CONCEPTION OF WAVE-MOTION
INTERFERENCE OF WAVES
CONSTITUTION OF SOUND-WAVES
ANALOGIES OF SOUND AND LIGHT
ILLUSTRATIONS OF WAVE-MOTION
INTERFERENCE OF SOUND-WAVES
OPTICAL ILLUSTRATIONS
PITCH AND COLOUR
LENGTHS OF THE WAVES OF LIGHT AND RATES OF VIBRATION OF
THE ETHER-PARTICLES
INTERFERENCE OF LIGHT
PHENOMENA WHICH FIRST SUGGESTED THE UNDULATORY THEORY
BOYLE AND HOOKE
THE COLOURS OF THIN PLATES
THE SOAP-BUBBLE
NEWTON'S RINGS
THEORY OF 'FITS'
ITS EXPLANATION OF THE RINGS
OVER-THROW OF THE THEORY
DIFFRACTION OF LIGHT
COLOURS PRODUCED BY DIFFRACTION
COLOURS OF MOTHER-OF-PEARL.


§ 1. _Origin and Scope of Physical Theories_.

We might vary and extend our experiments on Light indefinitely, and
they certainly would prove us to possess a wonderful mastery over the
phenomena. But the vesture of the agent only would thus be revealed,
not the agent itself. The human mind, however, is so constituted that