Prof. Norton on Molecular Physics. 433 



3. Induction-currents result from an electric polarization of the 

 molecules, suddenly induced by the same lateral action of a 

 primary current when first established, or by the increased 

 action of a previous electric or magnetic current — or suddenly 

 vanishing when the current is broken, or the force of action 

 decreases. The polarization in the first instance is the opposite 

 to that which prevails in the primary current, owing to the 

 indirect nature of the inducing action. 



4. The circular currents of a magnet consist of electric currents 

 that follow continuous chains of particles lying in the surface of 

 the compound molecules of the magnet. These currents have 

 their origin in an electric polarization of the particles, developed 

 by a direct action of the impulses propagated from the exciting 

 current. In permanent magnets the polarization thus originated 

 becomes permanently established, and a permanent current 

 remains as a necessary consequence of the play of the molecular 

 forces in the chain. A magnet therefore derives its power directly 

 from the inexhaustible primary forces of attraction and repulsion, 

 and must retain its virtue unimpaired until the chain of mole- 

 cules is broken by heat, or the excited molecular conditions upon 

 which the currents depend are removed by some external cause. 



5. Terrestrial magnetism is due to electric currents in the mass 

 of the earth running in the general direction from east to west, 

 and developed by the collision of the molecules with the aBther 

 of space. Both the rotatory and orbital motion of the earth are 

 concerned in producing these currents. A part of the force of 

 such currents must be converted into heat, and the earth derive 

 a portion of its heat from this source. If this be true, the 

 remarkable formal relations that subsist between the magnetism 

 and heat of the earth are probably the result in a great degree 

 of this physical bond by which the two principles are partially 

 united. (See the investigation, by the author, of these relations, 

 in an article on Terrestrial Magnetism, published in vol. iv. 

 second series, of Silliman's Journal.) 



This theory of the origin of terrestrial magnetism, as a part of 

 the general theory of molecular physics here presented, was 

 brought by the author to the notice of the Connecticut Academy 

 about two years since. It appears from a pamphlet recently 

 received by the editors of Silliman's Journal, that a theory quite 

 similar to this was propounded several years since by Gustav 

 Hinrichs of Copenhagen. Hinrich's theory, or one having the 

 same essential features, I find is advocated by Prof. Challis in 

 the Number of the Philosophical Magazine published in Fe- 

 bruary 1861. 



