98 Experimental Plnlosopliy. [Lecture 8. 



These phaenomena were not, however, all dis- 

 covered at once ; on the contrary, it was by slow 

 degrees that philosophy became acquainted with 

 the properties of this surprising fluid. It was, 

 however, long known that amber* and some 

 other matters, when rubbed on a soft and elastic 

 substance, had a power of attracting feathers, 

 straws, or other light bodies. We may, without 

 either pains or cost, make the experiment: by 

 taking a piece of sealing-w r ax, and rubbing it 

 quickly upon a coat sleeve, or any piece of woollen 

 cloth, we shall find that it will readily attract 

 hair, feathers, chaff, &c. A smooth bubble of 

 glass will answer still better. 



Sulphur is also a body that is capable of 

 exercising this power of attraction ; and to observe 

 more perfectly its effects, Otto Guericke, burgo- 

 master of Magdebourg (the same who is men- 

 tioned in a preceding lecture, as having afforded 

 hints for the construction of the air-pump), made 

 a large globe of sulphur, which he fixed in a 

 wooden frame, and, by whirling it about rapidly, 

 and rubbing it at the same time with his 

 hand, he was enabled to perform several experi- 

 ments. This may be regarded as the first elec- 

 trifying machine. He observed that a body 

 which was attracted by his globe was afterwards 

 repelled by it, but that if it touched another body, 

 it became after that capable of being attracted 

 again. Thus he was able to keep a feather sus- 



* Amber, electron in Greek, whence the name electricity. 



