ioo SEVENTEENTH CENTURY. FT. lit, 



Tycho had not spent his life in this dry conscientious work, 

 Kepler could never have discovered his laws. Galileo was 

 a warm-hearted enthusiastic observer ; he loved the beauty 

 of the heavens, and knew how to make others love it too ; 

 every observation he made he told in popular language to 

 the world, and taught people the truth of the Copernican 

 theory by showing them plainly how they could prove it for 

 themselves, if they chose to look at the heavens. Kepler 

 was quite different from either Tycho or Galileo ; he was a 

 mathematician, and worked everything out in his own brain 

 by accurate methods. He took Tycho's observations, which 

 he knew were true, and turned them this way and that way, 

 working out now one calculation, now another, and always 

 throwing them aside if they were not exactly true. He spent 

 years over his attempts, but it was worth while, for he 

 arrived at three true laws, which will remain for ever. There 

 was only one point he had not reached ; he knew that his 

 laws were true, but he did not know why they were true. 

 This was left for Newton to demonstrate nearly fifty years 

 afterwards. 



Chief Works consulted. Brewster's 'Martyrs of Science ;' Herschel's 

 'Astronomy;' Denison's 'Astronomy without Mathematics;' Airy's 

 ' Popular Astronomy ;' Drinkwater's * Life of Kepler ;' Baden Powell's 

 History of Natural Philosophy.' 



