IV PKEFACE. 



We say tranquil, and yet the word is almost 

 without meaning in the Cosmos; where do 

 we find tranquillity? The sea, the seat of 

 animal, vegetable, and mineral changes, is at 

 war with the earth, and the air lends itself to 

 the strife. The globe, the scene of perpetual 

 intestine change, is as a mass, acting on, and 

 acted on, by the other planets of our system, 

 and the very system itself is changing its place 

 in space, under the influence of a known force 

 springing from an unknown centre. 



For many years past the English public 

 have had the privilege of listening to the dis- 

 courses and speculations of Professor Faraday, 

 at the Eoyal Institution, on Matter and Forces, 

 and it is not too much to say that no lecturer 

 on Physical Science since the time of Sir 

 Humphry Davy has been listened to with 

 more delight. The pleasure which all derive 

 from the expositions of Faraday is of a some- 

 what different kind to that produced by any 

 other philosopher whose lectures we have ever 



