesting everyday things. As 

 a result of the study or reading of this book many of us began to 

 understand in a new way the world about us. 



It contained little mathematics. Such mathematical problems 

 as it did present could be solved by arithmetic and were not so 

 difficult as to detract from the interest of the book. 



In the intervening years I have always regarded this book as 

 most valuable. I have heard one of the most distinguished physi- 

 cists in our American universities say that books of this kind did 

 more to popularize science for the masses of the people than any 

 similar books with which he was acquainted. 



Since that time applied science has of course been greatly ex- 

 tended so that it touches our common lives at more points than 

 formerly. 



Mr. Daniel R. Hodgdon, a science teacher of experience, has 

 prepared a book similar to the one I have briefly described, as a 

 contribution to the field of general science as it exists to-day. It 

 is simple, it has little mathematics, it is free from technicalities, 

 it makes no pretense of being exhaustive, and it is, moreover, very 

 interesting. 



The kind of information that this book and similar books con- 

 tain should be in the possession of all our young people. This kind 

 of information causes them to understand the reason for many 

 of the common facts in the world about them; it unconsciously 



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