OOLOU IN NATUKE AND ART. 



Other: (similar in tliis respect to tlio atmos])lionc vibnitions which produce sounds 

 which enu'rjjiiig from silence .is the spectral colors emerge from darkness, run through 

 the scale of the musician, getting quicker and feebler in their vibrations, until they 

 again become inaudible, — the ear liearing sounds as the eye sees colors, only so long 

 as the vibrations continue within a certain range of velocity and force, \«Tiic,h varies 

 somewhat in difierent individuals and animals, — the savage Indian, for instance, hearing 

 pounds and seeing objects where we can see or hear nothing ; and dogs and the lower 

 creation exhibiting the same powers to a still greater extent).* ]5ut superimposed upon 

 this steadily ascending gamut of vibrations, we have another jdienomenon, namely, that 

 one-half of the rays of the spectrum are electrically positive, and give out heat, and that 

 the other half are negative, and produce chemical action ; f and that in the center, those 

 opposite influences neutralise each other. Tlie varjnng plienomena of color, then, are not 

 owing to a mere ditfcrence in the vibratoiy speed of the rays of tlie spectrum, but also 

 to the electric difterence of these rays, which, positive at the red end, and negative at 

 the blue, flash up into yellow or white light in the center where they meet. 



In considenng, then, the impression made on our eye by the colors of the spectrum, 

 there are two points to be considered. In regard to illuminating power, the strongest 

 point of the spectrum is the yellow, — in point of vibratory power, it is the red ; and 

 the color which makes the strongest impression on our visual sense is the red-orange, 

 or scarlet, which, lying between the red and yellow, combines in fullest force the illu- 

 minating and vibrating powers. Hence it would appear that color is a vibratory phe- 

 nomenon of the ethereal rays, — intermediate between heat on the one hand, and 

 actinism on the other, and attended by an overlapping of the electro-positive and 

 electro-negative rays, of which heat and actinism are the representatives. But whether 

 heat and actinism are not themselves the necessary products of a certain rate of vibra- 

 tion in the ether, and so the whole phenomenon of color be practically reducible to 

 one of ratio of vibration, we do not profess to say. Men will get at the root of all 

 those things by-and-by. Meanwhile, it is instructive to observe, from the paper upon 

 radiant heat, lately read before the British Association, by Professor Powell, that heat 

 rays, or rays emanating from a hot body, when refracted, present identically the same 

 phenomenon as those of light, namely : that the rays of the heat-spectrum which 

 vibrate most slowly have a heating but not an illuminating power; those of greater 

 velocity, a luminiferous property also ; and those of the greatest velocity, little heating 

 or luminiferous, but higher chemical power. The reflected rays from the moon form 

 a curious illustration of these and our preceding statements, — the strong electro-posi- 

 tive heat-rays of the solar beam being absorbed by the lunar orb, while the feebler 

 and more rapidly-vibrating rays are reflected to our planet, and bring us a certain 

 amount of illumination combined with a strong chemical influence ; which Jatter 

 shows itself, inter alia, (especially in tropical countries), by the well-established fact of 

 the rapid decomposition of butcher-meat, &c., when exposed to the lunar beams. 



* There is a Bosjesman tribe in South Africa, who exhibit in a remarkable manner the phenomenon call NycUilo- 

 phin, — sleeping and resting during the day, when their eyes, either from natural or acquired orgunizallon, cannot 

 bear the light ot the sun, and carrying on their main pursuits during the nighU 



t It is this difTerenec in the chemical action of the various rays which produce color that constitutes the greatest 

 stumbling block in the way of photography,— the colors at the blue end of the spectrum making an undue iniprcs- 

 the chemical surface compared with the others. This difficulty is being obviated, but much as photography 

 achieved, we believe the art is still in its infancy. 



