32 DR. FARADAY’S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XXVI.) 
certain limited space, be produced (2465.). In such a field the power does not vary 
either along or across the lines, but the distinction of direction is as great and im- 
portant as ever, and has been already marked and expressed by the term axial and 
equatorial, according as it is either parallel or transverse to the magnetic axis. 
2807. When a paramagnetic conductor, as for instance, a sphere 
of oxygen, is introduced into such a magnetic field, considered pre- 
viously as free from matter, it will cause a concentration of the 
lines of force on and through it, so that the space occupied by it 
transmits more magnetic power than before (fig. 1). If, on the 
other hand, a sphere of diamagnetic matter be placed in a similar 
field, it will cause a divergence or opening out of the lines in the 
equatorial direction (fig. 2) ; and less magnetic power will be 
transmitted through the space it occupies than if it were away. 
2808. In this manner these two bodies will be found to affect, 
Jirst the direction of the lines of force, not only within the space 
occupied by themselves, but also in the neighbouring space, into which the lines pass- 
ing through them are prolonged ; and this change in the course of the lines will be 
in the contrary direction for the two cases. 
2809. Secondly, they will affect the amount of force in any particular part of the space 
within or near them ; for as every section across the line of such a magnetic field 
must be definite in amount of force, and be in that respect the same as every other 
section, so it is impossible to cause a concentration within the sphere of oxygen (fig. 1) 
without causing also a simultaneous concentration in the parts axially situated as a a 
outside of it, and a corresponding diminution in the parts equatorially placed, h b. 
On the other hand, the diamagnetic body (fig. 2) will cause diminution of the mag- 
netic force in the parts of space axially placed in respect of it, c c, and concentration 
in the near equatorial parts, dd. If the magnetic field be considered as limited in its 
extent by the walls of iron forming the faces of opposed poles (2465.), then even the 
distribution of the magnetism within the iron itself will be affected by the presence of 
the paramagnetic or diamagnetic bodies ; and this will happen to a very large extent 
indeed, when, from among the paramagnetic class, such substances as iron, nickel or 
cobalt are selected. 
2810. The influence of this disturbance of the forces upon the place and position 
of either a paramagnetic or a diamagnetic body placed within the magnetic field, is 
readily deduced upon consideration and easily made manifest by experiment. A small 
sphere of iron placed within a field of equal magnetic power, bounded by the iron 
poles, has a position of unstable equilibrium, equidistant from the iron surfaces, and 
at such time a great concentration of force takes place through it, and at the iron faces 
opposite to it, and through the intervening axial spaces. If the sphere be on either side 
of the middle distance, it flies to the nearest iron surface, and then can determine the 
greatest amount of magnetic force to or upon the axial lines which pass through it. 
Fig. 1. 
