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XVI. On magnetic influence in the solar rays. By Samuel 
Hunter Christie, Esq. M. A. F.R.S. of Trinity College , 
Cambridge; Fellow of the Cambridge Philosophical Society: 
of the Royal Military Academy. Communicated November 15, 
1825. 
Read January 19, 1826. 
The object of the present communication is to show, by a 
series of experiments, that the solar rays possess sensible 
magnetic properties, which are observable in the vibrations 
of a magnetised needle exposed to those rays, independently 
of the effects produced by the heat which they impart. I 
propose likewise to point out the changes which take place 
in the intensity of a magnetised needle from changes of tem- 
perature, as deducible from the times of its vibration. I have 
before stated in my paper on the effects of temperature on the 
intensity of magnetic forces, that, in deducing the terrestrial 
magnetic intensity by means of the vibrations of a needle, a 
correction ought to be introduced where the observations 
have been made at different temperatures. I had not at the 
time made any experiments by which I could ascertain how 
far changes in the temperature of a needle would be sensible 
in the time of its vibration ; and the first observations which 
I made with this view being with a light needle, did not give 
very decided results : they however led me first to notice the 
very singular fact, that a magnetic needle comes to rest 
more quickly when vibrated exposed to the rays of the sun, 
than when vibrated in the shade. 
