THE BANISHMENT OF NIGHT 



had no conception. In the opening years of the follow- 

 ing century Francis Hauksbee obtained somewhat 

 similar results with glass globes and tubes, and made 

 several important discoveries as to the properties of 

 electricity that stimulated an interest in the subject 

 among the philosophers of the time. Gray in England, 

 and Dufay in France, who became enthusiastic workers 

 in the field, soon established important facts regarding 

 conduction and insulation, and by the middle of the 

 eighteenth century the production of an electric spark 

 had become a commonplace demonstration. 



But until this time it had not been demonstrated that 

 this electric spark was actual fire, although there was 

 no disputing the fact that it produced light. In 1744, 

 however, this point was settled definitely by the 

 German, Christian Friedrich Ludolff, who projected 

 a spark from a rubbed glass rod upon the surface of a 

 bowl of ether, causing the liquid to burst into flame. 

 A few years later Benjamin Franklin demonstrated 

 with his kite and key that lightning is a manifestation 

 of electricity. 



But neither the galvanic cell nor the dynamo had been 

 invented at that time, and there was no possibility of pro- 

 ducing anything like a sustained artificial light with the 

 static electrical machines then in use. It was not until 

 the classic discovery of Galvani and the resulting inven- 

 tion of the voltaic, or galvanic, cell shortly after, that 

 the electric light, in the sense of a sustained light, became 

 possible. And even then, as we shall see in a moment, 

 such a light was too expensive to be of any use com- 

 mercially. 



