Researches in Electricity 107 



About 1740 electricity began to receive serious atten- 

 tion in Germany, where the frictional machine of Hauks- 

 bee was revived by Professors Hausen and Winkler of 

 Leipzig. Winkler is said to have first substituted a 

 rubbing pad or cushion for the hand. Gordon of Erfurt 

 introduced the use of a cylinder instead of the glass 

 globe. Boze of Wittenberg further perfected the elec- 

 trical machine by the addition of a conductor of metal 

 insulated by silk threads. 



These improvements in electrical apparatus made it 

 possible to generate charges of much greater quantity 

 than before and to perform many new and surprising 

 experiments, such as the ignition of volatile substances 

 and the killing of small animals by means of the spark, 

 the bleaching of colors, the ringing of bells and the pro- 

 duction of various mechanical motions. Brilliant dis- 

 charges in vacuum tubes were produced by Grummert, 

 who even proposed to make use of this form of light m 

 mines. These demonstrations soon began to attract not 

 only scientific men but the general public. Prizes were 

 offered by the various learned societies and public exhi- 

 bitions were given. 



In 1745 the so-called Leyden jar was discovered by 

 von Kleist,' dean of the cathedral in Camin and a few 

 months later, independently, by Cuneus of Leyden. The 



^Hoppe: Geschichte der Elektricitat, p. i8. 



