PROGRESS IN ELECTRICITY 



with all the twine, will be electrified and the loose fila- 

 ments will stand out everywhere and be attracted by 

 the approaching finger, and when the rain has wet the 

 kite and twine so that it can conduct the electric fire 

 freely, you will find it stream out plentifully from the 

 key on the approach of your knuckle, and with this 

 key the phial may be charged; and from electric fire 

 thus obtained spirits may be kindled and all other 

 electric experiments performed which are usually done 

 by the help of a rubbed glass globe or tube, and there- 

 by the sameness of the electric matter with that of 

 lightning completely demonstrated." 5 



In experimenting with lightning and Franklin's 

 pointed rods in Europe, several scientists received se- 

 vere shocks, in one case with a fatal result. Professor 

 Richman, of St. Petersburg, while experimenting dur- 

 ing a thunder-storm, with an iron rod which he had 

 erected on his house, received a shock that killed him 

 instantly. 



About 1733, as we have seen, Dufay had demon- 

 strated that there were two apparently different kinds 

 of electricity ; one called vitreous because produced by 

 rubbing glass, and the other resinous because produced 

 by rubbed resinous bodies. Dufay supposed that these 

 two apparently different electricities could only be 

 produced by their respective substances; but twenty 

 years later, John Canton (171 5- 1772), an Englishman, 

 demonstrated that under certain conditions both might 

 be produced by rubbing the same substance. Canton's 

 experiment, made upon a glass tube with a rough- 

 ened surface, proved that if the surface of the tube 

 were rubbed with oiled silk, vitreous or positive elec- 



295 



