ISO RemarJiS on Professor Hansteen’s 
naturally suggests itself, in what ratio is the force distributed 
among the particles of that substance, or upon what function of 
the distance does its energy depend ? To answer this question, 
it seems necessary to attend to three things. Firsts According 
to what law do the individual particles of one magnet attract or 
repel those of another ? Their force evidently follows some in- 
verse ratio of the distance, because the former diminishes, while 
the latter augments : is that inverse ratio the distance simply, 
the square, or the cube, or any other power of it ? Secondly^ 
According to what law is the magnetic force shared among the 
individual particles lying in the line that joins the poles of the 
same magnet ; in other words, is the magnetic intensity of a par- 
ticle proportional directly to its distance from the middle point 
of the axis (where that intensity is nothing), or to the square, 
the cube, or any other power of its distance And, thirdly^ 
According to what law is the force distributed among the par- 
ticles of a section perpendicular to the axis or line joining the 
poles of the same magnet If these points were fully resolved, 
the magnetic action, of what sort soever we may conceive it, 
would be entirely submitted to calculation ; and though the esti- 
matioU of all its varieties would far exceed the actual powers of 
analysis, the problem being now fairly stated, its complete solu- 
tion would depend entirely upon the progress of mathematics. 
Experiment having done its part, the data yielded by it would 
require to be combined by another instrument. 
With regard to the first question, it seems so natural to con- 
sider every kind of force as some species of fluid or emanation, 
and it is so easy to see that every species of emanation will be 
dense, and therefore effective exactly in the inverse duplicate ra- 
tio of its distance from the emanating centre ; that tliis law, uni- 
versally operative in the case of gravitation, was first resorted 
to for explaining the attraction of magnets. But on attempting 
to establish the hypothesis by actual experiment, the obstacles 
were found sufficient to bring out false or very dubious results. 
‘‘ The great difficulty,’’ liambert observes *, met wnth in this 
fiort of researches, is, that when we wdsh to determine the fun- 
damental laws, probably in themselves very simple, it is neces- 
A)inh/!t€ de qt(elpics experience!} faites stir VAiman. 
