158 Mrs. M. Somerville on the magnetizing power 



the Mher half had neither glass nor ribbon over it ; and 

 althoiagh the heat was greater than on the preceding day, no 

 itiagnetism was produced. 



On the 2d of September, thermometer at noon 68**, a 

 ^iece of neutral white steel acquired polarity from exposure 

 to the sun, enveloped in green ribbon, one half being covered 

 with paper as before. 



Oh the 3d of Septertiber, thermometer at noon 68°, two 

 pieces of neutral spring became magnetic, one exposed in a 

 violet-coloured ribbon, and the other in blue glass, while 

 a similar piece of spring was in no way affected by exposure 

 to white light : the half of each was covered with paper. 

 ?' September the 4th, thermometer at noon 68**, five large 

 seiwirtg needles, two inches long, were exposed to the sun's 

 rays, one in blue glass, one in green glass, one in violet 

 ribbon, one in green ribbon, and one in white light ; the half 

 of each was covered with paper. Of all these two only 

 became magnetic, namely, those in the blue glass, and in 

 the violet ribbon. 



' 'On the 2oth of September, thermometer at 69^*^ I placed 

 pieces of steel enveloped in violet and green ribbon, and 

 Under glass of various colours, in different positions with 

 regard to the magnetic meridian and dip. Several acquired 

 polarity, the uncovered part being the north pole. A piece 

 of steel became more strongly magnetic than usual, exposed 

 in green ribbon, the position of which had been perpendicular 

 tb t!he horizon, and nearly in the magnetic meridian. For 

 Sdme time I still obtained similar results, though the mag- 

 netism became more feeble as the season advanced, from the 



