198 



SCIENTIFIC RECREATIONS. 



first substance to show attraction when rubbed, but Gilbert found out that 

 glass and sealing-wax, etc., possessed like properties with amber. 



If we rub a stick of sealing-wax with a piece of cloth, we shall see 

 that it will attract some small fragments of paper placed near it. Nothing 

 is easier than to construct a small pendulum to show with perfect clearness 

 the phenomenon of electric attraction. A piece of iron is fixed on a 

 wooden pedestal, and supports a thread of silk, to the end of which is 

 fastened a little ball cut out of a piece of cork. The stick of sealing-wax 

 after being rubbed with the cloth will attract the ball as shown in fig. 200. 



By means of a piece of paper we can produce a spark. I take a large, 



Fig. 200. Sealing-wax attracting a piece of cork. 



strong sheet of drawing paper, heat it very thoroughly, and lay it on a wooden 

 table. I rub it with a perfectly dry hand, or with a piece of woollen material 

 until it adheres to the table. That done, I place a bunch of keys in the 

 centre of the sheet of paper, which I raise, lifting it by two corners. If at 

 this moment any one touches the bunch of keys with his finger, a bright 

 spark will be elicited. The metal is charged with the electricity developed 

 on the paper ; if the weather is dry, and the paper thoroughly heated several 

 times, the spark may attain nearly an inch in length. 



We can easily construct other electrical apparatus. For instance, an 

 " Electrophorus," or instrument for obtaining electricity by means of induc- 

 tion, or a Leyden jar, can both be made at home. Let us proceed to 

 construct the former, of which we give an illustration (fig. 201). 



