132 WRITINGS OF JOSEPH HENRY. '[1838 



that the induced current in the first coil is a true secondary 

 current, and it is therefore neutralized by the action of the 

 secondary in the adjoining conductor; since this tends to 

 produce a current in the opposite direction. 



96. It would also appear from the perfect neutralization 

 which ensues in the arrangement just before described, that 

 the induced current in the adjoining conductor is more 

 powerful than that of the first conductor; and we can easily 

 see how this may be. The two ends of the second coil are 

 joined, and it thus forms a perfect metallic circuit; while 

 the circuit of the other coil may be considered as partially 

 interrupted, since k) render the spark visible the electricity 

 must be projected as it were through a small distance of air, 



97. We would also infer that two contiguous secondary 

 currents, produced by the same induction, would partially 

 counteract each other. Moving in the same direction, they 

 would each tend to induce a current in the other of an 

 opposite direction. This is illustrated bj'- the following ex- 

 periment: helix No. 1 and 2 were placed together, but not 

 united, above coil No. 1, so that they each might receive the 

 induction ; the larger was then gradually removed to a greater 

 distance from the coil, until the intensity of the shock from 

 each was about the same. When the ends of the two were 

 united, so that the shock would pass through the body from 

 the two together, the effect was apparently less than with 

 one helix alone. The result however was not as satisfactory 

 as in the case of the other experiments; a slight difference 

 in the intensity of two shocks could not be appreciated with 

 perfect certainty. 



SECTION VI. 



The production of induced Currents of the different Orders from 

 ordinary Electricity. 



98. Dr. Faraday, in the ninth series of his researches, re- 

 marks that " the effect produced at the commencement and 

 the end of a current (which are separated by an interval of 

 time when that current is supplied from a voltaic apparatus) 

 must occur at the same moment when a common electrical 



