90 Col. Gibbs on Magnetism. 



or has the most attraction to matter. But there are other 

 rays, which Herschel, who some years since discovered them, 

 calls invisible rays, which are still more refrangible, are next 

 beyond the violet, when refracted, and partake of most of its 

 properties, except that they are invisible. I have not yet 

 seen any account of the experiments of M. Morechini, other 

 than the notice in the journal; but I trust I shall soon be able 

 to determine whether those invisible rays do not possess the 

 magnetic power as well as the violet ; or, perhaps, possess it 

 exclusively. 



As the refraction of the atmosphere in the polar circles, is 

 at least ten times greater than in the tropics, a greater quan- 

 tity of the magnetic rays will there be separated and combined 

 than elswhere ; and of course arises excess of magnetism. 

 Hence the direction of magnetic bodies towards the northern 

 and southern extreme regions. The great absorption and 

 emission of light in the polar regions, by the ice and snow, 

 may cause the extraordinary illumination of that country during 

 the absence of the sun, and the emission of the magnetic rays 

 with electricity may, perhaps, give us the aurora borealis. 



The coincidence of the diurnal variation of the compass with 

 the solar influence, deserves particular notice, and will have 

 considerable weight on this subject. 



That there are many facts which cannot readily be explained 

 by the theory of light, I shall not deny ; but in the infancy of 

 this system we may be allowed to hope that future observa- 

 tions may enable us to remove present difliculties. One thing 

 must be admitted, that no theory has heretofore been published 

 relating to magnetism, which has received or seems entitled to 

 much confidence. In your next number I hope to be able 

 to furnish you with further remarks on this subject ; but, I 

 have no doubt that philosophy will finally determine that we 

 owe to the solar ray light, heat, electricity, and magnetism. 



G. GIBBS. 



Sunswick, January, 1818. 



