328 CONTRIBUTIONS TO ELECTRICITY AND MAGNETISM. 



105. When, however, the quantity of free electricity was increased, 

 by connecting the knob of the jar with a globe about a foot in diame- 

 ter, the intensity of magnetism appeared to be somewhat diminished, 

 if the extra quantity was on the negative side ; and this might be ex- 

 pected, since the free electricity, in its escape to the earth through the 

 riband, in this case would tend to induce a feeble current in the oppo- 

 site direction to that of the jar. 



106. The spark from an insulated conductor may be considered as 

 consisting almost entirely of this free or extra electricity, and it was 

 found that this was also capable of producing an induced current, pre- 

 cisely the same as that from the jar. In the experiment which gave 

 this result, one end of the outer riband of the cylinder (100) was 

 connected with the earth, and the other caused to receive a spark from 

 a conductor fourteen feet long, and nearly a foot in diameter. The 

 direction of the induced current was the same as that of the spark from 

 the conductor. 



107. From these experiments it appears evident that the discharge 

 from the Leyden jar possesses the property of inducing a secondary 

 current precisely the same as the galvanic apparatus, and also that this 

 induction is only so far connected with the phenomenon of the lateral 

 discharge as this latter partakes of the nature of an ordinary electrical 

 current. 



108. Experiments were next made in reference to the production 

 of currents of the different orders by ordinary electricity. For this 

 purpose a second cylinder was prepared with ribands of tinfoil, in a 

 similar manner to the one before described. The two were then so 

 connected that the secondary current from the first would circulate 

 around the second. When a discharge was passed through the outer 

 riband of the first cylinder, a tertiary current was induced in the 

 inner riband of the second. This was rendered manifest by the mag- 

 netizing of a needle in a spiral joining the ends of the last mentioned 

 riband. 



109. Also by the addition, in the same way, of a third cylinder, a 

 current of the fourth order was developed. The same result was like- 

 wise obtained by using the arrangement of the coils and helices shown 

 in Fig. 9. For these experiments, however, the coils were furnished 



