16 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XXII.) 
which showed that there was no axis of magnecrystallic force in the length or breadth 
of the plates. 
2523. Other plates were then found able to produce mixed effects, and those in 
different degrees. Thus, some, like the first, vibrated freely, pointed well, and pre- 
sented no indication of the arrest and revulsive phenomena. Others vibrated slug- 
gishly, set well, and showed a tendency to be arrested. Others pointed well, going 
up to their place with a dead set, but moving as if in a fluid ;.or, if the magnetic force 
were taken off before the piece had settled, it was revulsed feebly : and others were 
caught at once, did not set (within the time of my observation), and were strongly 
revulsed. 
2524. Finally, a careful investigation, carried on by means both of the horse-shoe 
(2485.) and the great electro-magnet (2247.), made the cause of these differences in 
the effects apparent. 
2525. It may be observed, in the first place, that sometimes a plate of antimony 
being selected (2517.), having planes very bright and perfect in their appearance, 
and, therefore, giving reason to think that it may point well in the magnetic field, 
when submitted to the horse-shoe magnet does not do so ; but points obliquely, 
feebly, and perhaps in two undiametral positions. This is, I have no doubt, because 
the crystallization is complicated and confused. Such a plate, if it be sufficiently 
broad and long (i. e. not less than a quarter or one-third of an inch), when submitted 
to the electro-magnet, will show the arresting (2310.) and revulsive (2315.) action 
well. 
2526. In the next place, we have to remember that, for the development of the 
induced currents that cause the arresting and revulsive action, the plate must have 
certain sufficient dimensions in a vertical plane (2329.). The currents occur in the 
mass and not round the separate particles (2329.), and the resultant of the magnetic 
lines of force passing through the substance, is the axis round which these currents 
are produced. Hence the reason why the effect does not occur with plates suspended 
in the horizontal position, which yet produce it well in the vertical position ; a result 
which a disc half an inch in diameter of thin foil or plate, being copper, silver, gold, 
tin, or almost any malleable metal will show; though the best conductors are the 
fittest for the purpose. Now this condition is of no consequence in respect of mag- 
necrystaUic action, and a narrow plate has as much force as a broad one, having the 
same mass. The first plate that I happened to select (2517.) was well crystallized, 
thick and narrow ; hence it was favourable for magnecrystallic action, unfavourable 
to the arresting and revulsive action, and showed no signs, comparatively, of the 
latter. 
2527. When a broad and well-crystallized plate is obtained, then both sets of 
effects appear : thus, if the plate is revolving when the magnetic force is brought 
into action, it quickens its velocity for an instant, then is stopped ; and if the mag- 
netic force is at once taken off, it is revulsed, exactly as a piece of copper would be 
