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at best exceedingly strained and artificial, at variance with ana- 

 logy of all other physical forces, and repugnant to our ideas 

 of that simplicity which seems to pervade all the operations of 

 the material world. All known forces, emanating from a certain 

 point and exerted upon another point, act in the direction of the 

 line joining these two points. Such is the effect of a stream of 

 water on a substance exposed to its action, and on a vane by 

 the wind, which always points in the direction of the current. 

 The same law applies to electric and magnetic actions, in all the 

 cases that belong exclusively to the one or to the other of these 

 two classes of phenomena. 



When two conducting w T ires, bent into helices, act upon one 

 another, which they do in a manner that imitates very exactly 

 the mutual action of two magnets, the action is called electrical, 

 and is exerted in the lines of direction that join the acting points. 

 The same is the case with two magnets in whatever position 

 they may be placed. When the latter is exposed to the effects 

 of the former, it indicates the spiral current above alluded to. All 

 fluids, when forced through tubes by a great force, have a ten- 

 dency to move in a spiral direction, as commonly observed in 

 a funnel. However, if we take the mean of the direction of the 

 spiral, we find that it corresponds to the direction of the wire ; 

 therefore we may safely consider that the magnetic needle, en- 

 veloped as it is in the great terrestrial magnetic fluid, indicates 

 the direction of the currents. 



We have now r to prove that the currents move through the 

 magnetic needle from south to north. In the battery we find 

 that the currents of hydrogen move from the zinc to the silver 

 plate, along or through the connecting wire. We find by ex- 

 periments that the south pole of a magnet has a greater affinity 

 for oxygen than the north pole. The difference in the oxidation 

 of the south pole, compared w r ith the north, is easily proved by 

 various simple methods. All that is required is to place the ends 

 of a magnet in water, and allow it to remain undisturbed for 

 several days, and the fact is soon proved. A very powerful horse- 

 shoe magnet will decompose water, and the oxidation will be 

 observed to go on at the south pole, and the evolution of the 

 hydrogen at the north pole : hence it is manifest that the currents 

 move from the south pole to the north of the needle : the magnet 



