and Phenomena of Magnetic Indnction. 273 



Chap. II. — Experiments illustrative of the Nature, In- 

 fluence, AND Phenomena of Magnetic Induction. 



Sect. 1 . Oftlie Nature of Magnetic Induction. > 



Magnetic Induction, some of the laws of which have now 

 been examined, is of most extensive influence in the science of 

 magnetism, being more or less engaged as an agent in almost all 

 its phenomena. The attraction of ferruginous bodies, not hav- 

 ing previous polarity, by the magnet^ depends simply on their 

 inductive capacity, — the proximate end of the magnet first de- 

 veloping a polarity different from its own, and then, according 

 to the general law of both magnetism and electricity, attracting 

 the contrary polarity thus developed. In whatever substance, 

 therefore, magnetism can be induced, there \vill be a capability 

 of being attracted by the magnet, the degree of attraction being 

 proportionate to the inductive capacity. It is also the general 

 influence by which polarity is developed in bodies capable of 

 permanent magnetism. 



Though we have no means of explaining the essential nature 

 of an agent so subtle and extraordinary as that of magnetism, 

 yet we may exhibit, by striking experiments, a variety of its 

 properties and phenomena. The connection of the magnetic 

 principle with iron is, as we have said, inherent and inalienable, 

 and the two denominations or polarities appear to have perma- 

 nent residence in each ferruginous particle, being mobile in the 

 particles but not separable from them. 



Ferruginous bodies are usually and naturally devoid of any 

 strong magnetic energy, the arrangement of the magnetisms of 

 the different particles being such as in a great measure to neu- 

 tralize each other. But the mere proximity of a magnet, or 

 even an electrical influence, as has been shown, disturbs the na- 

 tural equilibrium of the polarities, and tends to arrange them by 

 its inductive energy in a magnetic series. 



The development of the magnetic condition in a bar of iron, 

 then, is the mere arrangement of the inherent polarities in a 

 magnetic series, which arrangement appears to be the result of 

 two influences, — the direct inductive influence of the proximate 



VOL. Xlil. NO. XXVI. OCTOBER 1832. s 



