Discovery of his Theory of Colors. 257 
green; and a confusion of all with white, much after the manner 
that, in the sense of hearing, nature makes use of aerial vibra- 
tions of several bignesses, to generate sounds of divers tones ; 
for the analogy of nature is to be observed.” (Birch, iii, 262, 
Dec., 1675. 
“ Considering the lastingness of the motions excited in the 
pet in motion, less or more forcibly, by undulations differing 
ess or more from a perfect unison ; for instance, the undulations 
more forcibly, by undulations differing less or more from a per- 
fect unison.” This would suppose such a triple molecular con- 
Stitution of each nerve fibril as to cause the three species of 
its constituent molecules (or the atoms forming the molecules) 
to be 2n tune with the three rates of vibration corresponding 
oe to the undulations of the ether causing red, yellow 
and blue. “He afterward says: “and each sensitive filament of 
the nerve may consist of three portions, one for each principal 
