PHILOSOPHICAL TRANSACTIONS 
I. Experimental Researches in Electricity . — Nineteenth Series. 
By Michael Faraday, Esq., D.C.L. F.R.S., Fullerian Prof. Chem. Royal Insti- 
tution, Foreign Associate of the Acad. Sciences, Paris, Cor. Mernb. Royal and 
Imp. Acadd. of Sciences, Petersburgh, Florence, Copenhagen, Berlin, Gottingen, 
Modena, Stockholm, 8§c. &fc. 
Received November 6, — Read November 20, 1845. 
§ 26. On the magnetization of light and the illumination of magnetic lines of force*. 
i. Action of magnets on light. ii. Action of electric currents on light. 
iii. General considerations. 
i. Action of magnets on light. 
2146. I HAVE long held an opinion, almost amounting to conviction, in common I 
believe with many other lovers of natural knowledge, that the various forms under 
which the forces of matter are made manifest have one common origin ; or, in other 
* The title of this paper has, I understand, led many to a misapprehension of its contents, and I therefore 
take the liberty of appending this explanatory note. Neither accepting nor rejecting the hypothesis of an ether, 
or the corpuscular, or any other view that may be entertained of the nature of light ; and, as far as I can see, 
nothing being really known of a ray of light more than of a line of magnetic or electric force, or even of a line of 
gravitating force, except as it and they are manifest in and by substances ; I believe that, in the experiments I 
describe in the paper, light has been magnetically affected, i. e. that that which is magnetic in the forces of 
matter has been affected, and in turn has affected that which is truly magnetic in the force of light : by the 
term magnetic I include here either of the peculiar exertions of the power of a magnet, whether it be that which 
is manifest in the magnetic or the diamagnetic class of bodies. The phrase “ illumination of the lines of mag- 
netic force” has been understood to imply that I had rendered them luminous. This was not within my thought. 
I intended to express that the line of magnetic force was illuminated as the earth is illuminated by the sun, or 
the spider’s web illuminated by the astronomer’s lamp. Employing a ray of light, we can tell, by the eye, the 
direction of the magnetic lines through a body ; and by the alteration of the ray and its optical effect on the 
eye, can see the course of the lines just as we can see the course of a thread of glass, or any other transparent 
substance, rendered visible by the light : and this was what I meant by illumination, as the paper fully ex- 
plains. — December 15, 1845. M. F. 
D 
MDCCCXLVI. 
