THE BUTTERCUP EXPERIMENT. 249 



CHAPTER XXVH. 



THE EYE. 



WHEN a child holds a buttercup, in a bright sunny day, 

 under the chin of another child, if the light happens to 

 come right, a slight yellow tinge appears upon the skin 

 opposite to it. 



There are two explanations of this phenomenon. One 

 is the notional, and the other the scientific one. 



The notional explanation, which is the one generally 

 adopted by children, is, that the child on whom the exper- 

 iment is performed " loves butter." 



The scientific explanation is, that the petals of the but- 

 tercup having, in some mysterious way which no one pre- 

 tends to understand, the power of separating the rays of 

 white light which fall upon them from the sun into their 

 component parts, and of absorbing all but the yellow rays, 

 these yellow rays are reflected upward, and, falling upon 

 the chin at a place somewhat sheltered from the bright 

 light of the sun, are reflected to the eyes of the children 

 looking on. This second reflection depends altogether 

 upon the brightness of the light shining upon the butter- 

 cup and the relative position of the surfaces on which the 

 light shines, and not at all on the taste or inclination of 

 the subject of the experiment in respect to butter. 



This case is a pretty fair illustration of the difference be- 

 tween the notional and the scientifical explanations of the 

 phenomena taking place in nature all around us at all 

 times. 



The yellow rays, as we call them though we must not 

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