AND THEORY OF THE HEAVENS. 59 



distinction, will cover the field of the heavens on both 

 sides. 



The form of the starry heavens is therefore due to no 

 other cause than such a systematic constitution on the 

 great scale as our planetary world has on the small all 

 the suns constituting a system whose universal relative 

 plane is the Milky Way. Those suns which are least 

 closely related to this plane, will be seen at the side of 

 it; but on that account they are less accumulated, and 

 are much more scattered and fewer in number. They 

 are, so to speak, the comets among the suns. 



This new theory attributes to the suns an advancing 

 movement; yet everybody regards them as unmoved, and 

 as having been fixed from the beginning to their places. 

 The designation of them as c Fixed ' Stars, which they 

 have received from that view of them, seems to be 

 established and put beyond doubt by the observation of 

 all the centuries. This difficulty raises an objection 

 which would annihilate the theory here advanced, were 

 it well founded. But in all probability this want of move- 

 ment is merely apparent. It is either only excessively 

 slow, arising from the great distance from the common 

 centre around which the stars revolve, or it is due to 

 mere imperceptibility, owing to their distance from the 

 place of observation. Let us estimate the probability of 

 this conception by calculating the motion which a fixed 

 star near our sun would have, if we supposed our sun to 

 be the centre of its orbit. If, following Huygens, its 

 distance is assumed to be more than 21,000 times greater 

 than the distance of the sun from the earth, then accord- 

 ing to the established law of the periods of revolution 

 which are in the ratio of the square root of the cube of the 



