8o SIXTEENTH CENTURY. FT. in. 



time that Galileo was discovering these laws of motion, a 

 famous engineer, named Stevinus, of Bruges, published a 

 little book, in which he made known some very important 

 laws about the rest and motion of bodies, which formed the 

 foundation of the modern science of statics, or the study of 

 bodies at rest. 



Galileo's Observations on Musical Notes Galileo 

 appears also to have made some curious observations on 

 the subject of sound, and it was he who discovered that a 

 musical note is produced by a number of shocks following 

 rapidly and regularly one after the other, and that the more 

 quickly one shock succeeds the other, the higher the note 

 will be. He relates that one day, when he was scraping a 

 copper plate with an iron chisel to rub out some spots, he 

 heard a whistling noise, and found on looking, that the plate 

 was covered with fine streaks at regular intervals, and that 

 it was the production of these streaks which gave rise to the 

 musical sound. As he moved his hand more quickly the 

 note became more shrill, and the streaks closer together. 

 Galileo knew that the sound was caused by vibrations of 

 the particles of the air set in motion by the quivering of 

 the metal, and he stated quite correctly that the reason he 

 heard a higher note when the movement was more rapid, 

 was, that a greater number of these vibrations struck on the 

 drum of his ear in a certain space of time, thus causing it 

 to vibrate more rapidly. 



Summary of the Science of the Sixteenth Cen- 

 tury. And now we must pause for a moment in the his- 

 tory of Galileo, for his astronomical discoveries belong to 

 the next century, and before entering upon them we must 

 reckon up the advances which had been made in science 

 during the past hundred years. 



I think you will agree with me that at least one grand 



