15 



CHAPTER II. 



THE IDENTITY OF MAGNETIC AND GALVANIC CURRENTS. 



Although the sciences of magnetism, galvanism and electricity- 

 have been effectually blended, and proved by various experi- 

 ments to be the effects of one primary cause, the direction of 

 the magnetic currents compared with galvanic currents is con- 

 sidered different, i. e. that the magnetic currents move at right 

 angles to those of galvanism. This idea has arisen from the 

 effects of the spiral course in which the external current that 

 envelopes the connecting wire of a battery moves towards the 

 negative plate. For instance, if the connecting wire of a battery 

 be placed in the meridian, having its negative plate attached to 

 the north end and the positive plate to the south, the external 

 current enveloping the wire will move northward towards the 

 negative plate in a spiral form. On the upper side of the wire 

 it moves towards the north-west, and on the under side towards 

 the north-east ; on the western side it moves downwards, and 

 on the eastern side upwards. This spiral nature of the current 

 produces motion in a circular direction round the wire, which 

 is exhibited in various electro-magnetic machines. It is there- 

 fore very evident that the magnetic currents are not at right 

 angles to those of galvanism. Supposing the intensity of the 

 current causes the needle when held above the wire to deviate 

 thirty degrees to the west, in placing it underneath the wire it 

 will deviate thirty degrees to the east ; taking the mean of the 

 two, we find that the direction corresponds to that of the wire. 

 That this is the fact is proved by making the experiment. It will 

 therefore be observed, that the winding of a galvanic wire from 

 east to west around an artificial globe, to illustrate the effect of 

 the galvanic current on the magnetic needle, leads to very erro- 

 neous conclusions, by presenting the direction of one side of the 

 spiral and not the under one. 



The hypothesis of the magnetic currents being at right angles 

 to the direction of the needles, must be admitted to have been 



