Lenses and Waves

1655-1672 - DE ABERRATIONE 55
chapter examines these themes in a broader context of the scientific
revolution, and forms a conclusion of this account of Huygens’ dioptrics
prior to the metamorphosis of his optics discussed in the subsequent
chapters. So much can be said that Huygens’ passion was with the
instrument, not its employment. For Huygens telescopic astronomy was a
pastime rather than a full-time job. Although he had solved the puzzle of
Saturn’s bulges by systematic observation, this never became his vocation.
His fascination was with its design and manufacture of telescopes. 8 To this
we may also count his interest in dioptrical theory, being a means of
tinkering with the instrument and contemplating its workings.
In the ten or so years after 1653 when the brothers engaged in practical
pursuits, Huygens did not work on dioptrical theory (at least no traces ar
left). During the 1660s he returned to theory and set out for what should
have been the crowning glory of his dioptrical work: the design of a
telescope in which spherical aberration was nullified. Not by means of
imaginary lenses of the kind Descartes had thought up, but by means of
actual spherical lenses. In the design came together Huygens’ theoretical
understanding and practical experience with lenses and it brought him closer
to bridging the gap between theory and practice than any other in the
seventeenth century. Newton’s ‘New Theory’ of colors eventually
shipwrecked the project. Newton’s approach of mathematical optics
essentially differed from Huygens’. These differences shed light on the
character of the Huygens’ dioptrics and may explain why Huygens did not
manage to bridge the said gap completely.
3.1 The use of theory
Around 1600, spectacle makers had advanced their art far enough to enable
the discovery of the telescopic effect. 9 Astronomers in their turn discovered
the possibilities of this chance invention. Their pursuit demanded far greater
power than the first spyglasses offered. They needed skillful hands:
sometimes their own, but usually those of a craftsman. Galileo, not
particularly all fingers and thumbs himself, had the advantage of living close
to Venice, the center of European glass industry. After the success of Sidereus
nuncius he established a workshop for telescopes. Simon Marius, in Germany,
was less lucky: he had great trouble finding a good lens maker and could not
put the new invention to fruitful use. 10 During the first half of the
seventeenth century, the manufacture of telescopes for astronomy developed
into a small trade of specialized craftsmen. This section will not treat the
history of lens and telescope manufacture, it focuses on the relationship
between dioptrical theory and the art of telescope making. Central questions
are: to what extent was theoretical knowledge used in practical dioptrics, if it
8
Van Helden, “Huygens and the astronomers” 148, 157-158.
9
Van Helden, Invention, 16-20.
10
Van Helden, Invention, 26; 47-48.