[89] 



Art. XX. On The Connexion between Magnetism and 

 Light, By Col. Gibbs. 



Extract from a Letter to the Editor. 



J. VISITED, the last year, the mine of magnetic iron at 

 Succassunny, belonging to Governor Dickerson of New-Jersey. 

 The mine had not been worked for a year past, and I did not 

 descend it. The proprietor, a gentleman of distinguished 

 science, informed me of a singular circumstance attending it, 

 which was too important to be left unnoticed. The mine is 

 worked at the depth of 100 feet ; direction of the bed, north- 

 east and southwest ; inclination nearly perpendicular. The 

 ore in the upper part of the bed is magnetic, and has polarity ; 

 but that raised from the bottom has no magnetism at first, but 

 acquires it after it has been some time exposed to the influence 

 of the atmosphere. This fact, of which there is no doubt, 

 struck me as most singular. I could not recollect any similar 

 observation ; and it is only lately that I have found that Wer- 

 ner had observed, that iron sand, raised from the depth of 100 

 feet, had no magnetism. See Rees's Cyclopedia, Art. Sand. 



I could only account for this circumstance by supposing that 

 magnetism existed not in the interior of the earth, as was sup- 

 posed, but only on the surface, and in such bodies as received 

 this principle from atmospheric, or celestial influence. 



The late discovery of the magnetic influence of the violet 

 rays of light, by M. Morechini, a notice of which has since 

 reached us in the journals, connected with the above fact, 

 leads me to believe that light is the great source of magnetism. 

 A learned foreigner,* whose residence in this country has con- 

 tributed much to its scientific improvement, has also informed 

 me that other substances than metallic hare been found, by 

 compression, to be magnetic. 



It is well known that the violet ray is the most refrangible, 



* Mr. Correa de Serra, Minister of the King of Portugal. 



