1*559/1 XXI.] ELECTRIClTV. 125 



ly, or plus ; and when it has less than its natural 

 quantity, it is said to be electrified negatively, or 

 'minus. When bodies are electrified either of these 

 ways, they repel each other ; but if some be elec- 

 trified plus, and others minus, they mutually at- 

 tract ; or if one body be electrified plus, and the 

 other no way at all, they also attract each other. 



The following experiments will tend to shew 

 the reality of Electrical Attraction and Repulsion. 

 Cut two bits of cork into the shape and size of a 

 common pea. With a needle draw a thread 

 through each of the corks, so that they may be 

 made to hang at the ends of the threads with a 

 knot below them. Let the oilier ends of the 

 threads be inserted in the notch of a small 

 piece of wood, about a foot long, an inch broad, 

 and the thickness of a common match. Lay the 

 piece of wood over the mouths of two wine 

 glasses, a few inches asunder, so that the end 

 of it, in which the threads are, may project over 

 the edge of the glass nearest it, and the corks 

 may be in contact with one another. Take ano- 

 ther wine glass ; and having rubbed it heartily 

 with a piece of flannel, or upon the skirt, or 

 sleeve, of a woollen coat, hold its mouth to within 

 about an inch of the corks, and they will suddenly 

 start asunder and continue so for some time. 



Again, lay a pocket watch upon an horizontal 

 table, and take a common tobacco-pipe, and place 

 it on the face of the watch so that it may rest 

 thereon in equilibria : then, after rubbing a wine 

 glass (as described in the former experiment), 

 G 3 bring 



