nch, which gives quite a loud
sound.

Light is also composed of rills in the Ether, but the rill itself is
not Light, it is only Light when these rills strike, with a certain
enormous frequency, on a special organ adapted for, we might say,
counting these frequencies, and if these frequencies fall below that
certain number, or above twice that number per second, there is no
Sense of Sight.

How few people have ever realised what a wonderful Counting Machine
they possess in their organ of Sight! I think the best method I can
adopt, to bring this clearly before you, is to take our tuning-fork,
vibrating 500 times per second, a rapidity which to some will be even
difficult to comprehend, and then ask you to consider how long that
fork must continue to vibrate before it has accomplished the full
number of frequencies, which must necessarily impinge upon the eye in
one second of time, before the phenomenon of sight becomes possible.
That tuning-fork would have not only to continue its vibrations
without diminution for seconds, minutes, hours, weeks, months, years,
or hundreds of years, but for 30,000 years before it has accomplished
the full number of pulsations which, as Ether waves, must strike the
eye in one second of time, to give the impression of Light; the
calculation is easy, the rills of Red Light are so small that 40,000
of these only cover one inch of length, and light travels 186,000
miles per second. If therefore the number of inches in 186,000 miles
are multiplied by the 40,000, and the product is divided by the 500
times which the tuning-fork vibrates in one second, you have the
number of seconds that tuning-fork must vibrate, before it has
completed the number of impacts which, in one second of time, must
fall on our retina to give us the impression of red light; and that
tuning-fork would have to vibrate nearly twice as long, say 50,000
years, to reach the number of impulses which strike the eye in one
second of time and give the impression of violet light; and between
these two limits are situated the colours--Orange, Yellow, Green,
Blue, and Indigo.

What a marvellous sense then is Sight, when we find that, not only can
it grasp these innumerable vibrations, but can actually differentiate
colours, appreciating as a different colour each increase of about
one-tenth in these multitudinous frequencies; and it is principally by
means of this Sense of Sight that we gain a knowledge of what is
happening aro