GALILEO AND THE NEW PHYSICS 



netometer, and the first electrical indicating device. 

 Although three centuries have elapsed since his death, 

 the method of magnetizing iron first introduced by 

 him is in common use to-day. 



He made exhaustive experiments with a needle bal- 

 anced on a pivot to see how many substances he could 

 find which, like amber, on being rubbed affected the 

 needle. In this way he discovered that light sub- 

 stances were attracted by alum, mica, arsenic, sealing- 

 wax, lac sulphur, slags, beryl, amethyst, rock-crys- 

 tal, sapphire, jet, carbuncle, diamond, opal, Bristol 

 stone, glass, glass of antimony, gum -mastic, hard 

 resin, rock-salt, and, of course, amber. He discovered 

 also that atmospheric conditions affected the produc- 

 tion of electricity, dryness being unfavorable and 

 moisture favorable. 



Galileo's estimate of this first electrician is the ver- 

 dict of succeeding generations. "I extremely admire 

 and envy this author," he said. "I think him worthy 

 of the greatest praise for the many new and true ob- 

 servations which he has made, to the disgrace of so 

 many vain and fabling authors." 



STUDIES OF LIGHT, HEAT, AND ATMOSPHERIC PRESSURE 



We have seen that Gilbert was by no means lacking 

 in versatility, yet the investigations upon which his 

 fame is founded were all pursued along one line, so 

 that the father of magnetism may be considered one 

 of the earliest of specialists in physical science. Most 

 workers of the time, on the other hand, extended their 

 investigations in many directions. The sum total of 

 scientific knowledge of that day had not bulked so 

 VOL. ii. 9 11 



