The Sun and Solar System. 277 



orbit, (PI. XXV. fig. 110.) in which it goes 

 round the sun every year, according to the order 

 of the letters, that is, from west to east; and 

 turns round its axis the same way from the sun 

 to the sun again in every 24 hours. Let S be 

 the sun, and E (in fig. 109) a fixed star at such 

 an immense distance, that the diameter of the 

 earth's orbit is but a point in proportion to that 

 distance. Let N m be any particular meridian 

 of the earth, and N a given point or place upon 

 that meridian. When the earth is at A the sun 

 S hides the star E, which would be always hid 

 if the earth never removed from A ; and conse- 

 quently, as the earth turns round its axis, the 

 point N would always come round to the sun 

 and star at the same time. But when the earth 

 has advanced, suppose a twelfth part of its orbit 

 from A to B, its motion, round its axis will 

 bring the point N a twelfth part of a natural 

 day, or two hours, sooner to the star than to 

 the sun, for the angle N B n is equal to the 

 angle ASB : and therefore any star which comes 

 to the meridian at noon with the sun when the 

 earth is at A, will come to the meridian at 10 in 

 the forenoon when the earth is at B. When the 

 earth comes to C, the point N will have the star 

 on its meridian at 8 in the morning, or four hours 

 sooner than it comes round to the sun; for it 

 must revolve from N to n before it has the sun in 

 its meridian. When the earth comes to D, the 

 point N will have the star on its meridian at 6 in 



