CH. XII. THE RUDOLPHINE TABLES. 95 



CHAPTER XII. 



SCIENCE OF THE SEVENTEENTH CENTURY (CONTINUED). 



Kepler the German Astronomer — Succeeds Tycho as Mathematician 

 to the Emperor Rudolph — His description of the Eye — He tries to 

 explain the orbit of the planet Mars — And by comparing Tycho's 

 tables with observation discovers his First and Second Law of the 

 movements of the Planets — His delight at Galileo's discoveries — 

 Kepler's Third Law — Comparison of the labours of Tycho, Galileo, 

 and Kepler. 



Kepler, 1571-1630. — While Galileo was occupied in dis- 

 covering unknown worlds with his telescope, another famous 

 astronomer, named Johannes Kepler, was working out three 

 grand laws about the movements of the planets. John 

 Kepler was bom in 157 1. His parents, though noble, were 

 poor, and always in difficulties, but in spite of all obstacles 

 he managed to educate himself, and even to take his degree 

 at the University of Tiibingen. In 1594 he was made Pro- 

 fessor of Astronomy at Gratz, in Styria, and while there he 

 began his attempts to discover the number, size, and orbits 

 of the planets, but at first with no success. In 1597, when 

 the Catholics at Gratz rose against the Protestants, Kepler, 

 being a Protestant, was forced to leave the city, and would 

 have been in great difficulties if his friend Tycho Brahe 

 had not invited him to come to Prague as his assistant 

 in the observatory. Here Kepler worked with Tycho at 

 his astronomical tables, called the * Rudolphine Tables,' 

 in honour of the Emperor Rudolph ; and when Tycho died, 



