Mr. Watkins on Magneto-electric Induction. Ill 



•B 



philosopher observed that the effect was instantaneous, for the 

 needle returned to its natural position, and remained stationary 

 notwithstanding the proximity of the magnet to the wire. But 

 on removing the magnet from the wire, then a distinct and 

 separate action was seen on the galvanoscope, for the needle 

 again was deflected as far from its true position as in the first 

 instance, but in a contrary direction. This I take to be the 

 fundamental experiment of magneto-electricity. 



Well, then, what do we do with our most improved mag- 

 netic machines ? Why, instead of approaching a permanent 

 steel magnet to a metal wire, we coil around a soft-iron arma- 

 ture a large quantity of wire, by that means multiplying the ef- 

 fects; and then, by mechanical contrivances, make the soft-iron 

 armature revolve before the poles of a permanent steel mag- 

 net. The armature being of soft iron is only a magnet by in- 

 duction when opposite the poles of the permanent magnet, and 

 when slowly removed it loses all its magnetism. This is ac- 

 complished when the long axis of the armature is vertical, the 

 axis of the permanent magnet being horizontal ; therefore the 

 armature changes its poles twice in each revolution. Hence 

 we have in every slow revolution two actions and two re- 

 actions. One of these actions, it is true, tends to the same di- 

 rection as one of the reactions; but still we have two direc- 

 tions of the current, and these two are antagonizing, therefore 

 we have no true polar decomposition. Yet if the soft-iron 

 armature be made to revolve rapidly, and two vessels be em- 

 ployed to collect the gases from the decomposition of water, 

 their volumes are often found to be nearly as two to one. 

 The induced electricity cannot be said to be always in one 

 direction. Hence, as with my constantly revolving magnetic 

 needles, the effect must be due to the maximum of effects from 

 one or the other pole. In other words, that one extremity of the 

 soft-iron armature having acquired a particular polar state 

 by induction, and time being the essential element of that 

 state, although removed from the inducing pole and presented 

 immediately to another pole in the opposite state, the period 

 has not elapsed which is necessary for it to lose all its polarity 

 before it is again brought into approximation with the first or 

 original inducing pole, and there receiving a renewed impulse, 

 and so on successively: the phenomena exhibited, although 

 not strictly due to a current of electricity flowing in one di- 

 rection, still give results analogous to a current of that de- 

 scription, and, as far as I can see, proceed from the maximum 

 effects I have before alluded to. I deliver these observations 

 with great diffidence, but in my mind the reasoning here given 

 is such as is warranted by the facts before us. 



