PREFACE. 



THESE Lessons in Electricity and Magnetism are in- 

 tended to afford to beginners a clear and accurate 

 knowledge of the experiments upon which the Sciences 

 of Electricity and Magnetism are based, and of the 

 exact laws which have been thereby discovered. The 

 difficulties which beginners find in studying many 

 modern text -books arise partly from the very wide 

 range of. the subject, and partly from want of famili- 

 arity with the simple fundamental experiments. We 

 have, at the outset, three distinct sets of phenomena 

 to observe, viz. those of Frictional Electricity, of 

 Current Electricity, and of Magnetism ; and yet it is 

 impossible to study any one of these rightly without 

 knowing something of them all. Accordingly, the first 

 three Chapters of this work are devoted to a simple 

 exposition of the prominent experimental facts of these 

 three branches of the subject, reserving until the later 

 Chapters the points of connection between them, and 

 such parts of electrical theory as are admissible in a 

 strictly elementary work. No knowledge of algebra 

 beyond simple equations, or of geometry beyond the 

 first book of Euclid, is assumed. 



A series of Exercises and Problems has been added 

 at the end of the Book in order that students, who 



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