25S Magnetic Influence of Solar Light. 



light, and after exposure to repeat this process, the condi- 

 tions of experiment continuing unaltered. The heights 

 of the wires were measured from the surface of the table, 

 about a quarter of an inch above which was the plane of the 

 needle's vibration. Entire oxidation of the surface of a 

 wire was effected by covering it with a little acid, and allow- 

 ing this to act upon it for a few days, when the desired 

 result was invariably produced. 



To exhibit, if possible, the degree to which oxidation 

 of the metal contributed to susceptibility of magnetic in- 

 fluence, as indicated by the testing apparatus just described, 

 three soft steel wires of the same length, and nearly, al- 

 though not quite, of the same diameter, one of which 

 was brightly polished on the surface, another partially, and 

 a third wholly oxidated, were placed in turn before the 

 needle at the constant distance of three-quarters of an inch, 

 and the duration of oscillations observed before and after 

 exposure, with the results shewn in the annexed Table : — 



TABLE XII. 



Shelving Duration of Oscillations of Testing Needle, with Wires in different 

 degrees of oxidation in front, before and after exposure. 





Exp. 



Hour of 

 Exp. 







Temp. 





o . 



&. w 

 ° 



OP, 



11. with 

 Expos. 



itli par- 

 ire be- 



11. with 

 wire af- 



11. with 

 ire be- 



11. with 

 re after 



Exp. 









hi 



'3 

 A 



"3 <o 



Osci 

 ifter 



lt St 



'3 ^ 

 O O ^ 



5 x £ 



b « 



o 



6 

 Szj 



Date of 



A. M. 



P. M. 



Length oi 



Diam. of 



Before E: 



During E: 



No. of < 



Dur. of O 

 wire befo 



Dur. of 

 pol. wire j 



| Dur. of C 

 tially Ox 

 | fore Expo 



S 





1 Dur. of 



wholly O: 

 1 Expos. 



1 



2 

 3 



Feb 

 5th. 





i 



In. 



2 



Pol. W. 



0.05 

 P. Ox. W 



0.033 

 W. 0. w 



0.031 



59o 



92o 



10 

 10 



10 



77 

 77 



78 

 7S 

 7S 



80 

 SO 

 SO 



SO 

 SO 



so 



SI 

 SI 



S2 

 82 

 82 



4 

















10 

 10 



7S 



- 



77 



78 

 7S 



80 

 SO 



so 



80 



81 

 SI 



82 



■ 













bums. 





50 



386 



S90 



400 



■400 



407 



410 













Means. 





1 



7.72 



7.S0 



S.00 



S.00 



S.14 



8.20 



From the above results it is evident, that no increase of 

 intensity had taken place during two hours' exposure to a 



