xplanation of
light, Young renders full justice also. For himself he claims only the
merit of having demonstrated the theory which these and a few others of
his predecessors had advocated without full proof.

The following year Dr. Young detailed before the Royal Society
other experiments, which threw additional light on the doctrine of
interference; and in 1803 he cited still others, which, he affirmed,
brought the doctrine to complete demonstration. In applying this
demonstration to the general theory of light, he made the striking
suggestion that "the luminiferous ether pervades the substance of all
material bodies with little or no resistance, as freely, perhaps, as the
wind passes through a grove of trees." He asserted his belief also that
the chemical rays which Ritter had discovered beyond the violet end of
the visible spectrum are but still more rapid undulations of the same
character as those which produce light. In his earlier lecture he had
affirmed a like affinity between the light rays and the rays of
radiant heat which Herschel detected below the red end of the spectrum,
suggesting that "light differs from heat only in the frequency of its
undulations or vibrations--those undulations which are within certain
limits with respect to frequency affecting the optic nerve and
constituting light, and those which are slower and probably stronger
constituting heat only." From the very outset he had recognized the
affinity between sound and light; indeed, it had been this affinity that
led him on to an appreciation of the undulatory theory of light.

But while all these affinities seemed so clear to the great
co-ordinating brain of Young, they made no such impression on the minds
of his contemporaries. The immateriality of light had been substantially
demonstrated, but practically no one save its author accepted the
demonstration. Newton's doctrine of the emission of corpuscles was too
firmly rooted to be readily dislodged, and Dr. Young had too many other
interests to continue the assault unceasingly. He occasionally wrote
something touching on his theory, mostly papers contributed to
the Quarterly Review and similar periodicals, anonymously or
under pseudonym, for he had conceived the notion that too great
conspicuousness in fields outside of medicine would injure his practice
as a physician. His views regarding light (including the original papers
from the Philosophical Transactions of the Royal Society) were ag