INDUCTIVE ACTION OF AN ELECTRIC CURRENT. 49 



meter was introduced at x. Using an electro- magnet at D, and continuing contact, 

 a current was then indicated by the deflection, proceeding from P to N, in the direc- 

 tion of the arrow ; the cross wire serving to carry one part of the electricity excited 

 by the electromotor, and the arrangement ABD, as indicated by the arrows, the 

 other and far greater part. The magnetic needle was then forced back, by pins 

 applied upon opposite sides of its two extremities, to its natural position when unin- 

 fluenced by a current ; after which, contact being broken at G or E, it was deflected 

 strongly in the opposite direction ; thus showing, in accordance with the chemical 

 effects (1084.), that the extra current followed a course in the cross wires contrary to 

 that indicated by the arrow, i. e. the one produced by the direct action of the elec- 

 tromotor *. 



1088. With the helix only, these effects could scarcely be observed, in consequence 

 of the smaller inductive force of this arrangement, the opposed action from induc- 

 tion in the galvanometer wire itself, the mechanical condition and tension of the 

 needle from the eff'ect of blocking (1087.) whilst the current due to continuance of 

 contact was passing round it, and other causes. With the extended wire all these cir- 

 cumstances had still greater influence, and therefore allowed less chance of success. 



1089. These experiments, establishing as they did, by the quantity, intensity, and 

 even direction, a distinction between the primary or generating current and the extra 

 current, led me to conclude that the latter was identical with the induced current 

 described (6. 26.) in the first series of these Researches ; and this opinion I was soon 

 able to bring to proof, and at the same times obtained not the partial (1078.) but 

 entire separation of one current from the other. 



1090. The double helix (1053.) was arranged so that i should form the connecting 

 wire between the plates of the electromotor, ii being out of the current, and its ends 

 unconnected. In this condition i acted very well, and gave a good spark at the time 

 and place of disjunction. The opposite ends of ii were then connected together so as 

 to form an endless wire, i remaining unchanged : but now no spark, or one scarcely 

 sensible, could be obtained from the latter at the place of disjunction. Then, again, 

 the ends of ii were held so nearly together that any current running round that helix 

 should be rendered visible as a spark ; and in this manner a spark was obtained from 

 ii when the junction of i with the electromotor was broken, in place of appearing at 

 the disjoined extremity of i itself. 



1091. By introducing a galvanometer or a decomposing apparatus into the circuit 

 formed by the helix ii, I could easily obtain the deflections and decomposition oc- 

 casioned by the induced current due to the breaking contact at helix i, or even to 

 that occasioned by making contact of that helix with the electromotor ; the results in 

 both cases indicating the contrary directions of the two induced currents thus pro- 

 duced (26.). 



* It was ascertained experimentally, that if a strong current was passed through the galvanometer only, and 

 the needle restrained in one direction as above in its natural position, when the current was stopped, no viora- 

 tion of the needle in the opposite direction took place. 

 MDCCCXXXV. H 



