ELECTRICITY FROM Til ALES TO FARADAY. 243 



early as 600 b. c, by Tliales of Miletus, althougli he does not trans- 

 mit to US the name of the original observer of the phenomenon. 

 Homely as was the experiment, it marked a beginning in electrical 

 research. 



Not that scientific investigations in that or any line were pushed 

 very assiduously in those days, for there is a great gap between the 

 discovery of the property above alluded to and the acquisition of 

 any more solid knowledge pertaining to electricity. The phenom- 

 enon was at that time set down in the list of natural facts, and no 

 attempt appears to have been made to connect it with others. The 

 inquiring spirit of the present age can hardly be brought into more 

 striking relief than by a comparison of the, at present, almost daily 

 advances in scientific knowledge with the fact that twenty-two hun- 

 dred years elapsed between the discovery of the above-mentioned 

 l^ower of amber by the ancients and the later one that a very large 

 number of other substances, such as diamonds, vitrefactions of ail 

 kinds, sulphur, common resin, etc., possess the same property. A 

 few other scattered facts were, however, also noted by the ancients: 

 fire is said to have streamed from the head of Servius Tullius at the 

 age of seven, and Virgil asserts that flame was emitted by the hair of 

 Aseanius. 



In examining, now, the history of the rise of electrical science 

 we find, as just mentioned, the vast gap of over two millenniums 

 between the discovery of the attracting power of rubbed amber and 

 the mere extension of man's knowledge so as to include other sub- 

 stances. The philosophers Boyle and Otto von Guericke, who were 

 active during the latter half of the seventeenth century, added a 

 mass of new data in this line. Boyle, moreover, discovered the 

 equivalence of action and reaction between the attracting and the 

 attracted body, and that the rubbed amber or other " electric " re- 

 tained its attractive powers for a certain period after excitation had 

 ceased. 



Otto von Guericke made a vast step forward by constructing the 

 first electrical machine, in a crude form, truly, but which proved of 

 the utmost service in adding to our knowledge of the properties of 

 electricity. His machine was constructed very simply of a globe of 

 sulphur mounted on a spindle, which could be rotated by means of a 

 crank; the operator applied friction with the hand, his body receiv- 

 ing a positive charge, while the surface of the sulphur acquired a 

 negative. The fact of the two electrifications being separated at tho 

 surface of the sulphur was not, however, known at the time; the 

 only charge that Guericke observed being that appearing on the 

 sulphur. The reason for this was that the latter, being a noncon- 

 ductor, any electricity generated upon it was compelled to stay there, 



