the Colour- Sequence in the Spectrin n. 217 



point are determined, and finally adding np the contributions 

 of all the wave-lengths, the three components of the resultant 

 colour at that point become known. 



Fig. 2 a is a graphical representation of these components 

 for the various points. In fig. 2 b are given for comparison 

 the intensity curves for the three components in the case of a 

 pure spectrum showing the same number of bright and dark 

 bands observed by the method described in the next section. 



Fig. 2 a. 



<b (7 



Fig. 2 b. 



ib n 



In the latter case no re-distribution of energy has taken place. 

 and the sequence of colours is exactly the same as in a con- 

 tinuous spectrum, although the intensity varies from point to 

 point. But in fig. 2 a it will be observed that the proportions 

 of the components within a band are fairly constant in the 

 first three bands. In the last two bands on the violet side 

 of the spectrum the sequence of colour has been reversed 



