290 



Astronomy. 



[Lecture 19. 



A TABLE of the mean apparent diameters of the 

 sun, and of the primary planets, seen from the 

 earth ; and of the comparison of these diame- 

 ters with that of the sun. 



When once the apparent diameters of the 

 planets are known, seen all at the same distance, 

 it is easy to determine the size of each planet in 

 terrestrial diameters. And as the real diameter 

 of the earth is known in leagues, we may thence 

 calculate the number of leagues which the real 

 diameter of each planet contains. This may be 

 seen by the following Table, in which the terres- 

 trial diameter is taken for unity. 





