Magnetic Influence of Solar Light. 



259 



very powerful sun, the glare of light being on this occasion 

 very great, and the sky perfectly cloudless. I therefore feel 

 warranted in asserting, that the sun's light cannot communi- 

 cate magnetism to steel needles having oxidated surfaces. 



There is, however, a peculiar distribution of oxidation, 

 combined with polish, which existing in steel wires, has 

 been considered capable of insuring their magnetization 

 by solar light, and this is when oxidated and polished 

 portions alternate along the length of a wire. By employing 

 wires in this state, Mr. Baumgartner found, that after expo- 

 sure, they exhibited a south pole at each polished, and a 

 north pole at each oxidated part. In attempting to verify 

 these results, MM. Moser and Reiss failed completely, and 

 could produce no such effects. The point, therefore, requires 

 farther investigation, and I proceed to give the results of 

 my experiments upon it. 



The magnetic testing apparatus formerly described was em- 

 ployed throughout, and in the first series of experiments, the 

 vibrations of the needle were counted, while no wire was in 

 front, and then when the wire that had been exposed in the 

 meanwhile, was placed before it. The wire was placed at a 

 constant distance of one inch outside the glass cylinder. 

 TABLE~XIII. 



Shewing Duration of Oscillations of testing Needle, without and with steel 

 wire in front, before and after exposure. 



fExp. 



5M 



o . 



<u & 



Hour of 

 Exp. 



Tei 



up. 





o • 





f Osc. 



6 



CO ^ 



O a 6 



CJ CD 



8* 



o 



6 





A. M. 



P. M. 





CD P-i 



|£ 



to f-< 



O pH 



o 

 6 



Dur. c 

 with 

 Wi 



Q es 



1 



2 



Feb. 

 1 



12 



1 



63° 



88° 



In. 



0.05 



In. 



it 



Ox. 

 Pol. 





re 



75 



72 

 70 



o 



4 



... 













8 



2 f 



Ox. 

 Pol. 



10 

 10 



76 

 76 



70 

 71 



5 

















Ox. 



10 



75 



70 



6 

 7 















«i 



6 r 



Pol. 

 Ox. 



10 

 10 



76 

 76 



70 

 70 



