on Coloured Shadows. 57 



rendering the candlelight of a still deeper yellow, I 

 interposed before it a sheet of yellow or rather orange- 

 coloured glass, when a very unexpected and most 

 beautiful appearance took place : the colour of the 

 yellow shadow was changed to orange, the blue 

 shadow remained unchanged, and the whole surface 

 of the paper not covered by the shadows appeared to be 

 tinged of a most beautiful violet colour, approaching to 

 a light crimson or pink, almost exactly the same hue 

 as I have often observed the distant snowy mountains 

 and valleys of the Alps to take about sunset. 



Is it not more than probable that this hue is, in both 

 cases, produced by nearly the same combinations of 

 coloured light? In the one case, it is the white snow 

 illuminated at the same time by the purest light of the 

 heavens and by the deep yellow rays from the west ; 

 and in the other, it is the white paper illuminated 

 by broad daylight and by the rays from a burning 

 candle, rendered still more yellow by being transmitted 

 through the yellow glass. 



The beautiful violet colour which spreads itself over 

 the surface of the paper will appear to the greatest 

 advantage, if the pane of orange -coloured glass be held 

 in such a manner before the candle that only a part 

 of the paper half of it, for instance be affected by 

 it, the other half of it remaining white. 



To make these experiments with more convenience, 

 the paper, which may be about 8 or 10 inches square, 

 should be pasted or glued down upon a flat piece of 

 board, furnished with a ball and socket upon the 

 hinder side of it, and mounted upon a stand ; and the 

 cylinder should be fastened to a small arm of wood or 

 of metal, projecting forward from the bottom of the 



