THE INSULATING STOOL. 609 



straight part is drawn through the hole in each bell, and the other 

 ends are then bent into similar rings. To one of the lower rings a 

 piece of silver thread (of the kind used in embroidery- work) is tied, 

 having a length ofi several decimetres, and a wire hook is attached 

 to the other end of this thread, which serves for suspending it from 

 the stalk of the small brass ball of the conductor. A wire or small 

 chain could not be used instead of the silver thread, because they 

 would pull the little bell aside by their weight. The bell to which 

 the silver thread is tied is suspended by a thread of twisted silk, 

 and the other bell by a wire, to a cross-piece of stout wire which 

 also carries the clapper ; it is bent as shown in the figure, and 

 clamped in the retort-stand while used. 



A larger set of chimes may be made by giving to this cross-piece 

 the form shown at B in the figure ; clappers are suspended from a, 

 6, c, and d ; at 1, 8 and 5, bells are hung by wires, at 2 and 4 bells 

 are suspended by silk threads, and the bells at 2 and 5 are provided 

 with silver threads which by a joint hook are connected with the 

 conductor of the machine. 



If a small loose plug of cotton wool, about as large 

 as a thimble, be held between the tips of the forefinger 

 and thumb, at about 10 cm from the conductor, the 

 fibres will, in consequence of electrical attraction, point 

 towards the conductor. When the plug is let go, it flies 

 to the conductor, becomes charged with electricity, is 

 repelled back again to the hand, loses its charge, is then 

 attracted again, and so on. If the hand is brought 

 nearer to the conductor, the motion of the plug to and fro 

 becomes so rapid that it can scarcely be distinctly seen. 



The single fibres repel one other while in the electric state, 

 hence a number of them fly off and adhere to all parts of the 

 machine. They act like points, and must therefore be carefully 

 looked for and wiped off before the machine is used for other ex- 

 periments. 



For insulating conducting bodies of somewhat large 

 dimensions the 'insulating stool ' is used; it consists of 

 a board of hard wood, supported on glass legs covered 

 with varnish. The experimenter, by standing upon such 



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