C 132 3 



X. On the magnetizing power of the more refrangible solar rays. 

 By Mrs, M. Somerville. Communicated by W, Somerville, 

 M. D. F. R, S, Feb, 2. 1836. 



Read February 2, 1826. 



Xn the year 1813, Professor Morichini of Rome discovered 

 that steel, exposed to the violet rays of the solar spectrum, 

 becomes magnetic. His experiments were repeated by Pro- 

 fessor CoNFiGLiACHi at Pavia, and also by Mons. Berard, 

 at Montpellier, without success. I am not aware of any 

 one having attempted them in this country, perhaps from 

 the belief that experiments which had sometimes failed 

 in Italy, were not likely to succeed in our more northern 

 climate. The unusual clearness of the weather last summer, 

 however, induced me to try what could be accomplished in 

 this country. Accordingly, in the month of July, an equi- 

 angular prism of flint glass, the three sides of which were 

 each 1,4 by 1,1 inches, was fixed in a slit made to receive it 

 in a window-shutter : by this prism a coloured spectrum was 

 thrown on an opposite panel, at the distance of about five 

 feet. I used for the subject of experiment, a very slender 

 sewing needle an inch long, having previously ascertained 

 that it was quite free from magnetism, by repeated exposure 

 of both ends of it to the north and south pole of a very sen- 

 sible magnetic needle, when it was found equally to attract 

 either pole in every instance. The magnetic needle employed 

 as a test in this experiment, is made of a sewing needle mag- 



