86 From Matter to Man. 



— A needle, in common with all iron or steel bodies, 

 is magnetic, because it is composed of magnetic 

 atoms ; but the force of the atoms is not always 

 manifested uniformly, hence it may not attract and 

 repel polarly. The mixed polarity may have been 

 brought about in several ways. The poles of the 

 constituent atoms, for instance, may not have cohered 

 regularly in the formation of the needle ; consequently 

 they would not range regularly from end to end, or 

 if they did, the grinding and polishing processes may 

 have again broken up the polarity. If, however, the 

 needle be brought into contact with a magnet, the 

 scattered polarities of the atoms are mastered and 

 forced to set one way. From thenceforth all act in 

 concert. The ease with which this action is done is 

 comprehensible when we remember that the con- 

 stituent molecules of even a needle are, according 

 to the molecular theory of matter, separate from one 

 another, as well as in intense motion. 



A tube of iron filings may be induced and polarised 

 similarly. A question, however, arises. If, as the 

 evidence involves, every element and substance be 

 magnetic, why cannot we construct magnets of wood, 

 brick, and stone, as well as of. iron ? Simply because 

 no other element possesses the force so strongly. 

 No natural magnet so powerful as the loadstone 

 exists with which to effect magnetic induction in 

 other substances, for, as iron requires iron to 

 magnetise it, so sticks and stones would also require 



