Young’s Musical Optics 177
with science it fed and profited from. This audience also included women, still excluded
from the universities. Within a few months, Rumford quarreled with the other directors
and abandoned his fledgling institution; Young and Humphrey Davy carried it forward.
Though among the first in this eminent succession, Young was a less dramatically suc-
cessful public figure than those who followed him; he thought his public presentations
were too “ compressed and laconic, ” not “ very popular or very fluent. ”^50 On the other hand,
A Course of Lectures on Natural Philosophy and the Mechanical Arts (1807) was the most
comprehensive yet given in England, one of the first attempts of general synthesis in the
aftermath of Newton. Addressing a broad audience, Young presented a general picture,
emphasizing the leading concepts and omitting mathematical details. Reading him now,
we can see how Young ’ s synoptic project reflected his own work synthesizing sound and
light through the wave theory. His papers showed the importance of music and sound as
he discovered his new insights; his lectures showed how he continued to rely on sound
and music not only in the context of the discovery of his ideas but also in the context of
their public justification and popularization.^51
After 1803 and the remarkable series of papers considered above, Young left the Royal
Institution and active research in optics, discouraged by vitriolic attacks on his papers by
Lord Brougham, a fanatical adherent of the particle theory of light. Young then wrote on
medical subjects and increasingly worked on deciphering Egyptian hieroglyphics. Later,
he was greatly encouraged by the recognition and praise of the younger French researchers
in optics, especially Dominique Arago and Augustin-Jean Fresnel. The “ Young – Fresnel
theory, ” as it came to be called, prevailed by the 1820s, having converted all except for a
few stubborn partisans of Newtonian orthodoxy (such as Brougham). In 1817, Young
surveyed these confirmations in a magisterial article for the Encyclopaedia Brittanica
entitled “ Chromatics. ”^52
Indeed, many new things had emerged after 1803, particularly the discovery of the
polarization of light by É tienne-Louise Malus in 1807, which added a new level of puzzle-
ment that the undulatory theory of the time could not illuminate. Gazing through an Iceland
spar (calcite) crystal at the reflected sunlight from a neighboring glass window, Malus
noticed that the two images of the window would alternately disappear and appear as he
rotated the crystal. Somehow, the reflected light had some kind of directionality that the
crystal could transmit only when correctly oriented. The crystal would split the incoming
reflected light into two separate beams, each “ polarized ” differently, as Malus phrased it.
If indeed light is a wave, how could it exist in the different states of orientation Malus had
discovered?^53
By 1815, Young doubted that his theory could account for this new phenomenon, as he
wrote in his private correspondence at the time. But in a letter of 1817, he himself proposed
a solution that both used and reversed the analogy with sound. Writing to Arago, he noted
that “ it is a principle in this [wave] theory, that all undulations are simply propagated
through homogenous mediums in concentric spherical surfaces like the undulations of