Lenses and Waves

86 CHAPTER 3
on to lay down his doctrine of the origin of colors in the form of 13
propositions substantiated by the experiments he had described. 151
On 9 April, Huygens gave a first reaction to Newton’s theory:
“… I see that he has noticed like me the defect of the refraction of convex objective
glasses caused by the inclination of their surfaces. As regards his new Theory of colors,
I consider it quite ingenious, but it will have to be seen whether it is compatible with all
experiences.” 152
Two things stand out in this comment. In the first place, Huygens was
mainly interested in the significance of Newton’s findings for dioptrics. In
the second place, he seemed to miss the point of the theory of different
refrangibility. 153 In his view, Newton had merely confirmed what he had
observed earlier. Seemingly, he did not realize that Newton’s point was that
chromatic aberration is a consequence of the constitution of light, rather
than the shapes of lenses. In his next letter to Oldenburg, of July 1, Huygens
went more deeply into the matter, though still along the same lines. After
discussing Newton’s telescope a bit further, he wrote:
“As regards his new hypothesis of colors of which you ask my opinion, I admit that it
seems very plausible to me, and the experimentum crucis (if I understand it correctly, as
it is described somewhat obscurely) confirms it very much. But I don’t agree with what
he says about the aberration of rays through convex glasses. For while reading what he
writes, I find that following his principles this aberration must be twice as large as he
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takes it, to wit 25 the opening of the glass, which experience however seems to
contradict. so that this aberration may not always be proportional to the angle of
inclination of rays.” 154
We see what kind of ‘experiences’ Huygens had in mind when he cast doubt
on the validity of Newton’s theory: the colors he had seen in lenses. He did
not believe that chromatic aberration was as large as Newton claimed.
Consequently, Newton’s explanation of the aberration was questionable. But
it does not appear that Huygens had considered Newton’s theory of colors in
much detail. It seems that he had mainly read the part on lenses. He did not
use the term or notion of different refrangibility and only talked in terms of
aberrations.
151
Newton, Correspondence I, 96-100.
152
OC7, 165. “… je vois qu’il a remarquè comme moy le defaut de la refraction des verres convexes
objectifs a cause de l’inclination de leurs surfaces. Pour ce qui est de sa nouvelle Theorie des couleurs, elle
me paroit fort ingenieuse, mais il faudra veoir si elle est compatible avec toutes les experiences.”
153
See also: Sabra, Theories of Light, 268-267.
154
OC7, 186. “Pour ce qui est de sa nouvelle hypothese des couleurs dont vous souhaittez scavoir mon
sentiment, j’avoue que jusqu’icy elle me paroist tres vraysemblable, et l’experimentum crucis (si j’entens
bien, car il est ecrit un peu obscurement) la confirme beaucoup. Mais sur ce qu’il dit de l’abberration des
rayons a travers des verres convexes je ne suis pas de son avis. Car je trouvay en lisant son ecrit que cette
1
aberration suivant son principe devroit estre double de ce qu’il la fait, scavoir
25
de l’ouverture du verre, a
quoy pourtant l’experience semble repugner. de sorte que peut estre cette aberration n’est pas tousjours
proportionelle aux angles d’inclinaison des rayons.”