THE BANISHMENT OF NIGHT 



Some other substance must be found. The use of 

 carbon for arc lights and Edison's own experiments 

 with carbon in his work on the telephone naturally 

 suggested this substance as a possibility. It is said that 

 this idea was brought forcibly to the inventor's attention 

 by noticing the delicate spiral of vegetable carbon left 

 in his hand after using a twisted bit of paper, one day, for 

 lighting a cigar. This spiral of carbon was, of course, too 

 fragile to be of use in its ordinary form. But it occurred 

 to Edison that if a means of consolidating it could be 

 found, there was reason to hope that it would answer 

 the purpose. Experiments were begun at once, there- 

 fore, not only with processes of consolidation but also 

 with various kinds of paper, and neither effort nor 

 expense was spared to test every known variety of paper. 

 Moreover, many new varieties of paper were manufac- 

 tured at great expense from substances having peculiar 

 fibres. One of these, made from a delicate cotton grown 

 on some little islands off South Carolina, gave a carbon 

 free from ash, and seemed to promise good results; 

 but later it was found that the current of electricity did 

 not circulate through this substance with sufficient regu- 

 larity to get protracted and uniform effects. Neverthe- 

 less, since many things pointed to this fibre carbon 

 as the ideal substance, Edison set about determining 

 the cause of the irregularity in the circulation of the 

 current in the filament, and a number of other experi- 

 menters soon became interested in the problem. 



It was soon determined that the arrangement of the 

 fibres themselves were directly responsible for the dif- 

 ficulty. In ordinary paper the fibres are pressed to- 



