PROPERTIES OF STEEL MAGNETS. 5 



delicate experiments suspension is far superior. A 

 very small magnet may be carried by a single fibre as 

 spun by .the silk-worm : a larger magnet may be sup- 

 ported by a manufacturer's silk thread, formed by the 

 union of six or seven of the silk -worm's threads : and 

 the largest may be suspended by a skein consisting of 

 a number of these threads in parallel lines. In all these 

 cases of suspension, the torsion-power of the support is 

 very small, and there is an almost total absence of fric- 

 tion properly so called. 



7. The opposite ends of a magnet have different 

 properties. Explanation of the terms "red" and "blue" 

 magnetism, and of the symbols employed to represent 

 them. Allusion to horse-shoe magnets. 



Understanding then that one end of the magnet 

 thus freely suspended will point to the direction called 

 "Magnetic North" (not generally coinciding with Astro- 

 nomical or Geographical North, but at the present time, 

 in Greenwich, about 20 west of North), and that the 

 other end will point to the "Magnetic South," and that 

 if the magnet be disturbed in direction it immediately 

 returns to its first position, it is evident that the oppo- 

 site ends of the magnet possess different properties. 

 The magnetism of the end of the magnet which points 

 nearly to the geographical north will be called red mag- 

 netism, and that of the opposite end will be called blue 

 magnetism. The student is particularly requested to 

 observe that these words "red" and "blue" have here no 

 meaning whatever, except as distinguishing the two 



