1852. 
WEEKLY EVENING MEETING, 
Friday, January 23. 
Sir Joun P. Borxeau, Bart., F.R.S, V.P. in the Chair. 
Proressor Farapay, | 
On the Lines of Magnetic Force. 
Tuar beautiful system of power which is made manifest in the 
magnet, and which appears to be chiefly developed in the two 
extremities, thence called ordinarily the magnetic poles, is usually 
rendered evident to us in the case of a particular magnet by the 
attractive or repulsive effect of these parts on the corresponding 
parts of another magnet; and these actions have been employed, 
both to indicate the direction in which the magnetic force is 
exerted and also the amount of the force at different distances. 
Thus, if the attraction be referred to, it may be observed either 
upon another magnet or upon a piece of soft iron; and the law 
which results, for effects beyond a certain distance, is, that the 
force is inversely as the square of the distance. When the dis- 
tances of the acting bodies from each other is small, then this 
law does not hold, either for the surface of the magnets or for 
any given point within them. 
Mr. Faraday proposes to employ a new method, founded upon 
a property of the magnetic forces different from that producing 
attraction or repulsion, for the purpose of ascertaining the direction, 
intensity, and amount of these forces, not to the displacement of 
the former method but to be used in conjunction with it; and he 
thinks it may be highly influential in the further development of 
the nature of this power, inasmuch as the principle of action, 
though different, is not less magnetic than attraction and repulsion, 
not less strict, and the results not less definite. 
The term line of magnetic force is intended to express simply 
the direction of the force in any given place, and not any phy- 
sical idea or notion of the manner in which the force may be 
there exerted; as by actions at a distance, or pulsations, or 
waves, or a current, or what not. A line of magnetic force may 
be defined to be that line which is described by a very small 
magnetic needle, when it is so moved in either direction corre- 
