On Electric Phenomena. 15 



the current through the same and study its effect. We will 

 now submit a part of these effects to a more minute investi- 

 gation. 



As you mil already know, there is in Nature a body 

 which possesses the property of attracting iron; it is called 

 magnetite or magnetic iron ore. When steel is rubbed with 

 this magnetic iron, it imbibes the same quality and can then 

 transfer it to other steel. If we have such a magnet of steel 

 in the form of a needle which is so placed on a point, that 

 it can easily be turned round, we observe, that the needle 

 continually takes a certain direction, whereby the one end 

 turns towards the North, the other towards the South. If 

 we now pass the current of the galvanic chain over the needle, 

 we remark, that the needle leaves its usual place and turns 

 its North point either towards the East or the West, until it 

 comes to rest in a fixed position. If w^e interrupt the current, 

 the needle returns again to its natural situation. 



Such a needle can assist us to discern whether an elec- 

 tric current be present; but if the current be very weak, then 

 the deviation of the needle is very slight and scarcely per- 

 ceptible.. It can be made stronger, if w^e let the wire which 

 conducts the current, pass several times round the needle, by 

 wdnding the wire on a frame, in the middle of which the 

 needle can easily turn. That the current may not go dia- 

 gonally from one coil to another, but reaUy flow through every 

 coil one after the other, it is necessary to enclose the wire 

 in an insulated covering. This is effected by spinning silk 

 over the wire. In tliis case, the effect of the current on the 

 needle is greatly multiplied; therefore, such an instrument is 

 called a multiplicator. For greater convenience we can also 

 bring a hand on the needle, which plays on the outside of 



(137) 



