Lenses and Waves

Chapter 4
The 'Projet' of 1672
The puzzle of strange refraction and causes in geometrical optics
Huygens was in Paris in the autumn of 1672. He was still a leading scholar,
but some clouds had begun to appear in the sky. The discussions at the
‘Académie’ sometimes distressed him, in particular the interventions of
Roberval. 1 His status was challenged by aspiring newcomers. The previous
chapter described how Newton with his new theory thwarted his plans to
design a perfect telescope. And the successful entrée on the Parisian scene of
Cassini put serious pressure on his position as 'primes' under Louis' savants.
Cassini had arrived from Rome in 1669 and almost immediately had started
to adorn his patron with a series of astronomical observations, where
Huygens could set little against. 2
With all that, sickness had begun to plague him. In February 1670 he had
fallen ill and he went home to the ‘air natale’ of The Hague in September.
June 1671 Huygens returned to Paris to resume his activities, but in
December 1675 he would relapse into his ‘maladie’. Whether these illnesses
were caused by his ‘professional’ troubles is hard to tell. Huygens biographer
Cees Andriesse holds this view, developing a Freudian reading of Huygens’
personality, in which Christiaan identifies with his intellectual achievements
to make up for the early loss of his mother. 3 Still, going through his Paris
letters to his brother Constantijn gives the impression that Christiaan was
bothered by a good share of homesickness. And maybe the Paris
environment just was not that good for Huygens’ constitution. Whether or
not his failing health was related, it is certain that the move from the
confines of his parental home to the competitive milieu of Paris had put his
science under pressure in the early 1670s. Huygens did not stand by idly,
however. In 1672, he was in the middle of preparing the description and
explanation of his pendulum clock for publication. Horologium Oscillatorium,
his masterpiece, appeared in 1673 dedicated to his patron Louis. And
whoever might think that Huygens had given up on his dioptrics because of
Newton's interference, was dead wrong.
Huygens had discarded the results of his analysis of spherical aberration
in October 1672. Around the same time, he drew up a plan for a publication
1
Gabbey, “Huygens and mechanics”, 174-175; Andriesse, Titan, 235-243.
2
Van Helden, “Constrasting careers”, 97-101.
3
Andriesse, Titan, 244-247 and “The melancholic genius”, 8-11. I have discussed Andriesse’s account in
Dutch in Dijksterhuis, “Titan en Christiaan”.