CONTENTS. xv 



CHAPTER XVII. 



SCIENCE OF THE SEVENTEENTH CENTURY (CONTINUED). 



PAGE 



Malpighi first uses the Microscope to examine Living Structures 

 He describes the Air-cells of the Lungs Watches the Circula- 

 tion of the Blood Observes the Malpighian Layer in the Human 

 Skin Describes the structure of the Silkworm Leeuwenhceck 

 discovers Animalcules Grew and Malpighi discover the Cellular 

 Structure of Plants The Stomates in Leaves They study the 

 Germination of Seeds Ray and Willughby classify and describe 

 Animals and Plants The Friendship of these two Men . . 137 



CHAPTER XVIII. 

 SCIENCE OF THE SEVENTEENTH CENTURY (CONTINUED). 



1642, Birth of Newton His Education 1666, His three great 

 Discoveries first occur to him Method of Fluxions and Dif- 

 ferential Calculus First Thought of the Theory of Gravitation 

 Failure of his Results in consequence of the Faulty Measure- 

 ment of the size of the Earth 1682, Hears of Picart's new 

 Measurement Works out the result correctly, and proves the 

 Theory of Gravitation Explanation of this Theory Establishes 

 the Law that Attraction varies inversely as the squares of the 

 distance 1687, Publishes the 'Principia' Some of the Pro- 

 blems dealt with in this Work 147 



CHAPTER XIX. 



SCIENCE OF THE SEVENTEENTH CENTURY (CONTINUED) 



Transits of Mercury and Venus Kepler foretells their occurrence 

 1631, Gassendi observes a Transit of Mercury 1639, Hor- 

 rocks foretells and observes a Transit of Venus 1676, Halley 

 sees a Transit of Mercury, and it suggests to him a method for 

 Measuring the Distance of the Sun 1691-1716, Halley de- 

 scribes this method to the Royal Society Explanation of 

 Halley's method 156 



