9i Mechanical Philosophy, [Chap. L 



and sir Isaac Newton; but they continued to lie 

 in uncertainty and confusion, until 1709, when 

 Mr. Hawksbee, an English gentleman, wrote on 

 the subject, and distinguished himself by the ex- 

 periments and discoveries which he announced. 

 He first took notice of the great electric powers of 

 glass, together with a variety of phenomena relat- 

 ing to electrical attraction and repulsion ; insomuch 

 that his writings and experiments form a grand sera 

 in this branch of knowledge. From the time of 

 Mr. Hawksbee's publication, near twenty years 

 elapsed before any farther discoveries or improve- 

 ments were suggested. 



In 1729, the fundamental distinction between 

 conductors and 7ionconduciors was first ascertained 

 by Stephen Gray, a i3ritish philosopher, who had 

 for some time before amused himself with electrical 

 experiments, and who was now accidentally led to 

 the discovery of this important principle. Soon 

 afterwards M. du Fay, member of the Academy 

 of Sciences at Paris, in repeating Mr. Gray's ex- 

 periments, unexpectedly perceived, for the first 

 time, that dilference in the attractive powers of 

 different bodies, which he supposed to arise from 

 two different species of electric fluids, and which 

 he denominated the vitreous and resinous electri- 

 cities. Tlie drawing a spark from the living body 

 was also first observed by this gentleman, and his 

 companion, tlie abbe Nollet. The next person 

 who distinguished himself in this part of science 

 was Dr. Desaguliers, who, though he added but 

 little to the knowledge before possessed, yet made 

 some valuable experiments, and invented some 

 iechnical lerms^ such as conductor, electric per se, (S( c.. 



