Lenses and Waves

1655-1672 - DE ABERRATIONE 91
Philosophical Transactions (21 July O.S.). 175 Newton invited him once again to
compare by computation aberrations both of lenses and mirrors, but
Huygens did not respond anymore.
Thus came an end to a dispute that had run an odd course. In January
1672 Huygens had welcomed the newcomer on the scene of European
scholarship as a kindred spirit in matters dioptrical; in June 1673 he refrained
from discussing any further with someone who so obstinately clung to his
claims. But most striking about the state of affairs I find the relative late
moment at which Huygens recognized the purport of Newton’s paper. Until
the letter of September 1672, the fact that Newton’s theory concerned the
physical nature of light escaped him. And then again, he made only one –
apparently non-committal – objection. Only in the letter of January 1673 did
he engage in a dispute on Newton’s theory of colors, to break it off in the
next letter. Until the letters of Pardies were published, Huygens only paid
attention to what Newton had said about the aberrations of lenses. And even
at this point, he failed to grasp Newton’s message. He only talked of
chromatic aberration in the same terms as he had treated spherical
aberration. One gets a strong impression that in 1672 Huygens lacked a
certain sensibility for the kind of question Newton addressed, namely
concerning the physical nature of light. This is all the more surprising since
Huygens has become famous for a theory explaining the nature of light of
his own.
The preceding reconstruction sheds new light on this famous dispute.
Huygens was not a Cartesian that a priori rejected Newton’s theory for
reasons of its mechanistic inadequacy and untenability, like Hooke did and
Pardies too initially, and like he is usually presented in historical literature. 176
We should reconsider the his dispute from the perspective of Dioptrica.
Huygens entered the dispute from his background in dioptrics. He was
interested (and informed) in lenses and telescopes and he had something to
loose. At first he did not look beyond issues directly pertaining to lenses and
it took some time before he realized what Newton’s theory was about. He
began to raise mechanistic doubts only during the final stages of the dispute,
and probably when he realized the consequence for his project of nullifying
spherical aberration. For in anything may explain Huygens relative reluctance
in accepting Newton’s theory, it would be De Aberratione.
Somewhere along the line, Huygens must have realized that Newton’s
findings wrecked his project of perfecting the telescope. He crossed out the
‘Eureka’ of February 1669 and discarded a large part of his theory of
spherical aberration. ‘Newtonian’ aberration had rendered his designs
useless. Spherical aberration might be cancelled out by successive lenses,
chromatic aberration could never be prevented. Despite the objections he
raised in it, the letter of January 1673 reveals that Huygens had recognized
175
OC7, 328-333 and Newton, Correspondence I, 291-295. See also Shapiro, “Evolving structure”, 225-228.
176
For example Sabra, Theories of Light, 268-272.