74 SIXTEENTH CENTURY. pt. hi. 



CHAPTER X. 



SCIENCE OF THE SIXTEENTH CENTURY (CONTINUED). 



Baptiste Porta discovers the Camera Obscura — Shows that our Eye is 

 like a Camera Obscura — Makes a kind of Magic Lantern by Sun- 

 light — Kircher afterwards makes a Magic Lantern by Lamplight 

 — Dr. Gilbert's discoveries in Electricity — Tycho Brahe, the Danish 

 Astronomer — Builds an Observatory on the Island of Huen — Makes 

 a great number of Observations, and draws up the Rudolphine 

 Tables — Galileo discovers the principle of the Pendulum — Cal- 

 culates the velocity of Falling Bodies, and shows why it in- 

 creases — Shows that Unequal Weights fall to the Ground in the 

 same time— Establishes the relations of Force and Weight — Sum- 

 mary of the Science of the sixteenth century. 



Baptiste Porta's discoveries about Light, 1560. — The next 

 discovery in science was about Light, and it was made by a 

 boy only fifteen years of age. Baptiste Porta was bom in 

 Naples in 1545. He was so eager for new knowledge that 

 when quite a boy he held meetings in his house for any of fll 

 his friends to read papers about new experiments. These 

 meetings were called * the Academy of Secrets,' and in the 

 year 1560, when Porta was fifteen, he published an account of 

 them in a book called * Magia Naturalist or * Natural Magic* 

 In the seventeenth chapter of this book he relates the fol- 

 lowing experiment which he had made himself. 



He says he found that by going into a darkened room 

 when the sun was shining brightly, and making a very small 

 hole in the window-shutter, he could produce on the wall oi 



