92 THE FAIRY-LAND OF SCIENCE. 
other away. See! the magnet I am not holding runs 
away from the other. But if I bring a red end and 
a black end, that is, a positive and a negative end, to- 
gether, then they are attracted and cling. I will make 
a triangle (A, Pig. 22) in which a black end and a 
red end always come together, and you see the triangle 
holds together. But now if I take off the lower bar 
and turn it (B, Fig. 22) so that two red ends and two 
black ends come together, then this bar actually rolls 
back from the others down the cardboard. If I were to 
break these bars into a thousand pieces, each piece 
would still have two poles, and if they were scattered 
about near each other in such a way that they were 
quite free to move, they would arrange themselves 
always so that two different poles came together. 
You may not perhaps be able to easily obtain bar 
magnets, but you may easily repeat these experiments 
at home, and others even more interesting, with the 
help of a toy horseshoe magnet, which almost any child 
can get, a glass or bowl of water, and several sewing 
needles. Rub the needles along the magnet and they 
themselves will become magnets. Hold a needle par- 
allel to the surface of the water and very near it. Drop 
the needle, and it will float like a straw. This seems 
strange, for the metal of which the needle is made is 
much heavier than water, but a thin coat of air clings 
to the polished steel, and the needle is too light to break 
through it to the water. If the needle is not perfectly 
dry the air will not cling to it, and it will sink. Float- 
ing upon the surface of the water it will place itself 
with one end pointing north and the other south. In 
other words, it will be a compass. 
