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				Sundial 
				
				  
				
				
				Armillary sphere 
				
				  
				
				
				Photo n° 3  | 
              
				 
				
				The “armillae” were graduated metallic rings that were part of 
				ancient astronomic instruments. They made it possible to 
				simulate the movement of the planets, or to determine the 
				celestial coordinates, or more simply to determine the solar 
				time. 
				 
				
				
				Its origins go back to the age of the Greek 
				mathematicians, to the time of the great Ptolemy (AD 100–168).  |