Lesson*..] GKORGIUM SIDUS. 



43 



to one and the same law ; which is, that the squares of tht 

 periodical times of the primary planets, are proportional to tlie 

 cubes of their mean distances from the Sun ; and that t he squares 

 of the periodical limes of the secondaries of any primary, are to each 

 other, as the cubes of their distances from their primary. By no other 

 hypothesis which has been yet invented, can the motions of 

 the heavenly bodies be accounted for with such beauty and 

 simplicity, as by this ; nor is there any other system which 

 exhibits the fabric of the universe, in that regularity and 

 harmony, which is worthy the DIVINE ARCHITECT. 



It may not be improper to mention in this note, that the 

 planets differ in density as well as in magnitude, a circum- 

 stance which will make the ratio of their absolute masses 

 different from that of their apparent bulk or volume : assum- 

 ing that of the Earth as unity, the others will be expressed 

 in integers and decimals in the following table. 



Mercury < 

 Venus 

 The Earth 

 Mars 



Jupiter 

 Saturn 

 Uranus 



Sun 



Moon 



Volumes. 



0.05G5. 



0.8828- 



1.0000- 



0.1380- 



1280.9 



974.78 



S1.2G". 



1395324. 



0.2035 



Masses. 



0.1627 



0.9248 



1.0000 



0.1294 



308.94 



93.271 



1.6904 



329630. " 

 ..-.'0.0801 



LESSON 



