T II E 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



JULY 1855. 

 I. On the Induction Apparatus and its Effects. 



By J. C. POGGENDORFF*. 



THE following investigation was suggested by an examina- 

 tion of an induction apparatus constructed by Ruhmkorff 

 for the physical cabinet of the University of Berlin. There is 

 no doubt that its construction and action are superior to those 

 of any other instrument of the kind yet invented, but I feel con- 

 vinced it is by no means so perfect as it may yet be made, nor 

 have the phjenomena which it manifests ever yet been sufficiently 

 investigated in any published memoir. On this account the 

 present investigation will be divided into two parts ; the one will 

 be devoted to the construction of the apparatus, the other to its 

 effects. 



1. Construction of the Apparatus. 

 In its present form the apparatus consists of no less than six 

 parts ; viz. 1, the coil of wire in which induction is developed, the 

 induction coil ; 2, the coil which conducts the inducing galvanic 

 current, here called the primary coil ; 3, the soft-iron core ; 

 4, the current breaker ; 5, the condenser ; and 6, the voltaic 

 battery or primary source of electricity; to which parts, lastly, 

 some additional apparatus must be added. Each of these six 

 elements acts, more or less, upon the remaining five ; and the 

 ultimate result, the induced current, depends upon a suitable 

 distribution and arrangement of all. 



Induction Coil. 



On examining this coil, it appeared to me that hitherto it had 

 not been constructed on proper principles. Usually the wire 

 forms layers which extend, without interruption, from one end 

 * From Poggeiulorff' s Annalen, vol. xciv. p. 2. 



Phil. Mag. S. 4. Vol. 10. No. 63. July 1855. B 



