128 WRITINGS OF JOSEPH HENRY. [1838 



of the natural electricity of the wire, disturbed but for an 

 instant by the induction of the primary; yet this has the 

 power of inducing another current, but little inferior in 

 energy to itself, and thus produces effects apparently much 

 greater in proportion to the quantity of electricity in motion 

 than the primary current. 



82. Some difference may be conceived to exist in the action 

 of the induced currents, and that from the battery, since they 

 are apparently different in nature; the one consisting, as we 

 may suppose, of a single impulse, and the other of a succes- 

 sion of such impulses, or a continuous action. It was there- 

 fore important to investigate the properties of these currents, 

 and to compare the results with those before obtained. 



83. First, in reference to the intensity, it was found that 

 with the small battery a shock could be given from the cur- 

 rent of the third order to twenty-five persons joining hands; 

 also shocks perceptible in the arms were 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 in- 

 terposition of plates of metal between the conductors of the 

 different orders, as those which have been described in refer- 

 ence to the primary and secondary 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 experi- 

 ment 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 pri- 

 mary, 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. 



