266 FRAGMENTS OF SCIENCE. 
pended; bring the eye-end of the former near the eye-end 
of the latter; the suspended needle retreats: it is repelled. 
Make the same experiment with the two points; you obtain 
the same result, the suspended needle is repelled. Now 
cause the dissimilar ends to act on each other you have 
attraction point attracts eye, and eye attracts point. 
Prove the reciprocity of this action by removing the sus- 
pended needle, and putting the other in its place. You 
obtain the same result. The attraction, then, is mutual, 
and the repulsion is mutual. You have thus demonstrated 
in the clearest manner the fundamental law of magnetism, 
that like poles repel, and that unlike poles attract each 
other. You may say that this is all easily understood 
without doing; but do it, and your knowledge will not be 
confined to what i have uttered here. 
I have said that one end of your bar-magnet has a mark 
upon it; lay several silk fibers together, so as to get 
sufficient strength, or employ a thin silk ribbon, and form 
a loop large enough to hold your magnet. Suspend it; 
it turns its marked end toward the north. This marked 
end is that which in England is called the north pole. If 
a common smith has made your magnet, it will be con- 
venient to determine its north pole yourself, and to mark 
it with a file. Vary your experiments by causing your 
magnetized darning-needle to attract and repel your large 
magnet; it is quite competent to do so. In magnetizing 
the needle, I have supposed the point to be the last to quit 
the marked end of the magnet; the point of the needle is 
a south pole. The end which last quits the magnet is 
always opposed in polarity to the end of the magnet with 
which it has been last in contact. 
You may perhaps learn all this in a single hour; but 
spend several at it, if necessary; and remember, under- 
standing it is not sufficient: you must obtain a manual 
aptitude in addressing Nature. If you speak to your 
fellow-man you are not entitled to use jargon. Bad ex- 
periments are jargon addressed to Nature, and just as 
much to be deprecated. Manual dexterity in illustrating 
the interaction of magnetic poles is of the utmost impor- 
tance at this stage of your progress; and you must not 
neglect attaining this power over your implements. As 
you proceed, moreover, you will be tempted to do more 
than I can possibly suggest. Thoughts will occur to you 
