276 FRAGMENTS OF SCIENCE. 
the iron filings very small scraps of thin iron wire might 
be employed. I place a sheet of paper over the rnaguet; 
it is all the better if the paper be stretched on a wooden 
frame, as this enables us to keep it quite level. I scatter 
the filings, or the scraps of wire, from a sieve upon the 
paper, and tap the latter gently, so as to liberate the 
particles for a moment from its friction. The magnet acts 
on the filings through the paper, and see how it arranges 
them! They embrace the magnet in a series of beautiful 
curves, which are technically called "magnetic curves," or 
" lines of magnetic force." Does the meaning of these 
lines yet flash upon you? Set your magnetic needle, or 
your suspended bit of wire, at any point of one of the 
curves, and you will find the direction of the needle, or of 
the wire, to be exactly that of the particle of iron, or of 
the magnetic curve, at that point. Go round and round 
the magnet; the direction of your needle always coincides 
with the direction of the curve on which it is placed. 
These, then, are the lines along which a particle of south 
magnetism, if you could detach it, would move to the 
north pole, and a bit of north magnetism to the south 
pole. They are the lines along which the decomposition 
of the neutral fluid takes place. In the case of the mag- 
netic needle, one of its poles being urged in one direction, 
and the other pole in the opposite direction, the needle 
must necessarily set itself as a tangent to the curve. I will 
not seek to simplify this subject further. If there be any- 
thing obscure or confused or incomplete in my statement, 
you ought now, by patient thought, to be able to clear 
away the obscurity, to reduce the confusion to order, and 
to supply what is needed to render the explanation com- 
plete. Do not quit the subject until you- thoroughly 
understand it; and if you are then able to look with your 
mind's eye at the play of forces around a magnet, and see 
distinctly the operation of those forces in the production 
of the magnetic curves, the time which we have spent 
together will not have been spent in vain. 
In this thorough manner we must master our materials, 
reason upon them, and, by determined study, attain to 
clearness of conception. Facts thus dealt with exercise an 
expansive force upon the intellect they widen the mind 
to generalization. We soon recognize a brotherhood 
between the larger phenomena of Nature and the minute 
