PREFACE 5 



the average adult mind as well, is singularly non-logical and 

 incapable of continued concentration, and loses interest under 

 too consecutive thought and sustained style. For this reason 

 the author has sacrificed at times detail to general effect, 

 logical development to present-day interest and facts, and 

 has made use of a popular, light style of writing as well as 

 of the more formal and logical style common to books of 

 science. 



No claim is made to originality in subject matter. The 

 actual facts, theories, and principles used are such as have 

 been presented in previous textbooks of science, but the 

 manner and sequence of presentation are new and, so far 

 as I know, untried elsewhere. These are such as in my 

 experience have aroused the greatest interest and initiative, 

 and such as have at the same time given the maximum bene- 

 fit from the informational standpoint. In no case, however, 

 is mental training sacrificed to information ; but mental de- 

 velopment is sought through the student's willing and inter- 

 ested participation in the actual daily happenings of the 

 home and the shop and the field, rather than through formal 

 recitations and laboratory experiments. 



Practical laboratory work in connection with the study of 

 this book is provided for in my Laboratory Manual in General 

 Science, which contains directions for a series of experiments 

 designed to make the pupil familiar with the facts and theo- 

 ries discussed in the textbook. 



I have sought and have gained help from many of the 

 standard textbooks, new and old. The following firms have 



