vi PREFACE 



The author has tried to meet these two requirements by 

 finding the basis for both the selection and the organization 

 of material in the applications of science to the child's im- 

 mediate life. It seems best to group these applications 

 around two great centers, the home life and the community 

 life. There are certain phases of science that are more con- 

 spicuous in the home circle, while there are other phases 

 that are more prominent as one goes out into community 

 life. These phases are closely interrelated, and in some 

 cases no sharp line can be drawn between them ; but the 

 author believes that from the child's standpoint this division 

 forms a natural basis for organizing the text. 



The material has been organized from the human rather 

 than from the scientific point of view. The child sees first 

 the uses made of various things, then he is interested to 

 understand something of the construction and mode of opera- 

 tion of the machines involved, and finally he wishes to know 

 what their history has been. Consequently the great inven- 

 tions have been treated from the four standpoints of their 

 uses, their history, their construction, and their working. 



This is not a textbook in General Science in the sense that 

 it attempts to cover a little of all the sciences, just for the 

 sake of covering them all. The extent to which any par- 

 ticular science is included depends on the part that the 

 science plays in the immediate life of the child. Whether 

 any particular science or any particular topic in a science 

 should form a part of the course depends on the number and 

 value of the elements that it possesses in common with the 

 child's life. As a matter of fact, the two sciences that are 

 especially conspicuous in the child's daily life, and hence 

 dominate the text, are physics and hygiene. 



The author acknowledges his indebtedness to the following 

 firms for their courtesy in allowing illustrations from their 

 publications to be used as copy for illustrations made for this 

 book: American Book Co., The Century Co., Doubleday, 



