256 A. M. Mayer—History of Young’s 
in us a sensation of light of a white color; but if by any means 
those of unequal bigness be separated from one another, the 
largest beget a sensation of a red color, the least or shortest of a 
deep violet, and the intermediate ones of intermediate colors; 
much after the manner that bodies, according to their several 
sizes, shapes, and motions, excite vibrations in the air, of var- 
many fragments of such plates. These seem to be most plain, 
genuine, and necessary conditions of this hypothesis. And they 
agree so justly with my theory, that if the animadversor think 
fit to apply them, he need not, on that account, apprehend a 
divorce from it. But yet, how he will defend it from other dif 
ficulties, I know not.” (Phil. Trans., vii, 5088; Abr. I, 145, 
Nov., 1672 
ness, strength, or power; and therefore the ends of the capil- 
lamenta of the optic nerve, which pave or face the retina, being 
_ such refracting superficies, when the rays impinge upon them, 
they must there excite these vibrations, which vibrations (like 
those of sound in a trunk or nrg Bh will run along the 
