prior to the Introduction of the Potentials. 37 



repels light Bodies. The smallest parts of the glass are agitated 

 by the Attrition, and by reason of their elasticity, their motion is 

 vibratory, which is communicated to the Atmosphere above- 

 mentioned : and therefore that Atmosphere exerts its action the 

 further, the greater agitation the Parts of the Glass receive when 

 a greater attrition is given to the glass." 



The English translator of s'Gravesande's work was himself 

 destined to play a considerable part in the history of electrical 

 science. Jean Theophile Desaguliers (b. 1683, d. 1744) was an 

 Englishman only by adoption. His father had been a Huguenot 

 pastor, who, escaping from France after the revocation of the Edict 

 of Nantes, brought away the boy from La Kochelle, concealed, it is 

 said, in a tub. The young Desaguliers was afterwards ordained, 

 and became chaplain to that Duke of Chandos who was so 

 ungratefully ridiculed by Pope. In this situation he formed 

 friendships with some of the natural philosophers of the capital, 

 and amongst others with Stephen Gray, an experimenter of 

 whom little is known* beyond the fact that he was a pensioner 

 of the Charterhouse. 



In 1729 Gray communicated, as he says,f " to Dr. Desaguliers 

 and some other Gentlemen " a discovery he had lately made, 

 " showing that the Electrick Vertue of a Glass Tube may be 

 conveyed to any other Bodies so as to give them the same 

 Property of attracting and repelling light Bodies as the Tube 

 does, when excited by rubbing : and that this attractive Vertue 

 might be carried to Bodies that were many Feet distant from 

 the Tube." 



This was a result of the greatest importance, for previous 

 workers had known of no other way of producing the attractive 

 emanations than by rubbing the body concerned.* It was found 



* Those M*ho are interested in the literary history of the eighteenth century will 

 recall the controversy as to whether the verses on the death of Stephen Gray were 

 written hy Anna "Williams, whose name they bore, or by her patron Johnson. 



| Phil. Trans, xxxvii (1731), pp. 18, 227, 285, 397. 



j Otto von Guericke (b. 1602, d. 1686) bad, as a matter of fact, observed the 

 conduction of electricity along a linen thread ; but this experiment does not seem 

 to have been followed up. Cf. Experimenta novamagdeburgica, 1672. 



