ESSENTIALS OF PHYSICS 



By GEORGE A. HOADLEY, C.E., Sc. D., Professor 



of Physics, Swarthmore College. 



^1.25 



THIS is the author's popular and successful Elements ot 

 Physics enriched and brought up to date. Despite the 

 many changes and modifications made in this new 

 edition, it retains the qualities which have secured so great a 

 success tor the previous book. 



*^\ It tells only what everyone should know, and it does this 

 in a straightforward, concise, and interesting manner. It takes 

 into consideration the character of high school needs and con- 

 ditions, and, throughout, lays particular emphasis upon the 

 intimate relation between physics and everyday life. 

 ^ While the subject matter, as a whole, is unchanged, the 

 order of topics in many cases has been altered to adapt the 

 development of the subject to the habits of thought of high 

 school pupils. Instead of beginning the treatment of a sub- 

 ject with the definition and proceeding to a discussion of the 

 sub-topics, the author starts with a discussion ot well-known 

 phenomena and leads up to the definition of the subject dis- 

 cussed. The text, wherever possible, has been simplified, 

 more than fifty topics having been amplified, expanded, or 

 reworded. More familiar illustrations of the topics treated 

 are given, and the demonstrations of many of the experiments 

 are simplified by the use of materials that are readily obtain- 

 able in the classroom. 



^ There have been added a number of new topics, mostly 

 in connection wdth the recent advances in applied science. 

 The number both of questions and problems has been greatly 

 increased and the data in these all relate to actual, practical, 

 physical phenomena. More than one-fifth of the illustrations 

 in the book are new, many of the pictures of apparatus having 

 been redrawn to show modern forms. 



AMERICAN BOOK COMPANY 



<>S6) 



