Magnetic Influence of Solar Light, 



383 



apparatus employed would, I doubt not, have indicated it 

 distinctly. The silks employed were of various textures, but 

 in no single instance, even when slight variations of magnetic 

 condition were indicated by the testing needle, could the cha- 

 racteristic polar action of magnetised substances be obtained. 

 Formerly expressed opinions, therefore, of the non-existence 

 of any magnetic influence in solar light, receive additional 

 confirmation from the preceding experimental results. 



3. Experiments with Coloured Cloth Media. 



From an anxiety to set at rest, if possible, the long dis- 

 puted question of magnetic influence in light under any 

 circumstances, I determined to make some few experiments 

 with cylinders exposed as before, under differently coloured 

 pieces of cloth. The texture of the cloth admitted, to a cer- 

 tain extent, of the permeation of light, and the forms of 

 experiment were in every respect the same as in the series 

 immediately preceding. To multiply observations when I 

 found the results conformable to previous ones, appeared to 

 me unnecessary; the number of tables, under this branch 

 of the section, is accordingly but limited, although still suffi- 

 ciently extensive to warrant the inferences made. 



TABLE XII. 



Shewing Duration of Oscillations of Testing Needle, with Cylinder M in 

 front, before and after exposure. 

 Medium Red Cloth. 



Feb. 

 24th 



Hours of 

 Expos. 



From 



11| 



To 



n 



go 

 i-3 



In. 



2 



at 



In. 



0-05 



Temp. 



S « 



70< 



102° 



Sums ... 

 Means ... 



Duration of 

 Oscillations. 



Before 

 Expos. 



99 

 100 

 99 

 99 

 100 



497 



99-4 



After 



Expos, 



100 

 99 



100 

 99 



100 



498 



99-6 



Remarks. 



