118 ANNUAL OF SCIENTIFIC DISCOVERY. 



properties. The bleaching power of the sun's rays is familiar to every 

 one ; their power in developing fine colors is perhaps best seen on the 

 sides of peaches, apples, c., which, exposed to a mid-summer sun, 

 become highly colored. During the last open winter, a wall-flower 

 plant afforded me the proof of a like effect ; in the dark months there 

 was a slow succession of one or two flowers. These were of a uniform 

 pale-yellow hue ; in March, streaks of a darker color appeared on the 

 flowers, and continued slowly to increase, till, in April, they were va- 

 riegated brown and yellow, of rich strong colors. On the supposition 

 that these changes are accompanied by alterations in magnetic proper- 

 ties, we may hereafter be able to explain Mrs. Somerville's experi- 

 ments on steel needles exposed to the sun's rays under envelopes of 

 silk of various colors. The results obtained by this distinguished lady 

 have been the source of much discussion among men of science ; and 

 there can be no doubt that the most rigid experiments have failed to 

 magnetize steel needles in the colored rays of the spectrum. But to 

 magnetize them under envelopes of dyed silk is quite a different 

 experiment, and, if I do not much mistake, the effect in this case will 

 hinge on the chemical change ivrought in the silk and its dye, by the solar 

 rays. Consequently, to repeat the experiments hereafter, it will be 

 necessary to attend to the materials used in dyeing. In concluding 

 this inquiry, I may say, that I view the nature of the connection be- 

 tween color and magnetism to be, that there are forces which act in 

 common on the magnetism, and the power of the body in transmitting 

 or reflecting light. Faraday and Plucker have previously shown the 

 intimate connection between the crystalline and magnetic force ; while 

 the tendency of my experiments has been to show that the color, a 

 property much more strongly attached to a body than its crystalline 

 force, is likewise connected with the magnetism. When a number of 

 bodies are grouped together, the connection is seen clearly enough ; but 

 when single cases only are examined, apparent contradictions are not 

 unfrequent. This appears to indicate that color and magnetism are 

 mixed up Avith other qualities derived from the forces of aggregation, 

 together giving the various properties possessed by the bodies by which 

 we are on every side surrounded, while the further knowledge for the 

 unfolding of these may demand the labor of ages to come. 



OF THE NATURE AND SOURCE OF THE SUN'S LIGHT AND HEAT. 



THAT so brilliant a display is kept up by the combustion or destruc- 

 tion of something, appears to be generally, if not universally, main- 

 tained ; but what that matter is, and how supplied, no probable guess 

 has yet been made. The intensity of the solar light and heat is easily 

 proved, and that it resides chiefly, if not entirety, at the surface ; and 

 that surface, on being closely watched, is found to be in a state of 

 excessive agitation, and experiences periodical disturbances and altera- 

 tions of a very singular character. AVhen periodical changes are 

 seen, we may expect secular ones also ; and if the former were of a 

 regular character, the latter might be necessarily inferred ; but although 

 no regular law has yet been made out for the sun, the probability of 



