41 8 THE INTELIvECTUAL RISE IN ELECTRICITY. 



made many experiments so many indeed that lie has 

 learned that their event is "not always so certain as that 

 of many others, being sometimes much varied by seem- 

 ingly slight circumstances, and now and then by some 

 that are altogether overlooked" which is by no means 

 out of harmony with modern conclusions. Besides, he 

 has the backing of all the preceding philosophers von 

 Guericke alone excepted. There was Gilbert with his 

 effluvia, "like material rods;" Cabseus with his "shrink- 

 ing steams;" Descartes with his "ribbons shooting from 

 the pores of the glass;" Digby and Browne with "unctu- 

 ous filaments" contracting in the cold air; and Gassendi, 

 whom I have hitherto not mentioned, but who imagined 

 emanations which not only entered the pores of the chaff, 

 but became crossed therein, and thus getting a better hold 

 on it, pulled it back with greater force in retracting: every 

 one of these philosophers finding the electrical effects due, 

 not to a mere quality in Form, but to substantial emana- 

 tions from the attracting body; and thus all seeking to 

 solve the problem in a mechanical way. Heat, says 

 Boyle, building on this foundation, agitates the parts of 

 the body and makes it emit effluvia. Rubbing modifies 

 the motions of the internal parts and gives the body a 

 texture which disposes it to become vigorously electrical. 

 And so it continues even after the exciting cause is re- 

 moved, because some of the heat still remains. On a 

 warm day, he was able to move a pivoted steel needle with 

 an electric no larger than a pea, three minutes after the 

 rubbing had ceased. 



Then he remarks something altogether unaccountable; 

 (although the discovery was not original with him, for it 

 had been observed years before by the Florentine Acad- 

 emy del Cimento) namely, that an electric can apparently 

 /be moved by its own steams as he observed by suspend- 

 ing a piece of amber, rubbing it and then causing it to 

 swing so as to follow the rubbing cloth moved before it. 

 He is not at all sure as to what this portends, and in fact 



