186 DOVE ON THE ELECTRICITY OF INDUCTION. 



taneousness of the primary current which produces it, and in its 

 corresponding shortness of duration. 



93. From the experiments which Faraday has detailed in his 

 fifteenth series*, upon the electricity of the Gymnotus, and from 

 those instituted by Matteucci upon the Torpedo t, it may be 

 presumed that it will be possible to obtain secondary currents of 

 sufficient strength from the primary currents of those animals, 

 capable of being submitted to similar modes of trial to those 

 which have here been put in practice with secondary currents 

 from other sources of electricity. If the fish could be enclosed 

 by means of collectors in the inner spirals of a diiferential induc- 

 tor, we should then be able to ascertain, by allowing a bundle of 

 wires in the one spiral to oppose a solid iron cylinder in the 

 other, what influence the breaking up of a mass of iron into a 

 bundle of wires exerts upon these currents. We should thus be 

 able more acciu-ately to determine what position these currents 

 would occupy in the series in relation to those produced from 

 other sources of electricity. If these were arranged according 

 to the time which a given quantity of electricity requires to be 

 neutraUzed, they would form a series somewhat Uke the fol- 

 lowing : — 



1. The current of a discharging Leyden jar, extra current 

 from the same source, secondary currents of the first and higher 

 orders, and lastly, currents induced by bundles of iron wires, 

 which have been electro-magnetized by an electric battery. 

 These cm'rents exerting a powerful physiological action without 

 a retardation of the current, do not affect the galvanometer 

 needle. 



2. Currents induced by solid iron, magnetized by means of 

 frictional electricity. 



3. Currents of higher orders, induced by electro-magnetized 

 bundles of iron wires, when the primary current is of galvanic or 

 of magneto-electric origin. The lower the order of the cur- 

 rent, the more distinct is its galvanometric action. 



4. Currents of the first order induced by bundles of wires when 

 the magnetizing current is of galvanic, thermo-electric or mag- 

 neto-electric ori>^in. 



5. The same currents induced by solid iron. 



* Philosophical Transactions for 1839, Part I. 



t Eisai sur les PMnomenes Eleciriques des Animaux, Paris, 1840, 8. 



