90 
MR. HARRIS ON THE TRANSIENT MAGNETIC STATE, &C. 
known law of magnetic attraction, will be constantly endeavouring to place 
itself at right angles to the magnetic equator of the disc, whilst the position of 
the latter varies in its turn with the position of the bar : it is in fact owing to 
this circumstance that the bar at length revolves with the disc, as may be in 
great measure seen by substituting for the disc a similar disc of steel made 
permanently magnetic ; in which case the suspended bar will not revolve, it 
will be merely put into a state of disturbed vibration. 
