INTRODUCTION. 



For the benefit of the readers of Vol. Ill, 

 who have not read the general Introduction 

 found in Vol. I, a word as to the scope and 

 object of this volume will not be amiss. 



It will be plain to any one on seeing the size 

 of the little book that it cannot be an ex- 

 haustive treatise on a subject so large as 

 that of Electricity. This volume, like the 

 others, is intended for popular reading, and 

 technical terms are avoided as far as possible, 

 or when used clearly explained. The subject 

 is treated historically, theoretically, and prac- 

 tically. 



As the author has lived through the period 

 during which the science of Electricity has 

 had most of its growth, he naturally and 

 necessarily deals somewhat in reminiscence. 

 All he hopes to do is to plant a few seed- 

 thoughts in the minds of his readers that will 

 awaken an interest in the study of natural 

 science; and especially in its most fascinating 

 branch Electricity. 



