ASTRONOMY; 103 



stratad, that, whether it be the earth or the sun 

 which really moves* the one describes an ellipsis 

 round the other, placed in the focus of that curve ; 

 and that the line drawn from the moveable to the 

 immoveable body, (the radius vector), describes 

 areas round the latter proportional to the times. 

 From these two general laws, astronomers have 

 been able to determine the proportional distances 

 of the sun and earth, and their relative positions, 

 at all seasons of the year. 



e. The use of facts, in scientific investigation, could 

 not be better illustrated than by this example. 

 The simple factj that the sun on a particular day 

 had a certain apparent diameter, and a certain 

 rate of angular motion, is nothing in itself, and 

 cannot, taken alone, lead to any conclusion : But 

 a multitude of such facts, compared together, by 

 the assistance of geometry, leads to the knowledge 

 of the general law to which they are all subject ; this 

 law leads, conversely, to a more precise and com- 

 prehensive knowledge of facts, embracing at once 

 the past, the present and the future, and reducing 

 them all into one theorem. 



We are left, however, in the dark as to one question, 

 whether it be the sun or the earth which describes 

 the elliptic orbit. The appearance that the earth 

 is at rest, and that the sun is in motion, is no ar- 

 gument against the fact being entirely the reverse, 

 as has already been made evident in the case of 



the 



