iSB Mrs. M. Somerville on the magnetizing power 
the other half had neither glass nor ribbon over it ; and 
although the heat was greater than on the preceding day, no 
magnetism was produced. 
On the ad of September, thermometer at noon 6 8°, a 
piece of neutral white steel acquired polarity from exposure 
to the sun, enveloped in green ribbon, one half being covered 
with paper as before. 
On the 3d of September, 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 
sewing 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 20th of September, thermometer at 69 0 , 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 
to the horizon, and nearly in the magnetic meridian. For 
some time I still obtained similar results, though the mag- 
netism became more feeble as the season advanced, from the 
