322 



CONTRIBUTIONS TO ELECTRICITY AND MAGNETISM. 



small battery a shock could be given from the current of the third 

 order to twenty-five persons joining hands ; also shocks perceptible in 

 the arms vv^ere obtained from a current of the fifth order. 



84. The action at a distance was also much greater than could have 

 been anticipated. In one experiment shocks from the tertiary current 

 were distinctly felt through the tongue, when helix No. 1 was at the 

 distance of eighteen inches above the coil transmitting the secondary 

 current. 



85. The same screening effects were produced by the interposition 

 of plates of metal between the conductors of the different orders, as 

 those which have been described in reference to the primary and se- 

 condary currents. 



86. Also when the long helix is placed over a secondary current 

 generated in a short coil, and which is therefore, as we have before 

 shown, one of quantity, a tertiary current of intensity is produced. 



87. Again, when the intensity current of the last experiment is 

 passed through a second helix, and another coil is placed over this, a 

 quantity current is again produced. Therefore in the case of these 

 currents, as in that of the primary, a quantity current can be induced 

 from one of intensity, and the converse. By the arrangement of the 

 apparatus as shown in Fig. 9, these different results are exhibited at 

 once. The induction from coil No. 3 to helix No. 1 produces an in- 

 tensity current, and from helix No. 2 to coil No. 4 a quantity current. 



Fig. 9. 



a c 



a coil No. 1, J coil No. 2, c coil No. 3, i helix No. 1, e helix No. 2 and 3, /coil No. 4, and g 



magnetizing spiral. 



88. If the ends of coil No. 2, as in the arrangement of Fig. 8, be 

 united to helix No. 1 instead of coil No. 3, no shocks can be obtained ; 

 the quantity current of coil No. 2 appears not to be of sufiicient inten- 

 sity to pass through the wire of the long helix. 



89. Also, no shocks can be obtained from the handles attached to 



