40 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XXVIII.) 
3120. In this striking disposition of the forces of a magnet, as exhibited by the 
moving wire, it exactly resembles an electro-magnetic helix, both as to the direction 
of the lines of force in closed circuits, and in their equal sum within and without. 
No doubt, the magnet is the most heterogeneous in its nature, being composed, as 
we are well-aware, of parts which differ much in the degree of their magnetic deve- 
lopment ; so much so, that some of the internal portions appear frequently to act as 
keepers or submagnets to the parts which are further from the centre, and so, for the 
time, to form complete circuits, or something equivalent to them, within. But these 
make no part of the resultant of force externally, and it is only that resultant which 
is sensible to us in any way ; either by the action on a needle, or other magnets, or 
soft iron, or the moving wire. So also the power which is manifest within the magnet 
by its effect on the moving mass, is still only that same resultant ; being equal to, 
and by polarity and other qualities, identical with it. No doubt, there are cases, as 
upon the approach of a keeper to the poles, or the approximation of other magnets, 
either in favourable or adverse positions, when more external force is developed, or it 
may be a portion apparently thrown inwards and so the external force diminished. 
But in these cases, that which remains externally existent, corresponds precisely to 
that which is the resultant internally ; for when either the same, or contrary poles, 
of a powerful horseshoe magnet were placed within an inch and a half of the poles 
of the bar magnets, prepared to rotate with the attached wires (3092.), as before 
described, still, upon their revolution, not the slightest action at the galvanometer 
was perceived ; the forces within the magnet and those without perfectly compen- 
sating each other. 
3121. The definite character of the forces of an invariable magnet, at whatever 
distance they are observed from the magnet, has been already insisted upon (3109.). 
How much more strikingly does that point come forth now, that, being able to ob- 
serve within the magnet, we find the same definite character there ; every section of 
the forces, whether within or without the magnet, being exactly of the same amount! 
The power of a magnet may therefore be easily represented by the effects of any sec- 
tion of its lines of force; and as the currents induced by two different magnets may 
easily be conducted through one wire, or be, in other ways, compared to each other, 
so facilities may thus arise for the establishment of a standard amongst magnets. 
3122. On the other hand, the use of the idea of lines of force, which I recommend, 
to represent the true and real magnetic forces, makes it very desirable that we should 
find a unit of such force, if it can be attainable, by any experimental arrangement, 
just as one desires to have a unit for rays of light or heat. It does not seem to me 
improbable that further research will supply the means of establishing a standard of 
this kind. In the mean time, for the enlargement of the utility of the idea in relation 
to the magnetic force, and to indicate its conditions graphically, lines may be em- 
ployed as representing these units in any given case. I have so employed them in 
former series of these Researches (280/. 2821. 2831. 2874. &c.), where the direction of 
the line of force is shown at once, and the relative amount of force, or of lines of 
