420 THE INTELLECTUAL RISK IN ELECTRICITY. 



Boyle closed the series of experiments recorded in his lit- 

 tle treatise of 1675 l the first book entirely on electricity in 

 the English language with the doubts raised by the swing- 

 ing amber unsettled, and, indeed, intensified, for he had 

 encountered the same problem in other and even more enig- 

 matic shapes. He tells us that once when he approached 

 his finger to a down feather which had been attracted by a 

 large piece of amber, the pinnules of the feather applied 

 themselves to the finger u as it had been an electrical 

 body." This was very obscure to him. First he thought 

 that warm "steams" from his person might somehow 

 have caused this attraction, but when he presented to the 

 feather a rod of silver, an iron key, and a cold piece of 

 black marble, the pinnules "did so readily and strongly 

 fasten themselves to these extraneous and unexcited bodies 

 that I have been able (though not easily) to make one of 

 them draw the feather from the amber itself. ' * But this, he 

 is careful to note, happens only while the amber is suffi- 

 ciently excited to make it sustain the feather, otherwise 

 "neither the approach of my finger nor that of the other 

 bodies would make the downy feathers change their pos- 

 ture. Yet as soon as ever the amber was by a light afflic- 

 tion excited over again," the finger attracted the feather. 



He repeated this experiment over and over again, with 

 "years of interval," he says; tried innumerable feathers 

 and substituted brimstone for amber as the electric always 



frequently credited with the original discovery of electrical repulsion. 

 In the same connection he speaks, however, of the observation as one 

 which he " made many years ago, and which I have been lately informed 

 to have long been since made by the very learned Fabri." This was 

 published a year after the appearance of von Guericke's treatise, and 

 hence ten years after the visit of Monconys to Magdeburg. HonorS 

 Fabri, the French mathematician, to whom Boyle alludes, did not issue 

 his treatise on Physics untill 1669, so that not only is the actual date of 

 Boyle's reference to the phenomena long after that of von Guericke's 

 discovery, but there is nothing inconsistent with the priority of von 

 Guericke in Boyle's assertions that the fact had long been known to 

 himself and Fabri. 

 1 Cit. sup. 



