148 
Proceedings of the Royal Society 
sun S, fig. 1, be taken from homogeneous red light E, fig. 3, and 
refracted by the prism, we shall have its radiation ab at a little 
distance from the bright portion E, as in fig. 3. In homogeneous 
yellow light Y, fig. 4, the radiation ab will be at a greater distance 
from Y than in the red light. In homogeneous violet light Y, 
fig. 5, the radiation ab will be at a greater distance from Y than in 
the yellow light. 
If we now refract laterally these homogeneous radiant spectra, 
fig. 3 will be changed into fig. 6, fig. 4 into fig. 7, and fig. 5 into 
fig. 8, thus proving that the radiant portion of the spectra consists 
of lavs more refrangible than the portion EY and Y from which 
