DISCOVERIES OF KEPLER. 33 



Three of the asteroids, and the satellites of 

 Uranus, have been omitted, because their ele- 

 ments have not yet been fully ascertained. 

 The third column in the tables was obtained by 

 multiplying the distances by 2 ; which gives 

 the diameter of the orbits. On multiplying this 

 by 3*1416, and dividing the product by the 

 periodic times, we get the velocities with a suf- 

 ficiently near approximation to the truth for our 

 present purpose. 



After the establishment of the true solar system 

 by Copernicus,* the invention of the telescope, 

 and the discovery of Jupiter's satellites by 

 Galileo, the most important advance ever made 

 in Astronomy was that of the immortal Kepler, 

 announced in a work entitled " Harmonice Mun- 

 di" published in 1619. In that work, he demon- 



* We are informed by Aristotle and Plutarch, that the sun was 

 recognized as the centre of our system by Pythagoras, who learned 

 it in Egypt There is also reason to believe that some of the 

 early Chaldean astronomers were acquainted with the same theory. 

 But as it was unknown to all the Greek philosophers, except 

 Pythagoras, or was rejected by them, the knowledge of it must 

 have been always confined to a very small number of the ancients. 

 It is stated by Josephus, that an imitation of the sun, moon, and 

 five planets, was represented in the Jewish Tabernacle ; and the 

 general system of nature, on the robes of the high priest : that his 

 mitre was a symbol of heaven ; (as it was of the sun among the 

 Egyptians ;) his breast-plate of the earth in the centre of the uni- 

 verse ; the twelve stones set in it, of the twelve zodiacal signs ; 

 and the ephod of the four elements. (Jewish Antiquities, Book 

 iii. Sect. 7.) 



