CHAPTER XXXIII. 



ASTRONOMY. 

 INTROCUCTORY HISTORY OF ASTRONOMY NOMENCLATURE. 



ASTRONOMY is the science which treats of the heavenly bodies and the laws 

 which govern them. The term is derived from two Greek words, astron, a 

 star, and nomos y a law. It may be included in the study of Physics, for the 

 motion of the planetary bodies and equilibrium, gravity, etc., all have some- 

 thing to say to the arrangements and positions of the stars. The space in 



Fig. 493. Celestial globe. 



which they are set is infinite, and known as the " Firmament," or " Heaven." 

 The number of the heavenly bodies must therefore be infinite also. We 

 can see a few stars, comparatively speaking, and there must be numbers 

 whose light has never yet reached the earth. When we calmly reason upon 

 the immeasurable distances and the awful rapidity of motion, with the 

 masses of matter thus in movement, we are constrained to acknowledge that 



