FlG. 89. HUYGHENS. 



CHAPTER IX. 



ASTRONOMY AND PHYSICS OF THE SEVENTEENTH CENTURY. 



IN the present chapter we shall mention the labours of those astro- 

 nomers' who followed Galileo, and either preceded or were con- 

 temporary with Newton ; and we shall also describe the researches of 

 Newton and others in general physics. 



Among the most eminent of Galileo's followers was the celebrated 

 GASSENDI, better known, however, as a philosopher than as an as- 

 tronomer and physicist. In 1629 Kepler announced that astronomers 

 should be ready to observe on the yth of November, 1631, the transit 

 of the planet Mercury. Among the few who succeeded in witnessing 

 the predicted event was Gassendi, who observed the dark body of the 

 planet as a very small round spot. Kepler had also predicted the 

 passage of the planet Venus across the sun's disc for the 6th of De- 



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