General Objects and Principles. 5 



bow, and which Almighty God has made the 

 pledge, that he will not overflow the world with 

 another deluge. But do you understand how 

 this appearance is produced? It is, indeed, the 

 action of light upon the drops of the falling rain ; 

 but we can show you by what means this appear- 

 ance, and these vivid colours, are produced; 

 why it assumes the form of a bow ; why a se- 

 cond bow is often seen accompanying the first 

 or primary bow. We can measure the arch 

 which it inscribes, and explain the whole of this 

 wonderful spectacle. 



It must be well known to some of you from 

 observation, and to most of you by the informa- 

 tion of others, that the sea, at certain hours of 

 the day, varying with the age of the moon, 

 approaches, and overflows, to a certain height, 

 the sandy beach by which it is surrounded. This 

 flux and reflux of the ocean, as it is termed, 

 is known by the common name of the TIDE. 

 Antient tradition tells us, that a philosopher put 

 himself to death, because he was unable to find 

 out the cause ; but modern philosophy has laid 

 open the whole theory of the tides, and can de- 

 monstrate the nature of them upon irrefragable 

 principles. 



In some parts of the world there are fountains 

 of boiling water spouting from the earth. In 

 others, the earth itself opens and emits flames 

 and rivers of liquid fire, and throws out rocks 

 and stones of an immense size, with a force and 



