SUGGESTIONS TO TEACHERS vii 



Storage Battery Company, Independent Pneumatic Tool 

 Company, Riehle Brothers, National Carbon Company, Inc., 

 Worthington Pump and Machinery Company, Western 

 Electric Company, Greenfield Tap and Die Corporation. 



Acknowledgment is also made of indebtedness to the 

 teachers who have kindly read the manuscript and offered 

 valuable suggestions. 



The author will be pleased to receive any constructive 

 criticism of the book. 



WILLIAM H. DOOLEY. 



NEW YORK CITY, 

 August 15, 1919. 



SUGGESTIONS TO TEACHERS 



The arrangement of this book is such that it may be used 

 equally well by science teachers in the regular secondary and 

 technical schools and by science teachers in vocational 

 schools. When used in connection with a year's course in 

 industrial science in the technical, industrial, or manual 

 training courses of regular secondary schools, it will aid in 

 correlating the principles of science with shop observation and 

 experience. 



The method of presenting the subject of industrial science 

 in a vocational school should be different from the method 

 used in the regular high school, since there is a wide difference 

 both in the aims of the courses and in the types of pupils. In 

 the vocational school it is well to consider first the practices 

 pf the trades and industries as based on practical shop ex- 



