AUTHOR'S PREFACE 



Among animals, play often functions to prepare for adult 

 life. Wolf and dog puppies tussle in fun and so strengthen their 

 muscles and improve their strategy for the fights of maturity. 

 So the kitten plays with a stray spool or ball and goes through 

 all the antics she will use later in catching her prey. The play 

 activities of children are in many, instances imitative of adult 

 activities. Dolls are given as solicitous attention by the child 

 as is the baby of the household by the parents. The plan of the 

 play house built with blocks receives a deal of thought. The 

 play store must have its wares appropriately displayed; clerk 

 and purchaser must be properly decorous. 



One need only go through the toy department of a city store 

 to see that toys have followed the trend of a scientific age and 

 are themselves replicas of adult appliances. There are construc- 

 tion sets, railroads and trains, telephones, radio sets, aeroplanes, 

 magic lanterns, chemical sets. It seems a great opportunity with 

 this interest in scientific toys to secure for the child through play a 

 variety of experiences that will give him some elementary appre- 

 ciation of those principles of science which are so important in 

 the social and industrial life of the adult. 



It is the purpose of this book to organize the subject-matter 

 of elementary physical science or physical nature-study about 

 toys and familiar home appliances. It is hoped it may serve as 

 a guide in the workshop of the boy or girl who enjoys making 

 things, that it may help children understand how commonplace 

 appliances work and may aid parents and teachers in answering 

 the questions of inquisitive youngsters. It is a source book in 

 the sense that it brings together in one volume material else- 

 where scattered and difficult of access. This volume is supple- 

 mented by the practical constructions in the Field and Laboratory 



ix 



