INTRODUCTION. 



1. ASTRONOMICAL PRINCIPLES. 



1. General Views of the Universe. If we look upward, we observe a blue vault stretched 

 over our heads, which at night is illuminated by a multitude of stars. If we go to Europe, 

 we obsei've the same wonderful display above us. If we travel to Arabia, or China, or the 

 islands of the Pacific, or to the Polar regions, wherever we may go, still the sky is over 

 us, and the sun, moon, and stars shine down upon us. The earth is evidently swung in the 

 air like a ball, supported by no foundation, and only kept in its place by the power of an 

 Almighty Being. 



If we keep our attention fixed upon our earth and the heavenly bodies, we shall soon dis- 

 cover that several of them are in motion. The moon revolves around the globe. Some of 



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