FOREWORD. 



The author was, for eight years, the editor of 

 " The Observer," a magazine for naturalists ; for 

 three years editor of " Popular Science," and for 

 the past five years he has been the editor of the 

 department of Nature and Science in " St. Nicho- 

 las," a magazine for young folks, and as a lecturer 

 and teacher he is not without experience in the 

 department of study which this book aims to 

 treat. For these reasons, and for others which we 

 will allow the reader to discover, he has prepared 

 the book, hoping, like the author of every similar 

 work, to help, instruct, and perhaps inspire, the 

 earnest teacher, whose lot is always a laborious 

 one, whose leisure is always scanty, but whose 

 final reward is certain and great. 



Many of the chapters that compose this book 

 were originally published in " The Popular Edu- 

 cator," Boston, Mass. ; others are reproduced from 

 " The Journal of Education," Boston ; " The 

 School Journal," New York : " School Science," 

 Chicago ; " The Ohio Teacher," Athens, Ohio. 



