372 Magnetic Influence of Solar Light, 



results. I may however premise that the needle was partial- 

 ly oxidated on its exposed half. 



1. On approximating the north pole of the testing needle 

 to the exposed extremity of B strong repulsion ensued. 



2. On repeating this with the covered extremity, repul- 

 sion also was observed. 



3. On bringing the pole as above, to the centre of the 

 needle B, attraction was immediately indicated. 



4. A repetition of these observations with the south pole 

 of the testing needle, confirmed the distribution of Polarity 

 exhibited by them. 



From which it appears that northern Polarity had been 

 imparted to the two extremities of B, southern Polarity ac- 

 cumulated in the centre. This peculiarity was in all pro- 

 bability the result of the partial oxidation of the surface of 

 the experimental needle, as such a state has been already 

 shewn to produce like effects. 



I may now point out a source of interference with these 

 results, that prevents our attributing them to the magnetic 

 action of solar light. Since every magnet has a tendency to 

 act by induction on any matter in its vicinity capable of 

 being magnetised, it is very evident that the approximation 

 of the testing needle must produce a change in the magne- 

 tic condition of the needle under experiment. It is there- 

 fore impossible to say, how much of the effect observed is 

 due to this cause, how much to any other that may be 

 capable of producing similar effects ; and the uncertainty 

 thus introduced must ever prove an obstacle to the formation 

 of decided conclusions. The actions themselves were far- 

 ther observed to be so feeble, that to attempt to allot them 

 to different causes would be vain and unsatisfactory effort. 



There is yet another source of error to which I may 

 allude, namely, that which arises from the possibility of 

 minute electric currents being excited in the mass of the 

 needle under experiment, in consequence of one half of it 



